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

2021 ◽  
Vol 45 (2) ◽  
pp. 141-151
Author(s):  
Nesrine Boulaktout ◽  
El Hacene Mezaache ◽  
Abdelghani Laouer
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Exchanger ◽  
Phase Change ◽  
Phase Change Material ◽  
Melting Process ◽  
Initial Time ◽  
Tube Heat Exchanger ◽  
Change Material ◽  
Annular Tube

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.

Second-Law Efficiency of an Energy Storage-Removal Cycle in a Phase-Change Material Shell-and-Tube Heat Exchanger

1993 ◽  
Vol 115 (4) ◽  
pp. 240-243 ◽  
Author(s):  
Ch. Charach
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Phase Change ◽  
Phase Change Material ◽  
Latent Heat ◽  
Heat Storage ◽  
Latent Heat Storage ◽  
Tube Heat Exchanger ◽  
Shell And Tube ◽  
Change Material

This communication extends the thermodynamic analysis of latent heat storage in a shell-and-tube heat exchanger, developed recently, to the complete heat storage-removal cycle. Conditions for the cyclic operation of this system are formulated within the quasi-steady approximation for the axisymmetric two-dimensional conduction-controlled phase change. Explicit expressions for the overall number of entropy generation units that account for heat transfer and pressure drop irreversibilities are derived. Optimization of this figure of merit with respect to the freezing point of the phase-change material and with respect to the number of heat transfer units is analyzed. When the frictional irreversibilities of the heat removal stage are negligible, the results of these studies are in agreement with those developed recently by De Lucia and Bejan (1991) for a one-dimensional latent heat storage system.

scholarly journals Application of Phase Change Material-Based Thermal Capacitor in Double Tube Heat Exchanger—A Numerical Investigation

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4327
Author(s):  
Matthew Fong ◽  
Jundika Kurnia ◽  
Agus P. Sasmito
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Phase Change ◽  
Phase Change Material ◽  
Phase Change Materials ◽  
Oscillation Period ◽  
Temperature Oscillation ◽  
Tube Heat Exchanger ◽  
Inlet Conditions ◽  
Change Material

In many heat transfer related applications, there is a need for a stable, constant supply temperature. As a result, the integration of intermittent renewable sources of heat into these processes can prove to be challenging, requiring special temperature smoothing devices or strategies. This study focuses on the application of phase change materials integrated into a double tube heat exchanger as a possible thermal smoothing device. The objective of this study is to evaluate the ability of the exchanger to smoothen out temperature variations within the cold stream outlet while the hot stream is subject to oscillating inlet conditions. A computational fluid dynamics approach is used where a numerical model is developed, validated and then used to model the conjugate heat transfer within the heat exchanger. Four organic phase change materials (PCM) with different phase change temperatures were selected for investigation (myristic, octadecane, eicosane, and wax) to study the relationship between melting temperature and stabilization performance. A parametric study was then conducted by varying the Reynolds number of the flow as well as temperature oscillation period and amplitude to study the sensitivity of the system. The results confirm the potential of a phase change material-based thermal capacitor at dampening oscillations across the heat exchanger.

Natural Convective Heat Transfer Characteristics of the Bundle Heat Exchanger in the Latent Heat Microcapsulated Phase Change Material Slurry

2016 ◽  
Vol 852 ◽  
pp. 969-976
Author(s):  
Jian Zhang ◽  
Liang Wang ◽  
Yu Jie Xu ◽  
Yi Fei Wang ◽  
Zheng Yang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Exchanger ◽  
Phase Change ◽  
Convective Heat Transfer ◽  
Phase Change Material ◽  
Convective Heat ◽  
Latent Functionally Thermal Fluid ◽  
Potential Applications ◽  
Change Material

As a novel latent functionally thermal fluid, microcapsulated phase change material slurry (MPCMS) has many potential applications in the fields of energy storage, air-conditioning, refrigeration and heat exchanger, etc. In order to investigate the heat storage and heat transfer performance of MPCMS, natural convection in a rectangular enclosure heated by bundle heat exchanger has been studied numerically in this paper. The effects of mass concentration (Cm) of MPCMS, the vertical spaces of bundle heat exchanger on the natural convective heat transfer are investigated. The results indicate that, MPCMS with Cm=30% shows the best natural convectionperformance, and a lower position of bundle heat exchanger can strengthen the natural convection.

Effect of natural convection on conjugate heat transfer characteristics in liquid minichannel during phase change material melting

2013 ◽  
Vol 228 (3) ◽  
pp. 491-513 ◽  
Author(s):  
M Khamis Mansour
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Phase Change ◽  
Phase Change Material ◽  
Conjugate Heat Transfer ◽  
Thermal Characteristics ◽  
Melting Process ◽  
Heat Transfer Fluid ◽  
Local Surface Temperature ◽  
Change Material

