Analysis of NePCM melting flow inside a trapezoidal enclosure with hot cylinders : effects of hot cylinders configuration and slope angle

DATA AVAILABILITY : Data will be made available on request.Please read abstract in the article.Prince Sattam bin Abdulaziz University.https://www.elsevier.com/locate/csitehj2024Mechanical and Aeronautical EngineeringSDG-09: Industry, innovation and infrastructur

The Thermal Charging Performance of Finned Conical Thermal Storage System Filled with Nano-Enhanced Phase Change Material

A latent heat thermal energy storage (LHTES) unit can store a notable amount of heat in a compact volume. However, the charging time could be tediously long due to weak heat transfer. Thus, an improvement of heat transfer and a reduction in charging time is an essential task. The present research aims to improve the thermal charging of a conical shell-tube LHTES unit by optimizing the shell-shape and fin-inclination angle in the presence of nanoadditives. The governing equations for the natural convection heat transfer and phase change heat transfer are written as partial differential equations. The finite element method is applied to solve the equations numerically. The Taguchi optimization approach is then invoked to optimize the fin-inclination angle, shell aspect ratio, and the type and volume fraction of nanoparticles. The results showed that the shell-aspect ratio and fin inclination angle are the most important design parameters influencing the charging time. The charging time could be changed by 40% by variation of design parameters. Interestingly a conical shell with a small radius at the bottom and a large radius at the top (small aspect ratio) is the best shell design. However, a too-small aspect ratio could entrap the liquid-PCM between fins and increase the charging time. An optimum volume fraction of 4% is found for nanoparticle concentration

Thermal Charging Optimization of a Wavy-Shaped Nano-Enhanced Thermal Storage Unit

A wavy shape was used to enhance the thermal heat transfer in a shell-tube latent heat thermal energy storage (LHTES) unit. The thermal storage unit was filled with CuO–coconut oil nano-enhanced phase change material (NePCM). The enthalpy-porosity approach was employed to model the phase change heat transfer in the presence of natural convection effects in the molten NePCM. The finite element method was applied to integrate the governing equations for fluid motion and phase change heat transfer. The impact of wave amplitude and wave number of the heated tube, as well as the volume concertation of nanoparticles on the full-charging time of the LHTES unit, was addressed. The Taguchi optimization method was used to find an optimum design of the LHTES unit. The results showed that an increase in the volume fraction of nanoparticles reduces the charging time. Moreover, the waviness of the tube resists the natural convection flow circulation in the phase change domain and could increase the charging time

The influence of aspect ratios of two elliptical cylinders on the solid-liquid phase change flow

Nowadays, phase change materials are widespread in different engineering applications including cooling of electronics, thermal performance in building elements, heat exchangers, and many more. It is critical to gain thorough comprehension on phase change material behavior. The present research aims to numerically simulate phase change material in a heat storage unit having two isothermal elliptical elements. The formulated partial differential equations have been solved by the finite element technique taking into account the enthalpy-porosity approach and adaptive mesh refinement technique. The developed computational code has been validated using numerical and experimental data from the literature. The influence of the aspect ratios of the two elliptical cylinders on the melting phenomenon has been scrutinized, and the most efficient shapes have been identified. It has been found that more intensive melting occurs when the aspect ratios of the upper and lower cylinders are ARu = 0.25 and ARl = 4.0, with a reduction of 18.45 % in the melting time compared to the case with ARu = ARl = 1.0. Furthermore, the case with ARu = 1.0 and ARl = 0.5 shows the longest melting time, with an increase of 0.6 % in the melting time compared to the case with ARu = ARl = 1.0

The influence of aspect ratios of two elliptical cylinders on the solid-liquid phase change flow

Please read abstract in the article.Prince Sattam bin Abdulaziz University.https://www.elsevier.com/locate/aejhj2024Mechanical and Aeronautical EngineeringSDG-09: Industry, innovation and infrastructur

Employing RSM to model thermal performance and exergy destruction of LS-3 parabolic trough collector by coupling MCRT and CFD techniques

This study investigates the thermal performance and exergy destruction of parabolic trough collector by Response Surface Methodology. This collector is simulated by the Monte Carol Ray Tracing method and the results are coupled to the Computational Fluid Dynamics. Thermo-hydraulic performance and the characteristics of the thermodynamics second law are studied with the turbulence-inducing elements and hybrid nanofluid. The absorber tube features elements with a helical profile along its wall. New correlations are presented to describe thermal performance and exergy destruction, and the modeling output shows that these correlations have high prediction accuracy. Response Surface Methodology results also show that turbulators have a nonlinear effect on thermal performance while the Reynolds number has a nonlinear effect on exergy destruction. Fe3O4 nanoparticles and carbon nanotube lead to an increase of 13 % and 10 % of Nusselt number, respectively, at Re=12000. Also, it leads to a decrease of 7 % and 6.7 % of exergy destruction, respectively. Increasing the working fluid flow rate from 12000 to 22000 improves thermal performance up to 73 %, and decreases exergy destruction up to 48 %. The maximum value of thermal performance is equal to 2.1, and this value is related to the highest Reynolds number and the absorber tube including turbulence-inducing elements