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为减少中低温有机朗肯循环系统中由换热温差引起的不可逆损失,针对地热热源,提出一种新型ORC-f(有机朗肯循环-分流闪蒸)系统,并建立其热力学模型。以二元非共沸混合物R245fa/R152a为工质,分析比较了不同热源温度下,在有/无分流闪蒸的两个系统中,工质配比对系统热力性能的影响。研究结果表明:在不同热源温度下,热力性能呈现混合工质ORC-f系统>混合工质ORC系统>纯工质ORC(有机朗肯循环)系统的规律,在Tg=373 K时,净输出功及热回收率依次为333.24、259.62、241.70 k W,0.631 1、0.453 7及0.447 0;当混合工质配比在0-1之间变化时,系统热力性能存在两个极大值点,且对应配比不随热源温度变化而变化;随热源温度增加,采用混合工质及分流闪蒸使系统净输出功增幅提高,但热回收率增幅相对降低。若以净输出功为目标,在热源温度较高时,应优先采用非共沸混合工质ORC-f系统。
In order to reduce the irreversible loss caused by the temperature difference of heat exchange in the medium-low temperature organic Rankine cycle system, a new ORC-f (organic Rankine cycle-split flash) system is proposed for geothermal heat source, and its thermodynamic model is established. The binary non-azeotropic mixture R245fa / R152a was used as the working fluid to analyze the effect of working material ratio on the thermal performance of the system in two systems with / without shunt flashing at different heat source temperatures. The results show that at different heat source temperatures, the thermodynamic properties of ORC-f system> mixed-mode ORC system> ORC (organic Rankine cycle) system show that at Tg = 373 K, the net output The work and heat recovery rates are 333.24, 259.62, 241.70 k W, 0.631 1, 0.453 7 and 0.447 0, respectively. When the mixture ratio of the mixed medium varies from 0 to 1, there are two maximum points in the thermodynamic performance of the system, And the corresponding ratio does not change with the temperature of the heat source. With the increase of the temperature of the heat source, the increase of the net output power of the system is enhanced by the mixed working fluid and by the shunting and flashing, but the increase of the heat recovery rate is relatively lower. If the net output work as a target, the heat source temperature is higher, priority should be given to non-azeotropic mixed refrigerant ORC-f system.