【摘要】 本文选取湿流体R134a与R152a和干流体R123与R245fa为工质,对亚临界有机朗肯循环,采用不同的优化目标,进行了蒸发温度和冷凝温度的优化分析。在冷凝温度一定条件下,探讨了蒸发温度对系统性能的影响以及热源初始温度对工质最佳蒸发温度的影响。结果表明,在常见的排烟温度423.15 K条件下,采用干工质,不同优化目标下蒸发温度和冷凝温度优化值差异较大;而湿工质的蒸发温度和冷凝温度优化值差异较小。采用湿工质的系统优化的净电功大于干工质的,但热效率低。湿流体R134a与R152a临界温度低于热源初始温度(20±2)K时,系统存在最佳蒸发温度。可以合理调节系统部件中(火用)损来改变系统热力学性能。更多还原

【Abstract】 Taking wet fluids R134a,R152a and dry fluids R123,R245fa as the working fluid,this paper optimizes the evaporation temperature and condensation temperature in subcritical organic Rankine cycles with different objective functions.Furthermore,the effect of evaporation temperature on the performance of the system as well as the initial temperature of the waste heat source on the optimal evaporation temperature are analyzed under the given condensation temperature.The results demonstrate that the optimized evaporation temperature and condensation temperature are obviously different by using different objective functions for the dry fluids,while it is opposite as for the wet fluids under the waste heat temperature of 423.15 K.The optimized net power output for the system using wet fluids is bigger than one using dry fluids,while the optimized thermal efficiency is smaller, using wet fluids compared to dry fluids.The optimal evaporation temperature(OET) will appear for R134a and R152a when the critical temperatures of working fluids are lower than the waste heat temperatures by(20±2) K in this paper.The thermodynamic performance of the system will be improved by adjusting reasonably the ratio of exergy loss in components of the system.更多还原