Session: 02-05 Hardware Cooling I

Paper Number: 97434

97434 - A Control Strategy for Minimizing Temperature Fluctuations in High Power Liquid to Liquid CDUs Operated at Very Low Heat Loads 

The rising demand for high-performance central and graphical processing units has resulted in the need for more efficient thermal management techniques like direct-to-chip liquid cooling. Direct Liquid Cooling using cold plates is one of the most efficient and investigated cooling technology since the 1980s. Major data and cloud providers are actively deploying liquid-cooled data center infrastructure due to rising computational demands. Liquid to liquid heat exchanger used in liquid cool data centers are also referred as coolant distribution units (CDUs). Most of these CDUs selected by data center operator are based on the heat load of data center and available head with that CDU. In this study, three 52U racks with six high-power TTV based servers (Thermal Test Vehicle) in each rack were designed and deployed. Each server consists of 8 GPU TTVs and 6 NV switch heaters. A 450-kW liquid cooled CDU is used and propylene glycol 25% is used as coolant. Typical CDUs are designed to operate for 20 to 30% of rated heat load to get the stable secondary side coolant supply temperature. The present study will investigate operations of CDU at very low heat loads like 1% to 10% of CDU rated capacity. Large fluctuation in secondary side supply temperature were observed at these low loads. This large fluctuation can lead to failure of 3-way valve used in CDUs at primary side. In this paper a control strategy is developed to stabilize the secondary supply temperature within ± 0.5 °C at very low loads using the combination of flow control valve at primary side and PID control settings within the CDU.

Presenting Author: Pardeep Shahi University Of Texas Arlington