Transient analysis of PCM discharging in a rotary triplex tube with wave-shaped fins

Abstract

Phase change material (PCM) based thermal storage units have attracted attention in energy storage technology. To improve its effectiveness, researchers have introduced various techniques. In this study, a novel rotary triplex tube with sinusoidal wave-shaped fin design is proposed as a PCM based thermal storage unit, and its performance is compared with a conventional straight fin design. A two-dimensional numerical model is developed for the transient analysis of discharging process of PCM. The discharging process is modelled using enthalpy porosity technique. The validation of the model is done against the experimental result from the literature. The discharging process of PCM is analyzed at different rotational speeds. Thermal performance and fluid flow dynamics are evaluated by analyzing the molten portion, temperature, and velocity variation. The result showed that an increase in rotational speed led to an increase in the discharging rate of the PCM. When there is no rotation or slow rotation (0.05 and 0.1 RPM), the discharging is faster in the unit with straight fins compared to the unit with wave-shaped fins. However, at higher rotational speeds (0.2, 0.3 and 0.4 RPM), discharging is faster in the unit with wave-shaped fins. Overall, this study provides insights into the design and performance of PCM based thermal storage unit and suggests the use of wave-shaped fins for higher rotational speeds to enhance the discharging rate of PCM.