Cycle test stability and corrosion evaluation of phase change materials used in thermal energy storage systems

摘要

Phase change material (PCM) is a vital component of thermal energy storage (TES), particularly at a constant temperature. Various organic, inorganic, eutectic, and composite materials are used for storage applications. The major problems with the PCMs are their long-term stability and reliability because they generally degrade and lose their storage capability after long exposure to the ambient environment and with continuous melt/freeze cycles. Therefore, the cycle test stability of PCMs is essential to ascertain the long-term durability of the PCM before coupling it to the thermal system. The PCM's container is also susceptible to corrosion that reduces its life and deteriorates the functioning of the PCM. Various PCMs have been analyzed here that lie between the 6 degrees C and 218 degrees C melting temperature (MT) range having 30-340 kJ/kg of storage potential which is suitable for the low and medium temperature storage application. The maximum variation concerning MT and latent heat of fusion (LHF) observed was +/- 10% and +/- 40% respectively depending on the number of cycles. The organic materials were comparatively more stable and could be used for a longer duration of time when compared to inorganic materials. For any kind of PCM, at least 300 melt/freeze should be conducted to ascertain a year's applicability. The stainless steel was found the most resistant and compatible with the majority of the PCMs. The thermogravimetric analysis (TGA) has further shown that most of the materials do not degrade in their working temperature range.