24 June 2014

HEAT-DRIVEN ADSORPTION CHILLER SYSTEMS FOR SUSTAINABLE COOLING APPLICATIONS

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Thermally driven adsorption chillers enable utilization of low-grade heat below 100°C to drive refrigeration cycles at minimum electrical energy consumption. Therefore, this
technology is crucial to enable waste heat usage and substantially cut the power drawn from electrical grids and thereby improve the energy efficiency of air-conditioning infrastructure.
Two scenarios for the implementation of adsorption heat pumps are considered: (i) hot-water cooled datacenters and (ii) solar cooling. Simulation studies reveal distinct operating windows for the adsorption chiller in each application and, accordingly, the need for adsorbent materials tailored to the desired temperature lift to optimally use the driving heat. Adsorption experiments were carried out in a custom-built apparatus to quantify the cooling
power per unit mass of adsorbent and its thermal response in relation to the applied temperature swing. The results reveal poor adsorbent utilization in present adsorption chillers due to a mismatch between the adsorption characteristics of the adsorbent and the boundary conditions of the application as well as incomplete thermal cycling of the adsorbent due to poor heat transport.