Effect of non-uniform heating on conjugate heat transfer performance for nanofluid flow in a converging duct by a two-phase Eulerian–Lagrangian method

2021 ◽  
pp. 095440892110429
Author(s):  
Md. Faizan ◽  
Sukumar Pati ◽  
Pitamber R Randive
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Volume Fraction ◽  
Constant Heat Flux ◽  
Lagrangian Model ◽  
Uniform Heating ◽  
Nanofluid Flow ◽  
Two Phase

In this paper, the effect of non-uniform heating on the conjugate thermal and hydraulic characteristics for Al2O3–water nanofluid flow through a converging duct is examined numerically. An Eulerian–Lagrangian model is employed to simulate the two-phase flow for the following range of parameters: Reynolds number (100 ≤ Re ≤ 800), nanoparticle volume fraction (0% ≤  ϕ ≤ 5%) and amplitude of the sinusoidal heat flux ( A = 0, 0.5 and 1). The results reveal a similar affinity between the applied heat flux and local Nusselt number variation qualitatively, mainly at the middle of the duct. The results also indicate that there is a considerable enhancement of Nusselt number with the increase in Reynolds number and the thermal conductivity of wall materials. In addition, increasing the particle loading contributes to an enhanced rate of heat transfer. The heat transfer rate is lower for non-uniform heating when compared with the constant heat flux and the same can be compensated by the application of volume fraction of nanoparticles

scholarly journals Enhancement of Forced Convection Heat Transfer for SiO2 flow through Channel with Ribs at Constant Heat Flux

2018 ◽  
Vol 6 (06) ◽  
Author(s):  
Khudheyer Ahmed F. ◽  
Nawaf, Taha S.
Keyword(s):  
Heat Flux ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Friction Factor ◽  
Volume Fraction ◽  
Convection Heat Transfer ◽  
Constant Heat Flux ◽  
Channel Height ◽  
Forced Convective Flow ◽  
Volume Method

Numerical investigation of forced convective flow in a 2-dimensional microchannel. This investigation is analyzed with nanoparticles SiO2 and water as a base fluid studying the influence of turbulence model inside multi geometrical channel (Triangular, Trapezoidal, Semi-circular, and Rectangular) by using "Finite Volume Method (FVM)". The heat flux is applied on the lower wall of channel and the upper is insulated. The diameter of nanoparticles is 20 nm. The Reynolds number ranges are from 10000 to 30000 for ratio of groove width (B) to channel height (H) was used 0.75. The volume fractions range is between 1-4%. Triangular channel score higher Nusselt number and lower friction factor than other cases against Reynolds number. When the volume fraction was increase, the Nusselt number increased and friction factor decreased, this gives 4% has the optimal properties.

scholarly journals Analysis of the forced convection of two-phase Ferro-nanofluid flow in a completely porous microchannel containing rotating cylinders

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hamidreza Aghamiri ◽  
Mohammadreza Niknejadi ◽  
Davood Toghraie
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Porous Medium ◽  
Forced Convection ◽  
Entropy Generation ◽  
Volume Fraction ◽  
Rotating Cylinders ◽  
Nanofluid Flow ◽  
Two Phase ◽  
Porosity Percentage

AbstractIn the present work, the forced convection of nanofluid flow in a microchannel containing rotating cylinders is investigated in different geometries. The heat flux applied to the microchannel wall is 10,000 W m−2. The effects of Reynolds number, the volume fraction of nanoparticles, and the porosity percentage of the porous medium are investigated on the flow fields, temperature, and heat transfer rate. Reynolds number values vary from Re = 250–1000, non-dimensional rotational velocities 1 and 2, respectively, and volume fraction of nanoparticles 0–2%. The results show that increasing the velocity of rotating cylinders increases the heat transfer; also, increasing the Reynolds number and volume fraction of nanoparticles increases the heat transfer, pressure drop, and Cf,ave. By comparing the porosity percentages with each other, it is concluded that due to the greater contact of the nanofluid with the porous medium and the creation of higher velocity gradients, the porosity percentage is 45% and the values of are 90% higher than the porosity percentage. Comparing porosity percentages with each other, at porosity percentage 90% is greater than at porosity percentage 45%. On the other hand, increasing the Reynolds number reduces the entropy generation due to heat transfer and increases the entropy generation due to friction. Increasing the volume fraction of nanoparticles increases the entropy generations due to heat transfer and friction.

