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in subjects: "Nusselt Number"

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Numerical analysis of laminar forced convection in a spherical annulus

Calculations of steady laminar incompressible fluid-flow and heat transfer in a spherical annulus are presented. Steady pressures, temperatures, velocities, and heat transfer coefficients are calculated for an insulated outer sphere and a 0/sup 0/C isothermal inner sphere with 50/sup 0/C heated water flowing in the annulus. The inner sphere radius is 13.97 cm, the outer sphere radius is 16.83 cm and the radius ratio is 1.2. The transient axisymmetric equations of heat, mass, and momentum conser… more

Date: July 21, 1980

Creator: Tuft, D.B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Experimental study of the steady natural convection in a horizontal annulus with irregular boundaries

The natural convective heat transfer across an annulus with irregular boundaries was studied using a Mach-Zehnder interferometer. The annulus was formed by an inner hexagonal cylinder and an outer concentric circular cylinder. This configuration models, in two dimensions, a liquid metal fast breeder reactor spent fuel subassembly inside a shipping container. During the test, the annulus was filled with a single gas, either neon, air, argon, krypton, or xenon, at a pressure of about 0.5 MPa. Fro… more

Date: January 1, 1980

Creator: Boyd, R.D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Maximum wake temperature and Nusselt number behind blockages in sodium-cooled bundles

Two important correlations have been obtained to calculate the maximum coolant temperature and the Nusselt number in the wake (the flow recirculating zone) downstream of blockages in 19-pin sodium-cooled bundles. These correlations can be applied to predict the maximum temperature rise and the average heat transfer coefficient behind small non-heat-generating blockages in the fuel assemblies of the FFTF and the CRBR for the wide range of flow and power conditions. Experiments with partial block… more

Date: January 1, 1977

Creator: Han, J. T.; Fontana, M. H. & Wantland, J. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Additional capabilities and benchmarking with the SPERT transients for heavy water application of the PARET code

The capabilities of the PARET code have been expanded to include the ability to compute steady-state and transient results for heavy water reactors. A comparison is provided between PARET and the SPERT II series of transients. Another significant improvement in the code is the addition of a restart capability. The current capabilities of the code are summarized. 7 refs., 12 figs., 3 tabs.

Date: January 1, 1989

Creator: Woodruff, W.L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Comparative Analysis of Natural Convection Flows Simulated by both the Conservation and Incompressible Forms of the Navier-Stokes Equations in a Differentially-Heated Square Cavity

This report illustrates a comparative study to analyze the physical differences between numerical simulations obtained with both the conservation and incompressible forms of the Navier-Stokes equations for natural convection flows in simple geometries. The purpose of this study is to quantify how the incompressible flow assumption (which is based upon constant density advection, divergence-free flow, and the Boussinesq gravitational body force approximation) differs from the conservation form (… more

Date: January 1, 2009

Creator: Martineau, Richard C.; Berry, Ray A.; Esteve, Aurélia; Hamman, Kurt D.; Knoll, Dana A.; Park, Ryosuke et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Scoping heat transfer analysis of a completely-blocked Type-Q septifoil

Heat removal mechanisms for a completely-blocked Type-Q (new design) septifoil situated in an otherwise normally operating K-reactor are investigated in this report. The best-estimate maximum septifoil heat generation rate for a 26.2{degrees}C cooling water inlet temperature is 119 to 141 kW depending on the counter-current flow limitation correlation chosen. The corresponding reactor powers are 648 and 768 MW or 27 and 32% of 2400 MW (historical annual averaged full power). These estimates are… more

Date: December 1, 1991

Creator: Flach, G. P.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Natural convection heat transfer between arrays of horizontal cylinders and their enclosure

The natural convection heat transfer between arrays of horizontal, heated cylinders and their isothermal, cooled enclosure was experimentally investigated. Four different cylinder arrays were used: two in-line and two staggered. Four fluids (air, water, 20 cs silicone, and 96% glycerine) were used with Prandtl numbers ranging from 0.705 to 13090.0. There was no significant change in the Nusselt number between isothermal and constant heat flux conditions of the cylinder arrays. The average heat … more

Date: January 1, 1984

Creator: Weaver, R.A. & Warrington, R.O.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Convective heat transfer correlations for molten core debris pools growing in concrete. [LMFBR]

The heat and mass transfer processes taking place in volumetrically-heated pools are of interest because of their relevance in post accident heat removal analyses for fast reactors. Earlier studies on volumetrically-heated pools have focused on natural convection phenomena. These, however, do not apply for molten core debris pools growing in concrete since large amounts of gas will be released by the concrete. These gases will vigorously mix the pool. Knowledge of the heat transfer rates at the… more

