Selection And Packaging Technology Of The Phase Change Materials For Outer Wall In The South Area

It is so hot and long in summer in south area, but there is not an appropriate wayof heat insulation for a long time, resulting in widespread use for a long period oftime of air conditioning, consume huge amounts of energy and pollute theenvironment.This paper by using phase change materials and light porous compositeused in architectural appearance to achieve the purpose of insulation.Phase change materials in the broadest sense of the term refers to the materialcan store and release energy when changes of state,in a narrow sense of phase changematerials for solid-liquid phase change materials,the organic solid-liquid phasechange materials has become the research hot spot.According to the summer climatecharacteristics in south,this article chose octadecane, eicosane and are decanoic acidthree phase change materials in suitable temperature,and test the respective phasechange temperature and phase change enthalpy,accompanies with paraffin as thecomposite material ingredients,when octadecane: paraffin=1:2,the phase changetemperature of binary composite phase change material is33.01℃, phase changeenthalpy is156.2kJ/kg;when eicosane: paraffin=2:1, the phase change temperatureof the binary composite phase change material is33.05℃, the phase change enthalpyis195.3kJ/kg, the two binary composite phase change materials can be used in thisexperiment.Choosing expanded perlite, expanded vermiculite, lightweight porous ceramsiteas support material,through the experiment compared the adsorption rate of thevacuum adsorption and soak,experiments show that: under the same adsorption timeand adsorption temperature,the adsorption rate of the vacuum adsorption and soakalmost same,this paper choses soak adsorption.For soak adsorption, when thetemperature is certain, to extend the time of adsorption, adsorption rate can beimproved, but less increase; when the adsorption time is certain, to extend adsorptiontemperature, adsorption rate to rise, but after the temperature to80℃, the adsorptionrate of increase is decrease.So this study chooses the best adsorption method at80℃ under soak adsorption for2h.DSC test of the amorphous phase change materials, found that various shapesthe phase transition enthalpy of phase change materials compared with pure phasechange materials have change, and porous haydite lightweight formalization phasetransition enthalpy of phase change materials to reduce the most, three comparison,left out of this experiment.ESEM and EDS of amorphous phase change materialexperiment, shows that the porous material adsorption is phase change materials.ToFTIR experiments of amorphous phase change materials, infrared spectrum showedno changing functional groups, namely porous adsorption phase change materials is apurely physical process.Adsorption of porous material before and after adsorptionstatic nitrogen adsorption experiments, found that porous pore volume significantlyfewer, can also be proved that the adsorption phase change material in porousmaterials.Unwrapped figuration phase change material will leak at high temperatures, thisarticle adopts the way of wet wrapped cement powder to amorphous phase changematerial encapsulation, shelter rate experiment results show that the shapes of phasechange materials before and after the encapsulation shelter rate increase from71%to97%.After the encapsulation of amorphous phase change materials mixed withtraditional mortar, forming a100mm x100mm x10mm and100mm x100mm x15mm two mortar board, after the standard curing test its heat insulation performance,experiments show that: the same phase change material, and the phase change slurryphase plate thickness at the same time, increase the dosage of phase change materialsthermal insulation ability enhancement;Same phase change materials and the dosageof phase change materials phase at the same time, increasing the thickness of thephase change slurry plate its insulating ability enhancement.And the phase changeslurry heat stability experiment, the experimental results show that after25psychro-thermal cycles, eicosane and octadecane still have better heat insulationperformance, and decanoic acid, stearyl-paraffin composite phase change materialsand eicosane-poor thermal stability of paraffin composite phase change materials. In order to explore the construction technology of phase change slurry heatinsulation performance, the influence of multiple phase change slurry was studiedafter construction technology of heat insulation performance, the results show that thephase change slurry daub is on both sides of both inside and outside the wall all canplay a certain thermal insulation effect, compared with the benchmark wall under thesame illumination time has a certain temperature (low), and reach the sametemperature will have a long time delay;When choosing the same phase change slurry,apply phase change slurry to the medial than daub is on the outside wall has betterheat insulation performance, will be20mm thick eicosane phase change slurry daubis on the inside wall, near the eicosane phase change temperature has a maximumtemperature4.8℃, and with the time delayof temperature up to960s, and the sameconstruction technology conditions, eicosane phase transition of mortar is better thanoctadecane phase change heat insulation performance of mortar.Finally, the physical and mechanical properties of the phase change slurry test,the experimental results show that the28days octadecane phase change slurryflexural strength2.93MPa,25.45MPa compressive strength;Eicosane phase changeslurry of flexural strength2.65MPa,28days compressive strength23.66MPa,stearyl phase-change mortar bond strength of28days842kpa, eicosane phase changeslurry the average bond strength of778kpa, can meet the national standard GB/T20473-2006in building insulation mortar prescribed requirements.