Enhanced Heat Transfer Rates Caused by Magnetic Field for Natural Convection of Air in an Inclined Cubic Enclosure

2003 ◽  
Vol 10 (2) ◽  
pp. 159-170 ◽  
Author(s):  
Riki Noda ◽  
Masayuki Kaneda ◽  
Toshio Tagawa ◽  
Hiroyuki Ozoe
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Natural Convection ◽  
Enhanced Heat Transfer ◽  
Transfer Rates

Enhanced Heat Transfer From a Horizontal Finned Tube Situated in a Vertical Channel

1986 ◽  
Vol 108 (1) ◽  
pp. 62-69 ◽  
Author(s):  
E. M. Sparrow ◽  
M. A. Ansari ◽  
P. C. Stryker ◽  
R. Ruiz
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Free Space ◽  
Vertical Channel ◽  
Finned Tube ◽  
Geometric Parameters ◽  
Vertical Position ◽  
Heat Transfer Characteristics ◽  
Enhanced Heat Transfer ◽  
Transfer Rates

Experiments were performed to determine the heat transfer characteristics of a horizontal finned tube situated in a vertical channel which is open to the ambient at the top and bottom. The heat transfer from the finned tube is by natural convection and radiation. The response of the finned-tube heat transfer to three geometric parameters was investigated: (1) the vertical position of the tube in the channel, (2) the clearance between the fin tips and the channel walls, and (3) the height of the channel. Experiments were also carried out with the finned tube situated in free space. It was found that in-channel positioning of the finned tube gave rise to substantially higher heat transfer rates than did free-space positioning. With the finned tube situated in the channel, the heat transfer was enhanced by: (1) positioning the tube at the bottom of the channel, (2) small tip-to-wall clearances, and (3) tall channels.

Experimental Heat Transfer Rates of Natural Convection of Molten Gallium Suppressed Under an External Magnetic Field in Either the X, Y, or Z Direction

1992 ◽  
Vol 114 (1) ◽  
pp. 107-114 ◽  
Author(s):  
K. Okada ◽  
H. Ozoe
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Natural Convection ◽  
External Magnetic Field ◽  
Magnetic Fields ◽  
Vertical Wall ◽  
Vertical Direction ◽  
Heated Wall ◽  
Heating Rates ◽  
Transfer Rates

The heat transfer rates of natural convection of molten gallium were measured under various strengths of heating rates and three coordinate directional magnetic fields. Molten gallium (Pr = 0.024) was filled in a cubic enclosure of 30 mm × 30 mm × 30 mm whose one vertical wall was uniformly heated and an opposing wall was isothermally cooled, with otherwise insulated walls. An external magnetic field was impressed either perpendicular and horizontal to the heated wall (x direction) or in parallel and horizontal to the heated wall (y direction) of the enclosure or in a vertical direction (z direction). For the modified Grashof number, based on the heat flux, less than 4.24 × 106 and the Hartmann number less than 461, the average Nusselt numbers were measured. These results proved that our previous three-dimensional numerical analyses for an isothermal hot wall boundary were in good qualitative agreement. A much higher suppression effect is given in the x- and z-directional magnetic fields than that in the y-directional one. The measured heat transfer rates were correlated as follows: NuB−1Nu0−1=1−[1+(aGr1/3/Ha)b]−1/nMagneticfield¯a¯b¯c¯x-directional0.573.191.76y-directional4.192.071.45z-directional0.522.721.44

scholarly journals CuO–Water Nanofluid Magnetohydrodynamic Natural Convection inside a Sinusoidal Annulus in Presence of Melting Heat Transfer

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
M. Sheikholeslami ◽  
R. Ellahi ◽  
C. Fetecau
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Natural Convection ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Melting Heat ◽  
Melting Heat Transfer ◽  
Limiting Case ◽  
Good Agreement ◽  
Melting Parameter

Impact of nanofluid natural convection due to magnetic field in existence of melting heat transfer is simulated using CVFEM in this research. KKL model is taken into account to obtain properties of CuO–H2O nanofluid. Roles of melting parameter (δ), CuO–H2O volume fraction (ϕ), Hartmann number (Ha), and Rayleigh (Ra) number are depicted in outputs. Results depict that temperature gradient improves with rise of Rayleigh number and melting parameter. Nusselt number detracts with rise of Ha. At the end, a comparison as a limiting case of the considered problem with the existing studies is made and found in good agreement.

