工质对低温蒸汽闪蒸–双工质联合循环性能的影响

Thermodynamic Performance Analysis for Flashing-binary Cycle Using Different Working Fluids to Low Temperature Steam

为获得不同工质对新型双工质-闪蒸-双工质联合循环系统热力性能的影响规律及确定系统最佳工质,以流量27.8 kg/s,383.15 K的饱和蒸汽为热源,针对5种低沸点有机工质,以热力学第一、二定律为基础,编制计算程序,将不同工质对该联合循环系统热力性能的影响进行了对比分析。研究结果表明:在具有潜热的高压级双工质阶段,采用不同工质系统净输出功和热效率随蒸发压力增加均呈现出逐渐增加,增幅减小的趋势,热力性能表现为R600>R236fa>R114>R245fa>R123;对于不同温度热水热源,净输出功则表现出随蒸发压力的提高先增加后减小的特点,在汽轮机背压一定时,工质的沸点越低,其热力性能越好,热力性能表现为R236fa>R600>R114>R245fa>R123;在高压级、低压级双工质阶段分别采用R600,R236fa作为工质时,该联合循环系统取得最大净输出功6 466.1 kW、最大热效率9.46%和最小火用损失9 511.5 kW。

In order to obtain the thermodynamic performance of different organic working fluids on binaryflash-binary system and determine the best fluids, the saturated steam at 27.8 kg/s and 383.15 K was regarded as heat source. Based on the first and the second law of thermodynamic, the calculation program was written. The results show that in the high level binary stage which has latent heat, the net output work increases gradually with the evaporation pressure. And so does the thermal efficiency. But it increases more and more slowly, while the thermal performance shows R600〉R236fa〉 R114〉R245fa〉R123. As for the hot water heat source, the net output power increases at first and then decreases. When the back pressure is certain, the boiling point is lower, the thermodynamic performance is better. And the performance reveals to R236fa〉R600〉R114〉R245fa〉R123. The combined cycle system can reach the largest net output work of 6 466.1 kW, the maximum thermal efficiency of 9.46% and the minimum energy loss of 9 511.5 kW when R600, R236 fa are used respectively in high level and low level binary phase.