Formation of adsorbent thin layer on aluminum sheet by using a silane coupling agent for vapor adsorption refrigeration system

Abstract

Recently adsorbent coating technique was pointed for the aluminum fin in the ad/desorption chamber of an adsorption heat pump/chiller. This research proposes an aluminum substrate adsorbent coating method including examination of characteristics and adsorption isotherms. An aluminum substrate was dipped into the adsorbent-suspended solution to form a composite adsorbent layer on its surface. The adhesion of the adsorbents onto the aluminum substrate was evaluated by the peeling test. The aluminum oxide film on the aluminum substrate promotes the adhesion between adsorbent and aluminum substrate referring to the residual ratio. The suitable anodization condition of the aluminum oxide film is 150 volts for 2 min yielding the thin aluminum oxide film layer upon the aluminum substrate 67 nm of thickness. The suspended adsorbent solution was prepared at a mass ratio of 3 g-adsorbent g−1-coupling agent that provided the thickest adsorbent-coated layer by dip coating. Zeolite AQSOA-Z01 is a good choice to coat the aluminum substrate because it satisfied the adhesion strength and specific cooling capacity of 239.4 kJ kg−1 in the operating relative pressure range of adsorption heat pumps/chillers.