Ferro-nanofluid squeeze film lubrication with heat transfer

2021 ◽  
pp. 135065012110276
Author(s):  
Manimegalai Kavarthalai ◽  
Vimala Ponnuswamy
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Contact Time ◽  
Transfer Rate ◽  
Fluid Layer ◽  
Darcy Law ◽  
Squeeze Film ◽  
Mean Temperature ◽  
Special Cases ◽  
The Impact

A theoretical study of a squeezing ferro-nanofluid flow including thermal effects is carried out with application to bearings and articular cartilages. A representational geometry of the thin layer of a ferro-nanofluid squeezed between a flat rigid disk and a thin porous bed is considered. The flow behaviours and heat transfer in the fluid and porous regions are investigated. The mathematical problem is formulated based on the Neuringer–Rosensweig model for ferro-nanofluids in the fluid region including an external magnetic field, Darcy law for the porous region and Beavers–Joseph slip condition at the fluid–porous interface. The expressions for velocity, fluid film thickness, contact time, fluid flux, streamlines, pathlines, mean temperature and heat transfer rate in the fluid and porous regions are obtained by using a perturbation method. An asymptotic solution for the fluid layer thickness is also presented. The problem is also solved by a numerical method and the results by asymptotic analysis, perturbation and numerical methods are obtained assuming a constant force squeezing state and are compared. It is shown that the results obtained by all the methods agree well with each other. The effects of various parameters such as Darcy number, Beavers–Joseph constant and magnetization parameter on the flow behaviours, contact time, mean temperature and heat transfer rate are investigated. The novel results showing the impact of using ferro-nanofluids in the two applications under consideration are presented. The results under special cases are further compared with the existing results in the literature and are found to agree well.

Arithmetic Mean Temperature Difference and the Concept of Heat Exchanger Efficiency

2003 ◽  
Author(s):  
Ahmad Fakheri
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Rate ◽  
Temperature Difference ◽  
Heat Exchangers ◽  
Transfer Rate ◽  
Arithmetic Mean ◽  
Counter Flow ◽  
Mean Temperature ◽  
Optimum Heat

In this paper, it is shown that the Arithmetic Mean Temperature Difference, which is the difference between the average temperatures of hot and cold fluids, can be used instead of the Log Mean Temperature Difference (LMTD) in heat exchanger analysis. For a given value of AMTD, there exists an optimum heat transfer rate, Qopt, given by the product of UA and AMTD such that the rate of heat transfer in the heat exchanger is always less than this optimum value. The optimum heat transfer rate takes place in a balanced counter flow heat exchanger and by using this optimum rate of heat transfer, the concept of heat exchanger efficiency is introduced as the ratio of the actual to optimum heat transfer rate. A general algebraic expression as well as a chart is presented for the determination of the efficiency and therefore the rate of heat transfer for parallel flow, counter flow, single stream, as well as shell and tube heat exchangers with any number of shells and even number of tube passes per shell. In addition to being more intuitive, the use of AMTD and the heat exchanger efficiency allow the direct comparison of the different types of heat exchangers.

Alumina nanoparticle flow within a channel with permeable walls

2020 ◽  
Vol 31 (04) ◽  
pp. 2050050 ◽  
Author(s):  
Tran Dinh Manh ◽  
Nguyen Dang Nam ◽  
Gihad Keyany Abdulrahman ◽  
R. Moradi ◽  
Houman Babazadeh
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Power Law ◽  
Transfer Rate ◽  
Volume Fraction ◽  
Expansion Ratio ◽  
Hydrodynamic Characteristics ◽  
Stream Velocity ◽  
Main Stream ◽  
The Impact

The application of the nanoparticles for the heat transfer augmentation has extensively increased in the scientific and industrial applications. In this research, semi-analytic method is used to disclose the heat transmission and flow feature of the fluid with nanoparticles among the two parallel sheets. In our model, one plate is warmed with specific heat flux while fluid is streamed from another plate which extends over times. Nanoparticles of Al2O3 are applied in the main fluid to obtain nanofluid flow. To obtained viscosity coefficient and heat conductivity of the base fluid with nanoparticles, Koo–Kleinstreuer–Li (KKL) formula is applied as reliable approach. Comprehensive investigations on different factors are done to disclose the impact of important aspects such as volume fraction of the nanoparticles, main stream velocity and expansion ratio on the main thermal and hydrodynamic characteristics of the nanofluid. It was found that the rate of the Nusselt number upsurges when the velocity of main stream, volume portion of the nanoparticles and power law index is increased. However, the increasing of the expansion ratio declines the heat transfer rate in our model. Our findings disclose that heat transfer rate is directly proportional with velocity of nanofluid as index of power law equals to zero.

