Quantification of the natural convection perturbations on differential scanning calorimetry measurements of PCMs

Abstract

The paper investigates the effect of natural convection during differential scanning calorimetry measurements of phase change materials. We performed series of numerical simulations to characterize and quantify the perturbation on the measured thermogram. This perturbation becomes significant at the end of the fusion process. It manifests itself as an increase of the heat flux amplitude which accelerates the fusion process. Three correlations are built from the simulation results. The two first correlations quantify the amplitude of the heat flux deviation. The third correlation locates the time at which the perturbation occurs. The correlations are valid for large DSC capsules (around 1ml), and high Prandtl materials (paraffins, salt hydrates, fatty acids). They enable to define the experimental conditions for which natural convection becomes negligible.

Formulation and phase change mechanism of Capric acid/Octadecanol binary composite phase change materials

“…The most common used method for obtaining both the PLH and PTT of PCMs is the DSC test to obtain the curve diagram of temperature and heat flow value. Natural convection could accelerate the heat transfer between the phase front and the heat transfer fluid in PCMs energy storage systems and this phenomenon will also affect the DSC test results of PCMs [42][43][44]. Therefore, in the process of DSC testing, in order to limit the influence of natural convection when the PCM samples are the liquid phase [42,43,45], it is necessary to select appropriate test conditions, such as a small amount of samples (generally in the range of 5-10 mg), low heating rate (such as 10 • C/min or 5 • C/min) and small crucibles (about 10 μl) for measurement [46,47], and this is followed in the study.…”

Characterizing phase change materials using the T-History method: On the factors influencing the accuracy and precision of the enthalpy-temperature curve

“…Because natural convection has already been discussed even for small DSC sample sizes [24], it is likely that the phenomenon is even more pronounced in the larger T-History samples.…”