scholarly journals AN EXPERIMENTAL DETERMINATION OF MIXED AND FORCED CONVECTION HEAT TRANSFER COEFFICIENTS IN A MODELED NUCLEAR WASTE REPOSITORY

1986 ◽  
Author(s):  
R.L. Osborne ◽  
Richard N. Christensen ◽  
M. Carmel
Keyword(s):  
Heat Transfer ◽  
Experimental Determination ◽  
Nuclear Waste ◽  
Convection Heat Transfer ◽  
Nuclear Waste Repository ◽  
Convection Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Waste Repository

Determination of Local Convection Heat Transfer Coefficients Inside a Circular Pipe Using Pulsed Laser

2015 ◽  
Author(s):  
S.-C. Lin ◽  
S. Tambe ◽  
M.-C. Lai ◽  
S.-M. Jeng
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Finite Size ◽  
Pulsed Laser ◽  
Experimental Results ◽  
Convection Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

The determination of local convection heat transfer coefficients of pipe flow using pulsed laser heating (PLH) from a combination of experimental and numerical study is presented in this paper. The method is advantageous because it is fluid-independent, contact-free and high in spatial and temporal resolution. For simplicity, the experiment used water at different temperatures and flow rates inside two long circular tubes which were subject to radiation heating using a finite size (20 mm in diameter) pulsed laser beam. An infrared camera was used to image and measure its surface temperatures. Two correlations for convection heat transfer coefficient in the thermal/combined entry length region were used in this paper for comparison with the experimental results. The experimental results using the thermal circuit method processed by MATLAB® agree well with both correlations. To gain better insight and quantify the uncertainty, a 3-D conjugated heat transfer simulation was carried out using Fluent CFD. The implication of the accuracy and limitation of the PLH method on the determination of local heat transfer coefficients are also discussed in the analysis.

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.

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