Model and parameters for calculating the energy and exergy efficiency of a hybrid absorption-compression high temperature heat pump

This work explored a hybrid absorption-compression heat pump (HAC-HP) to upgrade and recover the industrial waste heat in the temperature range of 60°C–120°C. The new HAC-HP system proposed has a condenser, an evaporator, and one more solution pump, compared to the conventional HAC-HP system, to allow flexible utilization of energy sources of electricity and waste heat. In the system proposed, the pressure of ammonia-water vapor desorbed in the generator can be elevated by two routes; one is via the compression of compressor while the other is via the condenser, the solution pump, and the evaporator. The results show that more ammonia-water vapor flowing through the compressor leads to a substantial higher energy efficiency due to the higher quality of electricity, however, only a slight change on the system exergy efficiency is noticed. The temperature lift increases with the increasing system recirculation flow ratio, however, the system energy and exergy efficiencies drop towards zero. The suitable operation ranges of HAC-HP are recommended for the waste heat at 60°C, 80°C, 100°C, and 120°C. The recirculation flow ratio should be lower than 9, 6, 5, and 4 respectively for these waste heat, while the temperature lifts are in the range of 9.8°C–27.7 °C, 14.9°C–44.1 °C, 24.4°C–64.1°C, and 40.7°C–85.7°C, respectively, and the system energy efficiency are 0.35–0.93, 0.32–0.90, 0.25– 0.85, and 0.14–0.76.

本研究探讨了混合吸收-压缩式热泵（HAC-HP）在60°C至120°C的温度范围内对工业废热进行升级与回收的可行性。所提出的新型HAC-HP系统相较于传统HAC-HP系统，增加了冷凝器、蒸发器和另一台溶液泵，以实现电能和废热能源的灵活利用。在该系统中，发生器中氨水蒸汽的压升可以通过两条途径实现：一为压缩机压缩，另一为冷凝器、溶液泵和蒸发器。结果表明，通过压缩机流动的氨水蒸汽量增加，由于电能品质的提高，导致能源效率显著提升；然而，系统耗散效率仅发生轻微变化。随着系统循环流量比的增大，温度提升也随之增加，但系统的能源和耗散效率逐渐趋近于零。针对60°C、80°C、100°C和120°C的废热，分别推荐了HAC-HP的适宜操作范围。对于这些废热，循环流量比应分别低于9、6、5和4，而温度提升范围分别为9.8°C至27.7°C、14.9°C至44.1°C、24.4°C至64.1°C和40.7°C至85.7°C，系统的能源效率分别在0.35至0.93、0.32至0.90、0.25至0.85和0.14至0.76之间。