scholarly journals Enhanced Heat Transfer for NePCM-Melting-Based Thermal Energy of Finned Heat Pipe

Nanomaterials ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 129
Author(s):  
Sameh E. Ahmed ◽  
Aissa Abderrahmane ◽  
Sorour Alotaibi ◽  
Obai Younis ◽  
Radwan A. Almasri ◽  
...  
Keyword(s):  
Energy Storage ◽  
Phase Change Materials ◽  
Volume Fraction ◽  
Liquid Fraction ◽  
Melting Process ◽  
Flow Structures ◽  
The Finite Element Method ◽  
Flow Area ◽  
Governing System ◽  
Nanoparticles Volume Fraction

Using phase change materials (PCMs) in energy storage systems provides various advantages such as energy storage at a nearly constant temperature and higher energy density. In this study, we aimed to conduct a numerical simulation for augmenting a PCM’s melting performance within multiple tubes, including branched fins. The suspension contained Al2O3/n-octadecane paraffin, and four cases were considered based on a number of heated fins. A numerical algorithm based on the finite element method (FEM) was applied to solve the dimensionless governing system. The average liquid fraction was computed over the considered flow area. The key parameters are the time parameter (100 ≤t≤600 s) and the nanoparticles’ volume fraction (0%≤φ≤8%). The major outcomes revealed that the flow structures, the irreversibility of the system, and the melting process can be controlled by increasing/decreasing number of the heated fins. Additionally, case four, in which eight heated fins were considered, produced the largest average liquid fraction values.

scholarly journals Enhancement of the Thermal Energy Storage Using Heat-Pipe-Assisted Phase Change Material

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6176 ◽  
Author(s):  
Hamidreza Behi ◽  
Mohammadreza Behi ◽  
Ali Ghanbarpour ◽  
Danial Karimi ◽  
Aryan Azad ◽  
...  
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Heat Pipe ◽  
Latent Heat ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Liquid Fraction ◽  
Energy Storage Applications ◽  
Change Material

Usage of phase change materials’ (PCMs) latent heat has been investigated as a promising method for thermal energy storage applications. However, one of the most common disadvantages of using latent heat thermal energy storage (LHTES) is the low thermal conductivity of PCMs. This issue affects the rate of energy storage (charging/discharging) in PCMs. Many researchers have proposed different methods to cope with this problem in thermal energy storage. In this paper, a tubular heat pipe as a super heat conductor to increase the charging/discharging rate was investigated. The temperature of PCM, liquid fraction observations, and charging and discharging rates are reported. Heat pipe effectiveness was defined and used to quantify the relative performance of heat pipe-assisted PCM storage systems. Both experimental and numerical investigations were performed to determine the efficiency of the system in thermal storage enhancement. The proposed system in the charging/discharging process significantly improved the energy transfer between a water bath and the PCM in the working temperature range of 50 °C to 70 °C.

A General Model for Analyzing the Thermal Performance of the Heat Charging and Discharging Processes of Latent Heat Thermal Energy Storage Systems*

2001 ◽  
Vol 123 (3) ◽  
pp. 232-236 ◽  
Author(s):  
Yinping Zhang ◽  
Yan Su ◽  
Yingxin Zhu ◽  
Xianxu Hu
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Latent Heat ◽  
Thermal Performance ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
General Model ◽  
Phase Change Materials ◽  
Melting Process ◽  
Specific System

During melting of phase change materials (PCM) encapsulated in a container, the solid PCM sinks to the bottom or floats to the top of the container according to the gravitational force and buoyancy resulting from the difference between solid and liquid densities. Compared with the solidification process, the melting process has a quite different behavior. Although the heat transfer characteristics of melting processes in various typical kinds of containers have been studied, the general model for analyzing the thermal performance of both melting and solidification processes of latent heat thermal energy storage (LHTES) systems composed of PCM capsules has not been presented in the literature. The present paper describes such a model which can be used to analyze the instantaneous temperature distribution, instantaneous heat transfer rate, and thermal storage capacity of a LHTES system. For solidification, the model is validated with the results in the literature. The thermal performance during melting of a LHTES system composed of PCM spheres is analyzed as an example. The model is not limited to a specific system or a specific PCM, so it can be used to select and optimize system design and to simulate the thermal behavior of various typical LHTES systems.

