Experimental characterization and modelling of a compact adsorption chiller prototype for data Centre cooling

Authors: Alejandro Jose Di Cicco, Marcello Aprile, Walter Mittelbach, Angelo Freni.

Abstract: Data centre racks produce significant amounts of waste heat, which can be exploited to drive thermally driven cooling technologies such as adsorption chillers. However, integrating adsorption cooling systems close to the IT equipment requires compact machine configurations that facilitate their installation within data-centre cooling infrastructure. This work experimentally and theoretically characterizes a novel compact adsorption chiller prototype designed as a proof-of-concept for rack-integrated adsorption chillers. The prototype introduces a new configuration in which the conventional evaporator and condenser are replaced by direct evaporation/condensation chambers coupled to the adsorber modules. All refrigerant distribution throughout the machine is done in liquid phase, eliminating the need for large vacuum valves for vapor transport, allowing a simpler vacuum-system design. Experimental characterization was performed with hot-water temperatures between 55 and 85 ◦C and cooling-water temperatures between 25 and 30 ◦C, while the refrigerant pump flow rate was also varied. The prototype achieved an overall cooling capacity of 5–12 kW, combining high- and low-temperature thermal contributions for the target rack-integrated cooling application, with a maximum thermal COPth of 0.44. As a second contribution, a dynamic model of the new machine configuration was developed, combining a lumped-parameter approach with discretization of the adsorber modules and direct evaporation/condensation chambers. Energy and mass balances describe the thermal and mass-transfer processes within the core components. The combined experimental and theoretical characterization demonstrates the feasibility of the direct evaporation/condensation concept and provides a basis for further development of a compact rack-integrated adsorption chiller driven by low-temperature waste heat from data-centre racks.

Keywords: Adsorption chiller, Data Centre cooling, Rack-integrated cooling, Lumped-parameter model, Direct evaporation/condensation

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