Experimental investigation of a natural zeolite–water adsorption cooling unit

► Adsorption cooling unit using natural-zeolite-water was built and tested. ► System is simple and easy to operate. ► Novel condenser is used. ► A decreasing evaporator temperature during the adsorption process leads to a unique cycle diagram. In this study, a thermally driven adsorption cooling unit using natural zeolite–water as the adsorbent–refrigerant pair has been built and its performance investigated experimentally at various evaporator temperatures. The primary components of the cooling unit are a shell and tube adsorbent bed, an evaporator, a condenser, heating and cooling baths, measurement instruments and supplementary system components. The adsorbent bed is considered to enhance the bed’s heat and mass transfer characteristics; the bed consists of an inner vacuum tube filled with zeolite (zeolite tube) inserted into a larger tubular shell. Under the experimental conditions of 45 °C adsorption, 150 °C desorption, 30 °C condenser and 22.5 °C, 15 °C and 10 °C evaporator temperatures, the COP of the adsorption cooling unit is approximately 0.25 and the maximum average volumetric cooling power density (SCP v) and mass specific cooling power density per kg adsorbent (SCP) of the cooling unit are 5.2 kW/m 3 and 7 W/kg, respectively.