Mathematical Investigation for Flow Characteristics of Laminar Ferro-Nanofluid Incorporating Cobalt Ferrite Nanoparticles

2021 ◽  
Vol 68 ◽  
pp. 52-69
Author(s):  
Ahmed S. Rashed ◽  
Ehsan H. Nasr ◽  
Magda M. Kassem
Keyword(s):  
Boundary Layer ◽  
Base Fluid ◽  
Cobalt Ferrite ◽  
Volume Fraction ◽  
Flow Characteristics ◽  
Ferrite Nanoparticles ◽  
Group Method ◽  
Governing System ◽  
Mathematical Investigation ◽  
Nanoparticles Volume Fraction

The effect of a magnetic source of variable strength has been studied on ferro-nanofluid incorporating nanoparticles of Cobalt ferrite (CoFe2O4) with water as a base fluid. Group method has been used to remodel the governing system to a system of ordinary differential equations. The recent study was motivated by inspecting the effect of four parameters including nanoparticles volume fraction, , Prandtl number, , magnetic field strength of the source,, and temperature difference ratio with respect to ambient temperature, . The results showed that the nanofluid velocity and shear stress increased as long as and increase. On the other hand, both are inversely related to the increment in Pr and Temperature distribution inside the boundary layer was noticed to increase due to the increment in Pr values and decrease due to the increment ratios. Contrarily, the heat flux throughout the boundary layer decreased and increased due to increasing respectively. Key words: Ferro-hydrodynamic; Nanofluids; Group Method

Design of a Latent Thermal Energy Storage System From Constructal Approach

2017 ◽  
Author(s):  
Sylvie Lorente
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Optimal Allocation ◽  
Storage System ◽  
Melting Process ◽  
Energy Storage System ◽  
Theoretical And Numerical Analysis

This work presents a theoretical and numerical analysis of thermal energy storage obtained from Phase Change Materials. We start with a study of the early stages of natural convection in the liquid, followed by an analysis of the entire duration of the melting process. Both are based on scale analysis. The numerical simulations cover the entire process, and validate all the features predicted by theory. Next we apply the methodology to the design of an efficient storage system made of a tank filled with a Phase Change Material like paraffin wax. A hot fluid circulates through pipes located within the tank; it is heated by means of a solar panel. The total volume of tubes is fixed. We apply Constructal design to determine the optimal allocation of the hot tubes so that each transfer mode is used at the best moment. We demonstrate that the overall energetic performance can be improved by endowing the system with freedom to morph.

scholarly journals Control of the free convective heat transfer using a U-shaped obstacle in an Al2O3-water nanofluid filled cubic cavity

2021 ◽  
Vol 8 (7) ◽  
pp. 23-30
Author(s):  
Rajab Al-Sayagh ◽  
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Rayleigh Number ◽  
Free Convection ◽  
Convective Heat Transfer ◽  
Volume Fraction ◽  
Temperature Fields ◽  
Flow Structures ◽  
Nanoparticles Volume Fraction ◽  
Al2o3 Nanofluid

This paper deals with the study of free convection in a 3D enclosure filled with Al2O3-nanofluid and equipped with a U-shaped obstacle. The used U-shaped obstacle is considered perfectly conductive. The effect of the dimension and the orientation of the obstacle is investigated. In addition, the parameters governing the problem are varied as Rayleigh number (103 to 106), and nanoparticles volume fraction (0 to 7.5%). Results are depicted in terms of flow structures, temperature fields, and Nusselt number. Results show that the obstacle dimension and orientation can control the flow and optimize the heat transfer and the addition of nanoparticles enhances significantly Nusselt number.

scholarly journals Numerical analysis of melting of nano-enhanced phase change material in latent heat thermal energy storage system

2014 ◽  
Vol 18 (suppl.2) ◽  
pp. 335-345 ◽  
Author(s):  
Sina Kashani ◽  
Esmail Lakzian ◽  
Kazem Lakzian ◽  
Mohammad Mastiani
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Storage System ◽  
Energy Storage System ◽  
Particle Volume

The heat transfer enhancement in the latent heat thermal energy storage system through dispersion of nanoparticle is reported. The resulting nanoparticle-enhanced phase change materials exhibit enhanced thermal conductivity in comparison to the base material. Calculation is performed for nanoparticle volume fraction from 0 to 0.08. In this study rectangular and cylindrical containers are modeled numerically and the effect of containers dimensions and nano particle volume fraction are studied. It has been found that the rectangular container requires half of the melting time as for the cylindrical container of the same volume and the same heat transfer area and also, higher nano particle volume fraction result in a larger solid fraction. The increase of the heat release rate of the nanoparticle-enhanced phase change materials shows its great potential for diverse thermal energy storage application.

scholarly journals Preparation and Property Modification on Novel Energy Storage Material: n-Octadecane PCMs/Expanded Perlite Composite Gypsum Board

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Jianping Zhu ◽  
Benkai Guo ◽  
Huanhuan Hou ◽  
Wenyan Zhang
Keyword(s):  
Mechanical Properties ◽  
Energy Storage ◽  
Building Materials ◽  
Phase Change Materials ◽  
Volume Fraction ◽  
Vacuum Impregnation ◽  
Impregnation Method ◽  
Expanded Perlite ◽  
Gypsum Board ◽  
Transfer Delay

