Experimental challenges in differential scanning calorimetry for Hydrogen storage applications
Résumé
Dihydrogen appears to be a promising energy vector. Technological advances in its storage now make it possible to store it in its pure state in liquid, solid or gaseous form, or combined in molecules such as ammonia, methanol or methane. Another means of storage is adsorption in porous structures. However, this process is impacted by the thermal properties of the adsorbent materials, highlighting the importance of exploring thermal parameters in these materials.
The heat capacity (Cp) is one of these characteristics, it plays a primordial role in adsorption phenomena, as enhancing the heat capacity of a solid adsorbent helps reducing the adverse thermal effects resulting from the heat of adsorption. Differential scanning calorimeter (DSC) can be used to determine heat capacity. The implementation of this technique on powdery samples with low heat capacity is however delicate when precise quantification of these values is desired at low temperatures, from -180°C to 25°C.
As part of this study, the aim is to determine the heat capacity of metal-organic framework (MOF) powders, which are used for dihydrogen storage by adsorption. Few experimental measurements of their heat capacity at low temperatures exist, and results are sometimes inconsistent. The DSC used was the Q1000 from TA Instruments, employing the heat flow method with TzeroTM technology. After Cp measurement tests with the DSC Standard mode, the experiments were carried out in modulated mode. This mode, where a small sinusoidal modulation of a temperature is applied to the linear increase in temperature, provides more precise results than the DSC Standard mode. The analysis includes factors such as crucible positioning, pelletizing pressure, sample diameter, and volume in the crucible, to study their effects on heat capacity values.
Domaines
Physique [physics]Origine | Fichiers produits par l'(les) auteur(s) |
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Licence |
Domaine public
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