Three-Dimensional Natural Convection From Vertical Heated Plates With Adjoining Cool Surfaces

1992 ◽  
Vol 114 (1) ◽  
pp. 115-120 ◽  
Author(s):  
B. W. Webb ◽  
T. L. Bergman
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Control Volume ◽  
Three Dimensional ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Uniform Heat Flux ◽  
Infrared Thermal Imaging ◽  
Transfer Rates ◽  
Thermal Boundary Conditions

Natural convection in an enclosure with a uniform heat flux on two vertical surfaces and constant temperature at the adjoining walls has been investigated both experimentally and theoretically. The thermal boundary conditions and enclosure geometry render the buoyancy-induced flow and heat transfer inherently three dimensional. The experimental measurements include temperature distributions of the isoflux walls obtained using an infrared thermal imaging technique, while the three-dimensional equations governing conservation of mass, momentum, and energy were solved using a control volume-based finite difference scheme. Measurements and predictions are in good agreement and the model predictions reveal strongly three-dimensional flow in the enclosure, as well as high local heat transfer rates at the edges of the isoflux wall. Predicted average heat transfer rates were correlated over a range of the relevant dimensionless parameters.

Design of a Plane-Type Bidirectional Thermal Diode

1988 ◽  
Vol 110 (4) ◽  
pp. 299-305 ◽  
Author(s):  
K. Chen
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Transfer Rate ◽  
Reverse Bias ◽  
Energy Utilization ◽  
Heat Transfer Analysis ◽  
Transfer Rates ◽  
One Dimensional ◽  
Plane Type ◽  
Solar Energy Utilization

The design of a plane-type, bidirectional thermal diode is presented. This diode is composed of two vertical plates and several fluid-filled loops with their horizontal segments soldered to the vertical plates. This invention is simple in construction and low in cost. The direction of heat transfer in the invented thermal diode can be easily reversed. These features of the present invention make it very attractive to solar energy utilization. Natural convection analysis for thermosyphon operations was adopted for heat transfer calculations of the fluid-filled loops. A one-dimensional heat transfer analysis was employed to estimate the heat transfer rate and ratio of heat transfer rates of the diode under forward and reverse bias.

Enhancement of Natural Convection Heat Transfer by a Staggered Array of Discrete Vertical Plates

1980 ◽  
Vol 102 (2) ◽  
pp. 215-220 ◽  
Author(s):  
E. M. Sparrow ◽  
C. Prakash
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Transfer Enhancement ◽  
Parallel Plate ◽  
Convection Heat Transfer ◽  
Transfer Enhancement ◽  
Enhanced Heat Transfer ◽  
Maximum Heat ◽  
Maximum Heat Transfer ◽  
Parameter Ranges

An analysis has been performed to determine whether, in natural convection, a staggered array of discrete vertical plates yields enhanced heat transfer compared with an array of continuous parallel vertical plates having the same surface area. The heat transfer results were obtained by numerically solving the equations of mass, momentum, and energy for the two types of configurations. It was found that the use of discrete plates gives rise to heat transfer enhancement when the parameter (Dh/H)Ra > ∼2 × 103 (Dh = hydraulic diameter of flow passage, H = overall system height). The extent of the enhancement is increased by use of numerous shorter plates, by larger transverse interplate spacing, and by relatively short system heights. For the parameter ranges investigated, the maximum heat transfer enhancement, relative to the parallel plate case, was a factor of two. The general degree of enhancement compares favorably with that which has been obtained in forced convection systems.

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