Date: unknown

Creator: Felde, D. K.; Kim, H. S. & Abdel-Khalik, S. I.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Interferometric study of the natural convection characteristics of flat plate, slat and vee-corrugated solar collectors. Final report

The natural convection heat transfer relations for the heat transfer between absorber and cover plates of solar collectors have been studied. Interferometric techniques were employed to evaluate the local coefficients. Average values were obtained by integration of the local values. The results are presented in terms of correlations between Nusselt number and Grashof number. The investigations were carried out over tilt angles of 45 to 90 degrees. The Grashof number range tested was representat… more

Date: June 30, 1979

Creator: El Wakil, M.M. & Mitchell, J.W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Numerical results for the solution of the Graetz problem for a Bingham plastic in laminar tube flow with constant wall temperature

The Graetz problem of developing temperature profile in a tube for a fully developed laminar velocity profile has been numerically solved for a Bingham plastic. Constant properties were assumed and viscous dissipation was ignored. Results are presented for local Nusselt number, average Nusselt number, and bulk fluid temperature each as a function of axial distance from the tube inlet. The laminar Newtonian fluid is a special case of the Bingham plastic; the results presented in this article for… more

Date: August 1, 1984

Creator: Blackwell, B.F.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Experimental study of natural convection heat transfer through an aperture in passive solar heated buildings

The objective of this study is to obtain correlations between natural convection heat transfer through an aperture and temperature difference between the two rooms. A one-fifth similitude model of a two-room building is used. The model is filled with Freon gas to satisfy similarity of the experiment to full-scale conditions in air. The experimental apparatus and experimental techniques are explained. Experimental results are presented in terms of Grashof, Nusselt, and Prandtl numbers. The effec… more

Date: January 1, 1984

Creator: Yamaguchi, Kenjiro

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Condensation of steam on the underside of a horizontal surface in the presence of air and helium

Experiments and data analysis for the condensation of steam on the underside of a horizontal surface in a closed vessel are described. Previously reported results for film condensation with air as a noncondensable gas are reviewed and compared with new data with helium as the noncondensable in the same apparatus. Observations, including photographs of the condensate configurations, related to the occurrence of dropwise condensation are also discussed. It is noted that data reproducibility over … more

Date: January 1, 1987

Creator: Stein, R. P.; Cho, D. H. & Lambert, G. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Aspects of forced convective heat transfer in geothermal systems

A knowledge of convective heat transfer is essential to understanding geothermal systems and other systems of moving groundwater. A simple, kinematic approach toward convective heat transfer is taken here. Concern is not with the cause of the groundwater motion but only with the fact that the water is moving and transferring heat. The mathematical basis of convective heat transfer is the energy equation which is a statement of the first law of thermodynamics. The general solution of this equati… more

Date: July 1, 1978

Creator: Kilty, K.; Chapman, D. S. & Mase, C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Disruption shape effects on the performance of enhanced tubes with the separation and reattachment mechanism

A non-orthogonal, body-fitted numerical code is used to determine the thermo-hydraulic performance of enhanced tubes with transverse periodic sine-, semicircle-, arc-, and trapezoid-shaped disruptions. The turbulence closure was achieved with a two-layer turbulence model. It is shown that there is a tradeoff of the heat-transfer and pressure-drop performances when the disruption shape becomes more contoured; that is, both the heat transfer and the pressure drop increase. The local heat transfer… more

Date: August 1, 1992

Creator: Arman, B. & Rabas, T. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Disruption shape effects on the performance of enhanced tubes with the separation and reattachment mechanism

Date: January 1, 1992

Creator: Arman, B. & Rabas, T. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

EXPERIMENTAL INVESTIGATION OF NATURAL CONVECTION HEAT TRANSFER OF IONIC LIQUID IN A RECTANGULAR ENCLOSURE HEATED FROM BELOW

This paper presents an experimental study of natural convection heat transfer for an Ionic Liquid. The experiments were performed for 1-butyl-2, 3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide, ([C{sub 4}mmim][NTf{sub 2}]) at a Raleigh number range of 1.26 x 10{sup 7} to 8.3 x 10{sup 7}. In addition to determining the convective heat transfer coefficients, this study also included experimental determination of thermophysical properties of [C{sub 4}mmim][NTf{sub 2}] such as, density, vis… more

Date: July 18, 2011

Creator: Fox, E.; Visser, A. & Bridges, N.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The influence of the Prandtl number on the thermal performance of tubes with the separation and reattachment enhancement mechanism

