Development of a microchannel device for adsorption cooling application

Single-layer and three-layer microchannel adsorption devices were fabricated by procedure that was newly developed. Aluminum was chosen for metal housing while the adsorption pair was silica gel and water. Each adsorption layer contained two layers of 250 [mu]m-thick silica gel. Both silica gel layers opened to the same layer of adsorption channels. The layers of air flow channels were placed between two adsorption layers, including over the top and below the bottom adsorption layers. Each layer of adsorption channels and air flow channels contained array of six microchannels. Each microchannel was 400 [mu]m tall, 5.8 mm wide and 4.4 cm long. The device was bonded by B-staged epoxy thin film at moderate temperature of 120°C. The overall dimensions of the fabricated device were 5 cm x 5 cm x 10.2 mm for the three-layer device. A maximum coefficient of performance (COP) of 0.506 was achieved at the evaporator temperature of 22°C, adsorption temperature of 23°C and desorption temperature of 50°C. The highest specific cooling power (SCP) obtained was 601 W/kg silica gel when desorption temperature was increased to 70°C The overall performance of the device improved slightly when the air flow rate was increased. The COP increased by a factor of 2.4 when the number of adsorption layers increased from 1 to 3. The results from simulation model agreed with the experimental results and also showed that both COP and SCP decreased drastically when evaporator temperature was far below the adsorption temperature.