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有机朗肯循环是利用低温热源的有效措施之一,将非共沸混合工质应用于有机朗肯循环尚存在争论.从热力学角度研究了非共沸混合工质的选择与边界条件之间的关系,以典型的对称型混合工质R601a/R600和非对称型混合工质R245fa/R600a为例,以带内置热交换器的有机朗肯循环为研究对象,以系统净功最大化为目标,分析了冷凝泡点温度和冷却水温升固定时混合工质的最佳浓度及系统性能.研究结果表明不同边界条件的应用对非共沸混合工质的选择具有重大影响.当固定的冷凝泡点温度被采用时,非共沸混合工质的温度滑移现象会降低系统净功,当冷却水温升固定时,温度滑移的适当提高有利于系统净功的增加,但过高的温度滑移会降低系统净功.冷凝泡点温度等于冷却水初温和冷凝器节点温差之和时所对应的净功曲线对系统设计具备指导意义.“,”Organic Rankine cycle has been considered as a reasonable method to utilize lowtemperature heat sources.It is confused whether zeotropic mixtures should be used in Organic Rankine cycles.This paper researches the relationship between boundary conditions and zeotropic mixture selection on the view of thermodynamics.R245fa/R600a and R601a/R600 are selected as typical examples of asymmetric and symmetrical zeotropic mixtures.The organic Rankine cycle system with intermediate heat exchanger is considered as the research subject to maximize the net power.The research results show different applications of boundary conditions have huge influence on zeotropic mixture selection.The fixed condenser bubble temperature and the fixed cooling water temperature rise are considered as restrictive conditions.The results show that the temperature glide decreases the net power with the fixed condenser bubble temperature.However,the opposite phenomenon will happen when the fixed cooling water temperature rise is applied.If the condenser bubble temperature is equal to the sum of cooling water inlet temperature and condenser pinch temperature difference,the corresponding performance curve of net power is significant in system design.