有机朗肯循环发电系统多目标优化及变工况下的性能分析

Multi-Objective Optimization of ORC Systems and Performance Analysis under Off-Design Condition

摘要: 本文以R245fa为工质的再热型、回热型及基本型有机朗肯循环发电系统为对象，以热效率、火用效率及初投资作为优化变量，以实现系统对中低温热源回收的综合性能最优为目标，构建了优化函数，分析比较了三种系统的综合性能，分析表明，在给定余热条件下，采用回热型有机朗肯循环发电系统更适合。在此基础上，对回热型有机朗肯循环发电系统的变工况特性进行了分析，以输出功率最大为目标运行时，热源温度的改变对系统运行压力的影响相比热源流量的变化更大；输出功率及系统热效率随热源温度及流量增加而增加，热回收效率随热源温度的增加而增加，但却随热源流量的增加而降低，当热源温度及流量分别为423 K、12 kg∙s⁻¹时，系统热回收效率达到最小值4.39%，而当热源温度及流量分别为473 K、6 kg∙s⁻¹时，热回收效率达到最大值7.46%。

Abstract: This paper takes thermal efficiency, energy efficiency and the Initial investment cost as the opti-mization object, compared the comprehensive performance of Organic Ranking Cycle (ORC) with recuperator, reheat Organic Ranking Cycle and Organic Ranking Cycle power generation systems which using R245fa as working fluid. The result suggests that Organic Ranking Cycle with recupe-rator is more suitable for the recovery of the low-temperature heat source on the given parameters. Analyses of characteristics under off-design condition are conducted under this foundation. When the goal is to maximize the output power for the energy recovery system, the heat source’s temperature changes have a significant impact on the system operating pressure; the net power output and the thermal efficiency increased with increasing heat source’s temperature or mass flow rate. However, the heat recovery efficiency with increasing temperature of the heat source increases, but with the increase of heat flow decreases. Its minimum value, 4.39%, is achieved for heat source temperature and mass flow rate equal to 423 K and 12 kg∙s⁻¹, while its maximum value, 7.46%, is achieved for heat source temperature and mass flow rate equal to 473 K and 6 kg∙s⁻¹.