In addressing the problems of low thermal conductivity and susceptibility to leakage in phase change materials within solar photovoltaic thermal(PV/T)systems,composite shape-stabilized phase change materials comprising docosane-dodecanol and expanded graphite were prepared and their properties were experimentally studied.Herein,docosane-dodecanol phase change materials were prepared in the ratio of 6∶4,followed by the preparation of a series of composite shape-stabilized phase change materials with different expanded graphite contents through a melt blending method.In the experiment,the microstructure was observed using field emission scanning electron microscope,and various parameters such as latent heat and thermal conductivity were measured using a heat flow differential scanning calorimeter and a thermal conductivity measuring instrument,respectively.The physical compatibility,adsorption,and cycle stability of the material were also studied.The optimum ratio of expanded graphite and docosane-dodecanol and its various properties were explored.The results show that the composite shape-stabilized phase change material exhibits optimal performance when the mass fraction of expanded graphite is 15%.At this composition,the expanded graphite is sufficient to adsorb the phase change material,resulting in a permeability of only 3.85%with no noticeable exudation.The latent heat of melting and solidification phase change is 203.8 and 196.6 kJ/kg,respectively.After 50 cooling and heating cycles,minimal changes are observed in phase transition temperature and latent heat,and the thermal conductivity remains stable with a fluctuation range of only 5.9%.Additionally,the mass loss is only 0.0495 g,which shows good cycle stability.This research provides valuable theoretical data support for the subsequent application of shaped phase change materials in solar PV/T systems.
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