This article presents numerical and experimental simulation of three-dimensional conjugate heat transfer problem in mini-scaled thermal storage system. The conjugate problem includes melting process of phase change material in the presence of natural convection during laminar flow of heat transfer fluid through circular minichannel. The paraffin wax is used as a phase change material while the water is used as a heat transfer fluid. The main objective of this study is to investigate the effect of the phase change material natural convection during the melting process on the heat transfer fluid thermal characteristics as well as the impact of the natural convection on the melting performance itself. The thermal characteristics are represented by local Nusselt number ( Nu) and local surface temperature. The melting performance is evaluated by fusion time and liquid fraction profile. Two inlet temperatures and velocities of the heat transfer fluid are adopted to highlight the effect of the natural convection. Combination of the inlet temperatures and velocities of the heat transfer fluid forms four cases: case_1 (at [Formula: see text] = 353 °K, [Formula: see text] = 1 m/s), case_2 (at [Formula: see text] = 453 °K, [Formula: see text] = 1 m/s), case_3 (at [Formula: see text] = 353 °K, [Formula: see text] = 0.1 m/s), and case_4 (at [Formula: see text] = 453 °K, [Formula: see text] = 0.1 m/s). Experimental test rig was constructed to verify the computational results and good agreement between both results was achieved. The study shows that the heat transfer fluid encounters an erratic thermal behavior during the phase change material melting process. For example, the local surface temperature experiences dramatic increase and decrease at certain sections of the channel length. The magnitude of this temperature inconsistency interrelates closely to the strength of natural convection impact, and this can expose the minichannel (which has short length) to severe wall thermal stress. The local Nu experiences improvement in some section of the channel and at the same time it suffers from drastic deterioration in its value particularly at the channel end at which the convection current accommodates. The case with the lowest inlet velocity and the highest inlet temperature has the smallest fusion time at expense of the largest heat transfer fluid bulk temperature gradient before reaching the fusion time. The study is considered as a benchmark and helpful guidelines in the design of small-scaled thermal storage systems of phase change material.

scholarly journals Designs of PCM based heat exchangers constructions for thermal energy storage tanks – examples and case study for selected design

2018 ◽  
Vol 70 ◽  
pp. 01010
Author(s):  
Marta Kuta ◽  
Dominika Matuszewska ◽  
Tadeusz Michał Wójcik
Keyword(s):  
Energy Storage ◽  
Heat Exchanger ◽  
Phase Change ◽  
Phase Change Material ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
New Technologies ◽  
Tube Heat Exchanger ◽  
Change Material

Increasing energy consumption in residential and public buildings requires development of new technologies for thermal energy production and storage. One of possibilities for the second listed need is the use of phase change materials (PCMs). This work is focused on solutions in this area and consists of two parts. First one is focused on different designs of thermal energy storage (TES) tanks based on the phase change materials. The second part is the analysis of tests results for TES tank containing shelf and tube heat exchanger and filled with phase change material. Thermal energy storage tank is analyzed in order to use it in domestic heating and hot utility water installations. The aim of this research was to check the applicability of phase change material for mentioned purpose. Results show that using phase change materials for thermal energy storage can increase amount of stored heat. The use of properly selected PCM and heat exchanger enables the process of thermal energy storing and releasing to become more efficient.

Numerical Survey of the Melting Driven Natural Convection Using Generation Heat Source: Application to the Passive Cooling of Electronics Using Nano-Enhanced Phase Change Material

2019 ◽  
Vol 12 (2) ◽  
Author(s):  
Hamza Faraji ◽  
Mustapha Faraji ◽  
Mustapha El Alami
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Source ◽  
Phase Change ◽  
Phase Change Material ◽  
Metallic Nanoparticles ◽  
Simple Algorithm ◽  
Bottom Side ◽  
Volume Method ◽  
Change Material

Abstract The present paper reports numerical results of the melting driven natural convection in an inclined rectangular enclosure filled with nano-enhanced phase change material (NePCM). The enclosure is heated from the bottom side by a flush-mounted heat source (microprocessor) that generates heat at a constant and uniform volumetric rate and mounted on a substrate (motherboard). All the walls are considered adiabatic. The purpose of the investigation is analyzing the effect of nanoparticles insertion by quantifying their contribution to the overall heat transfer. Combined effects of the PCM type, the inclination angle and the nanoparticles fraction on the structure of the fluid flow and heat transfer are investigated. A 2D mathematical model based on the conservation equations of mass, momentum, and energy was developed. The governing equations were integrated and discretized using the finite volume method. The SIMPLE algorithm was adopted for velocity–pressure coupling. The obtained results show that the nanoparticles insertion has an important quantitative effect on the overall heat transfer. The insertion of metallic nanoparticles with different concentrations affects the thermal behavior of the heat sink. They contribute to an efficient cooling of the heat source. The effect of nanoparticles insertion is also shown at the temperature distribution along the substrate.

Numerical analysis of phase-change material melting in triplex tube heat exchanger

2020 ◽  
Vol 145 ◽  
pp. 867-877 ◽  
Author(s):  
Kun Yang ◽  
Neng Zhu ◽  
Chen Chang ◽  
Haoran Yu ◽  
Shan Yang
Keyword(s):  
Heat Exchanger ◽  
Numerical Analysis ◽  
Phase Change ◽  
Phase Change Material ◽  
Tube Heat Exchanger ◽  
Change Material

Numerical Simulation of Phase Change Thermal Storage in Finned Double-Pipe Heat Exchanger

2012 ◽  
Vol 232 ◽  
pp. 742-746 ◽  
Author(s):  
H. Shokouhmand ◽  
B. Kamkari
Keyword(s):  
Numerical Simulation ◽  
Natural Convection ◽  
Heat Exchanger ◽  
Phase Change ◽  
Phase Change Material ◽  
Numerical Investigations ◽  
Double Pipe ◽  
Change Material ◽  
Pipe Heat ◽  
Bare Tube

This paper presents numerical investigations on melting of phase change material using paraffin wax inside a double pipe heat exchanger. Numerical simulations are performed for melting of phase change material (PCM) in annulus while the inner pipe has two or four longitudinal fins and the results compared with inner bare tube. The aim of this study is to understand the PCM melting behaviors by observing the natural convection currents movement and melting fronts formation. It is concluded that melting performance of PCM can be significantly improved by applying longitudinal fins on the inner tube.

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