Correction of the enthalpy–temperature curve of phase change materials obtained from the T-History method based on a transient heat conduction model

Artikel i vetenskaplig tidskrift, 2017

Utilizing the latent heat of materials undergoing phase transitions, or so called phase change materials (PCMs), for thermal energy storage offers higher storage densities compared to purely sensible thermal energy storages. For evaluating different PCMs the T-History method has often been applied by researchers in order to determine the characteristic enthalpy versus temperature curves. In previous research many different T-History setups are described where the sample holder is insulated. The intention is to decrease internal temperature gradients inside the sample holder with PCM. However, in the mathematical model for evaluating the enthalpy curve of the PCM based on the measured temperature response, the thermal mass of the insulation around the sample holder has been neglected. In this study, a one dimensional numerical transient heat transfer model is used to show that neglecting the insulation thermal mass leads to a systematic error on the obtained enthalpy versus temperature curves. The error is caused by deviations in the transient heat flows for reference and PCM sample when both are cooled down or heated, respectively. These deviations can be corrected by introducing a correction factor.