Abstract

The technical, economical and environmental performances of combined cooling, heating and power (CCHP) system are closely dependent on its design and operation strategy. This paper analyzes the energy flow of CCHP system and deduces the primary energy consumption following the thermal demand of building. Three criteria, primary energy saving (PES), annual total cost saving (ATCS), and carbon dioxide emission reduction (CDER) are selected to evaluate the performance of CCHP system. Based on the energy flow of CCHP system, the capacity and operation of CCHP system are optimized by genetic algorithm (GA) so as to maximize the technical, economical and environmental benefits achieved by CCHP system in comparison to separation production system. A numerical example of gas CCHP system for a hotel building in Beijing is given to ascertain the effectiveness of the optimal method. Furthermore, a sensitivity analysis is presented in order to show how the optimal operation strategy would vary due to the changes of electricity price and gas price.

Introduction

Combined cooling, heating and power (CCHP) system is broadly identified as an alternative for the world to meet and solve energyrelated problems, such as increasing energy demands, increasing energy cost, energy supply security, and environmental concerns [1–۶]. A good CCHP system must yield economical savings, but more importantly must yield real energy savings as well as reducing the emission of pollutants. The performance of CCHP system is closely dependent on its design and operation. Aiming to maximize the benefits from CCHP system in comparison to traditional separation production (SP), it is necessary to optimize the design and operation strategy. Many studies have been reported on this topic. Better performances (e.g. operations cost, carbon dioxide emission reduction (CDER), and primary energy consumption (PEC)) can be obtained when the optimization was applied to design and/or operate CCHP systems. The optimized CCHP systems have different components. For example, the prime mover includes gas turbine [7–۹], steam turbine [10,11], gas engine [12,13], a steam Rankine process using biomass fuels [14], and the cooling system adopts compression [15], absorption [7,15], and ejector refrigeration cycle [11], etc.