Evaluation And Optimization Of Combined Cooling Heating And Power System Based On 30kW Micro-turbine

Combined Cooling Heating and Power(CCHP) system is developed on the basis of conventional cogeneration, which is based on natural gas as a primary energy,recycling the waste heat after generating electricity.It can provide cold, heat and electricity simultaneously to users to meet their needs for different energy.In recent years, the applications of CCHP system are widespread as its energy efficiency and flexibility,which can be more compact and decentralized installation in the vicinity of the users.Therefore, whether the CCHP system having the characteristics of energy conservation has become a hot topic.This thesis studies the 30 kW micro-turbine CCHP system according to both the first and the second law of thermodynamics.Firstly,the use of energy analysis to analyze the energy efficiency of cogeneration system comparing the separated system producing the same amount of cold, heat and electricity independently. These results show that the cogeneration system is energy efficient in winter, but in summer is not always energy-saving.Secondly, each components of the cogeneration system were analyzed using exergy analysis, found that the biggest part of system exergy lose is the combustion chamber.The reasons for lower energy efficiency of cogeneration system in summer is analyzed from the perspective of the second law of thermodynamics.In addition, the primary energy saving rate, exergy efficiency and exergy loss of cogeneration systems were studied in terms of sensitivity analysis;and the influence of the ambient temperature, thermoelectric ratio, compression ratio of compressor as well as compression efficiency of constant entropy and other factors were also considered on the performance of cogeneration system.Besides, this paper studies the characteristics of nitrogen oxides and carbon dioxide emissions of cogeneration system,resulting this cogeneration system can reduce emission comparing separated system,especially for the rate reduction of nitrogen oxides.Also, with the power generation system becoming more efficiency, emissions characteristics of the system has also increased.Finally,each independent parameters affecting operation effect of CCHP system is optimized using Matlab software programming and genetic algorithms to establish a trigeneration system optimization model.The objective function in this model is the weighted average of the exergy efficiency of trigeneration system with respect to primary energy saving ratio and emission reduction rate of separated system.