Research On The Performance Simulation For CCHP System Based On SOFC/Ammonia Absorption Refrigeration Chiller Technology

Traditional centralized power supply system generates electricity by burning fossil fuels to drive large capacity and high parameter units from power supply plants,forming a long-distance?ultra-high voltage and large-scale power grid mode.It is a device that converts the chemical energy in fuels to electricity,and there exist the problems of low utilization of fuel energy,high emission of pollutants,the waste of electric energy and so on.In recent years,our country has been devoting to the exploitation of clean fuel,saving energy and reducing emissions.Compared with the traditional centralized power supply system,Combined Cooling Heating and Power(CCHP)system is representative of second generation energy supply system,which is spread around the user,using clean energy as fuel to realize the integration of cold,heat and electricity supply.The principle for CCHP system should be utilized according to energy grade and matched the temperature and pressure of stream sources and consumers.CCHP system can explore new energy resource,improve energy efficiency,and reduce harmful gas emissions.What's more,CCHP system is of guiding significance for easing the environmental and energy problems in the world today.CCHP system in this paper adopts SOFC as the primary power system.The hydrogen making by natural gas reformation can react with oxygen in SOFC,which generate electricity and high temperature exhaust gas.Then,the exhaust-heat boiler recover the high temperature exhaust gas from SOFC to produce saturated steam,which is used to supply heat or refrigerate.In this dissertation,the one stage ammonia absorption type refrigerator is chosen to be as the cold source,which can provide a wider range of capacity(+10~-50?)than the direct-fired lithium bromide absorption refrigerator.When the system can't meet the cooling,heating or electricity of the building or district,electricity is purchased from power grid and inadequate heat load is supplied by nature gas after-burning.The main work of this thesis includes:The principle and framework of IIR-SOFC integrated with indirect internal reforming operation(IIR-SOFC)fueled by methane is introduced in detail.Then,the numerical analysis of the system input-output relationship was performed by MATLAB software.Combined with the thermophysical properties of ammonia solution and the state equation of Gibbs free energy,the paper sets up a mathematical model of the traditional ammonia absorption refrigeration system and writes computational programs of ammonia water thermodynamic properties.We use the exhaust-heat boiler to connect IIR-SOFC and refrigerating machine and compose the CCHP system,finding a better simulation accuracy whether stable or dynamic running condition.The calculation of exergy destruction and exergy destruction rate of the refrigerating machine are performed,and then,the absorption refrigeration cycles are studied based on the both first and second law of thermodynamics.In order to make CCHP system operate under the optimal scheme,we discuss the operation mode of FPL and FHL,and then establish an optimal operation model which takes the multi-objective evaluation index as the objective function.