The Influence of a Harmonic Motion on a Melting Process With Natural Convection

2013 ◽  
Author(s):  
Ruben Avila ◽  
Eduardo Ramos
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Heat Transfer Rate ◽  
Liquid Layer ◽  
Transfer Rate ◽  
Fluid Layer ◽  
Melting Process ◽  
Spectral Element ◽  
Melting Rate ◽  
Liquid System

We study the heat transfer rate in an oscillatory, two dimensional solid-liquid system which is melted from below. As the phase change process takes place, the height of the fluid layer in the lower part of the cavity is continuously enlarged. The influence of the angular frequency of the motion (Taylor number) and the melting rate (Stefan number) on: (i) the heat transfer in the liquid (Nusselt number), (ii) the temperature field and (iii) the shape of the interface, is analyzed. The governing equations together with the Stefan condition at the interface are solved by using a spectral element method. It is observed that as the height of the liquid layer increases, a non-steady unicellular flow appears, and it leads to an oscillatory behaviour of the Nusselt number. As the height of the liquid layer increases further, the onset of the thermal convection and its instabilities modify the shape of the interface, and the heat transfer rate in the molten material. We find that (i) for large Stefan numbers, the heat is transported mostly along the inclined walls, while for low Stefan numbers, a Rayleigh-Bénard type convection is dominant, and (ii) for large Taylor numbers, the motion induced by the oscillation is small, resulting in a Nusselt number that decreases monotonously as a function of time, in contrast, for small Taylor numbers, an oscillatory Nusselt number is displayed.

scholarly journals Origin of spray formation during impact on heated surfaces

Soft Matter ◽  
2017 ◽  
Vol 13 (41) ◽  
pp. 7514-7520 ◽  
Author(s):  
Michiel A. J. van Limbeek ◽  
Paul B. J. Hoefnagels ◽  
Chao Sun ◽  
Detlef Lohse
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Plate Thickness ◽  
Heated Plate ◽  
Spray Formation ◽  
Impact Process ◽  
The Impact

In many applications, it is crucial to control the heat transfer rate of impacting drops on a heated plate. Here we study how limited heat transfer, such as the plate thickness or low conductivity, affects the impact process.

scholarly journals Impact of Smoluchowski Temperature and Maxwell Velocity Slip Conditions on Axisymmetric Rotated Flow of Hybrid Nanofluid past a Porous Moving Rotating Disk

Nanomaterials ◽  
2022 ◽  
Vol 12 (2) ◽  
pp. 276
Author(s):  
Umair Khan ◽  
Aurang Zaib ◽  
Iskandar Waini ◽  
Anuar Ishak ◽  
El-Sayed M. Sherif ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Friction Factor ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Radial Direction ◽  
Velocity Slip ◽  
Hybrid Nanofluid ◽  
Al2o3 Nanoparticles ◽  
Suction Parameter ◽  
The Impact

