Performance analysis and comparative study of two compression-assisted absorption cycles for heat pump applications

This research puts forward the investigation of Hybrid-GAX (HGAX) absorption heating cycles using ammoniawater as the working fluid. Two configurations of HGAX absorption cycles were simulated and compared using a compressor at different positions, between the evaporator and absorber in HGAX 1, and between the desorber and condenser in HGAX 2. The effect of the design operating parameters on both models' performance and circulation ratio was also studied and analyzed. The results indicated that HGAX 1 has higher COPh, p under evaporator temperatures lower than 2.2 degrees C, while HGAX 2 COPh, p approached or exceeded that of HGAX 1 under higher evaporator temperatures. For the same heating capacity, compression ratio, and design temperatures, HGAX 1 achieved 6.98% higher COPh, p compared to HGAX 2. However, at some simulated conditions, HGAX 2 can yield 11.71% higher COPh, p compared to HGAX 1. The circulation ratio was found to be the prevailing factor in estimating the performance of HGAX 1 at low evaporator temperatures, and HGAX 1 always acquiring a lower circulation ratio compared to HGAX 2 under the same design temperatures and compression ratios. In addition, optimum values of the compression ratio were also found that maximize the COPh, p for each cycle.