Optimization of Fin Parameters to Reduce Entropy Generation and Melting Time of a Latent Heat Storage Unit

Abstract

One of the challenges in the design and development of a latent heat storage unit (LHSU) is to increase the charging and discharging rates which are inherently low because of low thermal conductivity of phase change materials (PCM). Out of various heat transfer enhancement techniques, employing annular fins is very simple, efficient and no fabrication complexity is involved. Fin parameters (fin size and number of fins) significantly influence the enhancement in heat transfer rate. Hence, optimization of fin parameters is necessary for the efficient design of an LHSU. While designing an LHSU along with heat transfer rate, entropy generation should also be considered in order to make it exergetically efficient. Therefore, the present study is aimed at multi-objective optimization of annular fin parameters to minimize the melting time and entropy generation. Fin diameter and the number of fins are taken as the variables. The influence of these two variables on the melting time, average Nusselt number, energy stored, and distribution of entropy is presented. The melting rate is increased, and global entropy generation decreased by increasing the number of fins up to 15. An increase in the fin diameter reduced the melting time while entropy generation got increased. For the multi-objective optimization, the multi-objective optimization based on ratio analysis (MOORA) technique is chosen and the optimized values of fin diameter and number of fins are observed to be 80 mm and 15 respectively. Finally, optimized parameters are represented in non-dimensional form to make them applicable for any size of the LHSU.

Investigation on compatibility and thermal reliability of phase change materials for low-temperature thermal energy storage

“…The thermal energy stored/released during the phase change process is latent heat. In recent years, thermal energy storage using phase change materials has been a major topic of research, due to its large energy density and nearly isothermal heat transfer process [6,7]. Based on the phase change process, phase change materials (PCMs) can be categorized into solid-solid, solid-liquid, solid-gas, and liquid-gas.…”

Influence of fin configuration on the thermal performance of nanoparticle-enhanced latent heat storage system

“…Kalapala and Devanuri 1 on reviewing several research works concluded that the optimized ratio of shell to tube diameter should be nearly 4. Kaplala and Devanuri 13 gave the nondimensional correlation for fin spacing and fin diameter by optimizing the melting time for radial finned LHTES HX. In the present study same pitch and diameter of fins are considered for radial and spiral finned LHTES HX.…”

“…The radius of the radial fins is considered from the nondimensional parameters given by Kalapala and Devanuri. 13 The same diameter is considered for spiral fins. The radial distance of longitudinal fins is considered to be equal to the radius of radial fins.…”

“…Therefore in the present study, the mass flow rate of the HTF is fixed at 1.4 Liters per minute (LPM). 13 The Reynolds number for the considered mass flow rate of HTF is 1710. Computational models of HXs are shown in Figure 1.…”

“…They also suggested that the ratio of pitch of fins to the radius of the tube should not exceed 4. Kalapala and Devanuri 13 carried out the numerical analysis on the radial finned shell and tube HX and gave a correlation for the optimized design of nondimensional fin diameter and fin pitch. Kalapala and Devanuri 14 conducted experimental and numerical analysis on radial finned shell and tube HX.…”