中文摘要：

利用150～350℃热源范围的中高温有机朗肯循环在可再生能源和工业余热利用领域具有广泛的应用前景。但是在中高温热源温度下,有机工质可能会发生热分解,因此热稳定性成为中高温有机朗肯循环工质筛选的首要限制条件。本文提出一种化学热力学方法来对有机工质的热稳定性进行预测。首先通过理论分析给出可能的反应途径;再选择吉布斯函数作为指标,计算各反应中ΔG=0时的温度,以最小值Tg作为表征热稳定性的参数。通过与已有的实验结果比较,发现不同有机工质Tg值的相对大小关系与热分解温度的相对大小关系基本一致。使用化学热力学方法对R152a的热分解温度范围进行预测并设计实验进行验证,实验结果与预测结果相符合。

英文摘要：

The high temperature（150～350℃） Organic Rankine Cycles（ORC） have wide application prospects in the renewable energy utilization and industry waste heat recovery.The working fluid thermal stability is the primary limitation for the high temperature ORCs due to the decomposition of working fluids at high temperatures.This paper presented a chemical thermodynamics prediction method for the working fluid thermal stability.The possible reaction paths were first analyzed by theory.The temperature of each reaction was calculated when the Gibbs function change was zero and the minimum value Tg was chosen as the indicator of thermal stability.The relative values of Tg were consistent with the relative values of existing experimental decomposition temperatures.A decomposition experiment was designed to verify the prediction method with R152 a as test fluid.The results showed that the prediction result was consistent with the experimental result.