摘要
To improve the overall thermal efficiency of the organic Rankine cycle（ ORC）, a simulation study was carried out for a combined heat and power（ CHP） system, using the Redlich-Kuang-Soave（ RKS） equation of state. In the system,R245 fa was selected as the working fluid. A scroll expander was modeled with empirical isentropic expansion efficiency.Plate heat exchangers were selected as the evaporator and the condenser, and detailed heat transfer models were programmed for both one-phase and two-phase regions. Simulations were carried out at seven different heat source temperatures（ 80,90, 100, 110, 120, 130, 140 ℃） in combination with eight different heat sink temperatures（ 20, 25, 30, 35, 40, 45, 50,55 ℃）. Results showthat in the ORC without an internal heat exchanger（ IHE）, the optimum cycle efficiencies are in the range of 7. 0% to 7. 3% when the temperature differences between the heat source and heat sink are in the range of 70 to90 ℃. Simulations on CHP reveal that domestic hot water can be produced when the heat sink inlet temperature is higher than40 ℃, and the corresponding exergy efficiency and overall thermal efficiency are 29% to 56% and 87% to 90% higher than those in the non-CHP ORC, respectively. It is found that the IHE has little effect on the improvement of work output and efficiencies for the CHP ORC.
为提高有机朗肯循环（ORC）的热效率,基于RKS状态方程编制模拟程序对热电联产系统进行模拟研究.其中,循环工质选用R245fa,涡旋膨胀机模型依据经验等熵膨胀效率建立,蒸发器和冷凝器选用板式换热器,并对单、两相区建立详细的传热模型.该程序模拟了7个热源温度（80,90,100,110,120,130,140℃）和8个冷源温度（20,25,30,35,40,45,50,55℃）下的循环工况.结果表明：在无内热交换器ORC中,当冷热源温差处于7090℃,最佳循环效率为7.0%7.3%;当冷源入口温度高于40℃,CHP ORC输出生活热水,且系统效率和热效率分别比非CHP系统增加了29%56%和87%90%;内热交换器对CHP ORC系统输出功及效率的改善很小.
基金
Special Fund for Industry
University and Research Cooperation(No.2011DFR61130)
