Characterization of thermophysical properties of nano-enhanced organic phase change materials using T-history method

Abstract

Nano-enhanced phase change materials (NEPCMs) have gained popularity as efficient thermal management and energy storage materials owing to their high latent heat and enhanced thermal conductivity. Conventionally, NEPCMs are characterized using standard calorimetry instruments and transient techniques. The temperature-history (T-history) method has been identified as a simple and effective method to measure the thermophysical properties of various PCM systems. In the experimental study presented here, the feasibility of using T-history method to determine the thermophysical properties of a solid–liquid organic phase change material (PCM) dispersed with nano-additives is examined. NEPCMs are prepared with three loading levels (0.1, 0.5 and 1.0 wt%) of nanoparticles of alumina and silica and GNP aggregates dispersed in a binary mixture of paraffin wax and stearic acid. Properties such as specific heat, latent heat of solidification and thermal conductivity are determined from the T-history data by plotting time–temperature curves. Temperature–enthalpy curves are also developed from the same data for the direct evaluation of change in enthalpy during the phase change process. Approximately 5% deviation was observed in the latent heat values computed via time–temperature curves and temperature–enthalpy curves. The values obtained via the T-history method are compared with those obtained from differential scanning calorimetry and transient planar source measurements. A maximum of 10% and 7% deviation was observed for the latent heat of solidification and thermal conductivity of NEPCMs, respectively. From the study, it is inferred that the T-history method is a cost-effective and reliable method for evaluating and comparing the thermophysical properties of NEPCMs.