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Measurements of average heat-transfer and friction coefficients for subsonic flow of air in smooth tubes at high surface and fluid temperatures

Description: An investigation of forced-convection heat transfer and associated pressure drops was conducted with air flowing through smooth tubes for an over-all range of surface temperature from 535 degrees to 3050 degrees r, inlet-air temperature from 535 degrees to 1500 degrees r, Reynolds number up to 500,000, exit Mach number up to 1, heat flux up to 150,000 btu per hour per square foot, length-diameter ratio from 30 to 120, and three entrance configurations. Most of the data are for heat addition to the air; a few results are included for cooling of the air. The over-all range of surface-to-air temperature ratio was from 0.46 to 3.5.
Date: December 31, 1950
Creator: Humble, Leroy V.; Lowdermilk, Warren H. & Desmon, Leland G.
Partner: UNT Libraries Government Documents Department

Forced-Convection Heat Transfer to Water at High Pressures and Temperatures in the Nonboiling Region

Description: "Forced-convection heat-transfer data have been obtained for water flowing in an electrically heated tube of circular cross section at water pressures of 200 and 2000 pounds per square inch, and temperatures in the nonboiling region, for water velocities ranging between 5 and 25 feet per second. The results indicate that conventional correlations can be used to predict heat-transfer coefficients for water at pressures up to 2000 pounds per square inch and temperatures in the nonboiling region" (p. 1).
Date: November 29, 1951
Creator: Kaufman, S. J. & Henderson, R. W.
Partner: UNT Libraries Government Documents Department

Heat Transfer from High-Temperature Surfaces to Fluids 3 - Correlation of Heat-Transfer Data for Air Flowing in Silicon Carbide Tube with Rounded Entrance, Inside Diameter of 3/4 Inch, and Effective Length of 12 Inches

Description: A heat-transfer investigation was conducted with air flowing through an electrically heated silicon carbide tube with a rounded entrance, an inside diameter of 3/4 inch, and effective heat-transfer length of 12 inches over a range of Reynolds numbers up to 300,000 and a range of average inside-tube-wall temperatures up to 2500 R. The highest corresponding local outside-tube-wall temperature was 3010 R.
Date: June 23, 1949
Creator: Sams, Eldon W. & Desmon, Leland G.
Partner: UNT Libraries Government Documents Department

Conceptual Design of Forced Convection Molten Salt Heat Transfer Testing Loop

Description: This report develops a proposal to design and construct a forced convection test loop. A detailed test plan will then be conducted to obtain data on heat transfer, thermodynamic, and corrosion characteristics of the molten salts and fluid-solid interaction. In particular, this report outlines an experimental research and development test plan. The most important initial requirement for heat transfer test of molten salt systems is the establishment of reference coolant materials to use in the experiments. An earlier report produced within the same project highlighted how thermophysical properties of the materials that directly impact the heat transfer behavior are strongly correlated to the composition and impurities concentration of the melt. It is therefore essential to establish laboratory techniques that can measure the melt composition, and to develop purification methods that would allow the production of large quantities of coolant with the desired purity. A companion report describes the options available to reach such objectives. In particular, that report outlines an experimental research and development test plan that would include following steps: •Molten Salts: The candidate molten salts for investigation will be selected. •Materials of Construction: Materials of construction for the test loop, heat exchangers, and fluid-solid corrosion tests in the test loop will also be selected. •Scaling Analysis: Scaling analysis to design the test loop will be performed. •Test Plan: A comprehensive test plan to include all the tests that are being planned in the short and long term time frame will be developed. •Design the Test Loop: The forced convection test loop will be designed including extensive mechanical design, instrument selection, data acquisition system, safety requirements, and related precautionary measures. •Fabricate the Test Loop. •Perform the Tests. •Uncertainty Analysis: As a part of the data collection, uncertainty analysis will be performed to develop probability of confidence in what is ...
Date: September 1, 2010
Creator: Sohal, Manohar S.; Sabharwall, Piyush; Calderoni, Pattrick; Wertsching, Alan K. & Grover, S. Brandon
Partner: UNT Libraries Government Documents Department

