Performance optimization for a novel combined cooling, heating and power-organic Rankine cycle system with improved following electric load strategy based on different objectives

Abstract

In this paper, a novel combined cooling, heating and power-organic Rankine cycle system is proposed. The purpose of the system is to enrich the approach of energy cascade utilization by using different grades of waste heat flexibly. In addition, an improved following electric load strategy for the system is introduced, which could control the prime mover and organic Rankine cycle to share electric demand. To explore the optimization potential of the system under the new strategy, several configuration parameters and operation parameters are synergistically optimized by using enumeration method. Herein, the optimization variables are rated capacity of prime mover, exhaust smoke temperature, exhaust smoke distribution coefficient and cooling load distribution coefficient. The optimization objectives are annual total cost saving, primary energy consumption saving, carbon dioxide emission reduction and comprehensive benefit. The results indicate that the optimal values of above objectives are 38.11%, 21.05%, 47.61% and 35.38%, respectively. Moreover, the variable characteristics, the system performance indexes and the energy dispatch for different objectives are compared and analyzed. To enhance the system flexibility, the variables are further optimized according to the load characteristics of different seasons by using genetic algorithm. The results show that the optimal values of above objectives are further increased by 4.8%, 10.7%, 3.7% and 5.9% respectively. The change of exhaust smoke temperature is conducive to improve the heat utilization efficiency in winter. These findings could promote the sustainable development of the integrated system.