不同工质对有机朗肯循环低温余热发电系统性能的影响研究

Influence of different working fluids on performance of organic Rankine cycle low temperature waste heat power generation system

目前有机朗肯循环低温余热发电系统的研究主要存在系统的评价指标不一、工质的可比性比较弱、不能全面地反映系统的综合性能等问题。针对90~240℃低温余热资源,从安全性、环保性、经济性和工质物性角度出发初选工质,得到R11、R123、R245fa和R365mfc等有机工质,通过MATLAB和REFPROP软件建立了该系统的数学模型,对系统进行了热力性能研究。研究结果表明:系统的热效率和净输出功均随着蒸发温度的升高而逐渐增大,随着冷凝温度的升高而逐渐降低;最佳蒸发温度与最佳的冷凝温度分别控制在120~140℃与20~30℃;氢氟烃类有较高的净输出功率,环保性能好,氯氟烃类工质热效率高于其他类工质;综合评价得出R365mfc净输出功率最高,㶲损失较少,环保又安全,为最佳制冷剂;系统各部件蒸发器的㶲损失最大,冷凝器和膨胀机次之,工质泵最小。

At present,researcheson organic Rankine cyclelow-temperature waste heat power generation system mainly haveproblems such as different evaluation indexes of the system,relatively weak comparability of working fluid,and incomprehensive performance response capability of the system.For the 90~240℃low-temperature waste heat resources,this paper selects the working fluids from theaspects of safety,environmental protection,economy and physical properties of the working fluids.The organic working fluids such as R11,R123,R245fa and R365mfc are selected.The software MATLAB and REFPROP are used to establish mathematical model of the systemtostudy the thermal performance of the system.The results show that,the thermal efficiency and net output of the system are directly proportional to the evaporation temperature and inversely proportional to the condensing temperature.The best evaporating temperature and condensing temperature are 120~140℃and 20~30℃,respectively.Hydrofluorhydrocarbons(HFC)has a higher net output powerandbetter environmental performance,and the thermal efficiency of chlorofluorocarbons(CFC)hashigher thermal efficiency thanother working fluids.Considering comprehensively,R365mfc has the highest net output powerandless exergy loss,and is environmentally friendlyand safe,whichis theoptimalrefrigerant.The evaporator in eachcomponent of the system has the largest exergy loss,then isthe condenser and expander,the working fluid pump hasthe smallestexergy loss.