Forced convection and transport effects during hyperbaric laser chemical vapor deposition

Description: This work explores mass transport processes during HP-LCYD, including the transverse forced-flow of precursor gases through a nozzle to enhance fiber growth rates. The use of laser trapping and suspension of nano-scale particles in the precursor flow is also described, providing insights into the nature of the gas flow, including jetting from the fiber tip and thermodiffusion processes near the reaction zone. The effects of differing molecular-weight buffer gases is also explored in conjunction with the Soret effect, and it is found that nucleation at the deposit surface (and homogeneous nucleation in the gas phase) can be enhanced/ retarded, depending on the buffer gas molecular weight. To demonstrate that extensive microstructures can be grown simultaneously, three-dimensional fiber arrays are also grown in-parallel using diffractive optics--without delatory effects from neighboring reaction sites.
Date: January 1, 2009
Creator: Maxwell, James L; Chavez, Craig A; Espinoza, Miguel; Black, Marcie; Maskaly, Karlene & Boman, Mats
Partner: UNT Libraries Government Documents Department

Regular and chaotic flow patterns upon impulsive spin-up of a Rayleigh-Benard convection cell

Description: A cylindrical, completely enclosed Rayleigh-Benard convection cell with radius-to-height ratio {Gamma}={1/2} is subjected to impulsive spin-up about its vertical axis. The authors study produces TLC (thermochromic liquid crystal) temperature measurements and PIV (particle image velocimetry) velocity reconstruction of the transient state between the two regimes of turbulent convection corresponding to the cell at rest and in steady rotation. The most persistent transient feature emerging is a sharply defined ringlike pattern characterized by a decrease in temperature and high azimuthal shear. The latter leads to formation of Kelvin-Helmholz vortices. Initially azimuthally regular, the pattern of these vortices loses its regularity and thus completes the transition to rotating convection state.
Date: October 1, 1997
Creator: Vorobieff, P. & Ecke, R.E.
Partner: UNT Libraries Government Documents Department

An experimental investigation of an air cooling scheme for the multichip modules of the multiplicity and vertex detector

Description: This report presents a summary of an experimental investigation of an electronics air cooling system for the multiplicity and vertex detector (MVD), a device used to determine and characterize the collision location of two accelerated heavy ions. Measurements of the flow rates of the cooling air and the temperatures of the air and electronic components were used to assess and optimize the performance of the proposed air cooling system, identify potential assembly problems and system limitations, and provide the necessary information for designing and sizing the final MVD cooling system components.
Date: July 1, 1997
Creator: Bernardin, J.D.; Bosze, E.; Boissevain, J. & Simon-Gillo, J.
Partner: UNT Libraries Government Documents Department

Design of an Ogive-Shaped Beamstop

Description: This paper addresses the evolution, design, and development of a novel approach for stopping cw (continuous-wave), non-rastered proton beams. Capturing the beam in vacuo within a long, axisymmetric surface of revolution has the advantages of spreading the deposited energy over a large area while minimizing prompt neutron backstreaming and reducing shield size and mass. Evolving from a cylinder/cone concept, the ogive shape avoids abrupt changes in geometry that produce sharp thermal transitions, allowing the beam energy to be deposited gracefully along its surface. Thermal management at modest temperature levels is provided with a simple, one-pass countercurrent forced-convection water passage outside the ogive. Hydrophone boiling sensors provide overtemperature protection. The concept has been demonstrated under beam conditions in the CRITS (Chalk River Injector Test Stand) facility.
Date: August 23, 1998
Creator: Van Hagan, T.H.; Doll, D.W.; Schneider, J.D. & Spinos, F.R.
Partner: UNT Libraries Government Documents Department

Design predictions and diagnostic test methods for hydronic heating systems in ASHRAE standard 152P

