High Performance Microchannel Adsorption Heat Pumps

ABSTRACT Adsorbent-coated microchannels are used for the design of adsorption heat pumps, based on component-level fluid flow, heat and mass transfer modeling of a representative proof-of-concept unit with a cooling capacity of 300 W at 5°C. Optimum channel geometry is determined using parametric studies. The use of adsorbent-coated microchannels results in operation with the heating time less than 10% of the total cycle time, opening the possibility for near continuous operation of the heat pump. Cyclic operation of the subject heat pump concept is simulated for the operating conditions used for silica gel-water chillers in the literature, and the results are used to document its benefits over those of existing designs. For a source temperature of 90°C, cooling temperature of 35°C, condenser inlet temperature of 42°C, and evaporator outlet temperature of 5°C, a Coefficient of Performance (COP) of 0.22 is attainable with a specific cooing capacity (SCC) of 177 W kg−1 without recovering any heat from the heating stage. COP > 0.55 and SCC ∼1134 W kg−1 can be achieved for less severe operating conditions typically used in the literature.