Study On Energy Storage And Discharge Characteristics Of Solar Energy Phase Change Wall Heating System In Rural Houses In Severe Cold Region

Energy is the basis of human survival.However,with the rapid progress of economic and technological levels,the scarcity of fossil energy and environmental pollution have become major issues restricting human development.The heating of rural buildings in China's severe cold regions not only consumes a lot of coal,but also the exhaust gas has an adverse impact on the environment and human health.Therefore,it is of great significance to China's energy conservation and emission reduction strategy to reduce the energy consumption of buildings in cold regions and developing new energy sources.Solar energy has become a hot spot in new energy research due to its advantages of cleanliness and huge energy.Phase change energy storage technology can maximize energy utilization,which is conducive to building energy conservation in severe cold areas.Based on the above background,this paper takes a rural building in severe cold areas as the research object,proposes a solar energy phase change wall heating system which combines solar energy and phase change energy storage technology.The design and energy storage law of this system are implemented to verify the feasibility of using this method in rural buildings in severe cold areas.This system is aiming to reduce the heating energy consumption of buildings in severe cold areas in winter,and provide a reference for energy conservation and emission reduction in severe cold areas.The main research contents are as follows:(1)The average solar radiation value of winter in a typical year was used as the design heat source,this paper had designed the solar phase change wall heating system by renovating the existing rural house in the cold region and calculating its heat load.The basic layout of the system,the type and amount of PCM,system parameters such as the area of the solar collector and the amount of circulating medium had been determined,and the energy saving rate of the system under the heating season conditions in severe cold areas had been calculated.The design calculation results show that the converted farm house can save31.80% of energy.(2)The energy storage and discharge characteristics of the solar phase change wall heating system were analyzed by the control variable method in order to study the heat transfer law of the phase change wall under a single working condition.The impact of the melting process of different tube diameters,inlet velocity and inlet temperature were compared.The results show that the inlet temperature is the most direct factor affecting the melting efficiency of phase change materials.The orthogonal simulation method is used to judge the influence level of different factors,and the order of influence was found to be inlet temperature> pipe diameter> inlet velocity.From the extreme point of view,pipe diameter and inlet flow rate have little effect on the melting efficiency of phase change materials and the levels are similar.The result shows that optimal operating condition of the system is thatthe pipe diameter is DN25,the inlet velocity is 0.3m/s,the inlet temperature is 310K(37?),the outlet temperature is 309K(36?),and the water inlet time is 4h.At the same time,the maximum tube spacing(107mm)in the phase change wall and the arrangement of the wall are determined,and the phase change cycle of the wall under heat release conditions is also determined.(3)The heat transfer law of the solar energy phase change wall with different fin parameters was studied through the control variable method and the orthogonal simulation method,and the analysis of the six fin process parameters on the liquid phase fraction was studied at the same time.Among them,the length of fins has the greatest influence,and the order of the influence of each factor is: fin length> fin thickness> fin spacing = fin layout method> fin material> fin shape.It is verified that under the condition of short fins,the tube spacing meets the minimum tube spacing of 125 mm for DN25 PB tubes and the effectiveness of adding fins is confirmed.Since then,a simulation study of the heat release performance of the solar energy phase change wall has been carried out.The phase change material is not completely solidified,which can effectively maintain the stability of the indoor temperature and also play a certain role in compensating the fluctuation of solar radiation.