Study On Thermal Profit Or Loss Of Distributed District Solar Heating Prosumers And Cluster Heating Characteristics

As a clean and renewable heating source,solar energy has been widely concerned by scholars at home and abroad.At present,the solar heating technology for single building is mature,but because the solar energy has the characteristics of fluctuation and low energy flow density,for the building that heat collection to load ratio is smaller,exists low solar energy guarantee rate and so on.Solar district heating system has the characteristics of high thermal stability and good economy,which is not applicable to some towns without redundant installation sites.Distributed district solar heating collects heat through the scattered roofs of many individual buildings and then gathers it into the centralized pipe network system.While saving a large number of dedicated collection sites,it can collect a considerable amount of solar energy.In the distributed district solar heating system,every single building user is not only the consumer of "heat",but also the producer of "heat",and each uers has the characteristic of thermal profit or loss.As a result,distributed district solar heating heating prosumers no longer only take heat from the central pipe network system as traditional heating consumers,but also release heat from the prosumers into the central pipe network.The existing analysis methods of single or centralized solar heating are no longer applicable to distributed district solar heating system.Therefore,in order to establish the design and optimization method of distributed district solar heating system,it is necessary to study the thermal profit or loss characteristics of a single distributed district solar heating prosumer and the cluster heating characteristics of multiple prosumers connected to the heat network.Through theoretical analysis,the thermal analysis model of distributed district solar heating system is established,and evaluation indexes such as average thermal profit or loss ratio of single prosumer are put forward.Through numerical simulation,the influence of roof utilization rate,building energy saving rate and thermal inertia of envelope structure on thermal profit or loss of prosumers under the condition of no self-heat storage is analyzed.A calculation method of maximum heat storage is proposed for distributed district solar heating prosumer’s system,and based on the simulation model of prosumer’s system,the influence of heat storage changes on the thermal profit or loss of different types of prosumers is analyzed.Finally,the cluster effect coefficient and other evaluation indexes are proposed according to the prosumers cluster heating characteristics,and the influence rules of prosumer types and prosumer distribution ratio on the thermal performance of the system are obtained through numerical simulation analysis.Through the above research,the following main conclusions are drawn:1)Based on the dynamic balance relationship between the prosumer’s heat collection,use and own heat storage,the thermal profit or loss calculation formula of distributed district solar heating prosumer is proposed.By analyzing the influence of the thermal performance of envelope structure and the design conditions of the prosumer’s system on the thermal profit or loss characteristics of the prosumer,it is found that under certain outdoor meteorological conditions,the roof utilization rate and the building insulation degree are the main factors that affect the prosumer’s profit or loss characteristics.2)The influence of prosumer’s own heat storage on the thermal profit or loss characteristics is mainly reflected in the fact that with the increase of heat storage,the heat exchange time between the prosumer and the centralized pipe network is gradually shortened,and there is a delay phenomenon for the prosumer to take and release heat from the centralized pipe network.In the ideal state,when the heat storage reaches the maximum value,the loss prosumer is only the intermittent heating customers for the centralized pipe network system;self-satisfied prosumers are independent users and can not be connected to the central pipe network;surplus prosumers are unstable heat sources.3)When there are both surplus and loss prosumers in the heating area,the prosumer cluster heating can effectively improve the overall solar heating rate and the utilization rate of heat collection equipment in the whole area.When the ratio of surplus and loss prosumers is taken as the main adjustment parameter,the thermal performance of distributed district solar heating system changes fastest.Therefore,designers can adjust the surplus and loss prosumers mainly,adjust the proportion of self-satisfied prosumers as a supplement,and quickly achieve the optimal thermal performance of distributed district solar heating system.Through the above research,the thermal profit or loss characteristics of a single distributed district solar heating prosumer is obtained,and on this basis,the prosumers cluster heating characteristics under different prosumer combinations are given,which will provide reference for the integrated design and system optimization of distributed district solar heating system.