低品位热能驱动有机朗肯循环的变工况特性

Off-design performance of organic Rankine cycle driven by low grade waste heat

构建有机朗肯循环变工况分析模型,研究热源条件对系统变工况性能的影响规律。结果表明:随着热源温度升高,系统的最佳蒸发压力线性增大,而涡旋膨胀机的等熵效率逐渐减小。相比额定工况,热源温度变化-30.0K与30.0K时,净输出功率变化了-32.4%与18.4%,热效率降低了4.0%与11.4%,热回收效率变化幅度分别为-9.8%及8.9%;当热源温度从423增大至483K时,系统不可逆损失的变化率为-37.1%与45.5%,火用效率的变化率为6.7%与-17.5%。相比热源流量,热源温度对系统变工况性能的影响更大。

An off-design model for an organic Rankin cycle（ORC）was developed and R245fa was used as a working fluid. The results show that operating pressure and the evaporation temperature increase at an almost constant rate as heat source temperature increases. However, isentropic efficiency of scroll expander decreases with the increment of heat source temperature. Within a heat source temperature variation of -- 30.0 to 30.0 K from design, there is a variation of - 32. 4% to 18. 4% for net power, - 4.0% to - 11.4% for thermal efficiency and - 9.8% to 8.9% for heat recovery efficiency. When heat source temperature increases from 423 to 483 K, there are variations of-37.1% to 45.5% and 6.7% to - 17.5% from design in the irreversibility and exergy efficiency. Besides, the influence of the heat source temperature on system performance is larger than that of mass flow rate.