Study On Dynamic Thermal Storage Property Of Cement Matrix Composite For Energy Storage Based On Two-Dimensional Shape-Stabilized Phase Change Materials

With the continuous growth of the world’s population and economy,the demand for building cooling and heating is increasing,and the energy consumption and carbon emissions during the operation and maintenance stage of buildings are gradually increasing as well.Therefore,researching and developing new building energy-saving technologies and energy storage materials to reduce energy consumption and carbon emissions during the operation and maintenance stage of buildings has become a top priority in the research of green building design in the new era,with important theoretical and practical significance for achieving China’s carbon peaking and carbon neutrality goals.Phase change materials have the advantages of high energy storage density,stable chemical properties,and wide range of phase change temperature,etc.,making them suitable for integrating into building materials to design new building energy storage composite materials,thereby realizing the energy storage and temperature control functions of building structures.In this paper,cement was used as the matrix material,and phase change paraffin encapsulated in thin-walled steel pipes was used as the energy storage unit to prepare cement-based composite energy storage materials.The energy storage efficiency and temperature control performance of the cementbased composite energy storage materials were analyzed through experiments and COMSOL Multiphysics finite element software,The main research content and conclusions are as follows:(1)Standard cubic cement-based energy storage test blocks were prepared,and their heat transfer performance was experimentally studied.The corresponding finite element calculation model was constructed,and the calculation results were in good agreement with the experimental results.Then,the melting mechanism of paraffin was analyzed by calculation,and it was found that natural convection promotes the melting of phase change materials.Compared with pure cement materials,cement-based composite energy storage materials have delayed peak temperature and reduced peak temperature,which can effectively regulate temperature.(2)Using numerical simulation method,composite energy storage material models with uniform distribution and random distribution of energy storage units in cement materials were established,and the dynamic heat transfer performance of cement-based composite energy storage materials with different spatial distributions and different numbers of energy storage units was studied to explore their energy storage and temperature control performance.The results show that the spatial distribution of phase change energy storage units has little effect on the overall thermal conductivity of composite materials,but it will change the local heat transfer.With the increase of the number of phase change energy storage units,the average temperature of the cement-based composite energy storage materials significantly decreases,and their energy storage and temperature control performances gradually increase.(3)Using numerical simulation method,the heat transfer performance of agglomerated energy storage units under different heating modes and different spacings was analyzed.The results show that the smaller the spacing between energy storage units,the faster the temperature rise rate of cement-based composite energy storage materials,and the stronger their thermal conductivity.On the contrary,the better their energy storage and temperature control effect.In summary,this paper studies the influence of the distribution form and volume content of phase change energy storage units in cement-based materials on the temperature control performance of composite energy storage materials through experiments and numerical simulation method,which provides a certain theoretical basis and application foundation for the application of phase change materials in the field of building energysaving.