3E Analysis Of Solar Heating System In Northern Rural Area Based On Life Cycle Theory

In recent years,solar energy has become one of the main energy sources used in mankind,where the use of solar heating is a new energy utilization technology.The heating sources in north rural areas are mainly coal and straw,which induce low energy utilization efficiency and direct discharge of untreated waste gas,as the main source of air pollution.From the perspective of building energy conservation,the application of solar energy in rural heating systems in northern of China can effectively reduce the use of traditional fossil energy,and improve the indoor heating effect and the quality of atmospheric environment.Taking a single building in north rural areas as an example,this paper conducted energy,environment and economy analysis for solar heating systems with different auxiliary heat sources.The specific research contents and conclusions are as follows:(1)De ST has been used to establish the model of a single building in north rural areas,in order to calculate the annual dynamic time-by-time heat load in Jinzhou City.Considering the instability of solar energy,four heating schemes were designed,i.e.,solar heating system combined with biomass boiler,solar heating system combined with gas boiler,solar heating system combined with coal-fired boiler,and solar heating system combined with electric heating boiler.Selection calculations of solar heat collector,heat storage tank,and auxiliary heat source were conducted.Optimal design for solar collector area and heat storage tank volume were carried out based on the annual value target function.(2)TRNSYS has been used to compare the operating characteristics and energy consumption for four systems.The results show that the solar heating system combined with coal-fired boiler has the largest energy consumption,followed by the solar heating system combined with biomass boiler,solar heating system combined with electric boiler.Due to the low cost of coal and the large energy consumption of coal-fired boiler,solar heating system combined with coal-fired boiler has the maximum energy consumption based on annual cost value.(3)Life cycle assessment(LCA)has been used to calculate and compare the environmental impact of four systems.The results show that the global warming and human health take high proportion in the total environmental impact of the solar heating systems,accounting for 67%～82% and 14%～31%,respectively,while acidification,eutrophication,photochemical oxidation,and resource consumption represent less proportion.Among life cycle phases of solar heating system,the production phase contributed most for the solar heating system combined with biomass boiler,while the usage phase contributed the most for the others.(4)Life cycle costing(LCC)has been used to calculate and compare the economic impacts of the four systems.The results show that the life cycle cost of solar heating system combined with gas boiler is the largest,and the minimum life cycle cost of solar heating system combined with coal-fired boiler is the smallest.(5)Eco-efficiency has been used to carried out 3E evaluation.Considering the environmental improvement,this study defined economic eco-efficiency indicator and energy eco-efficiency indicator.The results show that the economic eco-efficiency and energy eco-efficiency of solar heating system combined with biomass boiler is the smallest,and the economic eco-efficiency and energy eco-efficiency of solar heating system combined with electricity boiler is the largest;There is a trade-off relationship of the solar heating system has one of the four dimensions of energy consumption,environment,and economic evaluation,ignoring certain aspects may bring about the transfer of problems.