What Fluids are Used in Liquid Cooling ?

What Fluids are Used in Liquid Cooling

There are various types of fluids used in liquid cooling technology, and the specific choice depends on the application scenario, cooling needs, and cost. The following are the common types of fluids used in liquid cooling systems and their characteristics:

1. Deionized Water (DW)

Characteristics:

Deionized water is the most commonly used coolant in liquid cooling systems due to its high specific heat capacity and good thermal conductivity.

Deionized water is treated to remove minerals and ions to avoid electrical conductivity and corrosion problems.

Application Scenario:

Data center, high performance computing (HPC), bitcoin mining, etc.

2. Ethylene Glycol Water Solution (Ethylene Glycol/Water Mixture)

Features:

Ethylene Glycol is mixed with water in a certain ratio, usually 60% water + 40% Ethylene Glycol.

Ethylene Glycol has a low freezing point and a high boiling point, making it suitable for extreme temperature environments.

Application Scenario:

Automobile cooling system, industrial cooling system, liquid-cooled data centers in cold areas.

3. Mineral Oil

Features:

Mineral Oil is an insulating liquid that can be directly submerged in electronic equipment (immersion liquid cooling).

Application Scenario:

Immersion liquid cooling systems, commonly used in experimental data centers or high performance computing.

4. Fluorinated Liquids (FL)

Characteristics:

Fluorinated liquids are chemically inert liquids commonly used in immersion liquid cooling systems.

Common fluorinated liquids include 3M Novec and Fluorinert.

Application Scenarios:

High-end data centers, supercomputers, immersion liquid cooling systems.

5. Synthetic Coolants

Features:

Synthetic coolants are chemical fluids specifically designed for liquid cooling systems and typically have excellent thermal conductivity and corrosion resistance.

Application Scenarios:

High performance computing, industrial cooling system.

6. Liquid Metal

Features:

Liquid metals (e.g. gallium-based alloys) have extremely high thermal conductivity.

Application Scenarios:

Experimental cooling systems, extreme high performance computing.

7. Other Specialty Fluids

Nanofluids:

Nanoparticles are added to a base fluid (e.g. water or oil) to improve thermal conductivity.

Still in the research phase, high cost.

Phase Change Materials (PCM):

Cool equipment by absorbing heat and undergoing a phase change (e.g., solid to liquid).

Suitable for short time high power dissipation.

Summary

There are a variety of fluids used in liquid cooling systems, with the most common being deionized water, aqueous ethylene glycol solutions, mineral oils, and fluorinated fluids. The choice of fluid depends on the specific application, heat dissipation requirements, cost budget and environmental conditions. For example:

Deionized water is the most commonly used low-cost, high-efficiency coolant.

Fluorinated fluids are suitable for high-end immersion liquid cooling systems.

Glycol in water is suitable for low temperatures.

Mineral oils and liquid metals are used in special cases.

In practice, the design of a liquid cooling system also needs to take into account the fluidity, insulation, corrosiveness and maintenance costs of the fluid in order to ensure the system's efficiency and reliability.