Hubbry Logo
CoolantCoolantMain
Open search
Coolant
Community hub
Coolant
logo
7 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
Coolant
Coolant
Coolant
View on Wikipedia
from Wikipedia

A coolant is a substance, typically liquid, that is used to reduce or regulate the temperature of a system. An ideal coolant has high thermal capacity, low viscosity, is low-cost, non-toxic, chemically inert and neither causes nor promotes corrosion of the cooling system. Some applications also require the coolant to be an electrical insulator.

While the term "coolant" is commonly used in automotive and HVAC applications, in industrial processing heat-transfer fluid is one technical term more often used in high temperature as well as low-temperature manufacturing applications. The term also covers cutting fluids. Industrial cutting fluid has broadly been classified as water-soluble coolant and neat cutting fluid. Water-soluble coolant is oil in water emulsion. It has varying oil content from nil oil (synthetic coolant).

This coolant can either keep its phase and stay liquid or gaseous, or can undergo a phase transition, with the latent heat adding to the cooling efficiency. The latter, when used to achieve below-ambient temperature, is more commonly known as refrigerant.

A coolant reservoir captures overflow of coolant in a cooling system.[1]

Gases

[edit]

Air is a common form of a coolant. Air cooling uses either convective airflow (passive cooling), or a forced circulation using fans.

Hydrogen is used as a high-performance gaseous coolant. Its thermal conductivity is higher than all other gases, it has high specific heat capacity, low density and therefore low viscosity, which is an advantage for rotary machines susceptible to windage losses. Hydrogen-cooled turbogenerators are currently the most common electrical generators in large power plants.

Inert gases are used as coolants in gas-cooled nuclear reactors. Helium has a low tendency to absorb neutrons and become radioactive. Carbon dioxide is used in Magnox and AGR reactors.

Sulfur hexafluoride is used for cooling and insulating of some high-voltage power systems (circuit breakers, switches, some transformers, etc.).

Steam can be used where high specific heat capacity is required in gaseous form and the corrosive properties of hot water are accounted for.

Two-phase

[edit]

Some coolants are used in both liquid and gas form in the same circuit, taking advantage of the high specific latent heat of boiling/condensing phase change, the enthalpy of vaporization, in addition to the fluid's non-phase-change heat capacity.

Refrigerants are coolants used for reaching low temperatures by undergoing phase change between liquid and gas. Halomethanes were frequently used, most often R-12 and R-22, often with liquified propane or other haloalkanes like R-134a. Anhydrous ammonia is frequently used in large commercial systems, and sulfur dioxide was used in early mechanical refrigerators. Carbon dioxide (R-744) is used as a working fluid in climate control systems for cars, residential air conditioning, commercial refrigeration, and vending machines. Many otherwise excellent refrigerants are phased out for environmental reasons (the CFCs due to ozone layer effects, now many of their successors face restrictions due to global warming, e.g. the R134a).

Heat pipes are a special application of refrigerants.

Water is sometimes employed this way, e.g. in boiling water reactors. The phase change effect can be intentionally used, or can be detrimental.

Phase-change materials use the other phase transition between solid and liquid.

Liquid gases may fall here, or into refrigerants, as their temperature is often maintained by evaporation. Liquid nitrogen is the best known example encountered in laboratories. The phase change may not occur at the cooled interface, but on the surface of the liquid, to where the heat is transferred by convective or forced flow.

Liquids

[edit]
Device to measure the temperature to which the coolant protects the car from freezing

Water is the most common coolant. Its high heat capacity and low cost make it a suitable heat-transfer medium. It is usually used with additives, like corrosion inhibitors and antifreeze. Antifreeze, a solution of a suitable organic chemical (most often ethylene glycol, diethylene glycol, or propylene glycol) in water, is used when the water-based coolant has to withstand temperatures below 0 °C, or when its boiling point has to be raised. Betaine is a similar coolant, with the exception that it is made from pure plant juice, and is not toxic or difficult to dispose of ecologically.[2]

Polyalkylene glycol (PAG) is used as high temperature, thermally stable heat transfer fluids exhibiting strong resistance to oxidation. Modern PAGs can also be non-toxic and non-hazardous.[3]

Cutting fluid is a coolant that also serves as a lubricant for metal-shaping machine tools.

Oils are often used for applications where water is unsuitable. With higher boiling points than water, oils can be raised to considerably higher temperatures (above 100 degrees Celsius) without introducing high pressures within the container or loop system in question.[4] Many oils have uses encompassing heat transfer, lubrication, pressure transfer (hydraulic fluids), sometimes even fuel, or several such functions at once.

  • Mineral oils serve as both coolants and lubricants in many mechanical gears. Some vegetable oils, e.g. castor oil are also used. Due to their high boiling points, mineral oils are used in portable electric radiator-style space heaters in residential applications, and in closed-loop systems for industrial process heating and cooling. Mineral oil is often used in submerged PC systems as it is non-conductive and therefore won't short circuit or damage any parts.
    • Polyphenyl ether oils are suitable for applications needing high temperature stability, very low volatility, inherent lubricity, and/or radiation resistance. Perfluoropolyether oils are their more chemically inert variant.
    • A eutectic mixture of diphenyl ether (73.5%) and biphenyl (26.5%) is used for its wide temperature range and stability to 400 °C.
    • Polychlorinated biphenyls and polychlorinated terphenyls were used in heat transfer applications, favored due to their low flammability, chemical resistance, hydrophobicity, and favorable electrical properties, but are now phased out due to their toxicity and bioaccumulation.
  • Silicone oils and fluorocarbon oils (like fluorinert) are favored for their wide range of operating temperatures. However their high cost limits their applications.
  • Transformer oil is used for cooling and additional electric insulation of high-power electric transformers. Mineral oils are usually used. Silicone oils are employed for special applications. Polychlorinated biphenyls were commonly used in old equipment, which now can possess risk of contamination.

Fuels are frequently used as coolants for engines. A cold fuel flows over some parts of the engine, absorbing its waste heat and being preheated before combustion. Kerosene and other jet fuels frequently serve in this role in aviation engines. Liquid hydrogen is used to cool nozzles of rocket engines.

Waterless coolant is used as an alternative to conventional water and ethylene glycol coolants. With higher boiling points than water (around 370F), the cooling technology resists boil over. The liquid also prevents corrosion. [5]

Freons were frequently used for immersive cooling of e.g. electronics.

Molten metals and salts

[edit]
See also: Nuclear reactor coolant and Thermal energy storage § Molten salt technology

Liquid fusible alloys can be used as coolants in applications where high temperature stability is required, e.g. some fast breeder nuclear reactors. Sodium (in sodium cooled fast reactors) or sodium-potassium alloy NaK are frequently used; in special cases lithium can be employed. Another liquid metal used as a coolant is lead, in e.g. lead cooled fast reactors, or a lead-bismuth alloy. Some early fast neutron reactors used mercury.

For certain applications the stems of automotive poppet valves may be hollow and filled with sodium to improve heat transport and transfer.

For very high temperature applications, e.g. molten salt reactors or very high temperature reactors, molten salts can be used as coolants. One of the possible combinations is the mix of sodium fluoride and sodium tetrafluoroborate (NaF-NaBF4). Other choices are FLiBe and FLiNaK.

Liquid gases

[edit]

Liquified gases are used as coolants for cryogenic applications, including cryo-electron microscopy, overclocking of computer processors, applications using superconductors, or extremely sensitive sensors and very low-noise amplifiers.

Carbon Dioxide (chemical formula is CO2) - is used as a coolant replacement[6] for cutting fluids. CO2 can provide controlled cooling at the cutting interface such that the cutting tool and the workpiece are held at ambient temperatures. The use of CO2 greatly extends tool life, and on most materials allows the operation to run faster. This is considered a very environmentally friendly method, especially when compared to the use of petroleum oils as lubricants; parts remain clean and dry which often can eliminate secondary cleaning operations.

Liquid nitrogen, which boils at about -196 °C (77K), is the most common and least expensive coolant in use. Liquid air is used to a lesser extent, due to its liquid oxygen content which makes it prone to cause fire or explosions when in contact with combustible materials (see oxyliquits).

Lower temperatures can be reached using liquified neon which boils at about -246 °C. The lowest temperatures, used for the most powerful superconducting magnets, are reached using liquid helium.

Liquid hydrogen at -250 to -265 °C can also be used as a coolant. Liquid hydrogen is also used both as a fuel and as a coolant to cool nozzles and combustion chambers of rocket engines.

Nanofluids

[edit]

A new class of coolants are nanofluids which consist of a carrier liquid, such as water, dispersed with tiny nano-scale particles known as nanoparticles. Purpose-designed nanoparticles of e.g. CuO, alumina,[7] titanium dioxide, carbon nanotubes, silica, or metals (e.g. copper, or silver nanorods) dispersed into the carrier liquid enhance the heat transfer capabilities of the resulting coolant compared to the carrier liquid alone.[8] The enhancement can be theoretically as high as 350%. The experiments however did not prove so high thermal conductivity improvements, but found significant increase of the critical heat flux of the coolants.[9]

Some significant improvements are achievable; e.g. silver nanorods of 55±12 nm diameter and 12.8 μm average length at 0.5 vol.% increased the thermal conductivity of water by 68%, and 0.5 vol.% of silver nanorods increased thermal conductivity of ethylene glycol based coolant by 98%.[10] Alumina nanoparticles at 0.1% can increase the critical heat flux of water by as much as 70%; the particles form rough porous surface on the cooled object, which encourages formation of new bubbles, and their hydrophilic nature then helps pushing them away, hindering the formation of the steam layer.[11] Nanofluid with the concentration more than 5% acts like non-Newtonian fluids.

Solids

[edit]

In some applications, solid materials are used as coolants. The materials require high energy to vaporize; this energy is then carried away by the vaporized gases. This approach is common in spaceflight, for ablative atmospheric reentry shields and for cooling of rocket engine nozzles. The same approach is also used for fire protection of structures, where ablative coating is applied.

Dry ice and water ice can be also used as coolants, when in direct contact with the structure being cooled. Sometimes an additional heat transfer fluid is used; water with ice and dry ice in acetone are two popular pairings.

Sublimation of water ice was used for cooling the space suit for Project Apollo.

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Coolant

View on Grokipedia
from Grokipedia
A coolant is a substance, typically a , utilized to decrease or regulate the of a by absorbing from components and transferring it to a dissipation site. Effective coolants exhibit high to store , favorable thermal conductivity for efficient , and low to facilitate circulation, alongside to minimize degradation under operational conditions. In practice, coolants serve critical roles in preventing in applications ranging from internal combustion engines, where water-glycol mixtures inhibit corrosion and extend boiling points, to nuclear reactors employing specialized liquids or gases for extraction from fissile cores. While remains a baseline coolant due to its superior , additives like address limitations such as freezing in cold environments, though these introduce concerns necessitating careful handling and disposal to avert environmental contamination.

Definition and Principles

Fundamental Role in Heat Management

Coolants serve as intermediary fluids in thermal management systems, absorbing excess generated by operational processes—such as combustion in engines, electrical resistance in , or in machinery—and transporting it to a dissipation site, thereby maintaining components at functional temperatures to avert degradation or failure. Without effective heat removal, systems experience , where rising temperatures exacerbate heat generation rates, leading to inefficiencies, material stress, or meltdown; for instance, in heavy-duty diesel engines, approximately one-third of total energy must be extracted by the coolant to achieve . This role is grounded in the second law of thermodynamics, which dictates that flows from higher to lower regions, but requires augmentation beyond passive conduction or due to the localized and high-intensity nature of heat sources in engineered systems. The primary mechanism is , where pumps or fans drive coolant flow to enhance coefficients far beyond those of stationary fluids; heat enters the coolant via conduction across a thin at hot surfaces, then the bulk fluid's motion distributes it, leveraging the coolant's to minimize temperature rise per unit energy absorbed (Q = m c ΔT). In single-phase systems, dominates, while two-phase applications incorporate from or for superior density of energy storage and transfer, as seen in electronics cooling where liquids outperform air by orders of magnitude in convective efficacy. Circulation ensures uniform temperature profiles, preventing hotspots that could induce localized , , or corrosive in pumps and passages. Ultimately, coolants enable scalable heat rejection to environmental sinks like radiators or heat exchangers, where and further dissipate energy, sustaining steady-state operation across diverse scales from to power plants; this engineered intervention is essential because natural dissipation rates, reliant on surface area and ambient gradients, insufficiently match internal heat fluxes in compact, high-power-density designs.

