Coupled heat transfer characteristics in a spiral groove mechanical seal lubricated by magnetic fluid

2019 ◽  
Vol 71 (6) ◽  
pp. 758-765
Author(s):  
Penggao Zhang ◽  
Boqin Gu ◽  
Jianfeng Zhou ◽  
Long Wei
Keyword(s):  
Heat Transfer ◽  
Magnetic Fluid ◽  
Volume Fraction ◽  
Solid Particles ◽  
Mechanical Seal ◽  
Spiral Groove ◽  
Heat Transfer Characteristics ◽  
Content Type ◽  
Transfer Characteristics ◽  
Inner Radius

Purpose The purpose of this study is to investigate the heat transfer characteristics in a spiral groove mechanical seal lubricated by magnetic fluid. Design/methodology/approach The viscosity relationship of magnetic fluid in external electromagnetic field was deduced. The temperature distribution of sealing ring was calculated by the method of separation variables. Findings It has been found that the rotating ring absorbs most friction heat. The temperatures on the end faces of rotating ring and stationary ring decrease from inner radius to outer radius, the temperature of magnetic fluid film decreases from rotating ring to stationary ring and the highest temperature of the sealing system is at the junction of the inner radius and the end face of rotating ring. Originality/value Selecting the sealing rings with higher thermal conductivity and reducing the volume fraction of solid particles in magnetic fluid can reduce the temperature of sealing system effectively.

Pool Boiling Characteristics of Metallic Nanofluids

2011 ◽  
Vol 133 (11) ◽  
Author(s):  
K. Hari Krishna ◽  
Harish Ganapathy ◽  
G. Sateesh ◽  
Sarit K. Das
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Boiling Heat Transfer ◽  
Volume Fraction ◽  
Pool Boiling ◽  
Heat Fluxes ◽  
Solid Particles ◽  
Heater Surface ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics

Nanofluids, solid-liquid suspensions with solid particles of size of the order of few nanometers, have created interest in many researchers because of their enhancement in thermal conductivity and convective heat transfer characteristics. Many studies have been done on the pool boiling characteristics of nanofluids, most of which have been with nanofluids containing oxide nanoparticles owing to the ease in their preparation. Deterioration in boiling heat transfer was observed in some studies. Metallic nanofluids having metal nanoparticles, which are known for their good heat transfer characteristics in bulk regime, reported drastic enhancement in thermal conductivity. The present paper investigates into the pool boiling characteristics of metallic nanofluids, in particular of Cu-H2O nanofluids, on flat copper heater surface. The results indicate that at comparatively low heat fluxes, there is deterioration in boiling heat transfer with very low particle volume fraction of 0.01%, and it increases with volume fraction and shows enhancement with 0.1%. However, the behavior is the other way around at high heat fluxes. The enhancement at low heat fluxes is due to the fact that the effect of formation of thin sorption layer of nanoparticles on heater surface, which causes deterioration by trapping the nucleation sites, is overshadowed by the increase in microlayer evaporation, which is due to enhancement in thermal conductivity. Same trend has been observed with variation in the surface roughness of the heater as well.

scholarly journals Conduction and convection heat transfer characteristics of water-based au nanofluids in a square cavity with differentially heated side walls subjected to constant temperatures

2014 ◽  
Vol 18 (suppl.1) ◽  
pp. 189-200 ◽  
Author(s):  
Primoz Ternik ◽  
Rebeka Rudolf
Keyword(s):  
Heat Transfer ◽  
Rayleigh Number ◽  
Base Fluid ◽  
Volume Fraction ◽  
Heat Transfer Characteristics ◽  
Square Cavity ◽  
Onset Of Convection ◽  
Transfer Characteristics ◽  
Wide Range ◽  
Water Based

The present work deals with the natural convection in a square cavity filled with the water-based Au nanofluid. The cavity is heated on the vertical and cooled from the adjacent wall, while the other two horizontal walls are adiabatic. The governing differential equations have been solved by the standard finite volume method and the hydrodynamic and thermal fields were coupled together using the Boussinesq approximation. The main objective of this study is to investigate the influence of the nanoparticles? volume fraction on the heat transfer characteristics of Au nanofluids at the given base fluid?s (i.e. water) Rayleigh number. Accurate results are presented over a wide range of the base fluid Rayleigh number and the volume fraction of Au nanoparticles. It is shown that adding nanoparticles in a base fluid delays the onset of convection. Contrary to what is argued by many authors, we show by numerical simulations that the use of nanofluids can reduce the heat transfer rate instead of increasing it.

