Experimental Investigation of Heat Transfer in Coiled Annular Ducts

1988 ◽  
Vol 110 (2) ◽  
pp. 329-336 ◽  
Author(s):  
S. Garimella ◽  
D. E. Richards ◽  
R. N. Christensen
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Circular Tube ◽  
Convection Heat Transfer ◽  
Convection Heat ◽  
Transfer Coefficients ◽  
Dean Number ◽  
Average Heat ◽  
Circular Tubes ◽  
Heat Transfer Coefficients

Forced convection heat transfer in coiled annular ducts was investigated experimentally. Average heat transfer coefficients were obtained for both laminar and transition flows. Two coiling diameters and two annulus radius ratios were used in the study. The data were correlated with Dean number and Reynolds number separately and compared with the available studies of coiled circular tubes and straight annular ducts. It was found that coiling augments the heat transfer coefficients above the values for a straight annulus especially in the laminar region. However, the augmentation is less than would be expected for a coiled circular tube. The augmentation decreases as the flow enters the transition region.

Natural Convection Heat Transfer From Horizontal Rectangular Fin Arrays

1967 ◽  
Vol 89 (1) ◽  
pp. 32-38 ◽  
Author(s):  
F. Harahap ◽  
H. N. McManus
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Flow Field ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Transfer Coefficients ◽  
Average Heat ◽  
Heat Transfer Coefficients

Average heat-transfer coefficients are presented for fin arrays positioned with the base oriented horizontally. The flow field associated with the natural convection from the fin arrays was investigated and used as a model to find parameters to generalize the data. The proposed correlation overcomes the inadequacy of parameters available previously for horizontal rectangular fins.

Experimental Investigation of Natural Convection Heat Transfer in Volumetrically Heated Spherical Segments

1996 ◽  
Vol 118 (1) ◽  
pp. 31-37 ◽  
Author(s):  
F. J. Asfia ◽  
B. Frantz ◽  
V. K. Dhir
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Convection Heat Transfer ◽  
Reactor Vessel ◽  
Core Material ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
External Cooling

External cooling of a light water reactor vessel by flooding of the concrete cavity with subcooled water is one of several management strategies currently being considered for accidents in which significant relocation of core material is predicted to occur. At present, uncertainty exists with respect to natural convection heat transfer coefficients between the pool of molten core material and the reactor vessel wall. In the present work, experiments were conducted to examine natural convection heat transfer in internally heated partially filled spherical pools with external cooling. In the experiments, Freon-113 was contained in a Pyrex bell jar, which was cooled externally with subcooled water. The pool was heated using a 750 W magnetron taken from a conventional microwave. The pool had a nearly adiabatic free surface. The vessel wall temperature was not uniform and varied from the stagnation point to the free surface. A series of chromel–alumel thermocouples was used to measure temperatures in both steady-state and transient conditions. Each thermocouple was placed in a specific vertical and radial location in order to determine the temperature distribution throughout the pool and along the inner and outer walls of the vessel. In the experiments, pool depth and radius were varied parametrically. Both local and averages heat transfer coefficients based on pool maximum temperature were obtained. Rayleigh numbers based on pool height were varied from 2 × 1010 to 1.1 × 1014. Correlations for the local heat transfer coefficient dependence on pool angle and for the dependence of average Nusselt number on Rayleigh number and pool depth have been developed.

Experimental and Numerical Investigation of Convection Heat Transfer of CO2 at Supercritical Pressures in a Vertical Mini Tube

2004 ◽  
Author(s):  
Pei-Xue Jiang ◽  
Yi-Jun Xu ◽  
Run-Fu Shi ◽  
S. He
Keyword(s):  
Heat Transfer ◽  
Wall Thickness ◽  
Fluid Pressure ◽  
Convection Heat Transfer ◽  
Local Heat Transfer ◽  
Fluid Temperature ◽  
Convection Heat ◽  
Transfer Coefficients ◽  
Bulk Fluid ◽  
Heat Transfer Coefficients

Convection heat transfer of CO2 at supercritical pressures in a vertical mini tube with a diameter of 0.948 mm was investigated experimentally and numerically. The local heat transfer coefficients, bulk fluid temperatures and wall temperatures were measured and presented. The effects of inlet fluid temperature, fluid pressure, mass flow rate, heat flux and wall thickness on the convection heat transfer in the mini tube were investigated. The experimental results were compared with calculated results using well-known correlations and numerical simulations. The results showed that the variable thermophysical properties of supercritical CO2 significantly influenced the convection heat transfer in the vertical mini tube and that for the studied conditions the influence of the wall thickness on the convection heat transfer in the mini tube was not great. For bulk fluid temperatures higher than the pseudo-critical temperature, the simulation results and the correlation results for the convection heat transfer coefficients in the mini tube corresponded well to the experimentally measured results.

Finite Element Predictions of Free Convection Heat Transfer Coefficients of Simulated Electronic Circuit Boards

1989 ◽  
Vol 111 (2) ◽  
pp. 129-134 ◽  
Author(s):  
C. Rajakumar ◽  
D. Johnson
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Convection Heat Transfer ◽  
Circuit Board ◽  
Convection Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Heating Surfaces ◽  
Free Convection Heat ◽  
Microelectronic Components

A numerical simulation of the buoyancy-induced flow around microelectronic components mounted on a circuit board has been performed using the finite element method. The circuit board is modeled by a vertical plate on which rectangular strip heating surfaces are mounted. Computations have been performed in two-dimensional plane applying a simplifying assumption that the circuit board and the strip heating surfaces are infinitely long. The Navier-Stokes, the flow continuity and the energy equations for laminar flow have been considered in the finite element discretizations. Results of the computations are presented in the form of temperature contour plots and velocity vector plots in the flow field. The convection heat transfer coefficients at the surface of the microelectronic components are presented as a function of their height. The convection coefficients computed have been compared with experimental correlations of free convection heat transfer found in the literature.

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