Preparation Of Low-temperature Phase-change Energy Storage Materials And Investigation Of Their Phase-change Properties

This paper focuses on organic phase change energy storage materials and inorganic phase change energy storage materials with a phase transition temperature of3-12?.At this stage,the method for preparing low-temperature composite organic phase-change energy storage materials has high technological requirements and takes a long time.Therefore,this paper uses the eutectic method to calculate the phase transition temperature of the tetradecane-1-dodecanol binary eutectic mixture.Secondly,expanded graphite with high thermal conductivity(?)and high porosity was used to encapsulate the organic phase change energy storage material,and a low-temperature composite organic phase change energy storage material with higher thermal conductivity was prepared.In this paper,X-ray diffractometer(XRD)and Fourier Infrared Spectroscopy(FTIR)are used to investigate the chemical properties of the prepared low-temperature phase change energy storage materials,and the leakage rate is also characterized.To determine the best low-temperature composite phase change energy storage material.Differential Scanning Calorimeter(DSC),Thermal Conductivity Analyzer and Synchronous Thermal Analyzer(TGA)are used to analyze the effects of EG on the thermal performance of low-temperature composite phase change energy storage materials based on different particle sizes and different mass fractions.The hydrate solution in the inorganic phase change energy storage material has excellent thermal performance and low price,but it has problems of phase separation and super-cooling.In addition,the volume of the hydrate solution has a great influence on its thermal performance.Therefore,the T-history method is used to mathematically model the solidification temperature,solidification latent heat and solidification specific heat of the TBAB hydrate solution.This paper improves the phase change performance of TBAB hydrate solution,and provides guidance for inorganic phase change energy storage materials in air conditioning systems and cold chain logistics.The main work content and conclusions are as follows:(1)The tetradecane-1-dodecanol binary eutectic mixture/EG low-temperature composite phase change energy storage material was prepared by a two-step method.Firstly,based on theoretical calculations,the molar ratio of the tetradecane-1-dodecanol binary eutectic mixture is determined to be 73.7:26.3,and the mixture is mixed by high-speed emulsification.Secondly,the binary eutectic mixture is added to EG using the natural adsorption method,and the optimal addition amount of EG is determined to be 7%.(2)The melting and solidification temperatures(Tm and Ts)of the tetradecane-1-dodecanol binary eutectic mixture are 3.43°C and 4.17°C,respectively,and the corresponding latent heats of melting and solidification(H_mand H_s)are 212.96 J/g and 213.00 J/g,respectively.After EG natural adsorption,the best mass ratio of tetradecane-1-dodecanol binary eutectic mixture and EG composite is 93:7,and the corresponding melting and solidification temperatures are 3.63°C and 7.71°C,H_m and H_s are197.95 J/g and 198.81 J/g,respectively.In addition,the thermal conductivity values of the tetradecane-1-dodecanol binary eutectic mixture and the tetradecane-1-dodecanol binary eutectic mixture/EG low-temperature composite phase change energy storage material are0.2186W/(m?K)and 2.4070W/(m?K),respectively.(3)The low-temperature composite phase change energy storage experiment results based on EG with different particle sizes and mass fractions show that when the particle size of EG is 20 mesh and the mass fraction is 7%,the corresponding T_m and T_s are 3.45? and 7.02?,respectively.The corresponding H_m and H_s are197.90 J/g and 193.71 J/g,respectively.In addition,boundary scattering and phonon scattering are the main factors affecting the low-temperature composite phase change energy storage material?.Among them,the?of 20-low temperature composite phase change energy storage-7 is the highest at 25?,which is 3.2060W/(m·K).(4)In view of the dependence of the TBAB hydrate solution on the volume,the T-history method is used to mathematically model the thermal performance during the solidification process on the basis of adding sodium dodecylbenzene sulfonate(SDS)to the TBAB hydrate solution.So,the experimental results show that H_s is the largest,which is 185.883 J/g when the mass fraction of TBAB is 35% and the T_s is 8.67?.