Study On Heat Storage And Release Characteristics And Suitability Analysis Of Solar Phase Change Kang

In rural areas of Northern China,the winter is very cold.The traditional fire Kang is the mian heating method.However,there are many disadvantages in the traditional fire Kang,such as uneven temperature distribution on the surface of Kang,poor indoor environment and large fuel consumption.Therefore,it is urgent to innovate the traditional fire Kang.Solar energy is a clean,free,intermittent and renewable energy source.And the phase change energy storage technology can solve the problem that the supply and demand of solar energy do not match in time and space.Some scholars have studied the Kang with these new technologies,but most of them used experimental methods in the initial exploratory stage.The results show that the temperature of the surface of Kang and indoor thermal comfort have improved.However,the heat storage and release characteristics of the phase change Kang and the solar energy contribution of Kang have not been specifically studied.So,the heat storage and release characteristics of the phase change Kang and the influencing factors are studied by numerical simulation.The suitability of the solar phase change Kang in most areas of China is also analyzed in this paper,which provides a theoretical basis for the development of the solar phase change Kang in the northern region of China.The two-dimensional unsteady heat transfer model of the phase change Kang is established by using Fluent.The model in literature is studied numerically,and the results are in agree well with literature,which validates the correctness of the method.The heat storage and release capacity of Kang,liquid fraction of phase change material and the surface temperature of Kang are taken as evaluation indexes.Then the performance of phase change filling and concrete filling are compared and analyzed.Under the working condition of this article,the total heat gain increases by 66.36%.The stable temperatures of the upper surface of Kang of day and night increase by 2?and 4?,respectively.And the maximum temperature difference of surface of Kang decreases from 3.7?to 0.8?.The phase change Kang have the advantages of large heat storage and release capacity,high temperature of the upper surface of Kang,uniform temperature distribution and good heat-insulation property.Afterwards,the effects of phase change temperature,latent heat and thermal conductivity of phase change materials on the heat storage and release characteristic of Kang are researched by using single factor analysis.Under the calculation conditions in this paper,phase change materials with phase change temperature of 35?,latent heat of phase change of 150 kJ·kg^-1 and thermal conductivity of 0.149W·?m·K?^-11 should be selected as the most suitable filler for the Kang.To increase the temperature of upper surface of Kang at night,reduce the thickness of filling layer and add auxiliary heat source.The sensitivity of temperature of tube,thickness of phase change layer and position of tube and it inter action to the heat storage and release characteristics of the phase change Kang are studied by using orthogonal test.It is found that the temperature of tube and the thickness of phase change layer have greater influence than the position of tube.The higher the temperature of the tube and the thicker the phase change layer,the better the heat storage and release process of Kang.The position of the tube at the lower part of the phase change layer is more reasonable.The interaction between the thickness of phase change layer and the position of tube has some influence on the heat storage and release performance of Kang,and almost no interaction between other factors should be considered in the interaction of various factors.Finally,the suitability of solar phase change Kang with auxiliary heating layer in different areas are studied.Firstly,we select representative typical areas.According to the daily radiation during the heating season,the thickness of the phase change layer of Kang in different areas is designed and calculated.At last,the hourly average data of heating season is used to simulate the solar phase change Kang.The results show that the solar energy contribution rates of the Kang in Harbing,Beijing,Yinchuan can reach 49.9%,70.1%and76.5%respectively under the simulated condition.The solar phase change Kang can guarantee the comfort of Kang at night when the human is sleeping.It is proved that the solar phase change Kang have good effect in many areas of northern China.