scholarly journals Numerical Prediction of Non-isothermal Flow with Convective Heat Transfer Through a Rotating Curved Square Channel with Bottom Wall Heating and Cooling from the Ceiling

2019 ◽  
Vol 37 (3) ◽  
pp. 710-726 ◽  
Author(s):  
Mohammad Hasan ◽  
Rabindra Mondal ◽  
Giulio Lorenzini
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Isothermal Flow ◽  
Numerical Prediction ◽  
Bottom Wall ◽  
Square Channel ◽  
Heating And Cooling ◽  
Wall Heating

Investigation on Convective Heat Transfer over a Rotating Disk with Bottom Wall Subjected to Uniform Heat Flux

2012 ◽  
Vol 249-250 ◽  
pp. 443-451
Author(s):  
Jing Zhou Zhang ◽  
Xiao Ming Tan ◽  
Xing Dan Zhu
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Numerical Study ◽  
Rotating Disk ◽  
Outer Radius ◽  
Bottom Wall ◽  
Uniform Heat Flux ◽  
Uniform Heat

A three-dimensional numerical study on the flow and heat transfer characteristics over a rotating disk with bottom wall subjected to uniform heat flux was conducted with the use of RNG k- turbulent model. And some experiments were also made for validation. The effects of rotating angular speed and pin configuration on the temperature maps and convective heat transfer characte-ristics on rotating surface are analyzed. As the increase of rotating velocity, the impingement of pumping jet on the centre of rotating disk became stronger and the transition from laminar to turbu-lent occurred at the outer radius of rotating disk, which resulted in heat transfer enhancement. The pins on the disk made the pumping action of a rotating disk weaker. Simultaneously, they also acted as disturbing elements to the cyclone flow near the rotating disk surface, which made the overall heat transfer to be enhanced. Under the same extend areas of different pins, needle pin has higher convective heat transfer capacity than the discrete ring pin.

Turbulent convective heat transfer of nanofluids through a square channel

2011 ◽  
Vol 28 (12) ◽  
pp. 2230-2235 ◽  
Author(s):  
Mohammad Nasiri ◽  
Seyed Gholamreza Etemad ◽  
Rohollah Bagheri
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Square Channel

scholarly journals Magnetic Field Inhibition of Convective Heat Transfer in Magnetic Nanofluid

2021 ◽  
Vol 7 (2) ◽  
pp. 21
Author(s):  
Arthur Zakinyan ◽  
Stanislav Kunikin ◽  
Andrey Chernyshov ◽  
Vitali Aitov
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Two Dimensional ◽  
Hot Metal ◽  
Magnetic Nanofluid ◽  
Heating And Cooling ◽  
Exchange Processes ◽  
Metal Plates

Natural convection is the main mechanism of heat transfer in many natural and technological processes, which makes it urgent to study the possibilities of controlling it. In this work, the processes of development and damping of thermal convection in a flat vertical quasi-two-dimensional layer of magnetic nanofluid are considered experimentally. The presence of the magnetic properties of the nanofluid makes it possible to effectively apply the external magnetic fields to regulate convective heat transfer. The magnetic nanofluid layer was heated from below. It was shown in this work that the imposition of an external uniform stationary magnetic field perpendicular to the temperature gradient leads to the suppression of convection. The processes of heating and cooling the metal plates in a magnetic nanofluid are studied. It is demonstrated that the suppression of convection by a magnetic field leads to a slowdown in the heating of cold and cooling of hot metal plates in a magnetic nanofluid. The obtained results can be considered as a model for understanding similar exchange processes in liquids under the action of magnetic field.

scholarly journals Grain crops extrusion process mathematical model at a non-isothermal flow of their melt up to the temperature of the Maillard reaction start

2021 ◽  
Vol 83 (1) ◽  
pp. 23-29
Author(s):  
V. A. Afanasiev ◽  
L. N. Frolova ◽  
K. A. Sizikov ◽  
A. N. Ostrikov ◽  
S. N. Zobova
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Mathematical Model ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Maillard Reaction ◽  
Flow Direction ◽  
Viscous Medium ◽  
Isothermal Flow ◽  
Grain Crops

The equations of motion, the equation of continuity, the equation of energy (heat balance), the rheological equation were chosen to describe the non-isothermal flow of the cereals melt in the extruder as the initial equations. The following assumptions were made to solve the model: the flow of a moving viscous medium is assumed to be laminar and steady; the forces of inertia and gravity are so small compared to the forces of friction and pressure that they can be neglected; a viscous medium (melt) is an incompressible liquid characterized by constant thermal conductivity and thermal diffusivity; the change in thermal conductivity in the longitudinal direction was neglected due to the fact that convective heat transfer in the flow direction is higher than the heat transfer by thermal conductivity; heat transfer in the direction perpendicular to the flow of the melt occurs only due to thermal conductivity. The numerical finite difference method was used to solve a system of equations taking into account convective heat transfer. Its essence of use lies in the fact that the considered area (extruder channel) is divided into calculated cells using a grid. The grid consisted of rectangular cells with a constant step between nodes, which exactly lie on the boundaries of the integration region. In this case, the differential equations were transformed into difference equations by replacing the derivatives at a point with finite differences along the cell boundaries. The mathematical model of non-isothermal melt flow in the extruder channel was obtained as a result of the solution. To solve a mathematical model of the process of grain crops extrusion with a non-isothermal flow of their melts, a program in the algorithmic language C ++ was compiled. A non-isothermal mathematical model of the process of extrusion of grain crops at temperatures of the beginning of the Maillard reaction, i.e., up to 120–125 ?, was obtained. It allows us to identify the nature of the temperature change along the length of the extruder. Comparative analysis of the results of the numerical solution and experimental data showed good convergence: the standard deviation did not exceed 12.7%.

The Design of Transient Wall Heating Experiments for the Determination of Convective Heat Transfer Using Liquid Crystal Thermography

2000 ◽  
Author(s):  
David Graham ◽  
Jeff Rhine
Keyword(s):  
Heat Transfer ◽  
Liquid Crystal ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Operating Conditions ◽  
Transfer Coefficients ◽  
Liquid Crystal Thermography ◽  
Heat Transfer Coefficients ◽  
Wall Heating ◽  
Convective Heat Transfer Coefficients

The use of liquid crystals as surface temperature sensors in transient wall heating experiments, to measure steady-state convective heat transfer coefficients, is becoming increasingly popular. This paper describes a simple graphical method to assist in the design of these experiments. The analysis assumes that the test specimen, perspex in the given example, behaves as a semi-infinite solid. Given an expected range of convective heat transfer coefficients, the experimenter can determine the optimum combination of liquid crystal colour change temperature, bounding wall thickness and experiment duration. It is also possible to determine the sensitivity of experimental uncertainty to the operating conditions and the physical properties of the bounding wall. Emphasis is given to the use of liquid crystal thermography but the methodology could be applied when other temperature measurement devices are employed.

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