低温地热ORC-AHT联合循环系统热力性能分析

Thermal Performance Analysis of Low Temperature Geothermal ORC-AHT Combined Cycle System

为充分回收利用低温地热,利用第二类吸收式热泵升温原理,提出一种新型低温地热ORC-AHT联合循环发电热力系统。根据热力学第一、第二定律,建立热力学模型,编制计算程序并进行热力性能分析,结果表明:净输出功、热效率和火用效率随蒸发温度升高呈现先增加后减小的趋势,且随热源温度升高而增加。根据热力学模型设定条件,从T-Q图中可看出,与单级ORC系统相比,耦合系统可降低火用损失,提升联合系统热力性能。热源温度为373、383和393K时,耦合系统净输出功较单级ORC系统分别增加30.48%、21.9%和17.7%;热效率较单级ORC系统分别增加11.6%、7.25%和4.19%;火用效率较单级ORC系统分别增加45.45%、53.95%和60.05%。

A new type of ORC-AHT combined cycle power generation system was proposed for the better use of low-temperature geothermal resources. Using the heating principle for the second type of heat pump,the corresponding thermodynamic model for the combined cycle system was established according to the first and second laws of thermodynamics. The calculation program was developed and the system performance was analyzed. The results showed that the net output power,thermal efficiency and exergy efficiency increase first then decrease as the vaporization temperature increases,while they increases monotonically with the heat source temperature(T_g). Compared with the single ORC system,this proposed combined cycle system can reduce the energy loss and improve the thermal performance.When Tg= 373 K,383 K and 393 K,the thermodynamic model indicates,as seen in the T-Q figure,the net power output of the combined system increases by 30. 48%,21. 9% and 17. 7% compared to the single ORC system. The thermal efficiency is improved by 11. 6%,7. 25% and 4. 19%,and the exergy efficiency increases by 45. 45%,53. 95% and 60. 05%.