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A dynamic latent thermal storage (DLTS) system operates at elevated working temperatures to maximize the operation of the thermal system. It potentially deteriorates the phase change material (PCM) after specific cycles due to thermal aging. The present work assesses the impact of thermal aging of wax-based PCM (paraffin and beeswax) toward the technical parameter of a DLTS system. After thermal aging treatment, the charge and discharge performance for both PCM are degraded. The discharge rate of beeswax (BW) decreases by 23.2%, reducing the effective power rate and storage efficiency by more than 50%. The aged paraffin wax (PW) also experiences performance degradation, where the discharge and power rates decrease around 14.7% and 18.7%, respectively. However, the aged PW maintains sufficient efficiency (67.2%) compared to BW (41.1%), implying that the aging effect can vary for different PCM. Surface observation for the aged PCM demonstrates a fracture profile and microvoids which are probably affected by thermal stress that leads to physical deformation at the molecular level. The decomposition curve is also changed for the aged PCM, making thermal stability an important parameter in choosing a suitable PCM for long-term operation. The study demonstrates the urgency to consider suitable PCM and adjustment on the operation protocol of the DLTS system after a certain cycle operation to minimize the degradation of performance parameters of the thermal system.
Firman et al. (Fri,) studied this question.