Hydrothermal synthesis and application of adsorbent coating for adsorption chiller

To overcome the problem of peak electricity demand caused by the use of air-conditioning in the summer, researchers have been focusing their interest on adsorption chillers, which are an environmentally friendly technology in that they use waste heat as their power source and water as a refrigerant. In the present study, to improve the performance of an adsorption chiller, FAPO₄-5 adsorbents were synthesized using two hydrothermal synthetic methods, and then characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), N₂ adsorption/desorption isotherms and water adsorption isotherms. Coatings of the adsorbent were applied to an aluminum substrate. Six different coating solutions were used, with a 5.0 wt%, 10.0 wt%, and 15.0 wt% content of epoxy-based and silicone-based binders, respectively. The surface features of adsorbent coating were observed with scanning electron microscopy (SEM). To determine the variation in the water adsorption properties of the adsorbents according to the binder type, each adsorbent was subjected to water adsorption isotherm analysis at 25 °C. The coating thickness was calculated by three dimension coordinate measuring machine. Cross-cut tests (performed according to ISO 2409:2013) were carried out to assess the strength of the adhesion of the coating to the aluminum substrate.