Study of Thermal Behavior of a Horizontal Two Fins Annular Tube Heat Exchanger with Melting Phase Change Material: Fins Orientation Effects

Abstract

This paper investigates the effect of fins orientations of a horizontal two fins annular tube heat exchanger on enhancing the heat transfer during the melting process of n-eicosane, as phase change material (PCM) used in thermal storage systems. Based on the enthalpy-porosity method, two-dimensional model is performed and solved by Ansys Fluent. The impact of the fins orientation on melting rate, thermal conduction and natural convection, as the angle of the system varied from 0º (vertical fins) to 90º (horizontal fins) are discussed. Numerical predictions are validated by comparison with experimental data and numerical results reported in the literature. Good agreements are achieved. The results show that at initial time of the melting process, the conduction heat transfer is dominant. During the melting process, the heat transfer in the horizontal fins is more effective while the upper half of PCM melts and less effective as the lower half of PCM melts because fin arrangement resists natural convection occurs. However, the effectiveness of heat transfer and convection in the vertical fins is almost constant during the entire melting process. From comparison, better heat transfer performance is achieved with vertical fins system; complete melting was reduced 250% compared to horizontal fins case.

Heat Transfer Analysis of the Melting Process on Finned Tubes (A Review on performance enhancement)

“…Nesrine Boulaktout et al [1] conducted a numerical and practical study to improve the heat transfer of annular tube heat exchangers using fins to accelerate the melting rate of nicosan, which was examined in practice. The thermal potential energy of the porous material in nicosan was calculated and the phase type was changed, and it was found that the melting process of the material when changing the phase needs additional time .She also explained that the use of metal fins improves heat transfer and that changing their direction horizontally and vertically has an impact on thermal performance.…”

“…Basically, there are three basic types of thermal energy storage systems, as shown in Figure 1, i.e. thermochemical energy storage units, perceptible thermal energy storage units, and potential thermal energy storage units [1]. The depletion of the ozone layer and the rise in fuel costs have encouraged researchers to improve the efficiency of systems based on sustainable energy sources such as energy storage devices.…”

Progress in the Study of Enhanced Heat Exchange in Phase Change Heat Storage Devices

“…Yu 26 determined the optimal fin-splitting angle, while Zheng 27 determined that the optimal number of tree-like fin layers is 4 using the transient model enthalpy-porosity method. Notably, Boulaktout 28 and Chen 29 highlighted that heat conduction and heat transfer play a dominant role during the initial stage of PCM melting. The heat transfer at the fin level exhibits higher efficiency when the upper half of the PCM has melted, but it becomes less effective during the melting of the lower half of the PCM.…”

“…Notably, Boulaktout 28 and Chen 29 highlighted that heat conduction and heat transfer play a dominant role during the initial stage of PCM melting. The heat transfer at the fin level exhibits higher efficiency when the upper half of the PCM has melted, but it becomes less effective during the melting of the lower half of the PCM.…”

Melting of nano‐enhanced phase change material in a cavity heated sinusoidal from below: Numerical study using lattice Boltzmann method

“…Several active and passive methods, such as bubbles nuclei, 1 and ultrasonic vibrations, 2 have been used to manage water phase changes efficiently. Passive approaches such as inserting metallic fins, [3][4][5] nanoparticles, [6][7][8][9] and metal foam, 10,11 have been used to overcome PCM's limited heat conductivity. On the other hand, dispersion nanoparticles improve both the thermal conductivity and the subcooling impact of PCM water.…”