A numerical study on heat transfer of the nanofluid flow inside helical tube through the two-phase method

2016 ◽  
Vol 36 (1) ◽  
pp. 84-90 ◽  
Author(s):  
Hamed Khabir ◽  
Roghayyeh Motallebzadeh
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Phase Method ◽  
Nanofluid Flow ◽  
Two Phase ◽  
Helical Tube

Peristaltic Carreau-Yasuda nanofluid flow and mixed heat transfer analysis in an asymmetric vertical and tapered wavy wall channel

2020 ◽  
Vol 1 (1) ◽  
pp. 128-140 ◽  
Author(s):  
Mohammad Hatami ◽  
◽  
D Jing ◽  
Keyword(s):  
Heat Transfer ◽  
Least Square Method ◽  
Weissenberg Number ◽  
Least Square ◽  
Heat Transfer Analysis ◽  
Phase Method ◽  
Nanofluid Flow ◽  
Two Phase ◽  
Nanoparticles Concentration ◽  
The Right

In this study, two-phase asymmetric peristaltic Carreau-Yasuda nanofluid flow in a vertical and tapered wavy channel is demonstrated and the mixed heat transfer analysis is considered for it. For the modeling, two-phase method is considered to be able to study the nanoparticles concentration as a separate phase. Also it is assumed that peristaltic waves travel along X-axis at a constant speed, c. Furthermore, constant temperatures and constant nanoparticle concentrations are considered for both, left and right walls. This study aims at an analytical solution of the problem by means of least square method (LSM) using the Maple 15.0 mathematical software. Numerical outcomes will be compared. Finally, the effects of most important parameters (Weissenberg number, Prandtl number, Brownian motion parameter, thermophoresis parameter, local temperature and nanoparticle Grashof numbers) on the velocities, temperature and nanoparticles concentration functions are presented. As an important outcome, on the left side of the channel, increasing the Grashof numbers leads to a reduction in velocity profiles, while on the right side, it is the other way around.

A comparative analysis on the single-phase and two-phase mixture models for calculation of ferrofluid convective heat transfer in the presence of a magnetic field: a numerical study

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Hamed Jafari ◽  
Mohammad Goharkhah ◽  
Alireza Mahdavi Nejad
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Single Phase ◽  
Numerical Study ◽  
Phase Method ◽  
Two Phase ◽  
Content Type ◽  
Phase Models

Purpose This paper aims to analyze the accuracy of the single and two-phase numerical methods for calculation of ferrofluid convective heat transfer in the presence of a magnetic field. The findings of current study are compared with previous single-phase numerical results and experimental data. Accordingly, the effect of various parameters including nanoparticles concentration, Reynolds number and magnetic field strength on the performance of the single and two-phase models are evaluated. Design/methodology/approach A two-phase mixture numerical study is carried out to investigate the influence of four U-shaped electromagnets on the hydrodynamic and thermal characteristics of Fe3O4/Water ferrofluid flowing inside a heated channel. Findings It is observed that the applied external magnetic field signifies the convective heat transfer from the channel surface, despite local reduction at a few locations. The maximum heat transfer enhancement is predicted as 23% and 25% using single and two-phase models, respectively. The difference between the results of the two models is mainly attributed to the slip velocity effect which is accounted for in the two-phase model. The magnetic field gradient leads to a significant increase in the slip velocity which in turn causes a slight difference in velocity and temperature profiles obtained by the single and two-phase models in the magnetic field region. According to percentage error calculation, the two-phase method is generally more accurate than the single-phase method. However, the percentage error of both models improves by decreasing either magnetic field intensity or Reynolds number. Originality/value For the first time in the literature, to the best of the authors’ knowledge, the current work analyzes the accuracy of the single and two phase numerical methods for calculation of ferrofluid convective heat transfer in the presence of a magnetic field.

scholarly journals Numerical study on the boiling heat transfer induced by two heated plates

2020 ◽  
Vol 24 (Suppl. 1) ◽  
pp. 257-265
Author(s):  
Xiaopeng Shan ◽  
Geng Guan ◽  
Deming Nie
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Numerical Study ◽  
Present System ◽  
Two Phase ◽  
Before And After ◽  
Flow Features ◽  
Boltzmann Method ◽  
Departure Behavior ◽  
Heated Plates

A two-phase lattice Boltzmann method was used to numerically study the boiling heat transfer related to the liquid-vapor transition induced by two heated plates. The effects of the gravity force as well as the separation between the heated plates were examined. The focus is on the bubble departure behavior resulting from the interaction between bubbles, which can be roughly classified into four types of pat?tern according to the separation between plates. In particular, it is shown that the bubble merging may take place twice in one cycle when the separation is close to a certain value. This is referred to as the pattern of alternation of bubble merging before and after departure, for which a sudden jump is seen in the bubble release period. Furthermore, the heat flux and the flow features are also shown to illustrate the behavior of heat transfer in the present system.

Numerical study of mixed convection heat transfer inside a vertical microchannel with two-phase approach

2018 ◽  
Vol 135 (2) ◽  
pp. 1119-1134 ◽  
Author(s):  
Mohammad Reza Tavakoli ◽  
Omid Ali Akbari ◽  
Anoushiravan Mohammadian ◽  
Erfan Khodabandeh ◽  
Farzad Pourfattah
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Convection Heat ◽  
Two Phase ◽  
Phase Approach ◽  
Mixed Convection Heat Transfer ◽  
Vertical Microchannel

Phase Change Process Inside a Small-radii Cylinder Subjected to Cyclic Convective Boundary Conditions: a Numerical Study

2021 ◽  
Author(s):  
Yousef Kanani ◽  
Avijit Karmakar ◽  
Sumanta Acharya
Keyword(s):  
Heat Transfer ◽  
Surface Temperature ◽  
Phase Change ◽  
Phase Change Materials ◽  
Numerical Study ◽  
Convective Boundary Condition ◽  
Freezing Process ◽  
Fourier Number ◽  
Two Phase ◽  
Convective Boundary

Abstract We numerically investigate the melting and solidi?cation behavior of phase change materials encapsulated in a small-radii cylinder subjected to a cyclic convective boundary condition (square wave). Initially, we explore the effect of the Stefan and Biot numbers on the non-dimensionalized time required (i.e. reference Fourier number Tref ) for a PCM initially held at Tcold to melt and reach the cross?ow temperature Thot. The increase in either Stefan or Biot number decreases Tref and can be predicted accurately using a correlation developed in this work. The variations of the PCM melt fraction, surface temperature, and heat transfer rate as a function of Fourier number are reported and analyzed for the above process. We further study the effect of the cyclic Fourier number on the periodic melting and freezing process. The melting or freezing front initiates at the outer periphery of the PCM and propagates towards the center. At higher frequencies, multiple two-phase interfaces are generated (propagating inward), and higher overall heat transfer is achieved as the surface temperature oscillates in the vicinity of the melting temperature, which increases the effective temperature difference driving the convective heat transfer.

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