Optimization of cold-end system of thermal power plants based on entropy generation minimization

Cold-end systems are heat sinks of thermal power cycles,which have an essential effect on the overall performance of thermal power plants.To enhance the efficiency of thermal power plants,multi-pressure condensers have been applied in some large-capacity thermal power plants.However,little attention has been paid to the optimization of the cold-end system with multi-pressure condensers which have multiple parameters to be identified.Therefore,the design optimization methods of coldend systems with single-and multi-pressure condensers are developed based on the entropy generation rate,and the genetic algorithm(GA)is used to optimize multiple parameters.Multiple parameters,including heat transfer area of multi-pressure condensers,steam distribution in condensers,and cooling water mass flow rate,are optimized while considering detailed entropy generation rate of the cold-end systems.The results show that the entropy generation rate of the multi-pressure cold-end system is less than that of the single-pressure cold-end system when the total condenser area is constant.Moreover,the economic performance can be improved with the adoption of the multi-pressure cold-end system.When compared with the single-pressure cold-end system,the excess revenues gained by using dual-and quadruplepressure cold-end systems are 575 and 580 k$/a,respectively.