Investigation of the convective heat transfer and friction factor of magnetic Ni nanofluids within cylindrical pipes

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
M. Abdelkader ◽  
H. Ameur ◽  
Y. Menni
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Friction Factor ◽  
Turbulent Flows ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Constant Heat Flux ◽  
Particle Volume ◽  
Number Range

The current paper reports the results of numerical research on the magnetic Ni nanofluid flowing in a tube, developing turbulent flows under constant heat flux conditions. The numerical investigations are conducted for a Reynolds number range from 3,000 to 22,000, and a particle concentration range of 0% to 0.6%. The effects of the Reynolds number on the friction factor and Nusselt number are computed and compared satisfactorily with the experimental results of the literature. The classical correlations of Gnielinski, Notter – Rouse, and Pak and Cho are verified by predicting the Nusselt number of the Ni nanofluid. The obtained results revealed an enhancement in the heat transfer with the increase of magnetic Ni particle volume fraction and Reynolds number.

Heat Transfer Downstream of an Abrupt Expansion in the Transition Reynolds Number Regime

1987 ◽  
Vol 109 (1) ◽  
pp. 37-42 ◽  
Author(s):  
J. W. Baughn ◽  
M. A. Hoffman ◽  
R. K. Takahashi ◽  
Daehee Lee
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Narrow Range ◽  
Reynolds Numbers ◽  
Constant Heat Flux ◽  
Flow Instabilities ◽  
Constant Heat ◽  
Interesting Behavior

The heat transfer downstream of an axisymmetric abrupt expansion in a pipe in the transition Reynolds number regime has been investigated experimentally. In these experiments the wall of the downstream pipe was heated to give a constant heat flux into the air flow. The ratio of the upstream to downstream pipe diameters was 0.8 and the downstream Reynolds number ranged from 1420 to 8060. Within a narrow range of Reynolds numbers, around 5000, the position of the maximum Nusselt number was found to shift considerably. This interesting behavior may be associated with the flow instabilities in sudden expansions which have been observed by others.

Forced Convective Boiling of Refrigerant HCFC123 in a Mini-Tube

2010 ◽  
Author(s):  
Koichi Araga ◽  
Keisuke Okamoto ◽  
Keiji Murata
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Mass Flux ◽  
Pool Boiling ◽  
Constant Heat Flux ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Convective Boiling ◽  
Frictional Pressure Drop ◽  
Heat Transfer Coefficients

This paper presents an experimental investigation of the forced convective boiling of refrigerant HCFC123 in a mini-tube. The inner diameters of the test tubes, D, were 0.51 mm and 0.30 mm. First, two-phase frictional pressure drops were measured under adiabatic conditions and compared with the correlations for conventional tubes. The frictional pressure drop data were lower than the correlation for conventional tubes. However, the data were qualitatively in accord with those for conventional tubes and were correlated in the form φL2−1/Xtt. Next, heat transfer coefficients were measured under the conditions of constant heat flux and compared with those for conventional tubes and for pool boiling. The heat transfer characteristics for mini-tubes were different from those for conventional tubes and quite complicated. The heat transfer coefficients for D = 0.51 mm increased with heat flux but were almost independent of mass flux. Although the heat transfer coefficients were higher than those for a conventional tube with D = 10.3 mm and for pool boiling in the low quality region, they decreased gradually with increasing quality. The heat transfer coefficients for D = 0.30 mm were higher than those for D = 0.51 mm and were almost independent of both mass flux and heat flux.

Thermodynamic optimization of nanofluid flow over a non-isothermal wedge with nonlinear radiation and activation energy

2021 ◽  
Author(s):  
M R Acharya ◽  
P Mishra ◽  
Satyananda Panda
Keyword(s):  
Heat Transfer ◽  
Activation Energy ◽  
Reynolds Number ◽  
Entropy Generation ◽  
Volume Fraction ◽  
Mathematical Formulation ◽  
Bejan Number ◽  
Nanofluid Flow ◽  
Entropy Generation Number ◽  
Generation Number

Abstract This paper analyses the augmentation entropy generation number for a viscous nanofluid flow over a non-isothermal wedge including the effects of non-linear radiation and activation energy. We discuss the influence of thermodynamically important parameters during the study, namely, the Bejan number, entropy generation number, and the augmentation entropy generation number. The mathematical formulation for thermal conductivity and viscosity of nanofluid for Al2O3 − EG mixture has been considered. The results were numerically computed using implicit Keller-Box method and depicted graphically. The important result is the change in augmentation entropy generation number with Reynolds number. We observed that adding nanoparticles (volume fraction) tend to enhance augmentation entropy generation number for Al2O3 − EG nanofluid. Further, the investigation on the thermodynamic performance of non-isothermal nanofluid flow over a wedge reveals that adding nanoparticles to the base fluid is effective only when the contribution of heat transfer irreversibility is more than fluid friction irreversibility. This work also discusses the physical interpretation of heat transfer irreversibility and pressure drop irreversibility. This dependency includes Reynolds number and volume fraction parameter. Other than these, the research looked at a variety of physical characteristics associated with the flow of fluid, heat and mass transfer.