This paper demonstrates that the heat-transfer performance of an enhanced tube with transverse, rectangular disruptions can be predicted with a numerical modeling method, an accomplishment not previously achieved. This computer code is then used to determine the influence of the Prandtl number. The numerical simulation demonstrated that six distinct regions exist: the three rib surfaces, the upstream and downstream recirculation regions, and the boundary-layer development zone. Three zones domi… more

Date: January 1, 1992

Creator: Rabas, T. J. & Arman, B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Influence of Prandtl number and effects of disruption shape on the performance of enhanced tubes with the separation and reattachment mechanism

The pressure-drop and heat-transfer performance of an enhanced tube with transverse disruptions can be predicted with a numerical modeling method, an accomplishment not previously achieved. Two computer codes were employed to achieve this goal - an orthogonal code and a nonorthogonal, body-fitted code. The turbulence closure was achieved with a two-layer turbulence model. The orthogonal computer code was used to determine the influence of the Prandti number. The numerical simulations demonstrat… more

Date: April 1, 1992

Creator: Arman, B. & Rabas, T. J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Turbulent natural convection between a perforated vertical cylinder and a surrounding array

A number of situations can be hypothesized to occur in an advanced or special purpose nuclear reactor such that the core is filled with a gas but there is no forced flow to remove the thermal energy evolved. Experiments were conducted by resistively hearing a vertical circular cylinder of length-to-diameter ratio of about 160 centered inside a concentric perforated tube which was, in turn, surrounded by three larger diameter tubes cooled internally with water flow. The ratio of the test section… more

Date: September 1, 1992

Creator: McEligot, D. M.; Stoots, C. M.; Christenson, W. A.; O`Brien, J. E.; Mecham, D. C. & Lussie, W. G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Natural convection between a vertical cylinder and a surrounding array

The generic situation considered is natural convection between a single heated, vertical cylinder and a surrounding array of cooler vertical cylinders in a triangular pattern. The ratio of the test section temperature to the cooling tube temperature was varied up to 2.6 by adjusting the electrical power. The Rayleigh number, based on test section diameter and air properties evaluated at cooling tube temperature, ranged from 2.9 x 10{sup 4} to 4.6 x 10{sup 5}. Results indicate that the convectiv… more

Date: September 1, 1992

Creator: McEligot, D. M.; O`Brien, J. E.; Stoots, C. M.; Larson, T. K.; Christenson, W. A.; Mecham, D. C. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Advanced Energy and Water Recovery Technology from Low Grade Waste Heat

The project has developed a nanoporous membrane based water vapor separation technology that can be used for recovering energy and water from low-temperature industrial waste gas streams with high moisture contents. This kind of exhaust stream is widely present in many industrial processes including the forest products and paper industry, food industry, chemical industry, cement industry, metal industry, and petroleum industry. The technology can recover not only the sensible heat but also high… more

Date: December 19, 2011

Creator: Wang, Dexin

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Heat Transfer Enhancement for Finned-Tube Heat Exchangers with Vortex Generators: Experimental and Numerical Results

A combined experimental and numerical investigation is under way to investigate heat transfer enhancement techniques that may be applicable to large-scale air-cooled condensers such as those used in geothermal power applications. The research is focused on whether air-side heat transfer can be improved through the use of finsurface vortex generators (winglets,) while maintaining low heat exchanger pressure drop. A transient heat transfer visualization and measurement technique has been employed… more

Date: August 1, 2002

Creator: O'Brien, James Edward; Sohal, Manohar Singh & Huff, George Albert

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Heat Transfer Enhancement for Finned-tube Heat Exchangers with Winglets

This paper presents the results of an experimental study of forced convection heat transfer in a narrow rectangular duct fitted with a circular tube and/or a delta-winglet pair. The duct was designed to simulate a single passage in a fin-tube heat exchanger. Heat transfer measurements were obtained using a transient technique in which a heated airflow is suddenly introduced to the test section. High-resolution local fin-surface temperature distributions were obtained at several times after init… more

Date: November 1, 2000

Creator: O'Brien, James Edward & Sohal, Manohar Singh

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Heat transfer to isobutane flowing inside a horizontal tube at supercritical pressure

An experimental measurements of heat transfer coefficient of isobutane at 4.14 MPa (600 psia) has been performed using the experimental system developed by the Sea Water Conversion Laboratory. The experimental system simulates a geothermal power plant utilizing a binary cycle with isobutane as the working fluid. In this system, isobutane is heated inside a horizontal tube with steam condensing on the outside.

Date: November 1, 1979

Creator: Hsu, I.C.W.

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department