scholarly journals Impact of Fusion Temperature on Hydrothermal Features of Flow within an Annulus Loaded with Nanoencapsulated Phase Change Materials (NEPCMs) during Natural Convection Process

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Seyyed Masoud Seyyedi ◽  
M. Hashemi-Tilehnoee ◽  
M. Sharifpur
Keyword(s):  
Phase Change ◽  
Entropy Generation ◽  
Phase Change Materials ◽  
Control Volume ◽  
Convection Flow ◽  
Entropy Generation Number ◽  
Decision Variables ◽  
Study Characteristics ◽  
New Type ◽  
Energy And Momentum

A new type of nanofluids is nanoencapsulated phase change materials (NEPCMs), where nanoparticles are made of a shell and a core. In the current study, characteristics of free convection flow, entropy generation, and heat transfer of NEPCMs in an enclosure are investigated. The enclosure is an annulus between concentric horizontal circular and square cylinders with a porous medium. The governing equations (i.e., continuity, energy, and momentum) are written in the nondimensional form and then numerically solved by the control volume finite element method (CVFEM). The results of the validation are in good agreement with those of the literature. The effects of decision variables on the entropy generation number and the average Nusselt number are investigated. The outcomes discovered that there is a maximum for Nu ave and a minimum for N gen at θ f = 0.4 for each value of the Stefan number. Also, Nu ave and ECOP increase by 8.8% and 24.8%, respectively, while N gen decreases by 12.8% when ϕ increases from 0 (pure fluid) to 0.05 at θ f = 0.4 .

Effects of Energy Dissipation and Variable Thermal Conductivity on Entropy Generation Rate in Mixed Convection Flow

2018 ◽  
Vol 10 (4) ◽  
Author(s):  
Muhammad Qasim ◽  
Muhammad Idrees Afridi
Keyword(s):  
Thermal Conductivity ◽  
Energy Dissipation ◽  
Mixed Convection ◽  
Entropy Generation ◽  
Variable Thermal Conductivity ◽  
Convection Flow ◽  
Mixed Convection Flow ◽  
Entropy Generation Number ◽  
Similarity Transformations ◽  
Generation Number

Analysis of entropy generation in mixed convection flow over a vertically stretching sheet has been carried out in the presence of variable thermal conductivity and energy dissipation. Governing equations are reduced to self-similar ordinary differential equations via similarity transformations and are solved numerically by applying shooting and fourth-order Runge–Kutta techniques. The expressions for entropy generation number and Bejan number are also obtained by using similarity transformations. The influence of embedding physical parameters on quantities of interest is discussed through graphical illustrations. The results reveal that entropy generation number increases significantly in the vicinity of stretching surface and gradually dies out as one move away from the sheet. Also, the entropy generation number decreases with an increase in temperature difference parameter. Moreover, entropy generation number enhances with an enhancement in the Eckert number, Prandtl number, and variable thermal conductivity parameter.

A new type of heat storage system using the motion of phase change materials in an elliptical-shaped capsule

2019 ◽  
Vol 182 ◽  
pp. 508-519 ◽  
Author(s):  
Dong Ho Shin ◽  
Jinsoo Park ◽  
Sung Ho Choi ◽  
Han Seo Ko ◽  
Sarng Woo Karng ◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Heat Storage ◽  
Storage System ◽  
New Type

scholarly journals Integral Solution of Two-Region Solid–Liquid Phase Change in Annular Geometries and Application to Phase Change Materials–Air Heat Exchangers

Energies ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4474 ◽  
Author(s):  
Hamidreza Shabgard ◽  
Weiwei Zhu ◽  
Amir Faghri
Keyword(s):  
Liquid Phase ◽  
Boundary Conditions ◽  
Phase Change ◽  
Phase Change Materials ◽  
Volume Fraction ◽  
Control Volume ◽  
Solid Volume Fraction ◽  
Solidification Time ◽  
Design And Optimization ◽  
Solid Liquid

A mathematical model based on the integral method is developed to solve the problem of conduction-controlled solid–liquid phase change in annular geometries with temperature gradients in both phases. The inner and outer boundaries of the annulus were subject to convective, constant temperature or adiabatic boundary conditions. The developed model was validated by comparison with control volume-based computational results using the temperature-transforming phase change model, and an excellent agreement was achieved. The model was used to conduct parametric studies on the effect of annuli geometry, thermophysical properties of the phase change materials (PCM), and thermal boundary conditions on the dynamics of phase change. For an initially liquid PCM, it was found that increasing the radii ratio increased the total solidification time. Also, increasing the Biot number at the cooled (heated) boundary and Stefan number of the solid (liquid) PCM, decreased (increased) the solidification time and resulted in a greater (smaller) solid volume fraction at steady state. The application of the developed method was demonstrated by design and analysis of a PCM–air heat exchanger for HVAC systems. The model can also be easily employed for design and optimization of annular PCM systems for all associated applications in a fraction of time needed for computational simulations.

