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针对基于朗肯循环的汽油机尾气余热回收系统的特点,采用一种多层螺旋管式换热器作为蒸发器。根据蒸发器的结构和工作特点,在MATLAB中建立了计算模型,得到蒸发器各阶段的换热情况。模拟结果表明,工质流量的增加会导致工质与尾气在蒸发器出口处的温度降低,同时提高了废气利用率。工质的流量与过热度的增加会受换热面积的限制。为了进一步验证蒸发器的性能,建立并运行了朗肯循环余热回收试验。试验结果显示,该款蒸发器的效率最大为89.33%,实际的废气利用率最大为41.93%。
Aiming at the characteristics of exhaust heat recovery system of gasoline engine exhaust based on Rankine cycle, a multi-layer spiral tube heat exchanger is used as an evaporator. According to the structure and working characteristics of the evaporator, a calculation model is established in MATLAB, and the heat transfer conditions of each stage of the evaporator are obtained. The simulation results show that the increase of the working fluid flow will lead to the decrease of the temperature of the working fluid and tail gas at the outlet of the evaporator, and at the same time improve the utilization efficiency of the exhaust gas. Working fluid flow and superheat increase will be limited by the heat transfer area. In order to further verify the performance of the evaporator, Rankine cycle waste heat recovery test was established and operated. The test results show that the maximum efficiency of the evaporator is 89.33%, the actual maximum utilization of exhaust gas was 41.93%.