Performance Simulation Of Distributed Energy System With Cascade Phase Change Thermal Storage

Adding cold and heat storage technology into distributed energy system can largely avoid the mismatch between supply and demand caused by the fluctuation and asynchronism of users’ cold,heat and power loads,and can effectively improve the comprehensive utilization level of energy.Therefore,this paper takes the distributed energy system as the basic research object,introduces the cascade phase change device,and analyzes the operation characteristics of the cascade phase change distributed energy system.Firstly,the cascade phase-change distributed energy system is preliminarily designed,the equipment types of each subsystem are determined,and the mathematical models of some components of the system are established.Secondly,aiming at the important equipment of the system,double-effect lithium bromide absorption refrigeration unit and cascade phase change heat storage device,the mathematical models are established and verified statically and dynamically,and the changes of the parameters of each component of these two devices are analyzed through dynamic simulation when the flue gas temperature and flow rate are changed.Among them,the double-effect lithium bromide absorption refrigerator adopts modular modeling to simulate the change of import and export parameters of each equipment;The cascade phase change heat storage device adopts distributed parameter model through grid division,and simulates and analyzes the temperature changes of phase change materials at different storage time/positions and the outlet temperature of flue gas at each stage of the cascade phase change device.Then,according to the simulated cold,heat and electricity loads of a building,the cascade phase change distributed energy system is selected and designed,the design operating point parameters are determined,the system operation scheme is preliminarily designed to complete the system integration.Finally,a complete cascade phase-change distributed energy system is built on the simulation platform.According to the cold,heat and electricity loads of two typical meteorological days in summer and winter,the operation strategies of the system are designed and dynamic simulation experiments are carried out.The operation results are analyzed and evaluated by using evaluation indexes such as energy utilization coefficient,load satisfaction rate and heating(cold)supplement rate.The results show that the distributed energy system with cascade phase change devices can greatly improve the energy utilization rate of the system by designing a reasonable operation strategy to match the system output with the cold,heat and electricity loads at the end of the building.