基于粒子群算法的海洋温差能朗肯循环系统多目标优化

MULTI-OBJECTIVE OPTIMIZATION OF OTEC RANKINE CYCLE BASED ON PSO ALGORITHM

为提高海洋温差能发电系统的综合性能,以单位换热面积发电量和单位海水流量发电量为基础建立综合目标函数,选取蒸发温度、冷凝温度、蒸发器和冷凝器的海水出口温度为优化变量,利用粒子群算法对海洋温差能朗肯循环系统进行多目标参数优化。研究结果表明,在28℃温海水和5℃冷海水条件下,循环工质为R717时,蒸发器内的最佳蒸发温度为23.10℃,温海水出口温度为23.42℃;冷凝器内的最佳冷凝温度为12.31℃,冷海水出口温度为10.80℃;在换热器的海水进出口温差超过4℃时,换热器的海水出口温度对系统性能的影响较小。综上,采用多目标优化可实现对各评价指标间的协调,相比单目标优化的传统模型,多目标优化改善了系统的综合性能。

To improve the overall performance of the power generation system of ocean thermal energy conversion(OTEC),an integrated objective function based on the power capacity per unit heat exchange area and per unit seawater flow has been developed. The evaporating temperature,condensing temperature and seawater temperatures at the outlet of evaporator and condenser have been selected as optimization variables. The algorithm of particle swarm has been utilized to optimize the parameters of the Rankine cycle system of OTEC. The results obtained show that it is able to realize coordination of evaluation indicators with a multi-objective optimization model. When the temperatures of warm seawater and cold seawater are 28 ℃ and 5 ℃ respectively,the best evaporating temperature in the evaporator and the warm seawater outlet temperature are 23.10 ℃ and 23.42 ℃ respectively,and the best condensing temperature and cold seawater outlet temperature are 12.31 ℃ and 10.80 ℃ respectively,with R717 as working fluid. Moreover,when the temperature difference between seawater inlet and outlet in the heat exchanger is more than 4 ℃,the absolute value of temperature for the seawater outlet in the heat exchanger has less impact on the system performance. Compared with the traditional mono-optimization model,the integrated optimization has improved the overall performance of system.