Study On The Preparation And Thermal Characteristics Performance Of A New Type Of Phase Change Thermal Storage Foam Concrete

As global warming becomes more and more serious,people are increasingly concerned about energy saving and emission reduction.With the rapid development of urbanization in our country,the construction sector has become the largest energy consumption sector,accounting for about 40% of the total energy consumption.Heating,ventilation,and air conditioning(HVAC)systems account for the vast majority of building energy consumption in building energy consumption facilities,approximately 37%.In modern society,people's demands for thermal comfort are increasing.Especially in the hot summer,the frequency of use of air conditioners has been greatly increased,resulting in the continuous increase of energy consumption for cooling in buildings.In order to reduce the cooling energy consumption without affecting the indoor thermal comfort,passive building energy saving methods have been proposed and widely used in the field of building energy saving.Passive building energy saving is a method to prevent outdoor heat from entering the building through the building envelope by preventing natural heat transfer.In the building's envelope structure,the use of thermal insulation materials is a method of passive building energy saving.It aims to reduce the heat transfer coefficient of the envelope structure to reduce the transfer of outdoor heat to the interior.A phase change material is a functional material,and its phase change ability is why it can be used as a heat insulating material.This paper proposes a new type of phase change heat storage foam concrete block made by mixing phase-change materials with cement,which can be used for building exterior wall insulation.Because of its low thermal conductivity and suitable phase change temperature,it can reduce the heat transferred from the outdoor to the indoor through phase change heat storage,thereby reducing the cooling energy consumption,and is an ideal material for passive energy saving.Hydrophobic fumed silica has low thermal conductivity and abundant nanopores.Paraffin has a suitable phase transition temperature(about 44 ?)and a high latent heat of phase transition.Using fumed silica as the carrier of fused paraffin,the paraffin / fumed silica composite PCM with paraffin content of 45%(wt),50%(wt)and 55%(wt)was formed by the adsorption of paraffin with fumed silica by melt adsorption method.The phase change heatstorage foam concrete blocks with the content of 0%(wt)? 5%(wt)? 10%(wt)? 15%(wt)? 20%(wt)? 25%(wt)and 30%(wt)composite phase change materials were prepared by mixing paraffin content of 45%(wt)paraffin / fumed silica composite PCM and cement,and the density of each block was the same.The appearance characterization,liquid leakage test,SEM,XRD,DSC and thermal reliability test prove that the paraffin / fumed silica composite PCM with a paraffin content of 45%(wt)has the best adsorption effect,stable morphological structure and good thermal stability,and has a suitable phase change temperature(about 41 ?)and phase change latent heat(endothermic process is 113.3 J / g,exothermic process is-112 J / g).Through SEM,XRD,DSC,thermal conductivity test,compressive strength test and heating test,it is proved that the phase change thermal storage foam concrete has a stable morphological structure,and as the content of the composite phase change material increases,the thermal storage capacity increases,the thermal conductivity decreases,and the compressive strength decreases.UDF programming is used to define the change of the comprehensive temperature of the outdoor air on the wall surface of the ANSYS Fluent during the summer design day,and the heat transfer performance of the phase change wall constructed by the phase change thermal storage foam concrete is numerically simulated.The numerical simulation results show that the west-facing exterior wall of the building in Guangzhou is suitable for the use of phase change thermal storage foam concrete with a content of 25%(wt)composite phase change material,east,south and north facing external walls are suitable for phase change thermal storage foam concrete with 15%(wt)composite phase change material content.Combining the heating test results and the numerical simulation results,it is proved that the phase change thermal storage foam concrete is an insulating material with low thermal conductivity,and its phase change thermal storage capacity is an enhanced performance of its thermal insulation capability.Energy Plus was used to simulate the energy consumption of buildings using phase change thermal storage foam concrete respectively.The results show that buildings using phase change thermal storage foam concrete have an energy saving rate of 3.12% and higher comfort.At the same time,it also proves that the proposed phase change thermal storage foam concrete has the effect of "peak cutting" and energy saving,which can reduce indoortemperature fluctuations.