Preparation And Properties Of Organic-inorganic Composite Phase Change Energy Storage Materials

Due to the impact of energy shortage,energy conservation has gradually become an issue of concern.Among all of the energy consumption by human beings,building energy consumption occupies a considerable proportion,so it is very important to develop a material that could reduce the building energy consumption.As an energy-saving material,phase change materials(PCMs)which has attracted widespread attention can store and release heat during the phase change process,effectively reduce the building energy consumption and improve the indoor comfort.In this paper,an organic-inorganic composite PCM was prepared by emulsion polymerization which using paraffin and Na2HPO4·12H2O as the phase change core material.It has high latent heat,good thermal stability and cyclic stability,and has great research and application prospect.The following are the main research contents of this thesis:(1)The aqueous solution of acrylamide was used as the outer phase,and the melting paraffin was used as the inner phase to obtain the W/O emulsion.Then,by emulsion polymerization,the paraffin was encapsulated in the pores of PAM porous material to obtain the paraffin/PAM form-stable phase change materials(FSPCMs),with the paraffin encapsulation rate up to 68.16%.It's melting enthalpy and crystallization enthalpy decreased by 2.41%and 2.59%after 200 heat cycles.(2)Expanded vermiculite(EVM)was added to the body of paraffin/PAM FSPCMs,which effectively reduces the leakage of paraffin and improves the paraffin encapsulation efficiency of the FSPCMs and the cycle stability of the material.The paraffin encapsulation rate of the obtained FSPCMs can reach 71.05%,its melting enthalpy only decreased by 1.57%after 200 heat cycles,and its crystallization enthalpy decreased only by 1.68%.(3)In view of the characteristics of the layered structure of EVM,the inorganic PCMs Na2HPO4·12H2O was impregnated into the layered structure of EVM and added to the body of paraffin/PAM FSPCMs.A new organic-inorganic composite PCMs was obtained.Studies have shown that the addition of Na2HPO4·12H2O/EVM reduces the leakage of paraffin and improves the encapsulation efficiency of paraffin,while the addition of Na2HPO4·12H2O also further improves the latent heat of phase change of the material.More importantly,the supercooling degree of Na2HPO4·12H2O could be effectively reduced by impregnating Na2HPO4·12H2O into the structure of EVM's layer,because the nanoscale confined space generated by EVM's layer changed the phase behavior of Na2HPO4·12H2O and reduced the difficulty of phase change.The results show that the new organic-inorganic composite PCM has high latent heat of phase change(melting enthalpy is 111.69 J/g,crystallization enthalpy is 108.35 J/g),good thermal stability and cyclic stability,so it has a good application prospect.