Key Thermal and Physical Properties

Coolants exhibit a range of thermal and physical properties that determine their efficacy in absorbing, transferring, and dissipating while maintaining system integrity. Key thermal properties include thermal conductivity, which quantifies the rate of conduction through the fluid (measured in W/m·K), and , the energy required to raise the of a unit mass by one degree (J/kg·K). High values for both enable efficient management without excessive gradients or fluid volume changes; for instance, pure demonstrates superior thermal conductivity of approximately 0.6 W/m·K at 20°C and specific heat capacity of 4184 J/kg·K, outperforming organic alternatives like . However, glycols are often mixed with to extend operational ranges, yielding compromises such as reduced thermal conductivity in 50/50 ethylene glycol- mixtures (around 0.41 W/m·K) but enhanced stability. Physical properties critically influence flow dynamics and phase stability. (in mPa·s or cP) governs pumping requirements and convective ; low viscosity minimizes energy losses, with at ~1 mPa·s at 20°C far superior to pure 's ~16 mPa·s, though mixtures like 50/50 ethylene glycol- exhibit ~4-5 mPa·s, increasing drops in narrow channels. (kg/m³) affects mass flow rates and system weight; 's 998 kg/m³ at 20°C contrasts with ethylene glycol's higher 1113 kg/m³, impacting gravitational and inertial modes. and freezing points define temperature limits: boils at 100°C and freezes at 0°C under , while ethylene glycol raises to ~197°C and depresses freezing in mixtures (e.g., -37°C for 50/50), preventing or solidification in extreme conditions. For phase-change coolants, latent heat of vaporization (kJ/kg) enables high heat absorption via boiling, with water's 2257 kJ/kg at 100°C providing exceptional capacity, though and sites influence practical performance. Trade-offs arise across applications; liquid metals like sodium offer ultra-high thermal conductivity (>70 W/m·K) but pose reactivity risks, while fluids prioritize electrical insulation over peak thermal metrics.
PropertyPure Water (20°C)50/50 Ethylene Glycol-WaterPure Ethylene Glycol (20°C)
Thermal Conductivity (W/m·K)0.5980.410.249
(J/kg·K)4184~33002385
(mPa·s)1.0~4.016.0
(kg/m³)998~10601113
(°C, atm)100~106 (elevated under )197
Freezing Point (°C)0-37-13
These values, derived from standard references, underscore water's baseline superiority in efficiency, tempered by glycols' advantages in and anticorrosion roles for broader temperature envelopes.

Historical Development

Pre-20th Century Origins

served as the earliest known coolant, employed for its superior absorption and transfer properties in rudimentary mechanical and processes dating back to at least the . Its high —approximately 4.184 J/g·°C—enabled effective dissipation of frictional in basic and early engines, though it was prone to freezing and without additives. In , craftsmen in the pre-industrial era relied on sprays or immersion to cool tools and workpieces during cutting operations, preventing overheating and in operations like turning or . The advent of steam engines in the late marked a pivotal application of . James Watt's 1769 improvements to the Newcomen introduced a separate condenser cooled by circulating , which condensed exhaust more efficiently than air alone, reducing consumption by up to 75% compared to earlier designs. This system relied on 's of to absorb thermal energy, maintaining operational temperatures below critical thresholds. By the mid-19th century, water jackets—thin metal casings filled with surrounding cylinders—became standard in stationary engines to prevent overheating from residues and friction. In emerging internal engines toward the late , transitioned from applications. Karl Benz's 1885 Patent-Motorwagen, the first practical automobile, incorporated a single-cylinder engine with an evaporative cooling system using a , where was condensed via air flow over fins. Similarly, Nikolaus Otto's four-stroke engines from 1876 onward often featured water jackets to manage cylinder temperatures exceeding 200°C, averting material failure in components. These systems circulated water via effect—natural convection driven by density differences—without pumps, limiting efficiency but proving reliable for low-speed operations. Early refrigeration prototypes also utilized liquid coolants beyond water. In 1834, constructed the first practical vapor-compression machine employing as the working fluid, which absorbed during evaporation at low pressures before compression and condensation released it. Ether's low (34.6°C) facilitated cooling below ambient temperatures, though its flammability posed risks. This laid groundwork for mechanical cooling, distinct from mere dissipation in engines. By the 1850s, chemists like Charles-Adolphe Wurtz synthesized , initially for explosives rather than cooling, highlighting nascent chemical exploration of properties without immediate vehicular adoption.

20th Century Innovations and Standardization

In the early 1900s, remained the primary coolant for internal combustion engines, but its freezing at 0°C and at 100°C under limited reliability in extreme conditions, necessitating additives for and anti-boil properties. emerged as an early solution due to its low freezing point, but its high volatility, rapid evaporation, and fire hazard prompted searches for alternatives. By 1926, ethylene glycol-based formulations were introduced as superior agents, offering a of approximately 197°C and when mixed with , enabling effective without excessive loss. Commercialization accelerated in the 1930s with products like Prestone, which utilized diluted in to achieve a 50/50 mixture standard for optimal performance, providing freeze protection to -37°C and boil-over resistance exceeding 107°C in pressurized systems. This innovation addressed corrosion issues inherent in early glycol-water blends by incorporating basic inorganic inhibitors, such as sodium or potassium salts, though initial formulations still required frequent changes due to deposit formation. During , military applications in and vehicles demanded enhanced stability, leading to refined additive packages that mitigated and liner pitting in high-output engines. Post-1945, standardization efforts formalized coolant specifications through industry bodies. The Society of Automotive Engineers (SAE) and developed performance criteria emphasizing , material compatibility, and longevity, with ethylene glycol-based coolants classified under Inorganic Additive Technology (IAT) using silicates, phosphates, and borates for corrosion control in aluminum and components. By the 1950s, these green-dyed IAT coolants became the for automotive and industrial use, requiring replacement every 2-3 years or 30,000-50,000 miles to prevent additive depletion. In parallel, and coolants evolved from straight oils to soluble emulsions and synthetics by mid-century, incorporating glycols and polyalkylene oxides for improved and heat dissipation in high-speed operations, standardized via ISO viscosity grades to ensure consistency across tools and alloys. systems saw (CFC) coolants like Freon-12 patented in 1928 and commercialized in 1930, replacing toxic and with non-flammable, low-pressure alternatives that enabled widespread household and industrial adoption.

Post-1980 Regulatory Shifts

The Montreal Protocol on Substances that Deplete the Ozone Layer, adopted in 1987 and entering into force in 1989, marked a pivotal regulatory response to the discovery of stratospheric ozone depletion linked to chlorofluorocarbons (CFCs) and other ozone-depleting substances (ODS) commonly used as refrigerants in cooling systems. The protocol mandated a phased elimination of CFCs, such as R-12, which had been standard in refrigeration, air conditioning, and automotive systems since the mid-20th century; production and consumption in developed countries ceased by 1996, with developing nations following by 2010. This shift compelled the refrigeration industry to adopt hydrochlorofluorocarbons (HCFCs) like R-22 as transitional alternatives, though HCFCs were later targeted for phaseout due to their residual ozone-depleting potential, with U.S. production banned for new equipment by 2010 and full phaseout by 2020. Compliance drove innovations in hydrofluorocarbon (HFC) refrigerants, such as R-134a for automotive air conditioning, approved under the U.S. Environmental Protection Agency's (EPA) Significant New Alternatives Policy (SNAP) program established in 1994 to evaluate substitutes for ODS. Subsequent regulations addressed the high global warming potential (GWP) of HFCs, which, while ozone-safe, contribute significantly to ; for instance, R-134a has a GWP over 1,400 times that of . The 2016 Kigali Amendment to the committed 197 countries to phasing down HFC production and consumption by 80-85% over 30 years, with baselines set from 2020-2022 and initial reductions starting in 2019 for developed nations. In the United States, the American Innovation and Manufacturing (AIM) Act of 2020, enacted via the Consolidated Appropriations Act, authorized the EPA to enforce an 85% HFC reduction by 2036, accelerating transitions to low-GWP alternatives like hydrofluoroolefins (HFOs) such as R-1234yf in new automotive systems since 2017 model year mandates. European Union F-Gas Regulations, updated in 2014 and 2024, impose GWP thresholds—e.g., prohibiting refrigerants with GWP above 150 in new mobile from 2017 and banning those above 750 in certain stationary systems by 2025—further standardizing global adoption of natural refrigerants like (R-744) or hydrocarbons in specialized applications. For non-refrigerant coolants, such as -based in engine systems, post-1980 regulations focused on waste management and toxicity rather than composition overhaul. The EPA's (RCRA) rules, effective November 15, 1980, classified spent as potentially hazardous due to heavy metal contaminants like lead, requiring proper disposal and to prevent . Later measures, including state-level bans on disposal in septic systems and incentives for substitutes (less toxic but costlier), emerged in the 1990s and 2000s, though without the comprehensive phaseouts seen in s. These shifts prioritized environmental containment over reformulation, contrasting with the refrigerant sector's repeated molecular redesigns driven by international treaties.

Applications

Automotive and Transportation Systems

In automotive engines, coolant circulates through the and to absorb excess generated during , transferring it to the for dissipation into the atmosphere. This process maintains optimal operating temperatures, typically around 90-100°C, preventing thermal degradation of components and ensuring efficient . Coolants also inhibit freezing in cold climates by lowering the freezing point of the mixture— a 50/50 glycol-water blend freezes at approximately -37°C—and raise the to about 107°C at , or higher under system pressurization to 120-130 kPa. The primary component in most automotive coolants is (EG), typically mixed in a 50/50 ratio with distilled water (or using pre-mixed 50/50 solutions) to avoid mineral deposits and scaling from tap water, along with additives such as inhibitors, anti-foam agents, and dyes for identification. These dyes distinguish coolant types, with inorganic additive technology (IAT) formulations such as G11 typically appearing blue or green, and organic acid technology (OAT) types like G12 in red or pink. A well-maintained coolant exhibits clarity and vibrant color; cloudiness, brownish discoloration, or an oily appearance indicates potential contamination, degradation, or incompatibility. Coolant levels are assessed between the minimum and maximum marks on the expansion tank with the engine cold. EG-based formulations provide superior compared to alternatives like (PG), though PG offers lower toxicity at the cost of reduced thermal efficiency and higher . Inorganic additive technology (IAT) coolants, using silicates and phosphates, were standard until the 1990s, but organic acid technology (OAT) and hybrid OAT (HOAT) types now predominate for extended life and aluminum compatibility in modern engines. was first commercialized for automotive use in 1926, replacing earlier methanol-based antifreezes that evaporated quickly. In heavy-duty transportation like and , coolants must withstand higher loads and extended service intervals, often incorporating supplemental coolant additives (SCAs) such as nitrites for protection in diesel engines. cooling systems regulate temperatures under severe conditions, preventing overheating in semis and fleet vehicles where engines produce significantly more heat per unit volume. coolants, typically EG-based, are discharged as regulated industrial wastewater to avoid environmental contamination. engines, by contrast, rarely employ liquid coolants like EG due to weight penalties and reliability demands; engines rely on air-cooling fins, while turbines use and for heat management.

Industrial Machinery and Power Plants

In machinery, such as lathes, mills, and grinding equipment, coolants primarily function to absorb and dissipate frictional at the tool-workpiece interface, reducing temperatures that could otherwise cause , tool softening, or workpiece warping. Water-soluble coolants, including emulsions of oils in (typically 5-10% concentration), semi-synthetics, and full synthetics, provide effective cooling via 's high of 4.18 J/g·°C, while also lubricating to minimize and flushing to prevent recutting. These fluids extend tool life by 20-50% or more in high-speed operations by limiting built-up edge formation and oxidation, improve through reduced chatter and better chip evacuation, and inhibit on and non-ferrous metals via additives like nitrites or phosphates. Straight oils, used neat for low-speed heavy cuts, offer superior but inferior cooling, making them suitable for applications prioritizing boundary over . For broader industrial machinery, including compressors, hydraulic presses, and diesel engines in plants, specialized /coolants like extended-life formulations with inhibitors () or hybrid () protect against , scale buildup, and overheating under continuous high-load conditions. These - or glycol-based fluids maintain stability across -40°C to 120°C, preventing boil-over in pressurized systems and enabling efficient heat rejection through radiators or heat exchangers, which sustains machinery uptime and reduces energy losses from thermal inefficiencies. In conventional thermal power plants employing steam turbines, water acts as the dominant coolant in condenser systems, absorbing from low-pressure exhaust to facilitate phase change back to , with U.S. thermoelectric facilities withdrawing 47.7 gallons in 2021 primarily for once-through or recirculating setups. Recirculating systems, comprising 67% of consumptive use, rely on cooling towers that evaporate 1-2% of circulated per cycle to reject to the atmosphere, yielding consumption rates of 1,820-4,169 liters per MWh depending on wet-bulb temperatures and design. Inorganic salts or polymers in treated cooling mitigate and scaling, ensuring coefficients remain above 2,000-5,000 W/m²·K in tube bundles. Nuclear power plants predominantly use pressurized light as coolant and moderator in light water reactors, which constitute over 90% of operating units worldwide, circulating at 15-16 MPa to maintain subcooled boiling margins and transfer core heat to steam generators. Advanced designs incorporate alternatives for enhanced safety and efficiency: sodium-cooled fast reactors employ molten sodium (boiling point 883°C) for its thermal conductivity of 70-80 W/m·K—over 100 times that of —allowing passive removal without pumping. High-temperature gas reactors utilize at 7-10 MPa, leveraging its low absorption and high under to achieve outlet temperatures exceeding 750°C for cogeneration or electricity. Concentrated solar power plants integrate synthetic fluids, such as /diphenyl oxide mixtures, in or tower systems to capture and transport at 300-400°C to heat exchangers, bypassing high-pressure limitations and enabling dispatchable output with storage for nighttime generation. These fluids exhibit thermal stability up to 400°C without , outperforming in low-pressure operations but requiring blanketing to prevent oxidation.