Description: A new method of test for residential thermal distribution efficiency is currently being developed under the auspices of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). The initial version of this test method is expected to have two main approaches, or ``pathways,`` designated Design and Diagnostic. The Design Pathway will use builder`s information to predict thermal distribution efficiency in new construction. The Diagnostic Pathway will use simple tests to evaluate thermal distribution efficiency in a completed house. Both forced-air and hydronic systems are included in the test method. This report describes an approach to predicting and measuring thermal distribution efficiency for residential hydronic heating systems for use in the Design and Diagnostic Pathways of the test method. As written, it is designed for single-loop systems with any type of passive radiation/convection (baseboard or radiators). Multiloop capability may be added later.
Date: April 1, 1996
Creator: Andrews, J.W.
Partner: UNT Libraries Government Documents Department

Mixed Convection Heat Transfer Experiments in Smooth and Rough Verticla Tubes

Description: The mixed convection regime is a transitional heat transfer regime between forced convection and natural convection, where both the forced component of flow, and the buoyancy induced component are important. Aiding flow is when buoyancy forces act in the same direction as the forced flow (heated upflow or cooled downflow), while opposing flow is when the buoyancy force is in the opposite direction of the forced flow (cooled upflow or heated downflow). For opposing flow the buoyancy always increases the rate of heat transfer over the forced convection value. For aiding flow, as the heat flux increased, a reduction in heat transfer is encountered until a condition known as laminarization occurs, where the heat transfer is at a minimum value. Further increases in the wall heat flux causes re-transition to turbulence, and increased heat transfer. In this paper, for the first time, experiments were performed to characterize the effect of surface roughness on heat transfer in mixed convection, for the case of aiding flow. A correlation was developed to allow calculation of mixed convection heat transfer coefficients for rough or smooth tubes.
Date: December 22, 2004
Creator: Symolon, P; Neuhaus, W & Odell, R
Partner: UNT Libraries Government Documents Department

Measurement of the exterior convective film coefficient for windows in low-rise buildings

Description: The MoWiTT field facility is used to measure the convective film coefficient over the exterior surface of a window. The MoWiTT-measured data is compared to some commonly-used experimental and theoretical models. The comparison shows that the MoWiTT data disagrees with the previously used models such as the ASHRAE/DOE-2 model. The reasons for these disagreements are discussed. An experimental model, based on the MoWiTT data, is presented to correlate the film coefficient with the difference in temperatures of the exterior glass surface and the ambient, in the natural convection region, and with the site wind speed, in the forced convection region. The wind speed is considered both in windward and leeward hemispheres. The validity of the MoWiTT model for low-rise buildings is then discussed.
Date: October 1, 1993
Creator: Yazdanian, M. & Klems, J. H.
Partner: UNT Libraries Government Documents Department


Description: Industrial processes use mechanical draft cooling towers (MDCT's) to dissipate waste heat by transferring heat from water to air via evaporative cooling, which causes air humidification. The Savannah River Site (SRS) has cross-flow and counter-current MDCT's consisting of four independent compartments called cells. Each cell has its own fan to help maximize heat transfer between ambient air and circulated water. The primary objective of the work is to simulate the cooling tower performance for the counter-current cooling tower and to conduct a parametric study under different fan speeds and ambient air conditions. The Savannah River National Laboratory (SRNL) developed a computational fluid dynamics (CFD) model and performed the benchmarking analysis against the integral measurement results to accomplish the objective. The model uses three-dimensional steady-state momentum, continuity equations, air-vapor species balance equation, and two-equation turbulence as the basic governing equations. It was assumed that vapor phase is always transported by the continuous air phase with no slip velocity. In this case, water droplet component was considered as discrete phase for the interfacial heat and mass transfer via Lagrangian approach. Thus, the air-vapor mixture model with discrete water droplet phase is used for the analysis. A series of parametric calculations was performed to investigate the impact of wind speeds and ambient conditions on the thermal performance of the cooling tower when fans were operating and when they were turned off. The model was also benchmarked against the literature data and the SRS integral test results for key parameters such as air temperature and humidity at the tower exit and water temperature for given ambient conditions. Detailed results will be published here.
Date: February 10, 2009
Creator: Lee, S; Alfred Garrett, A; James02 Bollinger, J & Larry Koffman, L
Partner: UNT Libraries Government Documents Department

