Enhancing the performance of a zeolite 13X/CaCl₂–water adsorption cooling system by improving adsorber design and operation sequence

In this study, a compact dual adsorber adsorption cooling system (ACS) prototype was built using the zeolite 13X/CaCl₂ composite adsorbent with water as the adsorbate. The adsorbers were constructed by directly coating the composite adsorbent on parallel flow finned heat exchangers to enhance the heat and mass transfer performance. The compactness of the ACS is of great concern for use in buildings, where space is always limited. Through a better adsorber design, the specific cooling power (SCP) is largely improved from 106 W/kg to 377 W/kg (256% improvement) under the same desorption temperature, 85 °C, and chilled water inlet temperature, 14 °C, even though the cooling water temperature is increased from 22 °C to 28 °C. Besides, four different operation sequences, namely basic cycle, mass recovery cycle, pre-heating & pre-cooling cycle, and mass recovery with pre-heating & pre-cooling cycle, were studied to optimize the system performance. It is found that performing the pre-heating & pre-cooling cycle can further increase the SCP to 401 W/kg. This promising result shows that the ACS has potential to be installed in buildings to achieve the goals of heating/cooling energy saving.