Thermoeconomic multi-objective optimization of a dual loop organic Rankine cycle (ORC) for CNG engine waste heat recovery
Thermoeconomic multi-objective optimization of a dual loop organic Rankine cycle (ORC) for CNG engine waste heat recovery
复制标题
CNG 发动机余热回收双回路有机朗肯循环 (ORC) 的热经济多目标优化
DOI：
10.1016/j.apenergy.2017.08.127
复制
发表时间：
2017-11-01
期刊：
影响因子：
11.2
通讯作者：
Zhang, Jian
中科院分区：
文献类型：
--
作者：
Yang, Fubin;Cho, Heejin;Zhang, Jian
本文建立了双回路有机朗肯循环（ORC）系统的热经济模型，分析了压缩天然气（CNG）发动机废热回收中几种工质组的热力学和经济性能。研究了六个关键参数对双回路ORC系统热经济指标的影响。在此基础上，采用多目标遗传算法求解CNG发动机全工况下净功率输出最大化和总投资最小的Pareto最优解。筛选出最合适的工质组，确定最优参数区域。结果表明，较高的蒸发压力和较低的冷凝温度对双回路ORC系统的热经济性能有积极影响，而过热度和排气口温度的变化对系统热经济性能的影响不明显。高温循环ORC （HT循环）的最佳蒸发压力始终在2.5 MPa以上。高温循环的最佳冷凝温度、低温回路ORC （LT循环）的最佳蒸发温度和冷凝温度基本保持不变。此外，最优排气出口温度主要受发动机转速的影响。在额定工况下，双回路ORC系统的最大净输出功率为23.62 kW，最小产电成本（EPC）为0.41美元/kW h，整个运行范围内双回路ORC系统的热效率为8.97 ~ 10.19%。
In this paper, a thermoeconomic model of a dual loop organic Rankine cycle (ORC) system has been developed to analyze both the thermodynamic and economic performance of several working fluid groups for the purpose of compressed natural gas (CNG) engine waste heat recovery. The effects of six key parameters on the thermoeconomic indicators of the dual loop ORC system are investigated. Furthermore, a multi-objective genetic algorithm (GA) is employed to solve the Pareto optimal solutions from the viewpoints of maximizing net power output and minimizing total investment post over the whole operating range of the CNG engine. The most suitable working fluid group is screened out, then the optimal parameter regions are determined. The results show that a higher evaporation pressure and a lower condensation temperature exhibit a positive effect on the thermoeconomic performances of the dual loop ORC system while the effects of variation in superheat degree and exhaust outlet temperature on the thermoeconomic performances are not obvious. The optimal evaporation pressure of the high temperature loop ORC (HT cycle) is always above 2.5 MPa. The optimal condensation temperature of the HT cycle, optimal evaporation temperature and condensation temperature of the low temperature loop ORC (LT cycle) are all kept almost constants. In addition, the optimal exhaust outlet temperature is mainly influenced by the engine speed. At the rated condition, the dual loop ORC system has the maximum net power output of 23.62 kW and the minimum electricity production cost (EPC) of 0.41 $/kW h. The thermal efficiency of the dual loop ORC system is in the range of 8.97-10.19% over the whole operating range.