Numerical studies on the effect of location and number of containers on the phase transition of PCM-integrated evacuated tube solar water heater

The present work attempted to address and identify the best-fit configuration for the incorporation of latent heat thermal energy storage (LHTES) inside an evacuated tube collector type solar water heater (ETCSWH). Among the earlier reported investigations, this work stands out as it employs a computational approach to model and investigates a real-scale market available ETCSWH comprising the LHTES encapsulated in multiple containers. To bring out an effective comparative study to determine the influence of containers incorporated within the ETCSWH on the melting and solidification characteristics of the phase-change material (PCM), three positions or numbers of cylinders were chosen for the study. The main objective was to analyze the influence of the location and the number of LHTES containers on the phase-change behavior of paraffin wax in two modes of operation (namely, static and dynamic modes). A transient, three-dimensional, viscous-laminar solver aids in executing the present computational work using ANSYS-Fluent®. The study utilizes ETCSWH incorporated with PCM in three configurations with the operating variables held constant. The results suggest that the cylinder number and the duration required for complete melting are inversely proportional. Additionally, the location of containers inside the ETCSWH is a critical factor in deciding whether the integration of LHTES is beneficial or not. Furthermore, a functional relationship between the duration required for complete melting of PCM and the number of containers is derived.