MHD nanofluid heat transfer between a stretching sheet and a porous surface using neural network approach

2019 ◽  
Vol 30 (06) ◽  
pp. 1950048 ◽  
Author(s):  
Yuancheng Geng ◽  
A. Hassanvand ◽  
Mostafa Monfared ◽  
Rasoul Moradi
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Magnetic Parameter ◽  
Volume Fraction ◽  
Sensitivity Analyses ◽  
Integration Scheme ◽  
Group Method ◽  
Suction Parameter ◽  
Wall Injection

Magnetohydrodynamic flow of nanofluids and heat transfer between two horizontal plates in a rotating system have been examined numerically. In order to do this, the group method of data handling (GMDH)-type neural networks is used to calculate Nusselt number formulation. Results indicate that GMDH-type NN in comparison with fourth-order Runge–Kutta integration scheme provides an effective means of efficiently recognizing the patterns in data and accurately predicting a performance. Single-phase model is used in this study. Similar solution is used in order to obtain ordinary differential equation. The effects of nanoparticle volume fraction, magnetic parameter, wall injection/suction parameter and Reynolds number on Nusselt number are studied by sensitivity analyses. The results show that Nusselt number is an increasing function of Reynolds number and volume fraction of nanoparticles but it is a decreasing function of magnetic parameter. Also, it can be found that wall injection/suction parameter has no significant effect on rate of heat transfer.

A Numerical Investigation of Nanofluids Thermal Behavior in Microchannels Under Laminar Flow Conditions

2015 ◽  
Author(s):  
I. P. Koronaki ◽  
M. T. Nitsas ◽  
Ch. A. Vallianos
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Laminar Flow ◽  
Volume Fraction ◽  
Constant Heat Flux ◽  
Flow Conditions ◽  
New Techniques ◽  
Pressure Drops ◽  
Nanoparticles Volume Fraction ◽  
The Heat Transfer Coefficient

Due to large amounts of heat flux developed in electronic devices, it is essential to propose and investigate effective mechanisms of cooling them. Although microchannels filled with flowing coolant are a geometry often met in such devices, new techniques need to be developed in order to increase their effectiveness. Recent studies on nanofluids, i.e. mixtures of nanometer size particles well-dispersed in a base fluid, have demonstrated their potential for augmenting heat transfer. In the present work the 2D steady state laminar flow of different nanofluids along a microchannel is examined. It is considered that the microchannel walls receive uniform and constant heat flux. The problem’s modelling has as parameters the volume fraction of nanoparticles ranging from 0 to 5% and Reynolds number varying between 50 and 500. The results of the problem’s numerical solution are used to calculate the heat transfer coefficient, the pressure drop along the microchannel and the destroyed exergy. It is found that heat transfer is enhanced due to the presence of nanoparticles. On the contrary, pressure drops faster due to nanofluids increased viscosity leading to more pump power needed. Finally, further exergy destruction is observed when nanoparticles volume fraction increases.

Entropy Generation Minimization of Fully Developed Internal Convective Flows With Constant Heat Flux

2003 ◽  
Author(s):  
Eric B. Ratts ◽  
Atul G. Raut
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Reynolds Number ◽  
Laminar Flow ◽  
Turbulent Flow ◽  
Entropy Generation ◽  
Cross Sections ◽  
Constant Heat Flux ◽  
Constant Heat ◽  
Entropy Generation Minimization

This paper addresses the thermodynamic optimum of single-phase convective heat transfer in fully developed flow for uniform and constant heat flux. The optimal Reynolds number is obtained using the entropy generation minimization (EGM) method. Entropy generation due to viscous dissipation and heat transfer dissipation in the flow passage are summed, and then minimized with respect to Reynolds number based on hydraulic diameter. For fixed mass flow rate and fixed total heat transfer rate, and the assumption of uniform heat flux, an optimal Reynolds number for laminar as well as turbulent flow is obtained. In addition, the method quantifies the flow irreversibilities. It was shown that the ratio of heat transfer dissipation to viscous dissipation at minimum entropy generation was 5:1 for laminar flow and 29:9 for turbulent flow. For laminar flow, the study compared non-circular cross-sections to the circular cross-section. The optimal Reynolds number was determined for the following cross-sections: square, equilateral triangle, and rectangle with aspect ratios of two and eight. It was shown that the rectangle with the higher aspect ratio had the smallest optimal Reynolds number, the smallest entropy generation number, and the smallest flow length.

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