Application Of Distributed Thermal Energy Storage In District Heating System

Due to the imperfection of the automatic control system and the complexity of the unit adjustment to adapt to the load fluctuations,the mismatch of supply and demand has become one of the main reasons for the large energy consumption.The application of thermal energy storage technology alleviates the problem,and the commonly form is centralized thermal energy storage.With the expansion of the scale of district heating,the shortcomings of centralized thermal energy storage gradually become obvious,such as the delay effect of the regulation by centralized thermal energy storage is gradually increased.And it cannot take into account the difference in the thermal storage potential of different load types and the flexibility of centralized thermal energy storage is poor.Compared with centralized thermal energy storage,distributed thermal energy storage is closer to t he heat users,and more flexible to adjust,which is usually set at the heat transfer station.Therefore,the study of distributed thermal energy storage has some practical significance.First of all,the connection of distributed thermal energy storage tank and heat net are discussed with its advantages and disadvantages.At the same time,the factors that may affect the energy saving potential of the distributed thermal energy storage tank are analyzed.Then,in view of the load of residential building,this paper studies the influence of the application of distributed thermal energy storage tank in the system by the change of the capacity of the distributed thermal energy storage tank,the thermalization coefficient and the scale of heat transfer station,through the application of established system mathematical model and the base data obtained by simulating with De ST software.The results show that the capacity of tank and the thermalization coefficient have an influence on the application of the distributed thermal energy storage tank in the system,and the change of the scale of heat transfer station only affect the capacity of tank,and the maximum capacity of the thermal energy storage tank is almost proportional to the scale of the heat transfer station.The increase in the capacity of the thermal energy storage tank result in a reduction in the heating costs and CO₂ emissions,but the trend gradually slows down with its capacity increasing;The amount of reduction for the total heating costs and CO₂ emissions increase first and then decrease with the increase of the thermalization coefficient,which mainly because that the increase of thermalization coefficient leads to an increase in the heating costs and CO₂ emissions from the base heat source,so that the proportion saved by setting thermal energy storage tank is reduced.Finally,the influence of application of distributed thermal energy storage tank on hydraulic condition of the system is discussed.The paper mainly analyzes the influence of operation of the thermal energy storage tank on the hydraulic condition and pump energy consumption of the whole system,when the tank is set up at the most disadvantaged user,the user who has the maximum load and the user who near the heat source.The conclusion shows that the charging process has little effect on the hydraulic conditions of the system and the pump power consumption,and setting up the tank at the user who has the maximum load is the optimal program in the discharging process,only from the perspective of operation energy consumption.At present,the research on distributed thermal energy storage is still in the initial stage,and the related theoretical system is not mature.It is hoped that the research results of distributed thermal energy storage in this paper can provide some reference value for the further research.