Colloidal suspensions of regular fluids and nanoparticles are known as nanofluids. They have a variety of applications in the medical field, including cell separation, drug targeting, destruction of tumor tissue, and so on. On the other hand, the dispersion of multiple nanoparticles into a regular fluid is referred to as a hybrid nanofluid. It has a variety of innovative applications such as microfluidics, heat dissipation, dynamic sealing, damping, and so on. Because of these numerous applications of nanofluids in minds, therefore, the objective of the current exploration divulged the axisymmetric radiative flow and heat transfer induced by hybrid nanofluid impinging on a porous stretchable/shrinkable rotating disc. In addition, the impact of Smoluchowski temperature and Maxwell velocity slip boundary conditions are also invoked. The hybrid nanofluid was formed by mixing the copper (Cu) and alumina (Al2O3) nanoparticles scattered in the regular (viscous) base fluid (H2O). Similarity variables are used to procure the similarity equations, and the numerical outcomes are achieved using bvp4c in MATLAB software. According to the findings, double solutions are feasible for stretching (λ>0) and shrinking cases (λ<0). The heat transfer rate is accelerated as the hybrid nanoparticles increases. The suction parameter enhances the friction factors as well as heat transfer rate. Moreover, the friction factor in the radial direction and heat transfer enrich for the first solution and moderate for the second outcome due to the augmentation δ1, while the trend of the friction factor in the radial direction is changed only in the case of stretching for both branches.

scholarly journals Magnetohydrodynamic mixed convection in a nanofluid filled tubular enclosure

2020 ◽  
Vol 4 (1) ◽  
pp. 19-24
Author(s):  
Mohammad Mokaddes Ali
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Temperature Fields ◽  
Convection Flow ◽  
Governing Equations ◽  
Convection Regime ◽  
Special Cases ◽  
Flow Domain

Mixed convection flow in a tubular enclosure filled with nanofluid in the presence of a magnetic field is numerically investigated in the present study. The bottom and top curved wall of the enclosure are respectively kept isothermally hot and cool while the remaining walls are insulated. The governing equations are formulated based on Boussinesq assumptions and solved with finite element method. The computation is carried out for mixed convection regime (0.1 ≤ Ri ≤ 10) and also natural convection regime (10 < Ri ≤ 100) with fixed values of remaining parameters. A detailed parametric discussion is presented for the physical properties of flow and temperature distributions in terms of streamlines, isotherms, average heat transfer rate within the flow domain. The results show that the flow and temperature fields affected by varying of pertinent parameters. Moreover, heat transfer rate is increased by 139.50% with the increase in Richardson number from 0.1 to 100. The increasing rate of heat transfer due to Ri is respectively decreased by 58.11% with varying of Ha from 0 to 60 and increased by 23.97% with the addition of nanoparticles up to 3%. Comparison is performed against the previously published results on the basis of special cases and found to be in excellent agreement.

scholarly journals Numerical Simulation of the Thermally Developed Pulsatile Flow of a Hybrid Nanofluid in a Constricted Channel

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2410
Author(s):  
Amjad Ali ◽  
Zainab Bukhari ◽  
Gullnaz Shahzadi ◽  
Zaheer Abbas ◽  
Muhammad Umar
Keyword(s):  
Heat Transfer ◽  
Thermal Radiation ◽  
Heat Transfer Rate ◽  
Pulsatile Flow ◽  
Transfer Rate ◽  
Heat Transfer Analysis ◽  
Hybrid Nanofluid ◽  
Water Based ◽  
The Impact ◽  
Constricted Channel

Heat transfer analysis of the pulsatile flow of a hybrid nanofluid through a constricted channel under the impact of a magnetic field and thermal radiation is presented. Hybrid nanofluids form a new class of nanofluids, distinguished by the thermal properties and functional utilities for improving the heat transfer rate. The behaviors of a water-based copper nanofluid and water-based copper plus a single-wall carbon nanotube, i.e., (Cu–SWCNT/water), hybrid nanofluid over each of velocity, wall shear stress, and temperature profiles, are visualized graphically. The time-dependent governing equations of the incompressible fluid flow are transformed to the vorticity-stream function formulation and solved numerically using the finite difference method. The laminar flow simulations are carried out in 2D for simplicity as the flow profiles are assumed to vary only in the 2D plane represented by the 2D Cartesian geometry. The streamlines and vorticity contours are also shown to demonstrate the flow behviour along the channel. For comparison of the flow characteristics and heat transfer rate, the impacts of variations in Hartmann number, Strouhal number, Prandtl number, and the thermal radiation parameter are analyzed. The effects of the emerging parameters on the skin friction coefficient and Nusselt number are also examined. The hybrid nanofluid is demonstrated to have better thermal characteristics than the traditional one.

