Research On Optimization Design And Integrated Operation Performance Of CCHP System

With the continuous development of society and the continuous advancement of modernization,people’s requirements for the quantity and quality of energy are increasing.However,the disadvantages of centralized energy system based on the concept of scale effect are prominent,which has exposed the problems of low energy efficiency,poor flexibility and difficulty in renewable energy access.Therefore,constructing a new energy supply system that is efficient,clean,flexible,safe and interconnected is the only way for China’s energy transformation.Combined cooling heating and power(CCHP)system can fully tap the local resource endowment,has the advantages of environmental protection,high efficiency,economy,safety and flexibility.It can meet the diversified energy demand of users,and is of great significance to promote energy transformation and upgrading.In this context,this paper conducted optimization design research on CCHP system,aiming to provide new ideas and methods for related studies.In this paper,a direct-connected CCHP system with exhaust gas and supplementaryfired type absorption chiller was proposed,and the thermodynamic model and optimization model of the system were established.According to the two optimization methods of“annual optimization” and “hourly optimization” of electric cooling ratio,five schemes were proposed with the objectives of minimum annual total cost and annual total energy consumption,respectively.The enumeration method was used to collaboratively optimize the internal combustion engine capacity and electric cooling ratio of CCHP system under following electric load strategy.The capacity configuration,annual total cost and annual total energy consumption under different schemes were obtained,and the investment energy ratio was used as a comprehensive index to evaluate the cost performance of CCHP system.By comparing and analyzing the annual index values,economy and energy performance of the system under different schemes,the results show that when the hourly optimization objective and the annual optimization objective are both the minimum energy consumption,the annual total cost,annual total energy consumption and investment energy ratio of CCHP system are better than other schemes,which are 1796870.60 Yuan,5518865.91 k Wh and 1.4613 Yuan/k Wh,respectively.In this paper,a CCHP system with a solar thermal system and an organic Rankine cycle(CCHP-ST-ORC)was further proposed,and the thermodynamic model of the system was established.According to the structural and functional characteristics of the system,the electric cooling ratio,exhaust smoke flow ratio,exhaust smoke converge temperature and preheat ratio were set as operational optimization parameters.According to the relationship between partial load ratio of internal combustion engine and power generation of system,an improved following electric load strategy was proposed.With the objective of minimizing the hourly and annual energy consumption,a collaborative optimization model of configuration parameters and multi operation parameters was established.Finally,the annual index values of CCHP-ST-ORC system were analyzed,and the operation characteristics of the system in typical days of summer,winter and transition season were studied.The results indicate that the scheme with the objective of minimizing hourly and annual energy consumption is robust.Compared with CCHP system,the annual total energy consumption of CCHP-ST-ORC system is reduced by about 10.88%,and the annual total cost is only increased by about 0.78%.The cost performance of CCHP-ST-ORC system is higher,the energy saving of 1 k Wh is about 0.47 Yuan less than that of CCHP system.