scholarly journals Numerical investigation of entropy generation in laminar forced convection flow over inclined backward and forward facing steps in a duct under bleeding condition

2014 ◽  
Vol 18 (2) ◽  
pp. 479-492 ◽  
Author(s):  
Meysam Atashafrooz ◽  
Nassab Gandjalikhan ◽  
Babak Ansari
Keyword(s):  
Numerical Investigation ◽  
Forced Convection ◽  
Entropy Generation ◽  
Fluid Dynamic ◽  
Numerical Results ◽  
Convection Flow ◽  
Bejan Number ◽  
Entropy Generation Number ◽  
Forced Convection Flow ◽  
Laminar Forced Convection

A numerical investigation of entropy generation in laminar forced convection of gas flow over a recess including two inclined backward and forward facing steps in a horizontal duct under bleeding condition is presented. For calculation of entropy generation from the second law of thermodynamics in a forced convection flow, the velocity and temperature distributions are primary needed. For this purpose, the two-dimensional Cartesian coordinate system is used to solve the governing equations which are conservations of mass, momentum and energy. These equations are solved numerically using the computational fluid dynamic techniques to obtain the temperature and velocity fields, while the blocked region method is employed to simulate the inclined surface. Discretized forms of these equations are obtained by the finite volume method and solved using the SIMPLE algorithm. The numerical results are presented graphically and the effects of bleeding coefficient and recess length as the main parameters on the distributions of entropy generation number and Bejan number are investigated. Also, the effect of Reynolds number and bleeding coefficient on total entropy generation which shows the amount of flow irreversibilities is presented for two recess length. The use of present results in the design process of such thermal system would help the system attain the high performance during exploitation. Comparison of numerical results with the available data published in open literature shows a good consistency.

scholarly journals Effect of Inclined Magnetic Field on the Entropy Generation in an Annulus Filled with NEPCM Suspension

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Seyyed Masoud Seyyedi ◽  
M. Hashemi-Tilehnoee ◽  
M. Sharifpur
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Phase Change ◽  
Entropy Generation ◽  
Phase Change Materials ◽  
Transfer Problem ◽  
Mass Conservation ◽  
Melting Process ◽  
Industrial Applications ◽  
Inclined Magnetic Field

The encapsulation technique of phase change materials in the nanodimension is an innovative approach to improve the heat transfer capability and solve the issues of corrosion during the melting process. This new type of nanoparticle is suspended in base fluids call NEPCMs, nanoencapsulated phase change materials. The goal of this work is to analyze the impacts of pertinent parameters on the free convection and entropy generation in an elliptical-shaped enclosure filled with NEPCMs by considering the effect of an inclined magnetic field. To reach the goal, the governing equations (energy, momentum, and mass conservation) are solved numerically by CVFEM. Currently, to overcome the low heat transfer problem of phase change material, the NEPCM suspension is used for industrial applications. Validation of results shows that they are acceptable. The results reveal that the values of N u ave descend with ascending Ha while N gen has a maximum at Ha = 16 . Also, the value of N T , MF increases with ascending Ha . The values of N u ave and N gen depend on nondimensional fusion temperature where good performance is seen in the range of 0.35 < θ f < 0.6 . Also, Nu ave increases 19.9% and ECOP increases 28.8% whereas N gen descends 6.9% when ϕ ascends from 0 to 0.06 at θ f = 0.5 . Nu ave decreases 4.95% while N gen increases by 8.65% when Ste increases from 0.2 to 0.7 at θ f = 0.35 .

Entropy generation and natural convection flow of a suspension containing nano-encapsulated phase change particles in a semi-annular cavity

2020 ◽  
Vol 32 ◽  
pp. 101834
Author(s):  
Mehdi Ghalambaz ◽  
S.A.M. Mehryan ◽  
Masoud Mozaffari ◽  
Ahmad Hajjar ◽  
Mohamad El Kadri ◽  
...  
Keyword(s):  
Natural Convection ◽  
Phase Change ◽  
Entropy Generation ◽  
Convection Flow ◽  
Natural Convection Flow

Shape effect of nanosize particles in unsteady mixed convection flow of nanofluid over disk with entropy generation

