Conjugate Heat Transfer From a Vertical Plate With Discrete Heat Sources Under Natural Convection

1989 ◽  
Vol 111 (4) ◽  
pp. 261-267 ◽  
Author(s):  
S. Lee ◽  
M. M. Yovanovich
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Conjugate Heat Transfer ◽  
Vertical Plate ◽  
Power Level ◽  
Radiation Heat Transfer ◽  
Transfer Model ◽  
Heat Sources ◽  
Radiation Heat ◽  
Discrete Heat Sources

A quasi-analytical conjugate heat transfer model is developed for a two dimensional vertical flat plate with discrete heat sources of arbitrary size and power level under natural convection. The plate is located in an extensive, quiescent fluid which is maintained at uniform temperature. The model consists of an approximate analytical boundary layer solution and a one dimensional numerical conduction analysis in which an allowance is made to account for radiation heat transfer. These fluid and solid solutions are coupled through an iterative procedure. A conjugate problem is solved when a converged temperature distribution is obtained at the plate-fluid interface, concurrently satisfying the thermal fields on both sides of the interface. Comparisons of the surface temperature variations obtained by using the present model are made with existing numerical and experimental data which were obtained for cases with two strip heat sources mounted flush with the surface of a vertical plate in air. The model is shown to be in good agreement. In addition, the convection and radiation heat flux variations are presented. The results illustrate the importance of radiation heat transfer for estimating surface temperatures of the plate.

A Numerical Study on 2-D Flow and Heat Transfer in a Natural Gas Heater

2016 ◽  
Author(s):  
Yun Guo ◽  
Zhixiong Guo
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Natural Gas ◽  
Numerical Study ◽  
Radiation Heat Transfer ◽  
Transfer Model ◽  
Radiation Heat ◽  
Effective Measure ◽  
Heating And Cooling ◽  
Application Systems

The cylinder type natural gas heater with heat transfer medium is most widely used in gas application systems. But the conventional symmetrical arrangement of heat-exchange surfaces in cylinder is not conducive to the formation of an effective heat flow field. An effective measure of rotating the symmetrical layout structure at a certain angle is put forward creatively, which can optimize the overall heat transfer effect of the heater. The combined natural convection and radiation heat transfer model for both heating and cooling surfaces in the heat-exchanging cylinder is built. The finite volume method with unstructured body-fitted grids is employed. Analyses and comparisons of the flow conditions and temperature distributions of the cylindrical natural gas heater indifferent clockwise rotation angles (10°, 20°, 30°, 35°) are carried out. With increasing of the angle, the natural convection and radiation heat transfer will be correspondingly enhanced. When the angle exceeds than 30°, however, the natural convective circulation is destroyed instead. The numerical simulation shows the best rotation angle is 20∼30°.

scholarly journals Influence of Varying Pressure on Natural Convection and Radiation Heat Transfer in an Enclosure

PAMM ◽  
2005 ◽  
Vol 5 (1) ◽  
pp. 575-576 ◽  
Author(s):  
Jan Langebach ◽  
Stephan Senin ◽  
Christian Karcher
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Radiation Heat Transfer ◽  
Radiation Heat

2D Natural Convection and Radiation Heat Transfer Simulations of a PWR Fuel Assembly Within a Constant Temperature Support Structure

2006 ◽  
Author(s):  
Pablo E. Araya Go´mez ◽  
Miles Greiner
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Fuel Assembly ◽  
Heat Generation ◽  
Temperature Difference ◽  
Wall Temperature ◽  
Radiation Heat Transfer ◽  
Radiation Heat ◽  
Fuel Rods ◽  
Water Reactor

Two-dimensional simulations of steady natural convection and radiation heat transfer for a 14×14 pressurized water reactor (PWR) spent nuclear fuel assembly within a square basket tube of a typical transport package were conducted using a commercial computational fluid dynamics package. The assembly is composed of 176 heat generating fuel rods and 5 larger guide tubes. The maximum cladding temperature was determined for a range of assembly heat generation rates and uniform basket wall temperatures, with both helium and nitrogen backfill gases. The results are compared with those from earlier simulations of a 7×7 boiling water reactor (BWR). Natural convection/radiation simulations exhibited measurably lower cladding temperatures only when nitrogen is the backfill gas and the wall temperature is below 100°C. The reduction in temperature is larger for the PWR assembly than it was for the BWR. For nitrogen backfill, a ten percent increase in the cladding emissivity (whose value is not well characterized) causes a 4.7% reduction in the maximum cladding to wall temperature difference in the PWR, compared to 4.3% in the BWR at a basket wall temperature of 400°C. Helium backfill exhibits reductions of 2.8% and 3.1% for PWR and BWR respectively. Simulations were performed in which each guide tube was replaced with four heat generating fuel rods, to give a homogeneous array. They show that the maximum cladding to wall temperature difference versus total heat generation within the assembly is not sensitive to this geometric variation.

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