Investigation On The Application Of VM Cycle Heat Pump In Distributed Energy System

Distributed energy system can be placed near the user side, it can offer a variety of production of energy to meet user's requirements. It has the characteristics of high efficiency of energy utilization, low investment, low loss, and environmental friendly, etc. But for the small capacity of distributed energy system, it's a problem about how to select appropriate heating refrigeration equipment. So this article investigate the application of VM cycle heat pump in distributed energy system, in order to improve the cascade utilization of energy, relieve the energy emergency and environmental pollution.According to the standard specification, the required cold, heat, electricity and hot water load of a 100m~2 independent housing which is located in the suburb of Beijing was calculated. Through the comparative and analysis, biogas was used as the fuel, the micro gas turbine was used as power generation equipment. Three different schemes of distributed energy system were built, compression type, lithium bromide absorption and VM cycle heat pump was used respectively.Thermodynamic parameters of three different schemes were calculated by MATLAB based on law of the thermodynamics. It shows that, as the waste heat was not used sufficiently, first scheme's average efficiency is 60.02%, average exergy efficiency is 27.78%, it not reaches the general level of distributed energy system. Second scheme's average thermal efficiency is 85.32%, average exergy efficiency is 41.92%, it has good thermodynamic performanc. The third scheme's average thermal efficiency is 89.91%, the average exergy efficiency is 42.82%, is the tallest of the three schemes.Fuzzy comprehensive evaluation was used to compare three schemes. This article selects economic index, technical index and environmental protection index and the corresponding twelve secondary indexes.The results show that the second scheme was best, the comprehensive value is 0.8273. The third d scheme is in middle level, the comprehensive value is value is 0.7959. The first scheme was worst, the comprehensive value is 0.7647. But the capacity lithium bromide absorption heat pump limits the application of the second scheme, so the third scheme is a good choose in actual.the load often change in actual, which lead to the output of micro gas turbine doesn't match the output of VM cycle heat pump. Through thermodynamic calculation and analysis this articler adds energy-storage device, afterburning device and flue heat exchanger cooling device to improve the system structure. Through thermodynamic calculation it show that the optimized system can meet different load demand of users.