Thermal performance of an accumulator unit using phase change material with a fixed volume of fins

Abstract

Summary Melting rate enhancement inside an accumulator unit for a phase change material (PCM) has been numerically investigated in a shell‐and‐tube (S‐T) arrangement that incorporates the circular type of fins, considering a fixed total volume of fins. The number of fins was chosen as the design parameter. The heat transfer fluid (HTF) was chosen as water that flows through the selected accumulator unit during the process of melting. The computational fluid dynamics (CFD) technique has been utilized for the simulation of the accumulator using ANSYS FLUENT software by considering a two‐dimensional axisymmetric cylindrical accumulator in a vertical direction. During the melting process, two heat transfer mechanisms were considered, namely, conduction and convection. The HTF flow was 5 L/min with a flow temperature of 358 K for charging. The predicted complete melting time of the PCM decreased by 53.125%, 65.625%, 71.875%, and 71.875% for fins numbering 6, 18, 30, and 36, respectively, compared with the S‐T without fins where it took approximately 480 minutes to melt completely. The optimal fin parameters are recommended in this study as follows: number of fins N = 30, thickness t/d = 0.01858, interval d/L = 0.03227, and aspect ratio t/h = 0.015. These recommended values maximize the thermal performance of the selected accumulator unit. The effects of changing the flow rate of the heat transfer fluid and its inlet temperature have been found to be significant on the PCM melting rate. The total melting time of the PCM is found to be reduced by about 57% when the inlet flow temperature is increased from 343 to 358 K. Moreover, the total melting time reduces by about 70.5% with an increase in the heat transfer fluid mass flow rate from 0.15 to 5 L/min. Furthermore, increasing the HTF flow rate from 0.15 to 5 L/min leads to a reduction of about 61.1% in the predicted total time that is required for solidification. The temperature differences for low flow rates are greater than those for high flow rates. The novelty of this study is in investigating the performance at a fixed total volume of fins.

Recent Advances in CFD Simulations of Multiphase Flow Processes with Phase Change

“…Dekhil et al 84 and Rana et al 268 found that the melting time of the shell-andtube LHS system was reduced with the incorporation of fins, and the melting and solidification rate of longitudinal fins were twice of plain tubes and 1.14 times of the radial finned tubes. Amer et al 269 and Abreha et al 270 found that the melting time and solidification of the finned shell-and-tube LHS system were reduced by up to 70.5% by increasing the HTF flow rate and HTF inlet temperature. Shaker et al 271 found that the complete melting and solidification time of cylindrical encapsulated PCM was enhanced by 41% with increasing the fin number from 4 to 12.…”

“…Amagour et al 91 proposed an improved PCM-based coil tube heat exchanger configuration with 13 complete copper fins of 248 mm (long) × 50 mm (high) × 0.9 mm (thick) and 37 copper fins with dimensions of 248 mm × 25 mm × 0.9 mm, which can reduce the melting time by 9% compared with the original configuration. Xu et al 274 and Amer et al 269 concluded that the coupled effects of fin number, location, length, and thickness should be considered comprehensively to obtain an optimal fin structure. The critical value of total fin length was also proved to be increased with the increasing of the Rayleigh number…”

Utilization of Carbon-Based Nanomaterials and Plate-Fin Networks in a Cold PCM Container with Application in Air Conditioning of Buildings

“…They discovered that the staggered distribution of fins can improve the melting and heat charging rate by 37.2 and 59.1%, respectively. Amer et al [ 13 ] examined the melting process in a PCM-filled shell-and-tube (SAT) unit with a various number of circular fins. They showed that with 36, 30, 18, and 6 fins, 72, 72, 66, and 53% of melting rate enhancement can be obtained compared to the base SAT unit without fins.…”

Improving the solidification performance of a shell‐and‐tube latent‐heat thermal energy storage unit using a connected‐Y ‐shaped fin

“…Therefore, it has a broad application prospect. However, the low thermal conductivity of phase change materials (PCMs) limits the thermal energy charge/discharge rate of shell‐and‐tube LTESU 4 . For solving this problem, various methods to enhance heat transfer have been proposed by researchers, such as adding nanoparticles, 5,6 metallic foam, 7,8 and fins 9,10 .…”

“…However, the low thermal conductivity of phase change materials (PCMs) limits the thermal energy charge/discharge rate of shell-and-tube LTESU. 4 For solving this problem, various methods to enhance heat transfer have been proposed by researchers, such as adding nanoparticles, 5,6 metallic foam, 7,8 and fins. 9,10 Compared with other strengthening methods, fins have the advantages of easy manufacture, low cost, and long service life.…”