内燃机尾气余热驱动有机朗肯蒸汽压缩制冷循环的研究

设计了以内燃机尾气余热为热源驱动的有机朗肯蒸气压缩制冷循环系统。根据热力学定律,建立了循环系统的数学模型,提出了尾气换热夹点确定方法。以Matlab和Refprop软件为工具,研究了有机朗肯循环(organic Rankine cycle,ORC)各换热器负荷、做功量、热效率分别随蒸发压力、冷凝温度的变化关系,并确定了最优工质。研究了蒸汽压缩制冷循环(vapor compression refrigeration,VCR)各换热器负荷、制冷系数分别随蒸发温度、冷凝温度的变化关系。由于压缩比的限制,确定了多种制冷工质在不同冷凝温度下的最低蒸发温度,结合相关标准中所规定的各型冷藏车蒸发温度的范围,确定了各型冷藏车的可选制冷剂。研究了与可选工质对应的制冷系数随蒸发温度的变化关系,从而确定最优工质。计算了各型冷藏车在采用最优制冷剂时,在最严苛工况下的制冷量、制冷系数及综合系数。

Research on Organic Rankine Cycle-Vapor Compression Refrigeration System Driven by Exhaust Heat of an IC Engine

An organic Rankine cycle was selected to design a set of vapor compression refrigeration system driven by exhaust heat of an IC engine and using the mathematical model of the circulating system established according to the laws of thermodynamics, a method for determining the heat transfer pinch point of tail gas was proposed. Using Matlab and Refprop software as tools, the variation of the organic Rankine cycle heat exchanger''s load, cycle work and thermal efficiency with evaporation pressure and condensing temperature was studied to determine the optimum working fluid with highest thermal efficiency and largest output power. At the same time, the change of the refrigeration heat exchanger''s load and refrigeration coefficient with evaporation temperature and condensing temperature was also studied to determine the optional refrigerant with largest refrigerating capacity and highest refrigeration co-efficiency. Finally, in the case of using the best ORC working fluid and refrigerant, the refrigerating capacity, refrigeration coefficient and comprehensive coefficient were calculated under the most severe conditions for each type of refrigerated trucks.