Optimazation Research Of Multi-energy Complement Such As Geothermy In District Energy System

With the rapid development of global economy,the consumption of fossil energy is multiplying daily.Reasonable adjustment of energy structure,full utilization of renewable energy and reduction the energy consumption of HVAC system are the inevitable choice for sustainable development of the society.The district energy system,coupling various energy systems,integrates the supply,transmission and distribution of energy,and has great advantages over the independent energy system.Geothermal energy,as a clean,low-carbon and stable renewable energy,is an important component of the district energy system.With the improvement of geological exploration techniques,it is necessary to research the coupling optimization design,interaction mechanism and control strategies of the district energy system which couples shallow geothermal energy,middle and deep geothermal energy with other energy sources.This paper selects a district in Shijiazhuang as the research object,predicts the annual dynamic air-conditioning load of the district,and establishes the system model coupling multi energy sources.The model can optimize the capacity ratio of each subsystem with the lowest life cycle cost or annual carbon emission as the goal.In addition,this paper compares the performance of different optimization algorithms,and gives the suitable algorithm and related parameters for the optimization problem.Finally,this paper studies the effects of the water flow rate,injected and outlet water temperature of the geothermal water heating system;optimizes the design of scheme coupling geothermal energy and other energy sources;analyzes the differences between the economic and environmental aspects of several multi-energy complement schemes.The study finds that the capacity of the district energy system can be significantly reduced compared to the independent energy system by taking advantage of differences in peak building load time.The economy of energy storage system increases with higher outlet water temperature.And the effect of injected water temperature on the economy of the system is higher than the outlet water temperature.It is necessary that reduce injected water temperature and increase the flow rate to achieve the purpose of efficient utilization.Under the control strategy changing with electricity price,the scheme that geothermal energy coupled with CCHP system,energy storage system,etc.is better than that with a single form in economic aspect and the annual life cycle cost is the lowest among all schemes.The research results can provide a reference for the multi-energy complement optimization design of district energy system and the application of geothermal water heating system.