| At present, the current situation of making use of energy globally is gradually improvedas the emergence of thermal energy storage technology, particularly its application in buildingenergy-saving has aroused widespread concern in the whole world. For these issues, such ashow to prepare a new phase change heat storage materials, how to analyse their phase changedynamics features, how to improve the compatibility and stability between phase changematerials and constructive materials, etc, the in-depth study will make great practicalsignificance for the development of thermal storage technology and its application in buildingenergy-saving.In this paper, firstly, three kinds of expanded perlite(EP) based composite phase changematerials(PCMs) were prepared, in which expanded perlite acted as the supporting material,RT28, octadecane(OC) and lauryl alcohol(LA) were served as latent heat storage materialsrespectively. The structure and thermal properties of PCMs were then characterized by meansof adsorption saturation analysis, SEM, XRD, DSC, etc. It is shown that, expanded perlite hasa same maximum absorptive capacity as40%for all the three organic phase change materials,all of which still are form-stable with no liquid leakage performance after being heated. Inaddition, there was little difference of the phase change temperature between EP-basedcomposite PCMs and the pure organic PCM, were similar to that of the pure organic PCM,and their latent heat values were equivalent to the calculated values based on the mass fractionof the pure organic PCM in the PCMs.Took40wt%RT28/EG-PCM,40wt%OC/EP-PCM and40wt%LA/EP-PCM as theresearch objects to study the phase transformation kinetics, firstly the activation energy E andthe former factor A could be estimated by the Kissinger equation and Ozawa equation,through extrapolation processing with Coats-Redfern integral equation and Ozawa equation,then it could be concluded that, the mechanism functions for three kinds of materialsseparately in accordance with Mampel Power Rule, Mample single-line Rule (first class),Avrami-Erofeev Equation. The integral equations of mechanism function are G(α)=α3/2, G(α)=-ln(1-α) and G(α)=[-ln(1-α)]2/3respectively.In the research of the application of PCMs in construction materials, at first, according to a certain volume ratio, mixed RT28/EP-PCMs, which have been prepared well before, withcement and water to make the PCMs heat storage mortar, then PCMs cement boards andPCMs cement plates were prepared through the standard mold (70.7×70.7×70.7mm~3) andself-made mold (10×100×100mm~3) respectively. Compared with the normal swellingperlite cement boards, when the content of RT28reached40wt%, the values of apparentdensity,7-days compressive strength and thermal conductivity of PCMs cement boards orplates almost increased by37.2%,40%and35.2%, respectively, all of which were within thestandard values.A closed cube was made with six PCMs cement plates to measure the energy-savingefficiency by using the Xenon lampe simulating the solar radiation, of which the size was100×100×100mm~3and the thickness was10mm. Then the temperature variation of four testingpoint of the cube was measured respectively, which was divided into group A and group B test.Under the same conditions, the maximum temperature difference between the outside topplate and the internal room of the cube increased with the increasing amount of RT28inPCMs gradually. In addition, when the mass ratio of RT28increased to40wt%, the maximumtemperature difference of group A and B jumped to25℃and25.231℃, respectively. It canbe concluded that, the ordinary building materials, after being added with a certain amount ofPCMs, could play a role in adjusting and reducing the fluctuation of indoor temperature.Moreover, the higher content of RT28was, the energy-saving performance would be thebetter. |
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