Heat Transfer to Supercritical Water in Smooth-Bore Tubes

1965 ◽  
Vol 87 (4) ◽  
pp. 477-483 ◽  
Author(s):  
H. S. Swenson ◽  
J. R. Carver ◽  
C. R. Kakarala
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Supercritical Water ◽  
Convection Heat Transfer ◽  
Physical Property ◽  
Transfer Coefficients ◽  
Property Variation ◽  
Wide Range ◽  
Fully Developed Turbulent Flow ◽  
Data Points

Local forced convection heat-transfer coefficients for supercritical water flowing inside smooth-bore tubes were obtained experimentally over a range of pressures (3300 to 6000 psia) and bulk temperatures (167 to 1068 F). Because the thermophysical properties of supercritical fluids change rapidly with temperature in the pseudocritical range, conventional forced convection correlations were unable to fit the data. However, a satisfactory correlation for fully developed turbulent flow was obtained by properly modifying the conventional nondimensional model to account for the physical property variation across the boundary layer. Out of 2951 data points, 95 percent lie within ±15 percent of the correlation. It was also found that the same equation correlated supercritical pressure heat-transfer data of carbon dioxide over a wide range of conditions with good accuracy.

Fluidization in Supercritical Water: Heat Transfer between Particle and Supercritical Water

2018 ◽  
Vol 16 (7) ◽  
Author(s):  
Liping Wei ◽  
Youjun Lu
Keyword(s):  
Heat Transfer ◽  
Fluidized Bed ◽  
Forced Convection ◽  
Supercritical Water ◽  
Particle Surface ◽  
Physical Property ◽  
Fluidized Bed Reactor ◽  
Constant Property ◽  
Property Variation ◽  
Thermal Physical Property

Abstract Supercritical water fluidized bed reactor, which is used to gasify biomass and produce hydrogen, is a new member of fluidized bed family. Forced convection heat transfer between supercritical water and particles is a major basic heat transfer mechanism in supercritical water fluidized bed reactor. The object of this paper was to determine the heat transfer characteristics for a forced convection between a spherical particle and supercritical water (SCW) in a range of pressure from 23 to 27 MPa and temperature from 637 to 697 K. A numerical model fully accounting for thermal physical property variation of SCW has been solved using a finite volume method with Reynolds number up to 200. Comparing with constant property flow, high velocity and temperature gradient in the vicinity of the particle surface were observed when the variable thermal physical property of SCW was incorporated in calculation. Based on the numerical results, a correlation that takes into account the large thermal physical property variation was proposed for predicting Nusselt number.

A Study of Forced Convection Direct Air Cooling in the Downstream Vicinity of Heat Sinks

1990 ◽  
Vol 112 (3) ◽  
pp. 234-240 ◽  
Author(s):  
G. L. Lehmann ◽  
S. J. Kosteva
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Heat Sink ◽  
Convection Heat Transfer ◽  
Heat Sinks ◽  
Air Cooling ◽  
Transfer Coefficients ◽  
Packaging System ◽  
Transfer Rates ◽  
Heat Transfer Coefficients

An experimental study of forced convection heat transfer is reported. Direct air cooling of an electronics packaging system is modeled by a channel flow, with an array of uniformly sized and spaced elements attached to one channel wall. The presence of a single or complete row of longitudinally finned heat sinks creates a modified flow pattern. Convective heat transfer rates at downstream positions are measured and compared to that of a plain array (no heat sinks). Heat transfer rates are described in terms of adiabatic heat transfer coefficients and thermal wake functions. Empirical correlations are presented for both variations in Reynolds number (5000 < Re < 20,000) and heat sink geometry. It is found that the presence of a heat sink can both enhance and degrade the heat transfer coefficient at downstream locations, depending on the relative position.

Heat Transfer for Forced Convection Past Coiled Wires

1990 ◽  
Vol 112 (4) ◽  
pp. 921-925 ◽  
Author(s):  
M. Dietrich ◽  
R. Blo¨chl ◽  
H. Mu¨ller-Steinhagen
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Measured Data ◽  
Subcooled Boiling ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Coil Geometry ◽  
Coil Diameter ◽  
Wide Range ◽  
Laminar And Turbulent Flow

Heat transfer coefficients were measured for forced convection of isobutanol in crossflow past coiled wires with different coil geometries. Flow rate and heat flux have been varied over a wide range to include laminar and turbulent flow for convective sensible and subcooled boiling heat transfer. To investigate the effect of coil geometry on heat transfer, the wire diameter, coil diameter, and coil pitch were varied systematically. The measured data are compared with the predictions of four correlations from the literature.

