In the first part of this series, Glacier Coolant examined inorganic phase change coolants — ice, hydrated salts, dry ice, and liquid oxygen. Now, we turn to organic and composite phase change materials (PCMs), which offer distinct advantages and trade-offs for thermal storage applications.

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Organic Phase Change Coolants

Organic PCMs include materials such as paraffins, fatty acids, and polyols (alcohols) . Unlike their inorganic counterparts, they generally do not suffer from supercooling or phase separation — but they come with other limitations.

Paraffins: The Most Common Organic Choice

Paraffins are mixtures of straight-chain alkanes. Their molecular weight — and therefore their phase change temperature — increases with carbon chain length. By selecting paraffins with different carbon atom counts, manufacturers can tune the melting point to suit specific applications.

Advantages of paraffins:

• Excellent chemical stability

• Non-toxic and non-corrosive

• Readily available and low cost

Disadvantages:

• Low thermal conductivity, which significantly reduces charging and discharging efficiency

Glacier Coolant note: Low thermal conductivity can be mitigated through additives, encapsulation, or composite formulation — a topic we explore below.

Alcohols (Polyols & Glycols)

Alcohol-based PCMs, such as ethanol, ethylene glycol, and sugar alcohols, have received less attention for cooling applications. The reason is simple: their latent heat is relatively low, limiting their cooling capacity.

• Ethanol and ethylene glycol – weak thermal storage performance

• Sugar alcohols and polyethylene glycol (PEG) – typically used for heat storage rather than cooling, as their phase change temperatures are too high for most cold chain applications

Fatty Acids

Fatty acids offer higher latent heat than paraffins or alcohols, making them more attractive for thermal storage. However, they come with practical drawbacks:

• More volatile than paraffins

• Corrosive to certain metals

• Strong, unpleasant odor

• More commonly used for heat storage (high-temperature applications) than for cooling

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Key Differences: Organic vs. Inorganic

In short: Organics are stable but weak conductors. Inorganics are powerful but unstable.

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Composite Phase Change Coolants: The Best of Both Worlds

Composite PCMs are typically formed by combining organic and inorganic materials — or by adding high-conductivity fillers — to overcome the limitations of each.

What composites can achieve:

• Eliminate supercooling and phase separation

• Boost thermal conductivity (often through carbon-based additives, metal foams, or expanded graphite)

• Maintain high latent heat comparable to inorganics

• Adjust phase change temperature by varying component ratios

• Improve long-term stability

Market outlook

Composite phase change materials are currently the most researched category of PCMs, and they hold the greatest market potential. By carefully engineering the formulation, manufacturers can create tailored solutions that balance cost, performance, and reliability for specific applications — from cold chain logistics to building thermal management.

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Glacier Coolant: Advancing Composite PCM Technology

As a leader in thermal management fluids and phase change materials, Glacier Coolant is actively developing composite PCM solutions that deliver:

• ✅ High thermal conductivity

• ✅ Minimal supercooling

• ✅ Excellent cycling stability

• ✅ Tunable phase change temperatures

• ✅ Corrosion protection

Whether you need a reliable coolant for pharmaceutical cold chains, food storage, or industrial process cooling, Glacier Coolant can help formulate the right solution.

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Coming Up

This concludes Glacier Coolant's two-part series on the advantages and limitations of phase change coolants. For guidance on selecting the right PCM for your application — or to explore custom composite formulations — reach out to the Glacier Coolant team.