| In recent years,environmental pollution in northern China has become increasingly serious,caused very frequently haze weather.Especially after entering the heating season,the pollution has become more and more severely.On the basis of solar heat storage with the combination of electrical heating auxiliary function,a composite PCMs(phase change materials)storage Kang is designed with porous media using the porous metal and nonmetal rich pore structure by this article.It can increase the specific surface area of heat transfer,enhance the performance of thermal conductivity of PCMs,speed up the PCMs heat absorption and heat release rates,and also can increase sleepingaverage temperature and improve the overall comfort performance.The whole research contents are as follows:(1)Through the investigation and research on solar energy resources in northern of China,it can be concluded that solar energy resources are very abundant in winters,which can theoretically completely meet the demand for heat storage.By comparing heat collection efficiency of different types of solar collector,the trough solar collector which meeting the experimental requirements is selected for combining with the heat preservation tank with auxiliary electric heating.A solar energy storage system is designed to serve as a heat source of the PCMs storage Kang device.(2)Considering the comfort range of human body,the No.35 paraffin with both melting point and freezing point in the comfort range is selected as the PCMs.The latent heat of PCMs is determined by DSC test of paraffin.Further through the analysis and calculation of the indoor working conditions,the consumption of PCMs and the feasibility of the experiment are studied.The composite PCMs is prepared by pouring method,and the experimentequipmentis set up,locations of measuring points are determined,and the PCMs storage Kang system is constructed.A complete experimental platform is finished by connecting the solar energy storage system with pipe fittings.(3)Through the thermal performance research of paraffin composite PCMs storage Kang with 20 PPI,30PPI,40 PPI and honeycomb activated carbon,it is concluded that with the decrease of the pore density,the thermal conductivity of the composite PCMs is incraseing.The surface temperature of 20 PPI honeycomb activated carbon composite PCMs storage Kang can reach to the highest average temperature,highest heating rate and highest cooling rate.The fastest rising stage can shorten one hour than that of the pure paraffin Kang.It can play an important role in strengthen heat transfer ability.(4)The thermal performance has been studied for compositing paraffin with porous aluminum medium which possess excellent thermal conductivity among the porous metals.It can be concluded that heating rates of aluminum foam-paraffin composite Kang and honeycomb aluminum-paraffin composite Kang are 1.90℃/h and 2.28℃/h,respectively.Compared with pure paraffin Kang,the above heating rates can be improved speed up to 16.50% and 40%,respectively.It can also greatly shorten melting time of PCMs,improve shortcomings of low thermal conductivityof paraffin and enhance heat utilization ratio.(5)The thermal performances have been analyzed for porous aluminum medium Kang and honeycomb activated carbon composite Kang.It can be concluded that the surface average temperature gradient is less than 2%,remaining on the thermal stable stage.The data trend is the same and consistent with thermal analysis due to two winters recycling test period.The phenomenon illustrates that the two kinds of composite materials are only physically unioned,does not react with each other and can maintain their excellent properties respectively. |
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