Electronics Cooling and Data Centers

Liquid cooling systems in electronics utilize fluids with superior thermal conductivity compared to air to dissipate heat from high-power components such as processors and , preventing and extending operational life. These systems often employ closed-loop circuits with or water-glycol mixtures circulating through cold plates or heat exchangers attached directly to heat-generating surfaces, achieving coefficients up to 10,000 W/m²K, far exceeding air cooling's 100 W/m²K. In consumer and industrial electronics, such as servers and telecommunications gear, liquid coolants enable sustained performance under loads exceeding 300W per chip by maintaining junction temperatures below 85°C. Data centers, housing dense clusters of servers, consume substantial for cooling, accounting for 30-40% of total facility power in less efficient setups, with hyperscale operations as low as 7%. Rising power densities from AI accelerators, reaching 1kW+ per rack, have accelerated adoption of liquid cooling, with projected to exceed 20% by late 2025 from 10% in 2024. Direct-to-chip cooling, using non-conductive loops of deionized or propylene glycol solutions, attaches microchannel cold plates to CPUs and GPUs, reducing cooling by 20-30% versus air systems while supporting rack densities over 100kW. Immersion cooling submerges entire server boards in dielectric fluids, either single-phase (constant liquid state, e.g., mineral oils or engineered hydrocarbons) or two-phase (boiling/condensing, e.g., perfluorocarbons), eliminating fans and enabling uniform removal at rates 1,000 times more efficient than air. Single-phase immersion operates at 40-60°C, allowing extended in moderate climates and (PUE) below 1.05, while two-phase variants leverage for densities up to 200kW per rack. Dielectric fluids must exhibit low (<1 cP), high dielectric strength (>30 kV), and minimal flammability to prevent electrical faults, though fluorinated options face scrutiny for environmental persistence. The global data center liquid cooling market, valued at $5.38 billion in 2024, is forecasted to reach $17.77 billion by 2030, driven by AI workloads necessitating these technologies for energy efficiency gains of up to 40% over traditional methods. Challenges include fluid compatibility with materials, , and maintenance complexity, yet deployments in hyperscale facilities demonstrate reliability, with fluid recirculation systems over 99% of coolant volume annually.

Specialized High-Temperature and Nuclear Uses

In high-temperature applications beyond conventional systems, molten salts such as fluoride-based mixtures (e.g., FLiBe, composed of and fluoride) serve as coolants due to their high stability, with melting points around 450–600°C and points exceeding 1400°C, enabling at temperatures up to 1000°C without pressurization. These salts are employed in advanced high-temperature reactors like the Advanced High-Temperature Reactor (AHTR), where they facilitate efficient heat extraction from solid fuel elements while minimizing neutron moderation and corrosion risks through compatible materials. Liquid metals, including sodium and lead-bismuth eutectics, are also utilized for their superior coefficients—sodium's conductivity is approximately 70–80 W/m·K at operating temperatures—and ability to operate at 500–800°C, supporting compact designs in space and industrial heat exchangers. In nuclear reactors, specialized coolants enable operation at elevated temperatures for improved thermodynamic efficiency and process heat generation. Sodium-cooled fast reactors (SFRs) employ liquid sodium as the primary coolant, which remains liquid between 98°C and 883°C at , allowing core outlet temperatures of 500–550°C and reducing moderation to sustain fast neutron spectra for breeding plutonium-239. Historical prototypes like the Experimental Breeder Reactor-II (operated 1951–1994) demonstrated sodium's efficacy, though it requires inert atmospheres to prevent reactions with air or water. Lead-cooled fast reactors (LFRs) use molten lead or lead-bismuth alloys, with melting points of 327°C and 125°C respectively, achieving outlet temperatures up to 550°C; these offer higher boiling points (>1700°C) and via natural circulation but demand corrosion-resistant alloys like T91 . Gas-cooled reactors, particularly high-temperature gas-cooled reactors (HTGRs), utilize as an inert coolant, enabling core outlet temperatures of 750–950°C for or at efficiencies exceeding 50%. Helium's low absorption and high (approximately 5.2 J/g·K) minimize activation products, as evidenced in designs like the pebble-bed modular reactor, where it transfers heat via intermediate loops to avoid direct contamination. reactors (MSRs) dissolve fissile materials in or use separate molten / salts as coolant, operating at 600–700°C under low pressure; the (1965–1969) at Oak Ridge validated salt's chemical stability and online reprocessing potential, though salts' corrosivity necessitates Hastelloy-N alloys. These coolants prioritize high-temperature tolerance over aqueous systems' simplicity, trading off material compatibility challenges for enhanced safety margins like negative temperature coefficients.

Properties and Selection Criteria

Thermal Conductivity and Capacity

The thermal conductivity of a coolant, a measure of its ability to conduct expressed in watts per meter-kelvin (/m·K), directly influences the efficiency of from system components to the fluid, particularly in conduction-dominated regimes or as a factor in convective coefficients via the . Higher values enable faster extraction, reducing thermal gradients and component temperatures in applications like . Specific heat capacity, denoted cpc_p and measured in joules per kilogram-kelvin (J/kg·K), quantifies the heat absorption per unit mass per degree temperature rise, allowing coolants with elevated cpc_p to carry larger thermal loads with smaller temperature excursions, which stabilizes system performance and minimizes pumping power needs for a given heat duty. In selection, these properties are balanced against viscosity and phase stability; for instance, pure water offers optimal values—thermal conductivity of 0.598 W/m·K and cpc_p of 4184 J/kg·K at 20°C—but requires additives or alternatives for extreme temperatures due to freezing at 0°C and boiling at 100°C under atmospheric pressure. Common liquid coolants exhibit trade-offs in these properties. , widely used in mixtures for , has a lower thermal conductivity of 0.258 W/m·K and cpc_p around 2400 J/kg·K at 20°C compared to , reducing overall efficiency by 20-40% in 50% volumetric mixtures, where effective values drop to approximately 0.40 W/m·K and 3500 J/kg·K. shows similar reductions, with thermal conductivity near 0.26 W/m·K, prioritizing over thermal performance in food or medical systems. In high-temperature applications, such as molten salts for , sodium -potassium nitrate eutectics achieve cpc_p exceeding 1500 J/kg·K above 250°C but with conductivities below 0.6 W/m·K, suitable for storage rather than rapid conduction.
Coolant TypeThermal Conductivity (W/m·K at ~20°C)Specific Heat Capacity (J/kg·K at ~20°C)Typical Application Notes
Pure Water0.5984184Baseline for high-efficiency cooling; limited by phase change risks.
Ethylene Glycol (pure)0.258~2400Antifreeze base; dilutes performance in mixtures.
50% Ethylene Glycol-Water~0.40~3500Automotive standard; balances thermal and freeze protection.
Propylene Glycol (pure)~0.26~2500Non-toxic alternative; slightly inferior to ethylene glycol thermally.
Gaseous coolants like leverage exceptionally high thermal conductivity (0.182 W/m·K at 300 K, surpassing most gases) and cpc_p of 14,300 J/kg·K, enabling compact cooling in turbines despite low density requiring high flow rates. Empirical data from engineering correlations, such as Dittus-Boelter for turbulent flow, underscore that while conductivity sets conduction limits, capacity governs bulk transport, prioritizing water-glycol blends in most industrial contexts for their empirical superiority in over pure organics.

Corrosion Resistance and Additives

Corrosion in coolant systems arises primarily from electrochemical reactions involving water, dissolved oxygen, and dissimilar metals such as aluminum, , , and solder, leading to galvanic degradation, pitting, and that compromise system integrity and efficiency. These processes accelerate under high temperatures and varying levels, with aluminum particularly susceptible to localized attack in glycol-water mixtures. Effective corrosion resistance requires additives that maintain , scavenge oxygen, and form protective barriers on metal surfaces without promoting deposits or incompatibility. Corrosion inhibitors, comprising up to 10% of antifreeze formulations, function through anodic or cathodic mechanisms: anodic types like phosphates, borates, molybdates, and nitrites suppress metal dissolution by passivating positively charged sites, while cathodic inhibitors limit oxygen reduction; organic acid technologies (), such as carboxylates, provide targeted adsorption on vulnerable areas rather than uniform films, extending in modern aluminum-heavy engines. Inorganic inhibitors like silicates offer rapid protection for aluminum via gel-like layers but deplete faster and risk silicate dropout if mixed improperly, whereas phosphates buffer effectively for metals and but may form scales in . Hybrid formulations combine inorganic and organic inhibitors to balance immediate and long-term protection, reducing the need for frequent replenishment; for instance, silicate-phosphate blends enhance AA6060 aluminum inhibition in ethylene glycol coolants by synergistically minimizing uniform and pitting corrosion rates. Excessive inhibitor concentrations, however, can disrupt coolant stability, promote foaming, or induce reverse corrosion by overwhelming buffering capacity. Compatibility testing, often via ASTM D1384 glassware corrosion evaluations, is essential when selecting additives, as mismatched types—e.g., mixing silicate-based with OAT—can deplete inhibitors, foster sludge, or accelerate metal loss.

Viscosity, Stability, and Compatibility

The of coolants, a measure of their to flow, directly influences pumping requirements, losses, and convective efficiency in cooling systems. Low is generally preferred to minimize for circulation and to ensure adequate flow through narrow channels, though excessive thinness can reduce in components like pumps. Pure , often the baseline for comparison, has a dynamic of approximately 1.5 cP at 40°F (4.4°C), dropping to around 0.3 cP at 120°F (48.9°C), enabling high flow rates with low power input. In contrast, glycol-based mixtures, essential for properties, exhibit higher viscosities that rise with (EG) concentration and fall with temperature; for example, a 50% EG- solution measures 6.5 cP at 40°F and 1.5 cP at 120°F, while pure EG reaches 48 cP at the lower temperature. These properties are quantified in standards like ASTM D3306 for glycol-based engine coolants, which indirectly inform through performance requirements, though dedicated test methods such as proposed ASTM WK30376 address non-aqueous variants directly.
EG Concentration (% by volume)Viscosity at 40°F (4.4°C) (cP)Viscosity at 120°F (48.9°C) (cP)
0 ()~1.5~0.3
253.00.9
506.51.5
100 (pure EG)48.07.0
Coolant stability, encompassing , chemical, and oxidative resistance, determines long-term performance by preventing degradation that could impair or generate corrosive byproducts. Under operational stresses like elevated temperatures (e.g., above 90°C) and oxygen exposure, glycols oxidize to form acids such as glycolate, , and , reducing below 7 and depleting corrosion inhibitors. Technology () formulations maintain over 90% inhibitor retention under such conditions, outperforming mineral-based additives like silicates or phosphates, which prone to and gelation due to heat-induced insolubility. Additives including antioxidants, metal deactivators, and reserve (e.g., borates) enhance , with bench tests like ASTM D7820 simulating high-temperature oxidation to assess and fluid integrity. Bench-scale evaluations further differentiate coolant stability by monitoring byproduct formation and shifts, ensuring reliability in applications from engines to . Compatibility of coolants with system materials—metals, , , and seals—is essential to avert , swelling, leaching, or mechanical failure over time. In automotive cooling systems, glycol-based fluids must resist degrading nonmetals like hoses and water pump seals; immersion tests per modified ASTM protocols reveal that elastomer integrity changes and induced fluid chemistry alterations (e.g., solids formation) occur independently of versus bases, with traditional phosphate/borate-silicated coolants showing variable impacts on radiator tanks. For metals, compatibility hinges on inhibitor packages preventing electrochemical reactions, while in liquid cooling, mismatches can cause , elastomer swelling, or extraction into the fluid, leading to leaks, blockages, or diminished performance. Compatibility charts and material-specific guides, such as those for engineered coolants, recommend verifying interactions via short-term high-temperature exposure tests to ensure no permeation losses or at interfaces like tubing junctions. Overall, selecting coolants per ASTM D3306 or equivalent ensures balanced interactions, prioritizing formulations tested against aluminum, , and synthetic rubbers prevalent in modern systems.

