Simulation and optimization of the performance in the air-conditioning season of a BCHP system in China

Building cooling, heating and power generation (BCHP) is expected to play an important role in the sustainable energy strategy for buildings. However, in many cases the performance of BCHP systems is not as good as predicted and thus perplexes designers and building owners. In this paper the performance of a typical BCHP system is investigated using thermodynamic and thermoeconomic analyses based on the simulation of off-design operation and the performance optimization of the system with the help of a great number of real operation data of the system and the master data supplied by manufacturers. Two optimization problems using exergetic efficiency and gross benefit of the whole BCHP system, respectively, as objective functions are developed in virtue of curve fitting. Computations result in various graphs, which as references are helpful for judging whether or not the system operation is correct. The graphs show that only with enough high load rates can the system operation yield positive benefits. The simulation tells that the fuel cost of BCHP in China accounts for 70–80% of its total cost and therefore is the most important factor in spreading BCHP in the country.