蒸发压力对卡琳娜循环不同目标参数的影响

研究了蒸发压力对卡琳娜循环系统性能的影响。以基液氨浓度分别为65%、75%和85%的氨水工质为研究对象,建立一个数学模型进行模拟分析。在其他变量一定的情况下,通过改变蒸发压力,从热力学第一定律、第二定律和经济性3个角度,分析其对卡琳娜循环系统热力学过程的影响。结果表明:在基液氨浓度和热源一定的条件下,蒸发压力越高,基液氨和富氨蒸气质量流量越小,蒸发器和冷凝器换热量越小,系统热效率和(火用)效率越高;存在一个最佳的蒸发压力使系统净输出功达到最大,且最佳的蒸发压力会随基液氨浓度升高而增大;蒸发器和冷凝器所占系统总(火用)损比例随蒸发压力增大而增大,而汽轮机和回热器则正好相反;从经济性角度分析还得出:当蒸发压力大于2.5MPa时,换热器的投资相对有利,对汽轮机尺寸参数的优化设计则要综合考虑其成本和发电量。

Influences of evaporating pressure on different target parameters of Kalina cycle

This article studied the effects of evaporating pressure on the Kalina cycle system. Ammonia concentrations of the base solution were 65%, 75% and 85% and a mathematical model was established for simulation analysis. Evaporating pressure was the only variable in this experiment in order to analyze its effects on Kalina thermodynamics process from the aspects of thermodynamics first and second law of and economic efficiency. The results showed that when the ammonia concentrations of the base solution and heat source were fixed, mass flow rate of base liquid ammonia and rich ammonia steam decreased with the increase of evaporating pressure, and thermal efficiency and exergy efficiency of system increased with the decrease of heat transfer of evaporator and condenser. At the optimal evaporating pressure for ammonia solution at certain concentration, the net output power was maximized, and the optimal evaporating pressure increased with the increase of base liquid ammonia concentration. The exergy loss of evaporator and condenser increased as the evaporating pressure increased, but the results for steam turbine and regenerator were the opposite. When evaporating pressure was greater than 2.5MPa, the investment of heat exchanger was relatively favorable. Therefore, the cost and power generation should be considered in the optimal design of steam turbine.