Experimental study of organic Rankine cycle power generation system under various operating conditions

doi:10.16085/j.issn.1000-6613.2017-0487

Abstract

Abstract: Due to the instability of waste heat resource and environment temperature, the organic Rankine cycle (ORC)system should have strong various operating ability in practical application. In this paper, the experimental test of an organic Rankine cycle (ORC) system with R245fa as the working fluid under various operating condition were carried out. The effect of cold and heat sources temperature on ORC system performance were analyzed under the constant electric energy production operating. It was found that the decreased heat resource temperature would decrease the inlet temperature and superheat of expander. Because the expander internal leakage was increased, the expander isentropic efficiency was decreased, and the mass flow rate of the working fluid had to increase to maintain the constant output power. With the falling temperature of heat source, the heat transfer coefficient of evaporator and the electrical efficiency were increased. When the inlet temperature of cooling water was kept at 10℃, the electrical efficiency of ORC system was increased from 5.03% to 5.25% with decreasing heat resource temperature from 115℃ to 100℃. Therefore, the temperature of cold source significantly affected the pressure at expander inlet and outlet. With the inlet temperature of cooling water decreased, the expander isentropic efficiency was decreased, whereas the pressure ratio of the expander as well as the power output capability of unit mass of working fluid were increased. Hence, the electrical efficiency and pure efficiency of the system were increased. When the inlet temperature of cooling water was increased from 10℃ to 30℃ at the hot source temperature of 115℃, the electrical efficiency of ORC system was decreased from 7.01% to 6.08%.

Key words: organic Rankine cycle, cold and heat sources, various operating conditions, experimental validation, exergy

摘要： 受余热热源及环境温度不稳定特性的制约，有机朗肯循环（ORC）发电系统在实际应用中需要有较强的变工况能力。本文以R245fa为工质，实验研究了在不同冷热源温度时，ORC系统在相同负载容量及膨胀机转速下的变工况运行特性及各部件实际性能。实验结果表明：热源温度主要决定了膨胀机的入口温度及过热度。随着热源温度的降低，膨胀机内部泄漏量变大，其等熵效率变低，单位质量工质做功能力变差，维持膨胀机做功状态的工质质量流量增加。由于工质在蒸发器内整体吸热量变小，系统发电效率随热源温度的降低而升高。在10℃冷源温度下，热源温度从115℃下降至100℃，机组的最大发电效率从5.03%升高至5.25%。改变冷源温度，主要作用于膨胀机的进出口压力，改变了膨胀机的做功状态。降低冷源温度，膨胀机压比升高，单位质量工质做功能力变强，维持膨胀机做功状态的工质质量流量减小。但由于膨胀机过膨胀运行带来的不可逆损失增加，膨胀机的等熵效率随冷源温度降低而减小。在115℃热源温度下，冷源温度从30℃下降至10℃，系统最大发电效率从6.08%升高至7.01%。

关键词: 有机朗肯循环, 冷热源, 变工况, 实验验证, (火用)

CLC Number:

TK11⁺5

CAO Shuang, LIU Xiulong, ZHANG Ming, XU Jinliang. Experimental study of organic Rankine cycle power generation system under various operating conditions[J]. Chemical Industry and Engineering Progress, 2018, 37(01): 88-95.

曹泷, 刘秀龙, 张鸣, 徐进良. 有机朗肯循环发电系统变工况运行的实验研究[J]. 化工进展, 2018, 37(01): 88-95.

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