Studies On Ametabolic Phase Change Materials For Non-freezing Cold Chain

Phase change materials(PCMs),have been a main topic in research in recent years.The storage of latent heat in organic matters could be more higer than other material.In this work,6 kinds of organic matters,including n-Tetradecane,Lauric acid,Methyl laurate,n-Decanoi,n-Decanoic acid and Ethyl Salicylate were selected as original PCMs for non-freezing cold chain.The thermodynamic formula was used to calculate the onset temperature and latent heat of designed compounds.DSC,Stability tests and SEM were used to determine thermal properties,thermal Stability and microstructure of materials.Vacuum adsorption was used to prepare form-stable phase change composite of PCMs/SiO2 nH2O and PCMs/EG.The onset temperatures of n-Tetradecane,Methyl laurate and Decanoi were measured between 0 and 6?,with high phase change latent heat.The onset temperature of Lauric acid,n-Decanoic acid was higer than others,mainly used in the high temperature field.Therefore,Lauric acid,n-Decanoic acid were mixed with n-Tetradecane,Methyl laurate and Decanoi to achieve good performance,low cost of the composite.The DSC test results were close to the theoretical calculations of the ther modynamic formula,which was proved to have guiding significance.The results of formula development showed:Lauric acid/n-Tetradecane(mass ratio 3.12:96.88)had the optimal performance,with Onset temperature 4.03? and phase change latent heat 207.05 J/g;Lauric acid/n-Tetradecane(mass ratio 6.17:93.83)and n-Decanoic acid/n-Tetradecane(mass ratio 22.68:77.32)had a good perfor mance in thermal properties and cost,with Onset temperature 3.89 ?,3.19 ?and phase change latent heat 192.61 J/g and 191.06 J/g,respectively;n-Decan oic acid/n-Decanoic(mass ratio of decanoic acid 34.51%?47.24%),with onset t emperature of 0.96?3.60 ? and phase change latent heat of 155?171 J/g,was selected as 0 ? PCMs for its relatively wide range of adjustable Onset tem perature.This field has a broad prospection.5 kinds of composite were adsorbed into diatoms of SiO2·nH2O by vacuum adsorption method.The appropriate mass fraction of composite were 25%?35%.The SEM showed that diatoms of SiO2·nH2O were mostly filled with the composite.The permeability test showed that PCMs were difficult to leak out.Therefore,the form-stable materials(PCMs/SiO2·nH2O)were packed up easily,which had application prospects.5 kinds of composite were adsorbed into diatoms of EG by vacuum adsorption method.The appropriate mass fraction of composite were 86%?87%,which is more than PCMs/SiO2-nH2O.The SEM showed that diatoms of EG were mostly filled with the composite.The permeability test showed that PCMs were difficult to leak out.The form-stable materials(PCMs/SiO2·nH2O)would have better application prospects if the volume problem was solved.