A new concept of adsorption heat pumps: Proof-of-concept and feasibility assessment

Advances in adsorption heat pump technology have significantly improved their energy efficiency and waste heat utilization, making them a promising solution for sustainable cooling. However, issues like bulkiness and prohibitive costs limit their adoption. A new third-generation adsorption technology, featuring dual adsorber modules with direct evaporation/condensation and liquid-phase refrigerant distribution, addresses these challenges by eliminating the need for expensive and large vacuum valves and enabling compact vacuum systems, potentially unlocking their full market potential. The model is developed using MATLAB software and validated with relevant experimental results of a modular adsorption heat transformation test rig. Herein, a composite adsorbent of CaCl2@SG_25 with water refrigerant is used, where its isotherms, kinetics, and isosteric heat of adsorption are correlated. Parametric analysis demonstrate that increasing the inlet hot water temperature from 50 °C to 90 °C led to a 344% rise in cooling capacity and a 13% increase in coefficient of performance, while raising inlet cooling water temperature from 20 °C to 40 °C caused an 87% and 77% drop in cooling and heating capacity, respectively. The results indicate that direct evaporation and condensation within the adsorption modules significantly reduce the temperature difference and accordingly enhance their performance. Besides, a cost criteria comparative analysis is highlighted with the previously developed adsorption technologies.