Thermo-Electrical Performance Evaluation of a Bio-Based Synthetic Ester Dielectric Immersion Coolant by Functional Lab Scale Testing

Today, there is a lack of performance data that accurately address combined thermal and electrical effects in single-phase immersion cooling systems. In this work, the thermo-electrical performance of a bio-based synthetic ester dielectric coolant (L759, Oleon NV) was studied while immersing a single-board computer. A simple and low-cost testing unit was developed, allowing to efficiently screen single-phase dielectric immersion coolants in a development stage. Thermo-electrical performance data (i.e. CPU temperature, frequency and power) and coolant property analysis (focused on electrical resistivity, dielectric breakdown and flash point) pointed out that the studied ester can effectively and safely cool a single-board computer. The single-board computer (cf. material compatibility assessment via visual inspection) and synthetic ester coolant (cf. molecular structure analyses using gas chromatography and infrared spectroscopy) did not degrade upon operation. Overall, ester technology shows great potential in operating single-phase immersion cooling systems.