Correlations for Laminar Forced Convection with Uniform Heating in Flow over a Plate and in Developing and Fully Developed Flow in a Tube

1973 ◽  
Vol 95 (1) ◽  
pp. 78-84 ◽  
Author(s):  
S. W. Churchill ◽  
H. Ozoe
Keyword(s):  
Experimental Data ◽  
Flat Plate ◽  
Numerical Solutions ◽  
Plug Flow ◽  
Uniform Heating ◽  
Simple Correlation ◽  
Fully Developed Flow ◽  
Heated Tube ◽  
Developing Flow ◽  
Laminar Forced Convection

Asymptotic solutions for Pr → 0 and Pr → ∞ and numerical solutions for intermediate Pr were obtained for a uniformly heated flat plate. The method of Churchill and Usagi was utilized to construct a simple correlation for these values. The same method was used to develop simple correlations for plug flow and fully developed flow in a uniformly heated tube. These correlations were in turn combined to develop correlations for the available experimental data and computed values for developing flow in a uniformly heated tube. Derivations and test calculations in which convection normal to the wall was neglected reveal that this error is significant but insufficient to explain all of the discrepancies in the computed values.

Jet-to-Plate Distance Effect on Heat Transfer From a Flat Plate to an Impinging Jet at Various Reynolds Numbers

2012 ◽  
Author(s):  
Patricia Streufert ◽  
Terry X. Yan ◽  
Mahdi G. Baygloo
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Reynolds Number ◽  
Flat Plate ◽  
Numerical Solutions ◽  
Stokes Equations ◽  
Local Heat Transfer ◽  
Reynolds Numbers ◽  
Air Jet ◽  
Plate Distance

Local turbulent convective heat transfer from a flat plate to a circular impinging air jet is numerically investigated. The jet-to-plate distance (L/D) effect on local heat transfer is the main focus of this study. The eddy viscosity V2F turbulence model is used with a nonuniform structured mesh. Reynolds-Averaged Navier-Stokes equations (RANS) and the energy equation are solved for axisymmetric, three-dimensional flow. The numerical solutions obtained are compared with published experimental data. Four jet-to-plate distances, (L/D = 2, 4, 6 and 10) and seven Reynolds numbers (Re = 7,000, 15,000, 23,000, 50,000, 70,000, 100,000 and 120,000) were parametrically studied. Local and average heat transfer results are analyzed and correlated with Reynolds number and the jet-to-plate distance. Results show that the numerical solutions matched experimental data best at low jet-to-plate distances and lower Reynolds numbers, decreasing in ability to accurately predict the heat transfer as jet-to-plate distance and Reynolds number was increased.

scholarly journals Simulation of olive pits pyrolysis in a rotary kiln plant

2011 ◽  
Vol 15 (1) ◽  
pp. 145-158 ◽  
Author(s):  
Enzo Benanti ◽  
Cesare Freda ◽  
Vincenzo Lorefice ◽  
Giacobbe Braccio ◽  
Vinod Sharma
Keyword(s):  
Experimental Data ◽  
Temperature Profile ◽  
Rotary Kiln ◽  
Southern Italy ◽  
Flow Reactor ◽  
Plug Flow ◽  
Sensitivity Analyses ◽  
Pyrolysis Process ◽  
Simulation Results ◽  
Main Component

This work deals with the simulation of an olive pits fed rotary kiln pyrolysis plant installed in Southern Italy. The pyrolysis process was simulated by commercial software CHEMCAD. The main component of the plant, the pyrolyzer, was modelled by a Plug Flow Reactor in accordance to the kinetic laws. Products distribution and the temperature profile was calculated along reactor's axis. Simulation results have been found to fit well the experimental data of pyrolysis. Moreover, sensitivity analyses were executed to investigate the effect of biomass moisture on the pyrolysis process.

Experimental Investigation of Heat Transfer in Impingement Air Cooled Plate Fin Heat Sinks

2005 ◽  
Vol 128 (4) ◽  
pp. 412-418 ◽  
Author(s):  
Zhipeng Duan ◽  
Y. S. Muzychka
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Thermal Resistance ◽  
Thermal Performance ◽  
Heat Transfer Model ◽  
Heat Sinks ◽  
Transfer Model ◽  
Transfer Coefficients ◽  
Developing Flow ◽  
Rectangular Channels

Impingement cooling of plate fin heat sinks is examined. Experimental measurements of thermal performance were performed with four heat sinks of various impingement inlet widths, fin spacings, fin heights, and airflow velocities. The percent uncertainty in the measured thermal resistance was a maximum of 2.6% in the validation tests. Using a simple thermal resistance model based on developing laminar flow in rectangular channels, the actual mean heat transfer coefficients are obtained in order to develop a simple heat transfer model for the impingement plate fin heat sink system. The experimental results are combined into a dimensionless correlation for channel average Nusselt number Nu∼f(L*,Pr). We use a dimensionless thermal developing flow length, L*=(L∕2)∕(DhRePr), as the independent parameter. Results show that Nu∼1∕L*, similar to developing flow in parallel channels. The heat transfer model covers the practical operating range of most heat sinks, 0.01<L*<0.18. The accuracy of the heat transfer model was found to be within 11% of the experimental data taken on four heat sinks and other experimental data from the published literature at channel Reynolds numbers less than 1200. The proposed heat transfer model may be used to predict the thermal performance of impingement air cooled plate fin heat sinks for design purposes.