An Experimental Study on Forced Convection From a Rectangular Heated Block by Acoustic Excitation in a Channel Flow

2002 ◽  
Author(s):  
J. W. Moon ◽  
S. Y. Kim ◽  
H. H. Cho
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Reynolds Number ◽  
Forced Convection ◽  
Heat Transfer Rate ◽  
Channel Flow ◽  
Transfer Rate ◽  
Acoustic Excitation ◽  
Pulsation Amplitude ◽  
The Impact

An experimental study on forced convection from a heated block in a pulsating channel flow has been carried out. This problem is of particular interest in various thermal applications such as electronics cooling and industrial heat exchangers. A pulsating flow is imposed by an acoustic excitation at the channel inlet and a constant heat flux is given along the surfaces of the block. The impact of the important governing parameters such as the Reynolds number, the Strouhal number, and the pulsation amplitude on the heat transfer rate from the heated block is investigated in detail. The vortex shedding frequencies generated from the block are measured and the flow around the block is visualized by means of the particle visualization technique. The experimental results show that the inlet flow pulsation and the Reynolds number substantially affect thermal transport from the heated block. The heat transfer is dramatically enhanced at the frequencies of fF=75Hz and fF=150Hz. It is found by the flow visualization that this phenomenon is related to the intensified fluid mixing at the frequencies. The increase of the pulsation amplitude also significantly amplifies the heat transfer rate from the heated block.

Thermal Analysis and Optimization of Orthotropic Pin Fins: A Closed-Form Analytical Solution

2009 ◽  
Vol 132 (3) ◽  
Author(s):  
Syed M. Zubair ◽  
A. F. M. Arif ◽  
Mostafa H. Sharqawy
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Temperature Distribution ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Two Dimensional ◽  
Fin Efficiency ◽  
Pin Fin ◽  
Special Cases ◽  
Pin Fins

Analytical solutions for temperature distribution, heat transfer rate, and fin efficiency and fin effectiveness are derived and presented for orthotropic two-dimensional pin fins subject to convective-tip boundary condition. The generalized results are presented and discussed in terms of dimensionless variables such as radial and axial Biot numbers (Bir,Biz), fin aspect ratio, L/R, and radial-to-axial conductivity ratio k∗. Several special cases are derived from the general solution, which includes the insulated-tip boundary condition. It is also demonstrated that the classical temperature distribution and heat transfer rate from the two-dimensional isotropic pin fin introduced earlier in literature can easily be recovered from the general solutions presented in this paper. Furthermore, dimensionless optimization results are presented for orthotropic pin fins that can help to solve many natural and forced convection pin fin problems.

The Effect of Nano-Structured Surfaces on Droplet Impingement Heat Transfer

2011 ◽  
Author(s):  
Gary Rosengarten ◽  
Anggito Tetuko ◽  
Ka Kit Li ◽  
Alex Wu ◽  
Robert Lamb
Keyword(s):  
Heat Transfer ◽  
Surface Properties ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
High Speed ◽  
Liquid Droplet ◽  
Droplet Impingement ◽  
Cooling Effectiveness ◽  
Structured Surfaces ◽  
The Impact

Droplet impingement is a fundamental process for many applications particularly those involving heat transfer. While there has been considerable work over many years on understanding the flow and heat transfer processes, we have only recently been able to fabricate controllable nanostructured surfaces. Surface structure can have a massive impact on the droplet impact process dynamics and the associated convective heat transfer from the liquid droplet to the surface. In this paper we examine the impact dynamics and heat transfer using simultaneous high speed thermal imaging of the liquid from below, and high speed video camera images from the side for different surfaces, ranging from hydrophilic to superhydrophobic. In this way we characterize the heat transfer process as a function of the droplet dynamics and the surface properties. We show that the heat transfer rate is primarily affected by the contact line dynamics and the wetted area. Due to the superhydrophobic roughness scale being relatively small, the interface resistance offered by the trapped air has only a small effect on the heat transfer rate, and only in the inertia dominated region before maximum spreading diameter. Finally we show that the overall cooling effectiveness of as single impinging droplet is very dependent on the surface properties with hydrophilic surfaces offering the highest cooling effectiveness.

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