关键词: 压缩空气储能, 电加热, 氨水吸收式循环, 热力学分析

Abstract:

Combining compressed air energy storage (CAES) and renewable energy is recognized as an effective way to solve the dependence of the conventional compressed air energy storage system on fossil fuels and to increase the renewable energy penetration. In this paper, by integrating the CAES with an electrical heater (CH-CAES), the amount of heat storage in the thermal storage device is greatly improved, and, simultaneously, the capacity of the expander to output mechanical power in the compressed air energy storage system is improved. To recover the high temperature residual heat of the thermal storage device in the CAES, a novel combined heat and power system (CH-CAES-AHP) coupled with the CH-CAES and absorption heat pump cycle (AHP) is proposed in this paper for achieving the cascade utilization of energy. Parametric analyses were carried out in this paper to investigate the effect of four key parameters on the integration system performance using the control variable method. Meanwhile, the exergy analysis method based on the second law of thermodynamics was applied as a beneficial supplement to the energy analysis method to improve the evaluation of the system performance. The results show that the round-trip efficiency of the CH-CAES is greatly improved, also improving the energy utilization rate by integrating with the AHP. Under the fundamental working conditions, the round-trip efficiency and exergy efficiency of the CH-CAES-AHP increased by 29.96% and 1.87%, respectively, due to the integration system output being an additional 5790.53 kW heating power compared with the CH-CAES. The parametric analysis shows that the discharging pressure and the electrical heating temperature have a great influence on the performance of the integration system, while the rectification column pressure and the rectifier reflux ratio have little influence on the performance of the integration system. The parametric analysis also shows that the round-trip efficiency of the integration system is decreased with the discharging pressure and increased with the electrical heating temperature. Moreover, reducing the rectification column pressure and the rectifier reflux ratio can lead to more net heat being released by the ammonia absorption heat pump cycle and increasing the performance coefficient of the AHP; this is conducive to the improvement of the round-trip efficiency of the integration system. Simultaneously, the exergy efficiency of the integration system is increased with the discharging pressure and decreased with the electrical heating temperature, while the rectification column pressure and the rectifier reflux ratio have little influence on the exergy efficiency of the integration system.

Key words: compressed air energy storage, electrical heating, ammonia absorption cycle, thermodynamic analysis