前置喷射器的热机热泵联合循环热力性能研究

Study on Thermal Performance of Heat Engine and Heat Pump Combined Cycle with Pre-injector

为解决传统余热回收发电系统净发电效率与综合热经济性之间矛盾的问题,将有机朗肯循环与喷射式热泵相结合,将喷射式热泵系统布置在有机朗肯循环膨胀机进口侧,提出了前置喷射器的热机热泵联合循环,该系统可在保障电力输出的条件下对热用户供热。研究了系统主要参数对净发电效率与系统经济性的影响规律,分析了联合循环在热力优先模式和电力优先模式下的性能极限。结果表明:联合循环在净发电效率、净发电量较优时,系统的动态投资回收期较差,存在最优的冷凝压力使得系统动态投资回收期最优;与基本型ORC对比,联合循环电力优先模式可在保障冷源产生经济效益的前提下,使电力输出能力相对提高18.62%,热源利用效率相对提高19.29%,火用效率提高至34.87%;在热力优先模式下,联合循环最高可将冷源由15℃加热至59.38℃;当联合循环对外输出40℃/60℃二级管网热水时,系统净发电量相对减少3.8%,热源利用效率相对提高30.66%。

In order to solve the contradiction between the net power generation efficiency and the comprehensive thermal economy of the traditional waste heat recovery power generation system,the organic Rankine cycle is combined with the jet heat pump,and the jet heat pump system is arranged on the inlet side of the organic Rankine cycle expander.The combined cycle of engine and heat pump with pre-injector is proposed.This system can supply heat to the heat user under the condition of ensuring power output.The influence of the main parameters of the system on the net power generation efficiency and system economy is studied.The performance limit of the combined cycle in the heat priority mode and the power priority mode is analyzed.The results show that when the net power generation efficiency and net power generation of combined cycle are better,the dynamic investment recovery period of the system is poor,and the optimal condensing pressure makes the system dynamic investment recovery period optimal.Compared with the basic ORC,under the premise of ensuring the economic benefits of cold sources,the power priority mode of the combined cycle can increase the power output capacity by 18.62%,the heat source utilization efficiency by 19.29%,and the exergy efficiency to 34.87%.Under the heat priority mode,the combined cycle can heat the cold source from 15℃to 59.38℃.When the combined cycle externally outputs 40℃/60℃secondary circuit hot water,the net power generation of the system is reduced by 3.8%,and the heat source utilization efficiency is increased by 30.66%.