Analysis And Research Of Thermal Characteristics For Phase Change Thermal Storage Building Structures

"Energy revolution","low-carbon energy" and "clean heating" have become an important part of the national energy strategy.Promoting revolutionary changes in the energy system is also an important instructive orientation for energy strategy adopted by China.In recent years,in order to solve the problem of environmental pollution caused by coal-fired heating in northern heating areas,the development of clean energy electric heating has received extensive attention.The traditional cogeneration heating method in northern heating areas has hindered the development of clean wind power and caused the serious “disposal of wind” phenomenon.Regenerative electric heating system can not only meet the heating demands,but also respond well to the call of wind power.Therefore,wind power heating is one of the reasonable methods to solve the disposal of wind in the winter of the Three North.As a building envelope structure,the large storage area and its performance in thermal insulation and heat storage will directly affect the economical efficiency of the electric-direct heating systems and the energy-saving of the building.Via adopting various electric heating policies(i.e.the policy of “peak-valley electricity price”)and employing the beneficial conditions for large-area heat storage in the building envelopes,the development of “phase-change heat-storage electric heating heating building structures with electric heating” through combining the phase-change heat-storage materials and envelope structures,will effectively promote the “building industrialization” and “electric heating” and other related technologies.This article has developed a phase change heat storage material combined with electric heating assembly structure building envelope.By testing and analyzing the thermal properties of the phase-change heat-storage material,the paraffin wax microcapsule was selected as its the main body,in which the microcapsule structure was utilized to encapsulate the paraffin.Such design solved the problem of leaking liquid wax at the phase of low-temperature transition In addition,as a supportive structure for enhancing the heat transfer,the selected foamed copper improved the performance of heat-storage structures in aspects of both heat transfer and structural strength,which ensures its heat-supply performance while accumulating heat.Based on the theoretical analyses,Fluent software was employed to simulate the heat-storage processes using the pure paraffin and the foamed metal copper/paraffin phase-change microcapsules,respectively,which served as the reference and basis for following comparative experiments.Specifically,the comparative experiment involved three types of heat-storage materials,including the single paraffin wax microcapsule and the foamed copper/paraffin composite microcapsule with porosity rate of 95% and 90%.The data of temperature changes were collected,based on which the heat-storage and-release properties of all those three types of materials were estimated,respectivley.The overall thermal characteristic indexes of the “phase-change thermal storage heating structure” were obtained by analyzing the thermal properties of the samples in the intuitive map of Origin.The results demonstrated that:(i)via considering the heatload cycle of the building and the peak-to-valley electricity price difference,it is feasible to find certain period of night time,during which the heat supply and heat storage can be achieved simultaneously.Its heat storage capacity can meet the heat requirements of daytime heating;(ii)the regenerative layer added with foamed copper/paraffin microencapsule with porosity rate of 95% as the phase change material,displayed the best thermal effect in the process of heat storage and exhalation(SPSS statistical paired T test).In order to analyze the economical efficiency of the phase-change heat-storage electric heating system,this study also analyzed the initial investment,annual operating expenses,and the recovery period of simple investment,and etc.It was demonstrated that phase-change thermal storage electric heating structure can greatly save annual operating costs of the electric heating and its investment recovery period was also short.The designed product via using the building envelope structure for large-scale heat storage as developed in this project has established a theoretical basis for the development of clean wind power heating technology.