Types of Coolants

Gaseous Coolants

Gaseous coolants are fluids in the gas phase used primarily for convective in applications where liquid coolants are unsuitable due to high temperatures, corrosive environments, , or the need for phase-change avoidance. Unlike liquid or two-phase systems, they operate without or , relying on high flow rates to compensate for generally lower specific heat capacities and coefficients, typically on the order of 10-100 W/m²·K compared to thousands for liquids. Their selection prioritizes properties like thermal conductivity, , and inertness to minimize pumping power and material degradation. Common types include air, helium, carbon dioxide (CO₂), and hydrogen. Air, with a thermal conductivity of about 0.026 W/m·K at standard conditions, is widely used in forced-air systems for electronics cooling, such as CPU fans in computers and servers, where it dissipates heat via turbulence induced by impellers, achieving effective temperatures below 80°C in moderate loads. Helium excels in specialized high-performance roles due to its superior thermal conductivity (0.152 W/m·K at 300 K, roughly six times that of air) and chemical stability, preventing oxidation or reactions in extreme conditions. Hydrogen offers even higher conductivity (0.182 W/m·K) and low viscosity, enabling up to 14 times greater mass flow for the same power input versus air, though its flammability necessitates sealed, pressurized systems. CO₂, historically prominent, provides adequate cooling at moderate pressures but can decompose above 500°C, limiting its use. In power generation, hydrogen cools rotors and stators in large turbo-generators exceeding 150 MW, reducing windage losses by 90% compared to air and maintaining winding temperatures below 120°C under full load, a practice standard since the 1930s in designs from manufacturers like GE. Gas-cooled nuclear reactors employ helium or CO₂: early British Magnox and Advanced Gas-cooled Reactors (AGR) from the 1950s-1970s used CO₂ at 250-650°C inlet-outlet temperatures for graphite moderation, while modern high-temperature gas-cooled reactors (HTGRs), such as the Xe-100 design, utilize helium for outlet temperatures up to 750°C, enabling hydrogen production or process heat alongside electricity at efficiencies over 50%. Helium's low neutron activation and non-reactivity support Gen IV goals, with prototypes demonstrating core heat removal rates of 5-10 MW/m³. In cryogenics and superconductivity, helium cools MRI magnets to 4 K and particle accelerators, leveraging its boiling point of 4.2 K at atmospheric pressure for near-absolute zero operation without solidification. Advantages of gaseous coolants include resistance and compatibility with high-vacuum or radiation-heavy settings, but drawbacks encompass lower (e.g., at 5.2 kJ/m³·K versus water's 4,180 kJ/m³·K), requiring larger ducts and fans, and potential safety issues like asphyxiation from inert gases or explosion risks with . In , or variants enhance tool life by 3-4 times in dry processes via cryogenic effects, reducing without residue. Ongoing research focuses on for fusion reactors, where its inertness aids divertor cooling at 1000°C fluxes.

Liquid Coolants

Liquid coolants are fluids designed for convective in systems, absorbing thermal loads from sources such as engines, , and before dissipating them via radiators or heat exchangers. Their efficacy stems from high —often orders of magnitude greater than gases due to liquid densities exceeding 800 kg/m³ and specific heats around 2-4 kJ/kg·K—enabling compact designs with coefficients up to 10,000 W/m²·K in flows. This makes them indispensable in applications demanding rapid, efficient cooling, such as internal engines where they manage up to 30% of generated , or servers handling fluxes over 100 W/cm². Key performance metrics include thermal conductivity (typically 0.1-0.6 W/m·K), viscosity (influencing pumping power, ideally below 10 cP at operating temperatures), and stability across wide ranges, such as -50°C to 150°C for automotive uses. Pure water excels with a specific heat of 4,184 J/kg·K and conductivity of 0.6 W/m·K at 20°C, but its limitations—freezing at 0°C and promoting corrosion without inhibitors—drive the use of formulated mixtures. Additives like corrosion inhibitors (e.g., silicates or phosphates) and biocides extend service life to 5-10 years in closed loops, while pH control (7.5-11) prevents material degradation in copper, aluminum, or steel systems. In high-performance scenarios, such as aerospace turbines, coolants must also resist cavitation and foaming, with nucleate boiling thresholds above 100 kW/m² to avoid dry-out. Liquid coolants are categorized by base composition and application demands: water-based solutions dominate low-to-moderate temperature regimes for their unmatched ; glycol-organic blends provide freeze/boil protection at the cost of 10-15% reduced efficiency; and exotic variants like fluorocarbons or molten salts handle extremes from cryogenic to 600°C. Compatibility testing per standards like ASTM D1384 ensures minimal degradation, as incompatible fluids can increase corrosion rates by factors of 10 or more. Environmental and safety profiles vary, with non-toxic options like preferred over (LD50 ~4,700 mg/kg vs. 5,600 mg/kg in rats), though all require leak-proof systems to mitigate fire or toxicity risks in enclosed spaces. Ongoing research emphasizes biodegradable alternatives to reduce lifecycle impacts, but empirical data confirms water-glycol hybrids retain ~90% of pure water's performance in most real-world loops after accounting for penalties.

Water-Based Solutions

Water-based coolants consist primarily of , often deionized or purified to minimize conductivity and impurities, and are employed in applications requiring high efficiency due to water's of 4.184 J/g·K and thermal conductivity of approximately 0.6 W/m·K at ambient temperatures. These properties allow water to absorb and transport substantial thermal loads with low pumping energy demands, making it suitable for once-through or recirculating systems in power plants, where it cools turbine exhaust by rejecting to the atmosphere via cooling towers or rivers. In thermoelectric power , water-based systems account for the majority of cooling , with recirculating wet cooling reducing freshwater withdrawal compared to once-through methods, though still consuming significant volumes for evaporation. To mitigate corrosion—a primary drawback stemming from water's reactivity with metals like steel and aluminum—formulations incorporate inhibitors such as phosphates, azoles, or organic compounds, which form protective films on surfaces and reduce degradation rates by orders of magnitude in controlled tests. Deionized water is preferred in electronics and data center liquid cooling loops to prevent electrolytic corrosion and short circuits, achieving corrosion rates below 0.1 mm/year on compatible alloys when properly maintained. In industrial machinery, such as metalworking, water-based emulsions provide superior cooling for high-speed operations but lack lubricity, necessitating separate lubricants and risking bacterial growth if biocides are absent. Limitations include a freezing point of 0°C and of 100°C at , restricting use in extreme temperatures without pressurization or additives, and potential for scaling from minerals if untreated is used. Environmental concerns arise from in discharge waters, prompting regulatory shifts toward closed-loop systems that recycle up to 95% of the coolant volume in modern facilities. Despite these challenges, water's abundance and cost-effectiveness—typically under $0.01 per liter for treated variants—ensure its dominance in large-scale applications like nuclear reactors, where it also serves as a .

Glycol and Organic Mixtures

Glycol-based coolants primarily consist of (EG) or (PG) diluted with , typically at concentrations of 30-50% by volume, along with corrosion inhibitors, dyes, and stabilizers to prevent freezing in cold conditions while elevating the for elevated-temperature operations. These mixtures are widely employed in automotive engines, HVAC systems, and industrial heat exchangers to maintain operational temperatures between -37°C and 149°C depending on the blend ratio. EG exhibits higher thermal conductivity (approximately 0.25 /m· at 50% concentration) and lower than PG, enabling better efficiency and reduced pumping energy requirements, though both glycols lower the mixture's by 15-20% compared to pure . PG, while offering marginally higher specific heat, is preferred in applications requiring lower , such as or closed-loop systems accessible to humans, due to its lower acute oral toxicity (LD50 >20 g/kg versus EG's 4.7 g/kg in rats). A key limitation of glycol mixtures is their propensity for corrosion without additives, as they can degrade aluminum, , and in cooling systems unless buffered to a pH of 7.5-11 and supplemented with inhibitors like phosphates or azoles. Organic acid technology () formulations represent an advancement in glycol-based systems, utilizing salts and organic inhibitors instead of inorganic compounds like or nitrites, which reduces silicate gel formation and extends coolant life to 150,000-250,000 miles or 5-10 years in heavy-duty applications. coolants, often EG- or PG-based, provide slower but more persistent corrosion protection through adsorption on metal surfaces, minimizing electrochemical reactions in modern aluminum-intensive engines, though they may offer less immediate passivation for compared to inorganic additive technology (IAT) predecessors. Hybrid (HOAT) mixtures blend organic acids with limited inorganic silicates or phosphates, achieving compatibility across diverse metals while mitigating the rapid depletion seen in pure IAT systems; for instance, HOAT formulations maintain efficacy for 100,000 miles in mixed-fleet operations. These organic-enhanced glycols also exhibit improved stability against erosion in high-load scenarios, such as diesel engines, but require precise formulation to avoid reduced heat rejection rates—up to 10% lower than alone—necessitating larger radiators or fans in some designs. Environmental considerations favor PG-OAT over EG due to faster biodegradability, though EG remains dominant (over 90% ) for its superior performance in extreme conditions.

Molten Salts and Eutectic Metals

Molten salts serve as high-temperature coolants in advanced nuclear reactors and systems due to their liquid state over wide temperature ranges, low , and compatibility with fissile materials. Common compositions include salts such as FLiBe (2LiF-BeF₂, or 66.7 mol% LiF and 33.3 mol% BeF₂), which has a of approximately 459°C and a of 1430°C, enabling operation at without the risks of high-pressure systems. These salts exhibit high , low neutron absorption cross-sections, and behavior with viscosity decreasing exponentially with temperature per the , facilitating efficient in molten salt reactors (MSRs) and thermal storage. In MSRs, they function as both coolant and fuel carrier, dissolving or fluorides while maintaining chemical stability up to 700°C. In solar applications, nitrate-based molten salts (e.g., 60% NaNO₃–40% KNO₃, known as solar salt) operate between 250–565°C for storage and transfer, retaining for dispatchable power generation. Advantages include enhanced safety from inherent low and high , allowing higher operating temperatures (up to 700°C) than coolants for improved thermodynamic . However, challenges involve of structural materials like Hastelloy-N or , necessitating additives or coatings, and potential tritium production in nuclear contexts from lithium-6 impurities. Eutectic metals, particularly alloys, provide coolants for fast-spectrum nuclear reactors, leveraging high conductivity and boiling points exceeding 1600°C to enable compact, high-power-density designs. Lead-bismuth eutectic (LBE, ~44.5% Pb–55.5% Bi) melts at 125°C and remains liquid up to 1670°C, offering transparency and natural circulation potential in lead-cooled fast reactors (LFRs). Sodium, while not strictly eutectic in pure form, is used in sodium-cooled fast reactors (SFRs) with operating temperatures of 400–550°C, but its reactivity with air and poses fire risks, as demonstrated in incidents like the 1995 Monju reactor leak in . Pure lead coolants in LFRs avoid bismuth's alpha-emitting production (yielding ~10¹¹ Bq/kg/year), but require higher pumping power due to (10.5 g/cm³) and . Key advantages of these eutectics include from high boiling points preventing boil-off accidents and compatibility with fast neutron fluxes for breeding from U-238, supporting closed fuel cycles. Drawbacks encompass (e.g., LBE's dissolution of at >400°C, mitigated by layers), high system mass from , and seismic demands, though LFRs demonstrate passive removal via conduction. Development traces to Soviet Alfa-class using LBE in the –, with modern Gen-IV designs like Russia's BREST-OD-300 targeting deployment by 2026.