Phase change materials (PCMs) have been widely used to improve the thermal energy storage capacity of building materials. In this study, the n-octadecane (OD)/expanded perlite (EP) composite PCM, which was prepared by incorporation of liquid n-octadecane into EP using the vacuum impregnation method, was used to fabricate the gypsum board. The microscopic, thermal, and mechanical properties were studied. The SEM results showed that OD could be absorbed into the pores of EP uniformly. The FI-IR results showed that OD and EP have good chemical stability. It was found that the gypsum board has best heat transfer delay when the volume fraction of OD/EP was 20% (v/v). The mechanical property of the gypsum board with OD/EP decreased. To deal with the problem, the effect of nano-Al2O3 on the gypsum board was also studied. The results showed that the mechanical properties of the gypsum board were effectively increased when the dosage of nano-Al2O3 was 0.5 wt.%, and the gypsum board had the best thermal insulation effect when the nano-Al2O3 content was 0.3 wt.%. Considering the cost and the comprehensive property, it was suggested that the optimal addition content of nano-Al2O3 was 0.3 wt.%.

NUMERICAL STUDY OF THE ERYTHRITOL MELTING PROCESS IN A TRIDIMENSIONAL RECTANGULAR CAVITY

2015 ◽  
Vol 14 (1) ◽  
pp. 88
Author(s):  
J. F. Raymundo ◽  
R. Da S. Borahel ◽  
R. De C. Oliveski
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Volume Fraction ◽  
Numerical Study ◽  
Practical Interest ◽  
Melting Process ◽  
Rectangular Cavity ◽  
Computational Domain

Many areas of engineering, such as the petrochemical and food industries, use thermal energy storage to achieve better performance. Thermal energy storage can be used as a heat source or a heat sink. The thermal storage/release technology, based on the use of phase change materials (PCMs), which possess a great capacity of heat accumulation, has raised an important practical interest. Indeed, the improved storage density and the constant temperature release of energy allow a more compact heat exchange design and simplify system management. Phase change phenomena occurring during PCM melting and PCM solidification need to be carefully controlled. The aim of the present numerical study is to investigate the heat transfer and hydrodynamic characteristics of a phase change material (PCM) in a rectangular cavity and the melting process dependence on the cavity height. The geometry consists of a mini rectangular cavity which contains PCM. Water or steam flows in the longitudinal direction of the cavity, thus heating or cooling the PCM in the cavity. The computational domain is made of three materials: air, aluminum and PCM. The grid mesh is structured, hexaedrical and refined near the walls. The study is developed with different operation conditions of the mass flow and water temperature. The numerical simulation is developed through CFD (Computational Fluid Dynamics) with the Fluent code. The mathematical model was validated using results available in the literature. Results of temperature, velocity and volume fraction fields indicate that the cavity height has no impact on the melting process.

scholarly journals Melting of a phase change material in a horizontal annulus with discrete heat sources

2015 ◽  
Vol 19 (5) ◽  
pp. 1733-1745 ◽  
Author(s):  
Hooshyar Mirzaei ◽  
Abdolrahman Dadvand ◽  
Mohammad Mastiani ◽  
Seyed Sebti ◽  
Sina Kashani
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Phase Change Material ◽  
Liquid Fraction ◽  
Outer Cylinder ◽  
Melting Process ◽  
Cylinder Wall ◽  
Heat Sources ◽  
Discrete Heat Sources ◽  
Change Material

Phase change materials have found many industrial applications such as cooling of electronic devices and thermal energy storage. This paper investigates numerically the melting process of a phase change material in a two-dimensional horizontal annulus with different arrangements of two discrete heat sources. The sources are positioned on the inner cylinder of the annulus and assumed as constant-temperature boundary conditions. The remaining portion of the inner cylinder wall as well as the outer cylinder wall is considered to be insulated. The emphasis is mainly on the effects of the arrangement of the heat source pair on the fluid flow and heat transfer features. The governing equations are solved on a non-uniform O type mesh using a pressure-based finite volume method with an enthalpy porosity technique to trace the solid and liquid interface. The results are obtained at Ra=104 and presented in terms of streamlines, isotherms, melting phase front, liquid fraction and dimensionless heat flux. It is observed that, depending on the arrangement of heat sources, the liquid fraction increases both linearly and non-linearly with time but will slow down at the end of the melting process. It can also be concluded that proper arrangement of discrete heat sources has the great potential in improving the energy storage system. For instance, the arrangement C3 where the heat sources are located on the bottom part of the inner cylinder wall can expedite the melting process as compared to the other arrangements.

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