Working fluids can play a critical role in the working of an organic Rankine cycle system. A direct vapor generation solar organic Rankine cycle embedded with phase change material storage is analyzed in this study. The system comprised of an array of evacuated flat plate collectors, phase change material based thermal storage, expander, condenser, and organic working fluid pump. The storage tank model is modeled using a finite difference method in MATLAB programming environment while the 1D model of ORC system is used to evaluate the system performance. After a careful screen, 12 dry and isentropic working fluids were selected and their impact on the performance of the heat storage tank and the overall system is evaluated. The results show that the system efficiencies increase and decrease with the increment and decrement in the critical temperature of the working fluid. Moreover, the rise and fall of working fluid temperature, phase change material temperature, and the quantity of energy stored and released generally increase with an increase in the critical temperature of the working fluid. At the evaporation temperature of 10 °C higher and lower than the melting point temperature of the phase change material, Benzene has achieved the highest system efficiencies of 10.7% & 10.4% during charging and discharging mode, respectively. However, the maximum the rise and fall of working fluid temperature, phase change material temperature, and the quantity of energy stored and released during charging and discharging mode is attained by Heptane which is found to be 5.35 °C & 7.34 °C, 0.48 °C & 0.44 °C and 13.81 MJ & 23.04 MJ, respectively. Heptane has shown overall best performance among the selected working fluids and found to be feasible for phase change material storage based direct vapor generation solar ORC system.

中文翻译：

---

工质对相变材料存储直接蒸汽发电太阳能有机朗肯循环系统性能的影响

工作流体在有机朗肯循环系统的工作中发挥着关键作用。本研究分析了嵌入相变材料存储的直接蒸汽发生太阳能有机朗肯循环。该系统由一系列真空平板集热器、基于相变材料的蓄热器、膨胀器、冷凝器和有机工作流体泵组成。在MATLAB编程环境中采用有限差分法对储罐模型进行建模，并使用ORC系统的一维模型来评估系统性能。经过仔细筛选，选择了 12 种干燥等熵工质，并评估了它们对储热罐和整个系统性能的影响。结果表明，系统效率随着工质临界温度的升高和降低而升高和降低。而且，工作流体温度的升降、相变材料温度以及储存和释放的能量的量通常随着工作流体的临界温度的增加而增加。在比相变材料熔点温度高和低10℃的蒸发温度下，苯在充电和放电模式下分别实现了最高的系统效率，分别为10.7%和10.4%。然而，庚烷在充放电模式下工作流体温度、相变材料温度以及储存和释放能量的升降量最大，为5.35℃和7.34℃，0.48℃。分别为 C 和 0.44 °C 以及 13.81 MJ 和 23.04 MJ。庚烷在所选工作流体中表现出整体最佳性能，并且被发现对于基于相变材料存储的直接蒸汽发生太阳能 ORC 系统是可行的。