Cryogenic and Specialized Fluids

, with a of 4.2 (-269°C), serves as a primary cryogenic coolant for achieving in materials, enabling applications such as (MRI) machines and particle accelerators like those at . Its superfluid phase below 2.17 exhibits zero and enhanced , allowing efficient cooling of superconducting magnets without mechanical pumps in some designs. However, helium's scarcity and high cost—driven by global supply constraints—limit its use to high-value scientific and medical contexts, with consumption exceeding 100,000 cubic meters annually for MRI systems alone as of 2020 data. Liquid nitrogen, boiling at 77 (-196°C), functions as a versatile cryogenic coolant in industrial processes requiring rapid freezing or low-temperature maintenance, including , metal cryomilling, and . It provides high specific heat absorption during phase change, enabling cryomilling of tough materials into ultrafine powders with reduced contamination, as demonstrated in pharmaceutical and component production where particle sizes below 10 micrometers are achieved. Annual global production surpasses 30 million tons, primarily for these applications, though its asphyxiation risk necessitates stringent handling protocols in enclosed spaces. Specialized cryogenic fluids, such as (boiling point 20 K) and , address niche engineering needs like rocket propulsion cooling and operation, where their low density and high thermal conductivity outperform in vacuum environments. For instance, cools bearings in engines like the main engines, preventing thermal failure during cryogenic fuel handling at temperatures near 20 K. These fluids demand insulated storage systems like Dewar flasks to minimize boil-off, with losses typically under 1% per day in well-designed setups, but their flammability—hydrogen's wide explosive range of 4-75% in air—imposes costs exceeding those of inert alternatives.

Two-Phase and Phase-Change Systems

Two-phase cooling systems exploit the of to transfer more efficiently than single-phase liquid or gas coolants, as the phase change from liquid to vapor absorbs heat at nearly constant temperature, enabling high heat fluxes without proportional temperature gradients. The , often a liquid like perfluorocarbons or refrigerants such as R134a, evaporates upon contact with heated surfaces, creating vapor that migrates to a cooler condenser section where it releases heat and condenses back to liquid, driven by , gravity, or pressure differences. This cycle yields effective coefficients up to 10,000 W/m²·K, compared to 100-1,000 W/m²·K for single-phase . Heat pipes represent a passive embodiment of two-phase technology, comprising an evacuated, wick-lined tube partially filled with a like , , or , tailored to operating temperatures from cryogenic to 1,000°C. Invented in the but refined for in the 1960s, heat pipes achieve effective thermal conductivities of 10,000 to 100,000 W/m·K—orders of magnitude above copper's 400 W/m·K—allowing heat transport over meters with minimal temperature drop, as demonstrated in satellite thermal control systems handling 100-500 W loads. Limitations include orientation dependence in wickless thermosiphons and reduced performance against gravity, where axial can drop by 50-90% without pumping. Two-phase immersion cooling submerges components directly in boiling fluids, such as engineered fluorinated liquids with boiling points of 30-60°C, facilitating rack-level power densities exceeding 100 kW in data centers, where traditional air cooling caps at 20-40 kW. This method leverages nucleate boiling for heat transfer rates up to 10^5 W/m², reducing coolant flow rates by 90% versus single-phase immersion and enabling energy savings of 30-95% over air-cooled systems, per simulations and prototypes tested in high-performance computing environments. Fluid selection prioritizes low global warming potential alternatives to hydrofluoroolefins, amid concerns over material compatibility and vapor management to prevent dry-out. Phase-change materials (PCMs) augment coolant systems by storing during solid-liquid transitions, typically 150-250 kJ/kg for organic PCMs like paraffins, which melt at engineered temperatures (e.g., 20-60°C) to buffer peak loads in or building HVAC without active circulation. Integrated into heat sinks or coolants, PCMs extend cooling duration by 2-5 times during transients, as shown in evaluations for airborne where they maintained junction temperatures below 100°C under 500 W/cm² fluxes. Drawbacks include low thermal conductivity (0.1-0.5 W/m·K), often mitigated by encapsulation or doping, and cycling stability degradation over 1,000-10,000 cycles due to phase segregation. Inorganic salt hydrates offer higher s (200-300 kJ/kg) but risk and . In and electric vehicles, two-phase loop systems—variants of heat pipes with separate and condenser—dissipate 10-50 kW/m² while minimizing weight and volume by 50% over single-phase loops, as validated in U.S. Department of Energy prototypes from 2012 onward. Emerging adaptive designs, such as flexible heat pipes reported in 2025, conform to irregular geometries for , maintaining efficiency across orientations via dynamic wick structures. Overall, these systems excel in high-density applications but demand precise fluid properties to avoid instabilities like , which can halve rates.

Emerging Nanofluid and Solid-State Variants

Nanofluids represent an advanced class of coolants engineered by dispersing nanoscale particles, typically metals, oxides, or carbon-based materials such as TiO₂, Al₂O₃, or , into conventional base fluids like or mixtures. These suspensions enhance thermal conductivity by 10-40% compared to base fluids, enabling superior rates in applications including automotive radiators, electronics cooling, and fuel cell thermal management. For instance, a 2024 study demonstrated that adding 0.6% TiO₂ nanoparticles to engine coolants improved convective coefficients by up to 40.8% in internal combustion engines, potentially allowing for smaller radiator sizes and reduced pumping power requirements. Similarly, hybrid nanofluids combining multiple nanoparticle types have shown promise in vehicle cooling systems, with experimental data indicating 20-30% gains in heat dissipation efficiency under high-load conditions. Despite benefits, nanofluid stability remains a challenge, as agglomeration can degrade performance over time, though ultrasonic synthesis and surfactant stabilization mitigate this in recent formulations. Emerging research extends nanofluids to specialized sectors, such as polymer electrolyte membrane fuel cells, where they outperform traditional coolants by improving temperature uniformity and reducing hot spots, with numerical models projecting up to 25% enhancement in overall thermal management efficacy as of 2025. In radiators, nanofluid integration has been experimentally validated to lower operating temperatures by 5-10°C, supporting compact designs for applications. These developments stem from first-principles improvements in Brownian motion-driven particle-fluid interactions, which boost effective without proportionally increasing in optimized low-concentration dispersions (0.1-1% by volume). Solid-state coolant variants shift away from fluid-based systems toward materials that exploit intrinsic properties like caloric effects or phase transitions for heat absorption and rejection, eliminating refrigerants and mechanical components. Thermoelectric solid-state coolers, utilizing Peltier effect in nano-engineered thin-film semiconductors, achieved efficiencies twice that of bulk devices in 2025 prototypes, enabling silent, vibration-free operation for electronics and data centers. Elastocaloric systems, employing shape-memory alloys that cool upon stress release, emerged as a refrigerant-free alternative in Slovenian research announced in May 2025, demonstrating cooling capacities comparable to vapor-compression cycles with 20-30% lower energy use in prototype refrigerators. These technologies leverage causal mechanisms such as lattice changes under applied fields (electro- or magneto-caloric variants), offering scalability for building and vehicle cooling without from leaked fluids. Solid-to-solid phase-change materials (PCMs), a subset of solid-state variants, undergo reversible crystalline transitions to store , providing stable thermal buffering without leakage risks inherent to PCMs. Recent advancements in Ni-Mn-Ti alloys, reported in 2023 and refined through 2025, yield ultrahigh s exceeding 200 kJ/kg at temperatures above 500°C, suitable for high-temperature industrial cooling and heat sinks. Integration with thermoelectric modules enhances hybrid systems, where PCMs extend cooling duration by absorbing transient loads, as validated in prototypes achieving 15-20% efficiency gains over fluid-only setups. While commercialization lags due to material costs and cycling durability—typically limited to 1,000-10,000 cycles—these variants prioritize reliability in hermetic environments, contrasting fluid systems' and issues.

Safety, Health, and Environmental Impacts

Toxicity and Handling Risks

Liquid coolants, particularly those containing used in automotive and heating systems, pose significant risks due to their sweet taste, which attracts pets and children; even small amounts—such as one teaspoon for cats or one to two tablespoons for dogs—can lead to acute poisoning characterized by , , cardiopulmonary effects, and renal failure in humans and animals. , a less toxic alternative employed in some food-grade and environmentally sensitive applications, exhibits lower mammalian , with poisoning occurring rarely and primarily from massive overexposure, though it remains an irritant to and eyes upon contact. Gaseous refrigerants, such as certain hydrofluorocarbons or , carry hazards including at low concentrations, asphyxiation from oxygen displacement, and potential flammability, necessitating confined-space monitoring and during handling. Handling risks for glycol-based coolants include and eye irritation from direct contact, as well as low but present flammability when exposed to open flames or high , though they are classified as combustible rather than highly flammable liquids under standard storage conditions. Some formulations exhibit corrosiveness toward metals, requiring compatible materials and inhibitors to prevent system degradation. For coolants in high-temperature applications like advanced reactors, primary hazards stem from thermal burns, corrosiveness at elevated temperatures (often exceeding 500°C), and from fluoride components, demanding specialized protective equipment and inert atmospheres to mitigate reactions. Cryogenic coolants, such as or used in specialized cooling systems, present severe cold-related risks including , tissue freezing upon contact, and asphyxiation in enclosed spaces due to vapor expansion displacing oxygen, with safety protocols emphasizing insulated handling, ventilation, and pressure relief to avoid explosions from rapid boiling. General handling precautions across coolant types include using like gloves and , storing in well-ventilated areas away from ignition sources, and immediate spill to prevent environmental release or secondary exposure.

Ozone Depletion and Global Warming Potential

Certain coolants, particularly chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) used as refrigerants, possess (ODP) due to their release of atoms in the , which catalytically destroy molecules through chain reactions. ODP is quantified relative to CFC-11, assigned a value of 1; for instance, CFC-12 (R-12) has an ODP of 1.0, while HCFC-22 (R-22) has an ODP of 0.055. These substances contributed to the Antarctic ozone hole, with peak depletion observed in the 1990s, where springtime levels dropped by up to 60% over the continent. The , signed in 1987 and entering force in 1989, mandated global phase-out of CFCs by 1996 in developed nations and HCFCs by 2030, resulting in atmospheric concentrations of key ODS declining by over 99% since peak levels around 1993. Hydrofluorocarbons (HFCs), developed as ODS replacements with zero ODP, exhibit high (GWP), a metric comparing over 100 years relative to CO2 (GWP=1). Common HFC refrigerants like R-134a have a GWP of 1,430, and (a blend) has 2,088, making their emissions equivalent to thousands of times more CO2 by mass; HFC leaks from cooling systems accounted for about 2% of total anthropogenic in 2019, projected to rise without intervention. Non-fluorinated coolants, such as (R-717, GWP=0) or (R-744, GWP=1), show negligible contributions to either ODP or GWP, though their adoption is limited by toxicity or efficiency constraints in certain applications. The to the , adopted in 2016 and ratified by over 140 parties including the U.S. via the 2020 AIM Act, initiated HFC phase-down starting 2019, targeting an 85% reduction by 2036 in developed economies to avert 0.3–0.5°C of warming by 2100. This has spurred transitions to low-GWP hydrofluoroolefins (HFOs), like R-1234yf (GWP=4), though lifecycle emissions must account for higher energy use in some systems. Liquid coolants like , prevalent in automotive and industrial applications, have effectively zero ODP and GWP, as they biodegrade rapidly without stratospheric persistence or absorption potency.
RefrigerantTypeODP100-Year GWPCommon Use
R-12 (CFC-12)CFC1.010,900Historical refrigeration/AC
R-22 (HCFC-22)HCFC0.0551,810Air conditioning
R-134aHFC01,430Automotive AC, refrigeration
R-410AHFC blend02,088Residential AC
R-1234yfHFO0<1New automotive AC
R-744 (CO2)Natural01Emerging refrigeration
Empirical monitoring confirms the Protocol's success in halting further ozone loss, with projections of full recovery by 2066, though HFC-driven warming underscores the need for integrated assessments of direct emissions versus indirect efficiency losses in coolant substitutions.

