High-power-density adsorption chiller driven by data center waste heat using encapsulated composite as adsorbent

Achieving energy savings in the cooling system, the second-largest energy user, is crucial for reducing power usage effectiveness (PUE) in data centers (DCs). A promising energy conservation strategy for DCs with hybrid cooling systems involves repurposing waste heat from liquid-cooled circuits to drive adsorption chillers, which in turn cool air-cooled components. However, the application requires adsorption chillers capable of operating at ultra-low heat source temperature while possessing high cooling power density. In this paper, we develop a compact adsorption chiller using encapsulated LiCl-embedded silica gel (SG)-water as the working pair, free from corrosion and capacity degradation issues. The chiller is experimentally investigated under typical DC waste heat driven cooling conditions. It features an annular finned tube as the adsorber module to enhance mass transfer area, and a waterproof but breathable membrane encapsulated outside the adsorber to prevent solution leakage from the composite adsorbent. The developed chiller demonstrates a specific cooling power (SCP) of 102.35 W/kg and a volumetric cooling power (VCP) of 7.47 kW/m3 with hot/cooling/chilled water inlet temperatures of 50 °C/30 °C/23 °C, twice the performance of SG-water chillers. This work could advance heat recovery and energy savings in DCs and inspire more research interest into developing low-temperature-driven compact adsorption chillers.