In this paper, the simulation approach and exergy analysis of multi-stage compression high tempera- ture heat pump （HTHP） systems with R1234ze（Z） working fluid are conducted. Both the single-stage and multi-stage ...In this paper, the simulation approach and exergy analysis of multi-stage compression high tempera- ture heat pump （HTHP） systems with R1234ze（Z） working fluid are conducted. Both the single-stage and multi-stage compression cycles are analyzed to compare the system performance with 120℃ pressurized hot water supply based upon waste heat recovery. The exergy destruction ratios of each component for different stage compression systems are compared. The results show that the exergy loss ratios of the compressor are bigger than that of the evaporator and the condenser for the single-stage compres- sion system. The multi-stage compression system has better energy and exergy etticiencies with the increase of compression stage number. Compared with the single- stage compression system, the coefficient of performance （COP） improvements of the two-stage and three-stage compression system are 9.1% and 14.6%, respectively. When the waste heat source temperature is 60℃, the exergy efficiencies increase about 6.9% and 11.8% for the two-stage and three-stage compression system respec- tively.展开更多
The present paper aims at exploring a hybrid absorption-compression heat pump （HAC-HP） to upgrade and recover the industrial waste heat in the temperature range of 60℃-120℃. The new HAC-HP system proposed has a co...The present paper aims at exploring a hybrid absorption-compression heat pump （HAC-HP） to upgrade and recover the industrial waste heat in the temperature range of 60℃-120℃. 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 compres- sor 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℃, 80℃, 100℃, and 120℃. 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℃-27.7 ℃, 14.9℃~4.1 ℃, 24.4℃-64.1 ℃, and 40.7℃-85.7℃, respectively, and the system energy efficiency are 0.35-0.93, 0.32-0.90, 0.25- 0.85, and 0.14-0.76.展开更多
文摘In this paper, the simulation approach and exergy analysis of multi-stage compression high tempera- ture heat pump （HTHP） systems with R1234ze（Z） working fluid are conducted. Both the single-stage and multi-stage compression cycles are analyzed to compare the system performance with 120℃ pressurized hot water supply based upon waste heat recovery. The exergy destruction ratios of each component for different stage compression systems are compared. The results show that the exergy loss ratios of the compressor are bigger than that of the evaporator and the condenser for the single-stage compres- sion system. The multi-stage compression system has better energy and exergy etticiencies with the increase of compression stage number. Compared with the single- stage compression system, the coefficient of performance （COP） improvements of the two-stage and three-stage compression system are 9.1% and 14.6%, respectively. When the waste heat source temperature is 60℃, the exergy efficiencies increase about 6.9% and 11.8% for the two-stage and three-stage compression system respec- tively.
文摘The present paper aims at exploring a hybrid absorption-compression heat pump （HAC-HP） to upgrade and recover the industrial waste heat in the temperature range of 60℃-120℃. 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 compres- sor 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℃, 80℃, 100℃, and 120℃. 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℃-27.7 ℃, 14.9℃~4.1 ℃, 24.4℃-64.1 ℃, and 40.7℃-85.7℃, respectively, and the system energy efficiency are 0.35-0.93, 0.32-0.90, 0.25- 0.85, and 0.14-0.76.
