Palmitic Acid-Lauric Acid/Expanded Graphite as Form-Stable Composite Phase Change Material for Low-Temperature Energy Storage Applications

摘要

Low thermal conductivity of binary fatty acid mixture of palmitic and lauric acids(PA-LA)within the value range of 0.15-0.17 W/(m·K)restricts its wide utilization as thermal energy storage material in the active regime of solar heating applications at low operating temperatures.Nevertheless,this mixture as phase change material(PCM)has a suitable phase-change temperature and heat of 36℃and 176.3 J/g,respectively.Hence,the objective of this study is to formulate a novel form-stable composite PCM with the PA-LA mixture and expanded graphite(EG)as a thermal enhancer.PA-LA eutectic mixture with varied concentrations of EG was prepared and characterized.The thermal conductivity of PA-LA/EG increased gradually with the mass of EG.Optimum thermal properties were observed in PA-LA/(5%EG)composite,where its melting(T_(m)),freezing temperature(T_(t)),latent melting heat and thermal conductivity was 35.53℃,34.84℃,174 J/g,and 1.19 W/(m·K),respectively.Also,the composite PCM is characterized by good chemical-thermal stability and thermal reliability for long-term usage.In conclusion,it can be utilized as a prospective form-stable PCM for thermal energy storage in solar heating systems,overheat treatment systems,and other thermal storage applications at low operating temperatures.