15 Advanced Cooling Technologies II: Two-Phase Flow Cooling

As mentioned in Chapter 14, dielectric fluids are generally required for cooling of electronics, especially in direct-immersion cooling. Dielectric liquids such as Freon from Dupont and Fluorinert (FC series) from 3M Company are the most popular fluids used in direct cooling of electronics. The basic characteristics of those fluids are as follows:

1. Excellent electrical properties: high dielectric strength, low dielectric constant, and high electrical resistivity

2. High thermal stability

3. Low chemical reactivity

4. Poor thermal properties: low thermal conductivity, specific heat, and heat of vaporization (latent heat)

5. Extremely low surface tension

6. High solubility for air

As they can for the liquid phase, fluid figures of merit (FOMs) can be obtained and used as a guide to select the working fluid for a two-phase system.