A Thermal Barrier With Adaptive Heat Transfer Characteristics

1994 ◽  
Vol 116 (2) ◽  
pp. 302-310 ◽  
Author(s):  
P. Furmanski ◽  
J. M. Floryan
Keyword(s):  
Heat Transfer ◽  
Heat Flow ◽  
Volume Fraction ◽  
Large Temperature ◽  
Thermal Barrier ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Apparent Slip ◽  
Small Volume Fraction ◽  
Relative Thermal Conductivity

A thermal barrier with adaptive heat transfer characteristics for applications in zero gravity environments is considered. The barrier consists of a mixture of fluid with a small volume fraction of arbitrarily oriented, randomly distributed particles of ellipsoidal shape. Heat flux control is obtained by changing the orientation of the particles. Heat flow may be increased up to several hundred times by rotating the particles from being parallel to the walls to being transverse to the walls and by increasing their aspect ratio, volume fraction, and relative thermal conductivity. An increase in the size of the particles results in the appearance of wall effects, which may substantially reduce heat flow as compared to the case of an infinite medium. Very large temperature variation is found to occur near the walls where an apparent “slip” of temperature occurs for barriers whose thickness is large compared to the particle size.

Laminar Flow and Heat Transfer Characteristics of Colloid Suspensions in Water: A Numerical Study

2009 ◽  
Author(s):  
Khalid N. Alammar ◽  
Lin-wen Hu
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Heat Transfer Enhancement ◽  
Volume Fraction ◽  
Numerical Study ◽  
Volume Flow Rate ◽  
Transfer Enhancement ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer

Numerical analysis is performed to examine axisymmetric laminar flow and heat transfer characteristics of colloidal dispersions of nanoparticles in water (nanofluids). Effect of volume fraction on flow and heat transfer characteristics is investigated. Four different materials, Alumina, Copper, Copper Oxide, and Graphite are considered. Heat transfer and property measurements were conducted previously for Alumina nanofluid. The measurements have shown that nanofluids can behave as homogeneous mixtures. It is found that oxide-based nanofluids offer the least heat transfer enhancement compared to elements-based nanofluids. When normalized by friction pressure drop, it is shown that graphite can have the highest effective heat transfer enhancement. For a given volume flow rate, all nanofluids exhibited linear increase in heat transfer enhancement with increasing colloids volume fraction, up to 0.05.

Numerical Investigation of Free Convection in a Porous Corrugated Cavity Filled With Silver (Ag) Dispersed Nano-Fluid

2020 ◽  
Vol 13 (4) ◽  
Author(s):  
Saurabh Bhardwaj ◽  
Amaresh Dalal
Keyword(s):  
Heat Transfer ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Uniform Heating ◽  
Heat Transfer Characteristics ◽  
Closed Cavity ◽  
Transfer Characteristics ◽  
Nano Fluid ◽  
Increasing Trend ◽  
Irregular Motion

Abstract The present work examines the convective heat transfer characteristics in a two-dimensional (2D) corrugated closed cavity embedded with porous media. The cavity is considered to be filled with silver dispersed water-based nano-fluid. The bottom wall is heated uniformly and non-uniformly in two different cases keeping both side corrugated walls isothermally cold with an adiabatic top wall. The various parameters are selected to perform numerical simulation in the range of solid-volume fraction, 0% ≤ ϕ ≤ 10%, 103 ≤ Ra ≤ 106, and 10−4 ≤ Da ≤ 10−2. The investigation shows that the heat transfer rate shows an increasing trend at high values of Ra and Da due to strong buoyancy forces in uniform and non-uniform heating. However, an increase in heat transfer in uniform heating is more compared to non-uniform heating. It is also observed that the nano-fluid has a great impact on the heat transfer characteristics due to its high value of thermal conductivity and irregular motion of the particles. As a result, the average Nusselt number (Nuavg) shows an increasing trend for increasing solid-volume fraction values.

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