2016 ◽  
Vol 231 (4) ◽  
pp. 871-879 ◽  
Author(s):  
Ahmed Zeeshan ◽  
Moshan Hassan ◽  
Rahmat Ellahi ◽  
Muhammad Nawaz
Keyword(s):  
Heat Transfer ◽  
Entropy Generation ◽  
Rotating Disk ◽  
Spherical Particles ◽  
Convection Flow ◽  
Shape Effect ◽  
Entropy Generation Number ◽  
Unsteady Mixed Convection ◽  
Shape Effects ◽  
Nanolayer Thickness

The aim of this paper is to study the different shapes of nanoparticles on mixed convective steady flow over a rotating disk. For nanofluid, the copper nanoparticles of disk, cylindrical, and spherical shapes of different sizes and water as base fluid are considered. The physical problem is first modeled and then the governing equations are transformed into nonlinear ordinary differential equations. These equations are dimensionless using geometrical and physical flowfield-dependent parameters and solved analytically. A very good agreement is observed between the obtained results of the current study and previously published study in limiting cases. The shape effects on velocity profiles in radial, tangential, axial directions, and temperature distribution are displayed graphically with the reflection of specific range of nanolayer thickness and its conductivity. In addition, irreversibility due to heat and fluid friction is investigated that supports the heat transfer enhancement in renewable energy systems and industrial thermal management. For the analysis of the averaged entropy generation number, the results are shown in pie charts and tablet form. It is evident from the study that proper choice of nanoparticles will be helpful in controlling velocity and heat transfer. It is also observed that irreversibility process can be reduced by using nanoparticles, especially the spherical particles.

Minimization of Entropy Generation in MHD Mixed Convection Flow with Energy Dissipation and Joule Heating: Utilization of Sparrow-Quack-Boerner Local Non-Similarity Method

2018 ◽  
Vol 387 ◽  
pp. 63-77 ◽  
Author(s):  
M. Idrees Afridi ◽  
Muhammad Qasim ◽  
Najeeb Alam Khan ◽  
Oluwole Daniel Makinde
Keyword(s):  
Energy Dissipation ◽  
Mixed Convection ◽  
Entropy Generation ◽  
Joule Heating ◽  
Convection Flow ◽  
Physical Parameters ◽  
Mixed Convection Flow ◽  
Entropy Analysis ◽  
Entropy Generation Number ◽  
Similarity Method

This article aims to present the non-similar solution of MHD mixed convection flow using the Sparrow-Quack-Boerner local non-similarity method. Entropy analysis is also performed in the presence of energy dissipation and Joule heating. The buoyancy parameter is chosen as the non-similarity variable and the equations are derived up to the second level of truncation. The dependency of dimensionless velocity profile, temperature distribution, Bejan and entropy generation number on physical parameters has been discussed. As far as the knowledge of the authors is concerned, no attempt has been made on the entropy analysis of MHD mixed convection flow by the local non-similarity method.

Numerical and Experimental Investigation of Shell-and-Tube Phase-Change Material Thermal Energy Storage Unit

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Thomas H. Sherer ◽  
Yogendra Joshi
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Control Volume ◽  
Heat Transfer Fluid ◽  
Transient Temperature ◽  
Storage Unit ◽  
Shell And Tube

Solid liquid phase-change materials (PCMs) present a promising approach for reducing data center cooling costs. We review prior research in this area. A shell-and-tube PCM thermal energy storage (TES) unit is then analyzed numerically and experimentally. The tube bank is filled with commercial paraffin RUBITHERM RT 28 HC PCM, which melts as the heat transfer fluid (HTF) flows across the tubes. A fully implicit one-dimensional control volume formulation that utilizes the enthalpy method for phase change has been developed to determine the transient temperature distributions in both the PCM and the tubes themselves. The energy gained by a column of tubes is used to determine the exit bulk HTF temperature from that column, ultimately leading to an exit HTF temperature from the TES unit. This paper presents a comparison of the numerical and experimental results for the transient temperature profiles of the PCM-filled tubes and HTF.

Research on PCM Textiles with Material Properties in Sports Wear Application

2014 ◽  
Vol 910 ◽  
pp. 450-454 ◽  
Author(s):  
Dong Mao Ye
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Material Properties ◽  
Phase Change Materials ◽  
Manufacturing Technology ◽  
Preparation Methods ◽  
Textile Manufacturing ◽  
Sports Events ◽  
New Type ◽  
Change Material

A new type of intelligent PCM functional textile has been developed based on intelligent phase change material and advanced textile manufacturing technology. The application of such PCM textile in sports wear can help to enhance athletes performance. This paper analyzes the effects of intelligent PCM textile, characteristics of phase change materials and its preparation methods; discusses the possible effects of intelligent PCM textile to the results of sports events; suggests to make further study and research on phase change material in sports wear application so to develop more PCM sports wear suitable for different sports events.

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