基于内置换热器有机闪蒸循环的热性能研究

构建了内置换热器有机闪蒸循环（internal heat exchanger organic flash cycle, IHE-OFC）系统模型，采用100~200℃地热水作为热源，以R600a、R600、R601a、R601、R236ea、R227ea、R245fa、R123作为循环工质。研究了IHE-OFC系统的热性能，并以净输出功率为目标函数，对系统进行了优化。结果表明：当热源温度≤160℃时，R601 IHE-OFC系统的净输出功率最大；当热源温度≥190℃时，R601传统OFC系统的净输出功率最大；当热源温度为170℃时，R601a IHE-OFC系统的净输出功率最大；当热源温度为180℃时，R601a传统OFC系统的净输出功率最大。此外，每一工质均存在一个特征温度，为工质的0.85P_cri所对应的温度与加热器夹点温差之和。且因工质特征温度的影响，IHE-OFC系统的最优闪蒸压力、IHE冷流体温升和系统效率随热源温度的升高而均呈先增大后不变的趋势。

Thermal performance study of organic flash cycle based on internal heat exchanger

In this study, an internal heat exchanger organic flash cycle (IHE-OFC) system model was built, using 100—200℃ geothermal water as the heat source, and R600a, R600, R601a, R601, R236ea, R227ea, R245fa, R123 as circulating working fluid. Thermodynamic analysis of the IHE-OFC system is conducted, and the system is optimized with net power output as the optimization objective. The results show that when the heat source temperature is less than or equal to 160℃, the net power output of the R601 IHE-OFC system is maximal. When the heat source temperature is higher than or equal to 190℃，the net power output of the R601 traditional OFC system is maximal. When the heat source temperature is 170℃, the net power output of the R601a IHE-OFC system is maximal. When the heat source temperature is 180℃，the net power output of the R601a traditional OFC system is maximal. Moreover, there is a characteristic temperature for each working fluid, which is the sum of the temperature corresponding to 0.85P_cri and pinch point temperature difference of heater. Due to the influence of the characteristic temperature of the working fluid, the optimal flash pressure, IHE temperature rise on the low temperature side, and the system efficiency initially increases and then remains constant with increasing heat source temperature.