Recent advances of composite adsorbents for heat transformation applications

Low-temperature waste heat-powered adsorption heat transformation (AHT) is an energy-efficient and green technology, which is considered a promising alternative to the conventional vapor compression systems. The performance of an AHT system generally depends on the properties of adsorbents and adsorbates. The poor heat transfer and low packing density of adsorbent materials are the main limiting factors of an AHT system. Several researchers are working on composite adsorbents to overcome these drawbacks, and they observed enhanced thermal conductivity, packing density and volumetric adsorption capacity, which are very favorable to develop an efficient and compact system. There is hardly found any complete review on the composite adsorbents for heat transformation applications. This manuscript presents a comprehensive review on the thermophysical and adsorption properties of composite adsorbents developed so far for the AHT applications. This review also provides future research directions towards attaining adsorption-based efficient heat transformation systems. This review would greatly assist in selecting an optimum composite adsorbent or developing a new composite for a specific AHT application.