Research On Heat Transfer Characteristics Of Phase Change Layer In Phase Change Wall

Paraffin wax is widely used as a phase change material because of its wide phase change temperature range,large phase change latent heat,and non-toxic and harmless.The phase change material is combined with the building wall to form a phase change wall,which can not only strengthen the wall Thermal insulation performance can also improve heat storage performance and reduce building energy consumption.However,the heat transfer characteristics of phase change walls composed of different phase change materials are not the same.Therefore,in-depth research is needed in the combination of specific phase change materials and the wall,the construction of the phase change wall,and the heat transfer characteristics of the wall..In this paper,the core material is n-octadecane and the shell material is melamine resin.The microcapsule phase change material(MPCM)with a core-to-wall ratio of 9:1 is combined with cement mortar to produce energy storage mortar containing microcapsule phase change material.,Use SEM,DSC,TG,etc.to characterize the microstructure of the energy storage mortar containing microcapsule phase change materials,test its thermal properties,and analyze its feasibility in construction applications;by testing the compressive strength of the phase change mortar,The flexural strength was analyzed to analyze the influence of the MPCM content on the mechanical properties of the phase change mortar,and the thermal conductivity and heat storage coefficient of the phase change mortar were tested by the transient plane heat source method,and the thermal performance was analyzed.By building a test bench,one side of the wall is a constant temperature to simulate an indoor temperature environment,and the other side is an alternating temperature to simulate an outdoor temperature environment,to study the effect of the position of the phase change layer and the thickness of the phase change layer on the heat transfer characteristics of the phase change energy storage wall influences.Using evaluation indicators such as wall heat insulation performance,heat storage performance,and delay time,select the best phase change wall structure to provide guidance for actual engineering applications.The experimental research results are as follows:1.The structure of cement mortar mixed with MPCM is more compact,and the compressive strength and flexural strength of the composite phase change energy storage mortar gradually decrease with the increase of the amount of MPCM mixed.When the amount of MPCM is 10%,the compressive strength is reduced by 30%;when the amount of MPCM is 10%-15%,the flexural strength of the composite phase change energy storage mortar decreases the most,and the flexural strength decreases less than The reduction in compressive strength.2.Compared with ordinary mortar,the thermal performance of energy storage mortar containing microcapsule phase change material has been significantly improved.With the increase of the MPCM content,the thermal conductivity of the phase change energy storage mortar gradually decreases.When the test block is at the phase change temperature,the thermal conductivity decreases significantly;the heat storage coefficient first increases and then decreases,when the MPCM content is 10%,The heat storage coefficient is the largest,and the phase change energy storage mortar has the best heat storage and heat storage performance at this time.3.Apply 10% MPCM cement mortar to the enclosure structure wall to act as a phase change layer.By changing the position of the phase change layer and comparing it with ordinary walls,the results show that phase change walls are better than ordinary walls.The outer phase change energy storage wall is superior to the inner phase change energy storage wall in terms of heat insulation performance,heat storage performance,and delay time.On the basis of the outer phase change wall,the heat transfer characteristics of the phase change wall are studied by changing the thickness of the phase change layer.The results show that when the thickness of the phase change layer is 5mm,the phase change wall has a smaller difference from the ordinary wall.As the thickness of the variable layer increases,the thermal performance of the wall is significantly improved.