Regulatory Frameworks and Phase-Outs

The , adopted in 1987 and entering into force in 1989, established a framework for phasing out chlorofluorocarbons (CFCs) and other ozone-depleting substances (ODS) used as refrigerants and coolants, achieving near-total global elimination of CFCs by 2010 in developed countries and by 2010–2040 in developing nations through staggered schedules based on production and consumption baselines. The protocol's success in reducing stratospheric ozone depletion—evidenced by Antarctic ozone hole stabilization and projected recovery by mid-century—demonstrated effective multilateral enforcement, with compliance monitored via national reports to the UN Environment Programme. Hydrochlorofluorocarbons (HCFCs), transitional ODS refrigerants like R-22, faced accelerated phase-out under the Montreal Protocol's 1997 Montreal and 1999 Beijing Amendments; developed countries halted production and import for new equipment by January 1, 2010, with total phase-out by 2020, while Article 5 developing countries followed a 2013 servicing freeze and 2030 elimination. In the United States, the Environmental Protection Agency (EPA) enforced this via the Clean Air Act, banning virgin HCFC use in new systems post-2015 and restricting servicing stocks, prompting a shift to hydrofluorocarbons (HFCs) despite their zero ozone-depletion potential but high global warming potential (GWP). The 2016 Kigali Amendment to the Montreal Protocol, ratified by over 140 parties as of 2023 and entering force in 2019, initiated a global HFC phase-down to curb their climate impact, targeting an 80–85% reduction from baselines by 2047, with developed countries freezing production in 2018 and reducing 10% by 2019, escalating to 85% by 2036, while developing nations start later (2024–2028 freezes). In the US, the 2020 American Innovation and Manufacturing (AIM) Act codified this domestically, mandating phased reductions: 10% below historic levels by 2024, 40% by 2029, 70% by 2034, and 85% by 2036, alongside bans on high-GWP HFCs like R-404A and R-410A in new chillers from January 1, 2024, and sector-specific prohibitions (e.g., residential AC by 2025). The European Union's F-Gas Regulation complements this with HFC quotas declining 95% by 2030 from 2009–2012 baselines, banning refrigerants with GWP >150 in certain hermetic systems from 2022. For non-refrigerant coolants like -based in engines, regulations emphasize waste management over substance phase-outs; the US EPA classifies spent as if contaminated with or , requiring proper or disposal under (RCRA) rules, with states like mandating hazardous handling due to risks. Efforts to mitigate accidental include the 2005 Engine Coolant and Antifreeze Bittering Agent Act, which encourages denatonium benzoate addition but lacks federal mandates, while procurement guidelines promote extended-life, phosphate-free formulations to reduce environmental discharge without prohibiting outright. These frameworks prioritize containment and reclamation—e.g., rates exceeding 30% glycol concentration—over replacement, reflecting glycols' lower and GWP impacts compared to fluorinated refrigerants.

Controversies and Criticisms

Overregulation and Economic Costs

The American Innovation and Manufacturing (AIM) Act of 2020 mandates an 85% phase-down of (HFC) production and consumption by 2036, targeting refrigerants used in cooling systems to reduce (GWP). This regulatory framework, implemented by the EPA starting January 1, 2022, has driven significant economic pressures on industries reliant on HFC-based coolants, including HVAC, , and automotive sectors. Compliance requires transitioning to lower-GWP alternatives, often necessitating equipment retrofits or replacements, with upfront costs for a single commercial system upgrade estimated at $1–2.5 million. Refrigerant prices have surged due to supply constraints under the phase-down, exacerbating operational expenses; for instance, the cost of replenishing a 2,500-pound , previously around $60,000, could reach $180,000 by 2028 as HFC availability tightens. New cooling using low-GWP refrigerants incur 10–40% higher compared to legacy HFC setups, depending on scale and complexity. Non-compliance penalties further compound risks, with daily fines up to $60,000 per violation, alongside potential operational shutdowns and lost contracts. Industry reports from 2025 highlight supply shortages and price spikes straining HVAC contractors ahead of seasons, leading to delayed installations and higher consumer prices for cooling maintenance. Critics, including refrigerant manufacturers and trade groups, contend that such mandates constitute overregulation by prioritizing projected long-term benefits over immediate economic realities, potentially reducing energy efficiency in some applications and burdening small businesses with unaffordable transitions. In response to these pressures, the EPA proposed reforms in September 2025 to the Technology Transitions Rule under the AIM Act, aiming to ease restrictions on certain HFCs to mitigate affordability issues for essential equipment like household air conditioners. While EPA analyses project net societal benefits exceeding $6.1 billion from 2025–2050 through avoided damages, these estimates discount upfront industry and consumer costs, which empirical data from ongoing implementations reveal as substantial and unevenly distributed. Similar dynamics appear in cold storage and retail sectors, where AIM Act compliance could elevate expenses by 20–40% for new technologies and refrigerants.

Efficacy of "Green" Alternatives

"Green" alternatives to conventional coolants, such as propylene glycol-based antifreezes and low (GWP) refrigerants including hydrofluoroolefins (HFOs) and natural fluids like (CO₂), , and hydrocarbons, are promoted for reduced environmental impact but often exhibit trade-offs in thermal performance. These substitutes prioritize lower or GWP over optimized , leading to measurable reductions in cooling in empirical tests. In heat transfer applications, propylene glycol (PG) solutions, favored for lower mammalian toxicity compared to ethylene glycol (EG), demonstrate inferior capabilities. EG/water mixtures outperform PG/water blends by up to 20-30% in thermal conductivity and , resulting in higher radiator temperatures and reduced overall cooling efficiency under load. For instance, in automotive radiator simulations, 50/50 EG/ achieved better heat rejection than equivalent PG mixtures, with alone superior to both, underscoring PG's higher and lower convective as key limitations. Low-GWP refrigerants like HFO-1234yf or blends (e.g., ) replacing high-GWP HFCs such as show comparable but frequently slightly diminished (COP) in vapor-compression cycles, with capacity reductions of 5-10% in applications due to thermodynamic properties. alternatives exacerbate these issues: CO₂ systems in transcritical mode suffer efficiency losses exceeding 15% in high-ambient-temperature environments compared to HFC subcritical cycles, necessitating larger compressors and higher energy inputs. offers high volumetric capacity and COP advantages in industrial settings but requires specialized, corrosion-resistant equipment that offsets gains through increased system complexity and maintenance. refrigerants provide efficient akin to HFCs but their flammability demands charge limits and redesigns, potentially reducing system reliability without proportional environmental benefits in all scenarios. Overall, while these alternatives mitigate GWP or toxicity, peer-reviewed comparisons reveal consistent efficacy shortfalls—manifesting as elevated operating temperatures, reduced COP, or amplified energy demands—that challenge their seamless substitution without performance penalties or redesign costs. Regulatory mandates accelerating their adoption, such as F-Gas phases, have prompted industry critiques that unaddressed efficiency gaps could elevate total lifecycle emissions via higher consumption.

Reliability vs. Environmental Trade-Offs

In automotive cooling systems, ethylene glycol-based coolants provide superior efficiency compared to propylene glycol alternatives, with 50/50 ethylene glycol-water mixtures demonstrating up to 15-20% better thermal performance in tests under high-load conditions. This reliability edge stems from ethylene glycol's lower and higher , enabling effective prevention of overheating in extreme operating environments, such as heavy-duty trucking or racing applications where failure rates increase with less efficient fluids. However, , promoted for its lower aquatic toxicity and greater biodegradability, exhibits reduced cooling capacity, potentially leading to elevated temperatures and accelerated wear on components like pumps and seals due to higher requiring more for circulation. Propylene glycol's environmental advantages—such as reduced persistence in and ecosystems—often necessitate compromises in formulation, including additives for inhibition that can shorten or increase frequency, thereby undermining long-term system reliability. Empirical studies indicate that while meets regulatory preferences for lower human and ecological toxicity, its deployment in standard vehicles can result in 5-10% higher overall for cooling, indirectly elevating use and emissions in internal combustion engines. This highlights a causal disconnect in some environmental , where prioritizing biodegradability overlooks the net increase in operational inefficiencies that counteract global emission reductions. In refrigeration and air conditioning systems, hydrofluorocarbon (HFC) refrigerants offer established reliability through non-flammability and compatibility with existing infrastructure, maintaining consistent performance across varying ambient temperatures without the pressure extremes or toxicity risks of natural alternatives like or . Natural refrigerants, while possessing near-zero (GWP), demand specialized high-pressure components for systems, which can elevate failure risks in seals and compressors, or introduce flammability hazards with hydrocarbons, complicating scalability in commercial settings. For instance, systems achieve 10-15% higher energy efficiency in large-scale applications but require enhanced safety protocols due to , potentially increasing and costs in non-industrial environments where HFCs provide uninterrupted operation. These dynamics extend to emerging applications like liquid cooling, where synthetic coolants balance thermal reliability against environmental mandates; dielectric fluids with lower GWP may exhibit reduced dielectric strength or thermal stability, risking electrical faults under sustained high loads. Regulatory pushes toward low-GWP options, such as under the , have prompted transitions that sometimes yield mixed outcomes: while reducing direct emissions, they can impose redesign costs and efficiency penalties that delay adoption or lead to hybrid systems blending synthetic reliability with natural elements. Overall, first-principles reveals that environmental optimizations frequently peak performance for marginal ecological gains, with empirical underscoring the need for application-specific evaluations to avoid unintended reliability deficits.

Recent Developments

Advancements in Data Center and EV Cooling

The proliferation of workloads has driven toward liquid , where servers are submerged in non-conductive fluids to dissipate heat more efficiently than , reducing by up to 40% in high-density setups. Single-phase immersion uses stable synthetic hydrocarbons or esters that absorb heat without phase change, while two-phase systems employ fluorinated refrigerants with boiling points around 50°C to leverage from , enabling cooling of racks exceeding 100 kW. By mid-2025, immersion coolants like those from Dynalene—hydrocarbon-based or engineered synthetics—have been selected for their low , high conductivity, and compatibility with IT hardware, addressing the limitations of in AI-driven facilities projected to dominate new builds. In electric vehicles, advancements in battery coolants emphasize immersion fluids to prevent in lithium-ion packs during fast charging, with single-phase liquids pumped through cells or modules for uniform below 40°C. Shell's E-Fluids, formulations validated via simulations in 2023-2024, demonstrate superior during ultra-fast charging, maintaining battery temperatures under control without electrical conductivity risks. Similarly, Engineered Fluids' AmpCool AC-130 and AC-140 synthetic coolants, introduced for EV applications, offer low and high for direct battery immersion, enhancing pack by 10-15% over traditional glycol-based systems. Innovations like ' Pulsating , unveiled in December 2024, integrate advanced coolants to cut charging times while mitigating overheating in high-capacity packs up to 800V. These coolant developments prioritize materials with global warming potentials below 1 and biodegradability, such as bio-based esters in Cargill's Priolube EF 3446 for EV , balancing thermal performance with regulatory demands for reduced environmental impact. In data centers, two-phase fluorocarbons face scrutiny for higher costs but excel in density, with adoption rising 300% from 2023 to 2025 per industry tracking, while EV fluids like Castrol's low-viscosity variants enable compact designs without risks. Empirical tests confirm these fluids' efficacy, with immersion setups achieving ratings under 1.05, though scalability hinges on fluid purity to prevent contamination-induced failures.

Waterless and Biodegradable Innovations

Waterless coolants represent a class of non-aqueous formulations, typically based on or synthetic organics, designed to eliminate water-related failures in engine and industrial systems, such as , , and pocket formation. These fluids maintain boiling points above 180°C at , allowing operation without high system pressurization and reducing the risk of overheating in high-performance applications like engines or heavy-duty machinery. Evans Cooling Systems' High Waterless Coolant, for instance, has been formulated to protect against these issues while extending engine life through reduced . Similarly, Intelligence's Super Waterless Coolant targets extreme conditions, providing boil-over protection and compatibility with aluminum components without water's electrolytic effects. Empirical testing shows waterless coolants achieve 30-40% superior efficiency above 100°C relative to conventional ethylene glycol- mixtures, attributed to their higher stability and absence of phase-change limitations from . This performance drives adoption in sectors demanding reliability, with the global waterless engine coolant market projected to reach $338.5 million in 2025, fueled by demands for and durability in automotive and off-highway equipment. Innovations include integration with sensor-based monitoring for , optimizing fluid usage and minimizing in fleet operations. Biodegradable innovations focus on bio-derived or low-toxicity fluids that decompose naturally, addressing environmental concerns from persistent glycols like , which can contaminate waterways. Natural esters, derived from vegetable oils, serve as dielectric immersion coolants for batteries and , offering full biodegradability alongside non-conductive properties that prevent short-circuiting. These fluids exhibit higher specific heat capacities than traditional mineral oils—up to 20-30% greater in some formulations—enabling efficient heat dissipation in submerged systems while degrading via microbial action without long-term or residue. In applications, companies like Arteco have introduced bio-compatible synthetic fluids for direct-to-chip cooling, launched in 2025, which prioritize rapid breakdown and low over legacy hydrocarbons. Overlaps exist in hybrid waterless-biodegradable products, such as -based non-aqueous coolants, which inherently biodegrade faster than ethylene variants ( 301 standards confirm >60% degradation in 28 days for ). These advancements support regulatory pushes for sustainability, though challenges persist in matching the cost-effectiveness of water-diluted glycols, with lifecycle analyses indicating 10-20% higher upfront costs offset by reduced maintenance and disposal expenses. Adoption is accelerating in electric vehicles and high-density , where immersion with natural esters has demonstrated 15-25% improvements in over , per experimental data.