Oscillations of a moderately underexpanded choked jet impinging upon a flat plate

1996 ◽  
Vol 315 ◽  
pp. 267-291 ◽  
Author(s):  
Chih-Yu Kuo ◽  
Ann P. Dowling
Keyword(s):  
Experimental Data ◽  
Flat Plate ◽  
Pressure Ratio ◽  
Feedback Mechanism ◽  
Pressure Waves ◽  
Stagnation Flow ◽  
Stability Threshold ◽  
Shock Position ◽  
The Stability ◽  
Plate Distance

The oscillation of a moderately underexpanded choked jet impinging upon a flat plate is investigated both analytically and numerically. The feedback mechanism between oscillations of the standoff-shock and the plate is clarified. Pressure waves produced by the motion of the shock are reflected by the plate. In addition, oscillations in the shock position lead to downstream entropy fluctuations, which generate pressure waves as they are convected through the stagnation flow near the plate. A linear stability analysis is used to investigate the stability threshold and frequencies of oscillation, as a function of jet pressure ratio and nozzle-to-plate distance. The analytical predictions are compared to results from a numerical simulation and to the experimental data of Powell (1988) and Mørch (1963, 1964).

Recycling and Extraction of Zinc Ions in Disc-Donut Column Considering Forward Mixing Mass Transfer, Chemical Reaction and Effects of Pulsed and non-Pulsed Condition

2021 ◽  
Author(s):  
Mehdi Asadollahzadeh ◽  
Rezvan Torkaman ◽  
Meisam Torab-Mostaedi ◽  
Mojtaba Saremi
Keyword(s):  
Experimental Data ◽  
Mass Transfer ◽  
Flow Rate ◽  
Positive Impact ◽  
Plug Flow ◽  
Model Parameters ◽  
Zinc Ions ◽  
Zinc Extraction ◽  
Balance Equations ◽  
Transfer Rates

Abstract The current study focuses on the recovery of zinc ions by solvent extraction in the pulsed contactor. The Zn(II) ions from chloride solution were extracted into the organic phase containing D2EHPA extractant. The resulting data were characterized for the relative amount of (a) pulsed and no-pulsed condition; and (b) flow rate of both phases. Based on the mass balance equations for the column performance description, numerical computations of mass transfer in a disc-donut column were conducted and validated the experimental data for zinc extraction. Four different models, such as plug flow, backflow, axial dispersion, and forward mixing were evaluated in this study. The results showed that the intensification of the process with the pulsed condition increased and achieved higher mass transfer rates. The forward mixing model findings based on the curve fitting approach validated well with the experimental data. The results showed that an increase in pulsation intensity, as well as the phase flow rates, have a positive impact on the performance of the extractor, whereas the enhancement of flow rate led to the reduction of the described model parameters for adverse phase.

Phase transitions on partially contaminated surface under the influence of thermocapillary flow

2019 ◽  
Vol 877 ◽  
pp. 495-533 ◽  
Author(s):  
A. V. Shmyrov ◽  
A. I. Mizev ◽  
V. A. Demin ◽  
M. I. Petukhov ◽  
D. A. Bratsun
Keyword(s):  
Experimental Data ◽  
Numerical Solutions ◽  
Thermocapillary Flow ◽  
Creeping Flow ◽  
Stagnant Zone ◽  
Surface Velocity ◽  
Condensed State ◽  
Flow Forming ◽  
Perfect Agreement ◽  
Linear Temperature

We study, both experimentally and theoretically, the fluid flow driven by a thermocapillary effect applied to a partially contaminated interface in a two-dimensional slot of finite extent. The contamination is due to the presence of an insoluble surfactant which is convected by the flow forming a stagnant zone by the colder edge of the interface. The thermocapillary surface stress is produced by a special optocapillary system, which makes it possible, first, to get an almost linear temperature profile along the interface and, second, to apply a surface pressure large enough to force the surfactant to experience a phase transition to a more condensed state. This enabled us for the first time since the release of the paper by Carpenter & Homsy (J. Fluid Mech., vol. 155, 1985, pp. 429–439) to test experimentally their theoretical predictions and obtain new results for the case when the contamination exists simultaneously in two phase states within the interface. We show that one part of the surface is free of surfactant and subject to vigorous thermocapillary flow, while another part is stagnant and subject to creeping flow with a surface velocity which is approximately two orders of magnitude smaller. We found that the extent of the stagnant zone theoretically predicted earlier does not coincide with the newly obtained experimental data. In this paper, we suggest analytical and numerical solutions for the position of the edge of the stagnation zone, which are in perfect agreement with the experimental data.

Thermal stability in a rotating spherical fluid shell with non-uniform heating

1977 ◽  
Vol 353 (1674) ◽  
pp. 349-362 ◽  
Keyword(s):  
Shear Flow ◽  
Numerical Solutions ◽  
Initial Conditions ◽  
Rapid Change ◽  
Polar Angle ◽  
Quiescent State ◽  
Uniform Heating ◽  
Thermally Induced ◽  
Spherical Fluid ◽  
Geophysical Flow

The theory is developed for the convective stability of a rotating spherical shell of fluid upon which is initially imposed a stable thermally induced shear flow. The fluid shell contains heating sources which are distributed proportional to the sine of the polar angle squared. Thus the analysis has a number of similarities to some geophysical flow situations. It is found that the properties of the solution are strongly dependent on the initial conditions. Thus to obtain further insight concerning the stability of the system numerical solutions are obtained a t two shell thicknesses. The critical values of the Taylor number ( T ) and the Rayleigh number ( C ) are generally similar to those found in previous studies of rotating fluid shells. How ever the effect of the initial shear flow is to reduce the critical value of C for a given T , below that found for uniform heating and an initially quiescent state. The flows obtained at the onset of instability are toroidal cells which vary in number dependent on T and C .A maximum of six cells are found at large values of T . A significant effect of the initial shear flow is the occurrence of a rapid change in stability when the number of toroidal cells changes.

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