Design of LCCBM and LCCBN Loops

Description: The special fabrication requirements of the newer columbium alloys, particularly with respect to brazing, stress relieving, weld filler wire, etc., necessitates individual detail and layout drawings for the construction of forced convection corrosion loops from different columbium alloys. Accordingly, it is requested that detail and layout drawings be provided for two forced convection corrosion loops to the specifications outlined.
Date: March 1, 1960
Creator: Coyle, C.E.
Partner: UNT Libraries Government Documents Department

Single phase channel flow forced convection heat transfer

Description: A review of the current knowledge of single phase forced convection channel flow of liquids (Pr > 5) is presented. Two basic channel geometries are considered, the circular tube and the rectangular duct. Both laminar flow and turbulent flow are covered. The review begins with a brief overview of the heat transfer behavior of Newtonian fluids followed by a more detailed presentation of the behavior of purely viscous and viscoelastic Non-Newtonian fluids. Recent developments dealing with aqueous solutions of high molecular weight polymers and aqueous solutions of surfactants are discussed. The review concludes by citing a number of challenging research opportunities.
Date: April 1, 1999
Creator: Hartnett, J.P.
Partner: UNT Libraries Government Documents Department

Mechanistic modeling of CHF in forced-convection subcooled boiling

Description: Because of the complexity of phenomena governing boiling heat transfer, the approach to solve practical problems has traditionally been based on experimental correlations rather than mechanistic models. The recent progress in computational fluid dynamics (CFD), combined with improved experimental techniques in two-phase flow and heat transfer, makes the use of rigorous physically-based models a realistic alternative to the current simplistic phenomenological approach. The objective of this paper is to present a new CFD model for critical heat flux (CHF) in low quality (in particular, in subcooled boiling) forced-convection flows in heated channels.
Date: May 1, 1997
Creator: Podowski, M.Z.; Alajbegovic, A.; Kurul, N.; Drew, D.A. & Lahey, R.T. Jr.
Partner: UNT Libraries Government Documents Department

Application of a new time scale based low {kappa}-{var_epsilon} model to natural convection from a semi-infinite vertical isothermal plate

Description: The low {kappa}-{var_epsilon} model proposed by Yang and Shih (1992) is applied to the calculation of the turbulent natural convective boundary layer over a semi-infinite, vertical, isothermal surface. Using {kappa}/{var_epsilon} as the turbulent time scale will introduce a singularity in the {var_epsilon} equation, near the wall. This model uses a modified turbulent time scale near the wall to eliminate this singularity. The constants in the equation for damping function are modified to produce better results for both, natural convection and force convection. The results are compared with available experimental data and the results obtained from Chien`s model and are found to be in reasonable agreement. Here {kappa} represents the turbulent kinetic energy and {var_epsilon} represents the dissipation rate of turbulent kinetic energy.
Date: January 1, 1999
Creator: Woods, A. L.; Senthooran, S. & Parameswaran, S.
Partner: UNT Libraries Government Documents Department


Description: Forced-convection heat transfer to superheated steam in turbulent flow was experimentally investigated, utilizing two-channel geometries: a round tube, 0.333-in. ID by 12.00 in., and a thin rectangular channel, 0.047-in. wide, aspect ratio, 26.6: 1, and 12.00 in. in length. The experiments encompassed a Reynolds number range from 20,000 to 370,000, pressure range from 300 to 1500 psia, inlet superheat from 5 to 160 deg F, and film temperature differences from 30 to 550 deg F. (W.L.H.)
Date: September 1, 1960
Creator: Heineman, J.B.
Partner: UNT Libraries Government Documents Department