Effect of Buoyancy on Heat Transfer in Supercritical Water Flow in a Horizontal Round Tube

2005 ◽  
Vol 127 (8) ◽  
pp. 897-902 ◽  
Author(s):  
Majid Bazargan ◽  
Daniel Fraser ◽  
Vijay Chatoorgan
Keyword(s):  
Heat Transfer ◽  
Supercritical Water ◽  
Water Oxidation ◽  
Local Heat Transfer ◽  
Heat Fluxes ◽  
Supercritical Water Oxidation ◽  
Transfer Coefficients ◽  
Horizontal Pipe ◽  
Free Region ◽  
Wide Range

Heat transfer to supercritical water and buoyancy∕natural convection effects are becoming increasingly important areas of research due to current trends in nuclear reactor design and supercritical water oxidation facilities. A pilot-scale supercritical water oxidation loop was constructed at the University of British Columbia. For this work, the facility was used to study the relative importance of buoyancy effects on supercritical water flowing in a horizontal pipe. Local heat transfer coefficients at the top and bottom surfaces of the horizontal test section were systematically measured over a wide range of conditions at supercritical pressures between 23 to 27 MPa, uniform heat fluxes were up to 310kW∕m2, and the mass flux ranged from 330 to 1230kg∕m2s. It was found that neglecting buoyancy effects could cause large discrepancies between the predictions of available empirical correlations and the experimental data. The data was used to assess available criteria for the buoyancy-free region during horizontal supercritical fluid flows. The criterion of Petukhov and Polyakov, which, for the range of parameters in this study, was found to be accurate in predicting the onset of buoyancy effects. The experimental investigation is confined to supercritical flows with heat addition only. Hence, no heat loss conditions at supercritical temperatures were investigated.

Transient Forced Convection Heat Transfer to Helium During a Step in Heat Flux

1983 ◽  
Vol 105 (2) ◽  
pp. 350-357 ◽  
Author(s):  
P. J. Giarratano ◽  
W. G. Steward
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Forced Convection ◽  
Carbon Film ◽  
Convection Heat Transfer ◽  
Fast Response ◽  
Operating Conditions ◽  
Convection Heat ◽  
Transfer Coefficients ◽  
Forced Convection Heat Transfer

Transient forced convection heat transfer coefficients for both subcritical and supercritical helium in a rectangular flow channel heated on one side were measured during the application of a step in heat flux. Zero flow data were also obtained. The heater surface which served simultaneously as a thermometer was a fast response carbon film. Operating conditions covered the following range: Pressure, 1.0 × 105 Pa (1 bar) to 1.0 × 106 Pa (10 bar); Temperature, 4 K–10 K; Heat Flux, 0.1 W/cm2−10 W/cm2; Reynolds number, 0–8 × 105. The experimental data and a predictive correlation are presented.

Anomalous Enhancement of Heat Transfer to H2O/CO2 Mixtures in Near-Critical Region

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Hanlin Zhang ◽  
Haomin Wu ◽  
Sha Li ◽  
Dong Liu ◽  
Qiang Li
Keyword(s):  
Heat Transfer ◽  
Critical Point ◽  
Heat Transfer Enhancement ◽  
Convection Heat Transfer ◽  
High Mass ◽  
Transfer Enhancement ◽  
Transfer Coefficients ◽  
Property Variation ◽  
Mass Fractions ◽  
Efficient Heat Transfer

Abstract Heat transfer to supercritical H2O/CO2 mixtures (24 MPa, 310 to 430 °C, and CO2 mass fractions up to 18.5%), the working fluids of a novel power generation system with coal gasified in supercritical water, was experimentally investigated for typical working conditions of this system. For these conditions, i.e., high mass velocities (above 1200 kg m−2 s−1) and low heat flux (below 300 kW m−2), the convection heat transfer coefficients (HTCs) of supercritical pure fluids usually increase with temperature, peak near the pseudo-critical point, i.e., heat transfer enhancement, and then decrease for higher temperatures. Here, we experimentally demonstrated a new heat transfer enhancement phenomenon for supercritical H2O/CO2 mixtures. A high-temperature and high-pressure apparatus was setup to measure the convection HTCs of the supercritical H2O/CO2 mixtures. Experimental results show that surprisingly two distinct peaks of convection HTCs appear, with one corresponding temperature being the pseudo-critical point of the H2O/CO2 mixture, i.e., the thermophysical property variation induced mechanism, and the other one being the critical miscible point of the mixture, i.e., the dissolution-induced mechanism. These results pave the way to efficient heat transfer devices that use supercritical mixtures as heat transfer fluids.

Experimental Study of Forced Convection From Isothermal Circular and Square Cylinders and Toroids

1997 ◽  
Vol 119 (1) ◽  
pp. 70-79 ◽  
Author(s):  
G. Refai Ahmed ◽  
M. M. Yovanovich
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Forced Convection ◽  
Convection Heat Transfer ◽  
Reynolds Numbers ◽  
Empirical Models ◽  
Experimental Program ◽  
Convection Heat ◽  
Forced Convection Heat Transfer ◽  
Wide Range

Experimental studies of forced convection heat transfer from different body shapes were conducted to determine the effects of Reynolds number and different characteristic body lengths on the area-averaged Nusselt number. Although the bodies differed significantly in their shapes, they had approximately the same total surface area, A = 11,304 mm2 ± 5%. This ensured that for a given free stream velocity and total heat transfer rate all bodies had similar trends for the relationship of Nusselt and Reynolds numbers. The experimental program range was conducted in the Reynolds number range 104≤ReA≤105 and Prandtl number 0.71. Finally, the empirical models for forced convection heat transfer were developed. These empirical models were valid for a wide range of Reynolds numbers 0≤ReA≤105. The present experimental correlations were compared with available correlation equations and experimental data. These comparisons show very good agreement.

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