Preparation And Properties Of Phase Change Energy Storage Materials For Cement Base Wax

With the development of the economy,the energy consumption of buildings in my country is relatively large,and carbon emissions are large when used.Cement-based paraffin phase change energy storage materials are used in buildings,which can improve energy utilization,reduce energy consumption,improve comfort,and reduce environmental pollution.However,the current application of cement-based paraffin phase change energy storage materials still has problems such as complex preparation process,low strength,poor thermal performance,and poor durability.In order to solve the above problems,this paper proposes a new method for making cement-based paraffin phase change energy storage materials.The paraffin wax is used as the raw material,and the compound surfactant is used to emulsify it to prepare the paraffin oil-in-water emulsion;then the paraffin wax oil-in-water emulsion,water reducing agent and cementitious material are compounded to prepare cement-based paraffin wax phase change energy storage material.This paper studies the strength,thermal properties and durability of the materials prepared by this method.The results of the study are as follows:1.Preparation of cement-based paraffin phase change energy storage materials:(1)The phase change material can be prepared by using 10% emulsifier,70% water,and 20%paraffin,and the prepared oil-in-water paraffin emulsion is stable and uniform.(2)Adding polycarboxylic acid water-reducing agent to the system significantly improves the compatibility of cement and paraffin wax emulsion.The optimum content is 0.15%,which increases the fluidity of the material with 12% paraffin wax to 67.7%.Paraffin wax is not conducive to the fluidity of cement-based paraffin phase change energy storage materials.When the content of water reducing agent is 0.15%,the fluidity of the slurry with the content of 12% paraffin wax is 130 mm.2.Performance of cement-based paraffin phase change energy storage materials:(1)Strength: Polycarboxylic acid water reducer can increase the strength of cement-based paraffin phase change energy storage material,and water reducer can increase the 28 d strength of 12% paraffin wax material by 16.9%.Paraffin significantly reduces the mechanical properties of cement-based paraffin phase change energy storage materials.When the content of water reducing agent is 0.15% and the content of paraffin is 12%,the 28 d strength of cement-based paraffin phase change energy storage materials is12.3MPa.(2)Thermal performance: When the content of paraffin wax is 12%,the thermal conductivity of cement-based paraffin wax phase change energy storage materials is0.096W/(m?K).The latent heat of phase change is 30.2J/g,which is better than the latest research of 12.8J/g.The phase change energy storage rate of the cement-based paraffin phase change energy storage material is 3.68W/kg,which is better than the existing best research 3.403W/kg.(3)Thermal stability: When the paraffin content is 12% and the number of phase change cycles is 200,the mass and strength loss rates are 5.69% and5.89%,respectively.Compared with the latest research,the material with 15% phase change component content undergoes 100 phase change cycles,and the mass loss rate is7.05% and 6.13%,the material in this study has high thermal stability and is not prone to leakage during use.The method proposed in this paper effectively solves the above-mentioned problems of cement-based paraffin phase change energy storage materials.