References

  1. https://www.sciencedirect.com/topics/earth-and-planetary-sciences/coolant
  2. https://www.sciencedirect.com/topics/materials-science/coolant
  3. https://www.energyencyclopedia.com/en/glossary/coolant
  4. https://pubchem.ncbi.nlm.nih.gov/compound/Ethylene-Glycol
  5. https://www.machinerylubrication.com/Read/841/coolant-fundamentals
  6. http://physics.bu.edu/~redner/211-sp06/class23/notes23_transfer.html
  7. https://www.electronics-cooling.com/2006/05/an-overview-of-liquid-coolants-for-electronics-cooling/
  8. https://www.excelcalcs.com/calcs/repository/Fluids/50-50-Ethylene-glycol-water--and--air-properties/
  9. https://www.engineeringtoolbox.com/ethylene-glycol-d_146.html
  10. https://www.engineeringtoolbox.com/dynamic-absolute-kinematic-viscosity-d_412.html
  11. https://www.engineeringtoolbox.com/antifreeze-d_1543.html
  12. https://inis.iaea.org/collection/NCLCollectionStore/_Public/43/095/43095088.pdf
  13. https://www.dober.com/history-of-coolants
  14. https://www.fusioncoolant.com/blog/evolution-of-machining-coolants
  15. https://www.idolz.com/en/dolz-water-pumps-a-brief-history-throughout-the-years/
  16. https://www.quora.com/When-were-cars-first-made-with-radiators
  17. https://powervacamerica.com/the-cool-history-of-coolant/
  18. https://www.tomorrowstechnician.com/long-life-coolants-explained/
  19. http://www.crankshift.com/history-of-antifreeze/
  20. https://automotivetechinfo.com/2018/12/antifreeze-the-chemistry-behind-the-genuine-article/
  21. https://gmb.net/blog/inorganic-vs-organic-coolants/
  22. https://gmb.net/blog/inorganic-vs-organic-coolants
  23. https://pmc.ncbi.nlm.nih.gov/articles/PMC8739722/
  24. https://www.unep.org/ozonaction/who-we-are/about-montreal-protocol
  25. https://www.c2es.org/content/the-montreal-protocol/
  26. https://www.epa.gov/ozone-layer-protection/recent-international-developments-under-montreal-protocol
  27. https://www.epa.gov/mvac/acceptable-refrigerants-and-their-impacts
  28. https://ecology.wa.gov/blog/march-2025/chilly-refrigerants-contribute-disproportionately-to-warming-the-earth
  29. https://www.sciencedirect.com/science/article/pii/S2214629621001614
  30. https://www.epa.gov/archive/epa/aboutepa/epas-hazardous-waste-regulations-effective-november-19-1980.html
  31. https://ww2.arb.ca.gov/resources/fact-sheets/small-containers-automotive-refrigerant-what-you-need-know
  32. https://www.scfuels.com/the-sc-fuels-guide-to-coolants/
  33. https://www.valvolineglobal.com/en-eur/coolant-chemistry-understanding-the-ingredients-and-their-functions/
  34. https://www.prestone.com/how-to/flush-and-fill/
  35. https://www.fcpeuro.com/blog/how-to-pick-the-right-coolant-for-your-car
  36. https://www.rohnertparktransmission.com/blog/coolant-system-service-signs-symptoms-guide
  37. https://www.autozone.com/diy/antifreeze-coolant/how-to-check-your-coolant-level
  38. https://www.uti.edu/blog/automotive/car-coolant
  39. https://www.nationalfleetmgt.com/articles/an-in-depth-guide-to-how-heavy-duty-coolant-systems-work
  40. https://www.kmtruckrepair.com/articles/purpose-of-coolant-and-antifreeze-in-trucks
  41. https://www.tercenter.org/locomotive_coolant_discharge.php
  42. https://monroeaerospace.com/blog/why-dont-airplanes-use-coolant/
  43. https://www.firetrace.com/fire-protection-blog/importance-of-coolants
  44. https://www.zebraskimmers.com/blogs/coolant-management/a-comprehensive-guide-to-metalworking-coolants-types-uses-and-benefits
  45. https://netoolcorp.com/top-10-benefits-of-using-coolant/
  46. https://www.mntap.umn.edu/industries/facility/machine/coolant/
  47. https://www.chevronlubricants.com/en_us/home/products/product_category/coolants_antifreezes/industrial.html
  48. https://www.ascendummachinery.com/machine-coolant-tips/
  49. https://metalfluids.com/metalworking/machine-coolants.html
  50. https://www.eia.gov/todayinenergy/detail.php?id=56820
  51. https://www.usgs.gov/mission-areas/water-resources/science/thermoelectric-power-water-use
  52. https://climate-adapt.eea.europa.eu/en/metadata/adaptation-options/reducing-water-consumption-for-cooling-of-thermal-generation-plants
  53. https://www.netl.doe.gov/research/Coal/energy-systems/gasification/gasifipedia/water-usage
  54. https://www.energyencyclopedia.com/en/nuclear-energy/the-nuclear-power-industry/coolant
  55. https://www.energy.gov/ne/articles/3-advanced-reactor-systems-watch-2030
  56. https://www.innovationnewsnetwork.com/the-importance-of-helium-coolant-in-nuclear-reactors/35349/
  57. https://globalhtf.com/applications/
  58. https://thermalprocessing.com/heat-transfer-fluids-growing-in-visibility-and-importance/
  59. https://flexpowermodules.com/the-basics-of-liquid-cooling-in-ai-data-centers
  60. https://www.sciencedirect.com/science/article/abs/pii/S0360544224026203
  61. https://www.iea.org/reports/energy-and-ai/energy-demand-from-ai
  62. https://www.wri.org/insights/us-data-centers-electricity-demand
  63. https://www.wesco.com/us/en/knowledge-hub/articles/liquid-cooling-for-data-centers-what-you-need-to-know.html
  64. https://www.coresite.com/blog/liquid-cooling-steps-up-for-high-density-racks-and-ai-workloads
  65. https://www.parkplacetechnologies.com/blog/direct-to-chip-cooling-how-it-works-effectiveness/
  66. https://www.vertiv.com/en-us/about/news-and-insights/articles/blog-posts/advancing-data-center-performance-with-immersion-cooling/
  67. https://cen.acs.org/business/Data-centers-take-plunge/103/web/2025/08
  68. https://www.upsite.com/blog/exploring-immersion-cooling-part-1-the-advantages/
  69. https://www.parkplacetechnologies.com/blog/what-is-immersion-cooling-data-centers/
  70. https://www.opteon.com/en/applications/two-phase-immersion-cooling
  71. https://www.grandviewresearch.com/industry-analysis/data-center-liquid-cooling-market-report
  72. https://www.datacenterfrontier.com/cooling/article/55292167/liquid-cooling-comes-to-a-boil-tracking-data-center-investment-innovation-and-infrastructure-at-the-2025-midpoint
  73. https://tark-solutions.com/thermal-technical-library/application-notes/common-coolant-types-and-their-uses-liquid-cooling-systems
  74. https://info.ornl.gov/sites/publications/Files/Pub57476.pdf
  75. https://fhr.nuc.berkeley.edu/wp-content/uploads/2014/09/AHTR.Nuclear.Technology.Article.May20.2003.pdf
  76. https://www-pub.iaea.org/MTCD/Publications/PDF/P1567_web.pdf
  77. https://www-pub.iaea.org/MTCD/Publications/PDF/TE_1696_web.pdf
  78. https://whatisnuclear.com/coolants.html
  79. https://world-nuclear.org/information-library/nuclear-fuel-cycle/nuclear-power-reactors/nuclear-power-reactors
  80. https://www-pub.iaea.org/mtcd/publications/pdf/te_1645_cd/pdf/tecdoc_1645.pdf
  81. https://world-nuclear.org/information-library/current-and-future-generation/molten-salt-reactors
  82. https://gain.inl.gov/resources/nuclear-technologies/molten-salt-reactors/
  83. https://www.boydcorp.com/blog/best-heat-transfer-fluids.html
  84. https://www.engineeringtoolbox.com/thermal-conductivity-liquids-d_1260.html
  85. https://alliancechemical.com/blogs/articles/maintaining-peak-cooling-performance-ethylene-glycol-inhibited-in-hvac-chillers
  86. https://apps.dtic.mil/sti/trecms/pdf/AD1170629.pdf
  87. https://www.electronics-cooling.com/2009/02/antifreeze-coolants/
  88. https://www.sciencedirect.com/science/article/abs/pii/S0167732223010711
  89. https://thermtest.com/thermal-conductivity-ethylene-glycol-water-mixtures
  90. https://penray.com/resources/cooling-system-tech-facts/metal-corrosion/
  91. https://www.sciencedirect.com/science/article/abs/pii/S0010938X22001068
  92. https://www.boydcorp.com/blog/avoiding-galvanic-corrosion.html
  93. https://learnoilanalysis.com/lube-oil-test-analysis-lab-lubrication-reliability-maintenance/coolant-properties-corrosion-inhibition-testing/
  94. https://gmb.net/blog/common-coolant-additives-explained/
  95. https://polarislabs.com/why-too-much-coolant-corrosion-inhibitor-can-be-harmful/
  96. https://www.gatestechzone.com/en/news/2021-07-cooling-system-maintenance
  97. https://www.astm.org/d3306-21.html
  98. https://www.astm.org/news/press-releases/astm-engine-coolants-committee-announces-creation-new-subcommittees-non-aqueous-coolants-diesel
  99. https://www.arteco-coolants.com/en/innovation/knowledge-hub/thermal-stability-of-coolant
  100. https://www.astm.org/d7820-19.html
  101. https://www.astm.org/jai100634.html
  102. https://www.astm.org/stp38245s.html
  103. https://www.electronics-cooling.com/2022/04/why-chemical-compatibility-is-vital-to-your-liquid-cooling-system-2/
  104. https://www.engineeredfluids.com/our-resources/compatibility-guides/
  105. https://www.sciencedirect.com/topics/engineering/gaseous-coolant
  106. https://www.azom.com/article.aspx?ArticleID=14630
  107. https://www.power-eng.com/hydrogen/cooling-generators-with-hydrogen-is-it-safe/
  108. https://www.iaea.org/topics/gas-cooled-reactors
  109. https://x-energy.com/reactors/xe-100
  110. https://cer.ucsd.edu/_files/publications/UCSD-CER-14-03.pdf
  111. https://soltexinc.com/wp-content/uploads/2023/09/Liquid-Cooling-Theory-and-Application-in-Systems-Design.pdf
  112. https://tark-solutions.com/sites/default/files/ckfinder/files/resources/Application-Notes/Common-Coolant-Types-and-their-Uses-in-Liquid-Cooling-Systems/Common-Coolant-Types-and-their-Uses-in-Liquid-Cooling-Systems-Appnote.pdf
  113. https://www.sciencedirect.com/science/article/abs/pii/S1359431124004757
  114. https://www.qats.com/cms/2017/11/13/fluids-can-used-liquid-cold-plates-electronics-cooling/
  115. https://www.astrodynetdi.com/blog/choosing-a-coolant-for-liquid-cooling
  116. https://world-nuclear.org/information-library/current-and-future-generation/cooling-power-plants
  117. https://www.ucs.org/resources/water-power-plant-cooling
  118. https://ntrs.nasa.gov/api/citations/20130011331/downloads/20130011331.pdf
  119. https://www.researchgate.net/publication/343179938_Corrosion_in_Liquid_Cooling_Systems_with_Water-Based_Coolant_-_Part_1_Flow_Loop_Design_for_Reliability_Tests
  120. https://www.me.psu.edu/chang/taiwan/fluids.pdf
  121. https://pmc.ncbi.nlm.nih.gov/articles/PMC8542508/
  122. https://www.engineeringtoolbox.com/freeze-protection-d_1155.html
  123. https://www.eia.gov/todayinenergy/detail.php?id=14971
  124. https://deepatomic.com/white-paper-why-water-excels-as-a-reactor-coolant/
  125. https://nvlpubs.nist.gov/nistpubs/Legacy/circ/nbscircular474.pdf
  126. https://goglycolpros.com/pages/ethylene-glycol-vs-propylene-glycol
  127. https://www.monarchchemicals.co.uk/Information/News-Events/700-/The-difference-between-Propylene-Glycol-and-Ethylene-Glycol-in-antifreeze
  128. https://alliancechemical.com/blogs/articles/chilling-tales-of-ethylene-glycol-vs-propylene-glycol-an-epic-battle-for-the-crown-of-best-antifreeze
  129. https://nvlpubs.nist.gov/nistpubs/Legacy/circ/nbscircular506.pdf
  130. https://www.valvolineglobal.com/en-ksa/all-you-need-to-know-about-coolants/
  131. https://usradiator.com/does-coolant-matter
