Thermal Design and Performance Modeling of a High Compute Density Liquid Cooled Chiller Less Modular Edge Data Center

Abstract

Abstract. Holistic design of a modular energy-efficient edge datacenter with a compute density of 20 kW/m3 is presented. The datacenter uses a single chiller-less liquid loop to extract heat from server components and reject it to the ambient using a mixture of 25% propylene glycol and water. Heat is extracted from the chips using a multiple unit-cell shedding enhanced (MUSE) cold plate and rejected to the ambient air using a counterflow microchannel polymer heat exchanger (MPHX) dry cooler. The MUSE cold plate consists of a manifold to split flow into parallel paths and a large aspect ratio (7.3:1) microscale pin fin heat sink fabricated using electrochemical additive manufacturing. The counterflow MPHX dry cooler design can provide higher effectiveness than metallic finned tube heat exchangers for identical air side pressure drop. Experiments of the cold plate and MPHX components are presented, and a system model of the cooling loop is developed. At an outdoor temperature of 40 °C, baseline results indicate that optimized liquid and fan flow rates reduce cooling power to 2.1% of compute power for a graphical processing unit (GPU) case temperature of 75 °C and heat flux of 74 W/cm2. Sensitivity studies are performed to assess the impact of improvements in thermal interface material, cold plate convective resistance, and dry cooler air-side heat transfer coefficient on system performance. Results show that, for this heat flux, the thermal interface material (TIM) and dry cooler have the largest impact on the system, with the best-case cooling power being under 1% of compute power.