Research On Heat Transfer Characteristics Of Interlayer Walls With Phase Change

The proportion of building energy consumption in China's primary energy consumption is increasing year by year,which poses a great challenge to achieve the double carbon goal,and the assembled building.As a new type of building method,provides an important way to promote new building energy-saving technologies.Currently,phase change energy storage is widely used in the field of building energy saving by virtue of its superiority.Phase change materials have the advantages of large heat storage capacity,selectable phase change temperature,stable phase change process,low price,easy operation of experiments,and non-corrosiveness.Adding phase change materials to the building wall structure can make use of the heat absorption and discharge performance of phase change materials to increase the thermal inertia and thermal storage capacity of the wall structure,reduce the heating and cooling load of the building wall,improve the indoor thermal environment of the building,improve the thermal comfort of human body,achieve the purpose of building energy saving,and lay a good foundation for the research of green building.In this thesis,the application of phase change materials in walls is investigated using a combination of experimental research and numerical simulation,and the unsteady heat transfer mechanism and heat transfer law of walls containing phase change interlayer are explored with assembled buildings as the research background.In this thesis,28# paraffin wax is selected as the phase change material,and a nylon solid skeleton is made by 3D printing technology,which is encapsulated by Plexiglas and formed into a phase change wall with phase change interlayer with common building materials.The heat transfer test bench of the phase change wall was built,and the temperature changes of the inner side of the common wall and the phase change wall were measured with time,and the temperature changes of the inner side of the common wall and the phase change wall were measured by infrared thermography,and the phase change process of the material in the interlayer of the phase change wall was observed,and the heat transfer process and the heat transfer law of the common wall and the phase change wall were compared.The result shows that,compared with ordinary walls,the temperature fluctuation of the inner side of the wall with different thicknesses of phase change interlayer is significantly smaller in the heating stage,which effectively slows down the heat transfer to the inner side of the wall;in the cooling stage,the wall with phase change interlayer has good heat storage and insulation performance,and the temperature decrease of the inner side of the wall is significantly slowed down,and the thicker the phase change interlayer is,the more obvious the effect is and the greater the thermal inertia of the wall is.The comprehensive thermal insulation effect of the wall is best when the thickness of the phase change interlayer is 3cm.By analyzing and comparing the cases that the phase change interlayer is located in the inside,middle and outside of the wall,it is found that the thermal performance of the wall is significantly better when the phase change interlayer is located in the inside of the wall than in the middle and outside of the wall.By analyzing and comparing the cases of 50?,55? and 60? for the heating temperature of the outer surface,it is found that the comprehensive thermal insulation effect of the wall is better when the phase change interlayer is located on the inner side of the wall and the temperature of the heat source side is55?,and the utilization rate of the phase change characteristics of the phase change material in the phase change interlayer is higher.The heat transfer process of the phase change wall with phase change interlayer was numerically simulated by using the finite unit method and compared with the experimental study results,and the two agreed well.