A Novel Functional Accelerated Thermal Aging Methodology for Single-Phase Dielectric Immersion Coolants

Area of Science:

• Thermal Management in Data Centers
• Immersion Cooling Technologies
• Dielectric Coolant Performance and Longevity

Background:

• High-performance computing drives the need for advanced data center thermal management.
• Immersion cooling offers efficient cooling for high-density racks and reduces energy consumption.
• Limited research exists on dielectric coolant behavior and lifespan under operational conditions.

Purpose of the Study:

• To introduce a comprehensive aging methodology for evaluating dielectric immersion coolant quality over time.
• To predict the lifespan of coolants in single-phase immersion cooling applications.
• To validate the performance and safety of a biobased synthetic ester coolant (L759).

Main Methods:

• Accelerated thermal aging of a dielectric immersion coolant at 100 °C for six months.
• Validation of thermo-electrical performance using an immersed Raspberry Pi 4 Computer.
• System-oriented aging methodology integrating material compatibility, thermal stress, and functional performance.

Main Results:

• The biobased synthetic ester coolant (L759) exhibited excellent heat transfer properties and met safety guidelines (high flash point, electrical resistivity, dielectric breakdown).
• Minimal interactions were observed with polyvinyl chloride cable insulation.
• Acid value, specific heat capacity, and electrical resistivity were identified as key lifespan indicators; aged coolant effectively cooled the Raspberry Pi 4 CPU.

Conclusions:

• The biobased synthetic ester coolant (L759) is suitable for current and next-generation server lifespans (5-10 years).
• Ester technology shows significant potential for single-phase immersion cooling systems.
• The developed aging methodology is adaptable for alternative coolants and related industrial applications.