Absorption chiller waste heat utilization to the desiccant dehumidifier system for enhanced cooling – Energy and exergy analysis

Abstract Recently, combining the absorption chiller and dehumidifier is a well-favored implementation for high-quality air cooling. However, the coefficient of performance of the absorption chiller is limited because of the low-grade input energy, and in most previous works, the dehumidifier's energy requirement is independently supplied by solar energy or other high-grade energy. This paper addresses these problems by utilizing the condenser waste heat of the absorption chiller for dehumidification, which is achieved by regenerating a desiccant solution. A mathematical model of the absorption chiller and dehumidification was developed in MATLAB. Here, the energy, exergy value of the absorption chiller outputs is first analyzed with respect to the varying desiccant regeneration temperature, which shows that the condenser waste heat contains significant amounts of useable exergy. Then, an energy, exergy, and technical analysis of the dehumidifier and subsequently the coupled system reveals that utilizing the proposed integrated concept could greatly increase the air-cooling exergy efficiency from a conventional 6%–14%. This was achieved by setting the regeneration temperature to be at least 6 °C above ambient. Overall, the waste heat utilization concept enabled a more efficient building space cooling and dehumidification system than conventional multi-energy complementary systems in hot and humid climates.