Performance optimization and comparison towards compact and efficient absorption refrigeration system with conventional and emerging absorbers/desorbers

Absorption refrigeration system (ARS) is significant for renewable/waste energy utilization to mitigate global warming. To select the best-performing ARS, four systems, namely falling-film horizontal tube ARS, falling-film vertical tube ARS, plate heat exchanger ARS, and microchannel membrane-based ARS, are compared systematically. System models have been established with validated accuracies to evaluate the coefficient of performance (COP) and volumetric cooling effect (q_v). The results show that under a design driving power of 0.5 kW, the COP increases with the tube outer diameter/length in falling-film ARS and channel width in plate heat exchanger ARS and microchannel membrane-based ARS. q_v decreases with tube outer diameter/length in falling-film ARS and channel width/height in plate heat exchanger ARS and microchannel membrane-based ARS. With geometry optimization, microchannel membrane-based ARS provides the highest COP of 0.855 with q_v = 385 kW/m³, followed by plate heat exchanger ARS of 0.846, falling-film horizontal tube ARS of 0.832, and falling-film vertical tube ARS of 0.801. Meanwhile, microchannel membrane-based ARS also produces the maximum q_v of 1147 kW/m³ with COP = 0.840, followed by plate heat exchanger ARS of 714 kW/m³, falling-film horizontal tube ARS of 391 kW/m³, and falling-film vertical tube ARS of 197 kW/m³. Thus, microchannel membrane-based ARS is advantageous in both efficiency and compactness among four ARSs. This work aims to facilitate absorbers/desorbers structure design towards compact and efficient ARS.