  132. https://www.bgprod.com/blog/the-secret-of-coolant-colors/
  133. https://on-sitefleetservice.com/blog-article/7-types-of-coolant
  134. https://www.h2xengineering.com/blogs/glycol-in-heating-and-cooling-systems/
  135. https://starfire.com/the-truth-about-antifreeze-understanding-types-technology-and-color/
  136. https://www.superradiatorcoils.com/blog/how-are-ethylene-and-propylene-glycol-different-which-should-i-use
  137. https://inldigitallibrary.inl.gov/sites/sti/sti/5698704.pdf
  138. https://pubs.acs.org/doi/10.1021/acs.jced.2c00212
  139. https://www.sciencedirect.com/science/article/abs/pii/S016773222202342X
  140. https://dspace.mit.edu/bitstream/handle/1721.1/123988/Romatoski_SaltPropertyReview02.pdf?sequence=1&isAllowed=y
  141. https://www.linseis.com/en/wiki/molten-salts-heat-transfer-of-the-future/
  142. https://www.bnl.gov/newsroom/news.php?a=120814
  143. https://publications.anl.gov/anlpubs/2019/09/154904.pdf
  144. https://www.iaea.org/publications/8589/liquid-metal-coolants-for-fast-reactors-cooled-by-sodium-lead-and-lead-bismuth-eutectic
  145. https://www.oecd-nea.org/science/reports/2007/pdf/chapter1.pdf
  146. https://www.gen-4.org/generation-iv-criteria-and-technologies/lead-fast-reactors-lfr
  147. https://iopscience.iop.org/book/mono/978-0-7503-6069-2/chapter/bk978-0-7503-6069-2ch12
  148. https://world-nuclear.org/information-library/current-and-future-generation/fast-neutron-reactors
  149. https://www.anl.gov/article/10-things-you-may-not-know-about-superconductivity
  150. https://cds.cern.ch/record/1974065/files/CERN-2014-005-p453.pdf
  151. https://cds.cern.ch/record/808569/files/p375.pdf
  152. https://specialtygases.messergroup.com/liquid-helium
  153. https://pmc.ncbi.nlm.nih.gov/articles/PMC11084919/
  154. https://www.aiche.org/resources/publications/cep/2015/september/cool-down-liquid-nitrogen
  155. https://www.noblegencryogenics.com/news/cryomilling-applications-using-liquid-nitrogen
  156. https://demaco-cryogenics.com/blog/liquid-nitrogen-uses-and-applications/
  157. https://trc.nist.gov/cryogenics/cryocoolers.html
  158. https://www.sciencedirect.com/topics/physics-and-astronomy/cryogenic-cooling
  159. https://www.redriver.team/cryogenic-cooling-system-applications/
  160. https://cryospain.com/cryogenic-liquids-what-they-are
  161. https://dataairflow.com/the-physics-of-two-phase-cooling-explained-simply/
  162. https://www.calyos-tm.com/news-article/analyzing-two-phase-data-center-cooling-solutions-the-physics-the-challenges-and-the-future
  163. https://www.1-act.com/resources/learning-center/heat-pipes/
  164. https://www.crtech.com/blog/two-phase-musing-part-2
  165. https://2crsi.com/two-phase-immersion-cooling
  166. https://www.kenfatech.com/two-phase-cooling-advanced-thermal-management-guide/
  167. https://www.sciencedirect.com/science/article/abs/pii/S1359431122015447
  168. https://www.1-act.com/thermal-solutions/passive/pcm/heat-sinks/
  169. https://www.energy.gov/eere/vehicles/articles/two-phase-cooling-technology-power-electronics
  170. https://www.sciencedirect.com/science/article/pii/S1364032119307877
  171. https://www.nature.com/articles/s41467-025-56960-1
  172. https://www.boydcorp.com/about-boyd/resources/technical-papers-and-guides/two-phase-thermal-solution-guide.html
  173. https://pmc.ncbi.nlm.nih.gov/articles/PMC10647477/
  174. https://www.nature.com/articles/s41598-024-68701-3
  175. https://www.nature.com/articles/s41598-024-78631-9
  176. https://www.hielscher.com/coolants-based-on-thermoconductive-nanofluids.htm
  177. https://onlinelibrary.wiley.com/doi/10.1002/fuce.70005
  178. https://www.sciencedirect.com/science/article/pii/S2214157X25007038
  179. https://www.tandfonline.com/doi/full/10.1080/23311916.2024.2434623
  180. https://www.jhuapl.edu/news/news-releases/250821-apl-refrigeration-tech-wins-rd-100-award-2025
  181. https://iifiir.org/en/news/slovenian-researchers-explore-solid-state-cooling-to-replace-harmful-refrigerants
  182. https://rmi.org/clean-energy-101-solid-state-cooling/
  183. https://www.sciopen.com/article/10.26599/NRE.2023.9120103
  184. https://www.sciencedirect.com/science/article/pii/S2352152X22025580
  185. https://advanced.onlinelibrary.wiley.com/doi/10.1002/adma.202202457
  186. https://wwwn.cdc.gov/TSP/MMG/MMGDetails.aspx?mmgid=82&toxid=21
  187. https://veterinarypartner.vin.com/default.aspx?pid=19239&catId=102898&id=6047934
  188. https://www.atsdr.cdc.gov/toxprofiles/tp96-c1.pdf
  189. https://pubmed.ncbi.nlm.nih.gov/10451263/
  190. https://archive.cdc.gov/www_atsdr_cdc_gov/csem/ethylene-propylene-glycol/images/WB4342_EGPG_Web_Ready_Version_CSEM_EGPG-Updated_Oct_2020.pdf
  191. https://www.epa.gov/snap/refrigerant-safety
  192. https://www.webmd.com/a-to-z-guides/what-is-refrigerant-poisoning
  193. https://nj.gov/health/eoh/rtkweb/documents/fs/0878.pdf
  194. https://www.jennychem.com/blogs/news/is-antifreeze-flammable
  195. https://cpcworldwide.com/Thermal-Campaigns/Liquid-Cooling-and-Chemical-Compatibility
  196. https://info.ornl.gov/sites/publications/Files/Pub126864.pdf
  197. https://www.energy.gov/sites/prod/files/2014/01/f7/csp_review_meeting_042413_garciadiaz.pdf
  198. https://ehs.wisc.edu/labs-research/chemical-safety/chemical-safety-guide/cryogenic-liquids/
  199. https://www.airproducts.com/-/media/files/en/900/900-13-079-us-safe-handling-of-cryo-liquids-safetygram-16.pdf
  200. https://researchsafety.uky.edu/chemical-safety/chemical-hazards-information/cryogenic-materials
  201. https://www.engineeringtoolbox.com/Refrigerants-Environment-Properties-d_1220.html
  202. https://www.epa.gov/climate-hfcs-reduction/frequent-questions-phasedown-hydrofluorocarbons
  203. https://www.epa.gov/climate-hfcs-reduction/technology-transitions-gwp-reference-table
  204. https://ndlindustries.com/refrigerant-table/
  205. https://treaties.un.org/pages/ViewDetails.aspx?src=IND&mtdsg_no=XXVII-2&chapter=27&clang=_en
  206. https://www.epa.gov/sites/default/files/2015-07/documents/phasing_out_hcfc_refrigerants_to_protect_the_ozone_layer.pdf
  207. https://eelp.law.harvard.edu/tracker/hydrofluorocarbons-and-kigali-amendment-to-montreal-protocol/
  208. https://www.danfoss.com/en/about-danfoss/our-businesses/cooling/refrigerants-and-energy-efficiency/hfc-phase-down/danfoss-on-f-gas-regulation/
  209. https://www.epa.gov/sites/default/files/2016-02/documents/antifreeze.pdf
  210. https://www.congress.gov/committee-report/109th-congress/senate-report/220/1
  211. https://www.noranews.org/page/AntifreezeInfo
  212. https://www.era-environmental.com/blog/epa-aim-act-hfc-refrigerants
  213. https://www.pillsburylaw.com/en/news-and-insights/american-innovation-manufacturing-act-comprehensive-hfc-phasedown.html
  214. https://carbonconnector.com/blog/hfc-phasedown-truce/
  215. https://bellomyims.com/the-shift-to-eco-friendly-refrigerants-and-its-impact-on-costs/
  216. https://fexa.io/blog/the-cost-of-non-compliance-understanding-aim-act-fines-and-risks
  217. https://www.wbir.com/article/tech/science/environment/law-leaves-hvac-companies-grappling-with-high-refrigerant-prices-and-low-supply/51-23d0a41c-5cd6-416b-835f-38e7983165d5
  218. https://insideepa.com/pfas-news/industry-cautions-against-severe-economic-impact-refrigerant-bans
  219. https://www.epa.gov/newsreleases/epa-proposes-reforming-biden-technology-transitions-rule-lower-costs-american-families
  220. https://polarking.com/cold-storage-is-changing-what-you-need-to-know-about-the-aim-act/
  221. https://www.turi.org/wp-content/uploads/2025/04/2025-Refrigerant-Report-041025-FINAL.pdf
  222. https://www.sciencedirect.com/science/article/abs/pii/S0140700718301075
  223. https://www.sae.org/papers/comparative-performance-ethylene-glycol-water-propylene-glycol-water-coolants-automobile-radiators-960372
  224. https://www.researchgate.net/publication/353409395_Comparative_Performance_of_Low_Global_Warming_Potential_GWP_Refrigerants_as_Replacement_for_R-410A_in_a_Regular_2-Speed_Heat_Pump_for_Sustainable_Cooling
  225. https://www.sciencedirect.com/science/article/abs/pii/S1364032118301977
  226. https://www.opteon.com/en/support/knowledge-hub/so-called-naturals
  227. https://maccold.com/en/academy/the-advantages-and-challenges-of-natural-refrigerants
  228. https://pubs.acs.org/doi/10.1021/acssuschemeng.1c05985
  229. https://www.tandfonline.com/doi/full/10.1080/1943815X.2020.1768551
  230. https://dergipark.org.tr/en/pub/ijastech/issue/60881/914901
  231. https://www.hydratech.co.uk/news-thoughts-blog/Propylene-glycol-vs-ethylene-glycol-in-antifreeze/92
  232. https://penriteoil.com.au/knowledge-centre/Coolant%2520-%2520Miscellaneous/150/what-is-the-difference-between-mono-ethylene-glycol-and-propylene-glycol/1050
  233. https://www.littleonline.com/insights/facing-the-heat-the-environmental-challenges-of-refrigerants/
  234. https://consensus.app/search/environmental-impact-assessment-of-natural-refrige/GnSnxFbCQB6Z2f0VMWGufA/
  235. https://www.openaccessgovernment.org/hfo-refrigerants/112698/
  236. https://www.sciencedirect.com/science/article/abs/pii/S0959652619303208
  237. https://www.researchgate.net/publication/330680947_Trade-off_analysis_between_global_impact_potential_and_local_risk_A_case_study_of_refrigerants
  238. https://www.dynalene.com/immersion-coolants-for-data-centers-selection-criteria/
  239. https://www.bytebt.com/trends-liquid-cooling-ai-data-centers-2025/
  240. https://www.idtechex.com/en/research-article/ev-direct-dielectric-cooling-immersion-cooling-and-thermal-management/32646
  241. https://www.shell.com/what-we-do/digitalisation/computational-science/supercomputers-demonstrate-shell-e-fluids-to-be-best-in-class-coolants-for-ev-batteries.html
  242. https://shop.engineeredfluids.com/products/ac-130
  243. https://evmagazine.com/charging-and-infrastructure/hyundai-mobis-ev-battery-cooling-technology
  244. https://www.cargill.com/bioindustrial/doc/1432258610234/dielectric-fluids-for-immersion-cooling.pdf
  245. https://msdspds.castrol.com/bpglis/FusionPDS.nsf/Files/D624D17ADC694EE5802585E000488D9E/%24File/wepp-btfn9c.pdf
  246. https://www.sciencedirect.com/science/article/pii/S1364032124009948
  247. https://evanscoolant.com/products/high-performance-waterless-coolant
  248. https://liquidintelligence.com.au/products/super-waterless-coolant
  249. https://www.intelmarketresearch.com/waterless-coolant-market-9680
  250. https://www.archivemarketresearch.com/reports/waterless-coolant-366781
  251. https://www.linkedin.com/pulse/waterless-coolant-market-comprehensive-analysis-drivers-trends-atlzc/
  252. https://www.mdpi.com/1996-1073/18/15/4145
  253. https://www.datacenterdynamics.com/en/news/cooling-fluids-firm-arteco-moves-into-data-centers-launches-liquid-cooling-offering/
  254. https://eureka.patsnap.com/report-exploring-antifreeze-alternatives-for-reduced-toxicity
  255. https://www.wissenresearch.com/wp-content/uploads/2024/02/Non-Aqueous-Based-Coolants.pdf
Add your contribution
Related Hubs
User Avatar
No comments yet.