Optimizing the compression/absorption heat pump system at high temperatures.

Two separate simulation models were developed comprising a two-stage compression-absorption heat pumps (CAHP) system and an ammonia-water absorber model. The two-stage CAHP system was simulated at four different compressor discharge temperature limitations: 150, 175, 200 and 250°C. The absorber model was used for comparison of five different compact heat exchangers for heating air in a cross-flow. The two-stage process showed the benefits of the desuperheater. Maximum supply temperatures were obtained at 171.8°C with a COP of 2.08, when the maximum discharge temperature was set to 250°C. Simulations from the absorber model yielded air mass flow rate up to 20 times larger than the ammonia-water mixture. The heat exchange between the air and the mixture was sensitive to the absorber height and the mass flow rate of air, which resulted in large fan work up to 162 kW. Finned flat tube heat exchangers showed best results with respect to the absorber height and fan work of 2.5 m and 8.7 kW.

本研究构建了两套独立的仿真模型，分别为两级压缩吸收式热泵（Compression-Absorption Heat Pump, CAHP）系统模型与氨-水吸收器模型。针对该两级CAHP系统，设置150、175、200与250℃四种不同的压缩机排气温度限值开展仿真测试。氨-水吸收器模型则用于对比五种不同的错流紧凑型换热器在空气加热场景下的性能表现。两级循环结构凸显了减温器的应用优势。当最大排气温度设定为250℃时，系统可实现最高供热温度171.8℃，对应的性能系数（Coefficient of Performance, COP）为2.08。吸收器模型的仿真结果显示，空气质量流量最高可达氨水溶液混合物流量的20倍。空气与氨水溶液间的换热过程对吸收器高度与空气质量流量较为敏感，由此产生的风机耗功最高可达162 kW。在吸收器高度为2.5 m、风机耗功为8.7 kW的工况下，翅片扁平管换热器的综合表现最优。