On free convection experiments in inclined air layers heated from below

1980 ◽  
Vol 96 (3) ◽  
pp. 461-479 ◽  
Author(s):  
Douglas W. Ruth ◽  
K. G. T. Hollands ◽  
G. D. Raithby
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Convective Motion ◽  
Secondary Transition ◽  
Transfer Data ◽  
Experimental Heat ◽  
Experimental Heat Transfer ◽  
Air Layers ◽  
Rayleigh Numbers ◽  
Theory And Experiment

The heat transfer and free convective motion, in inclined air layers heated from below, for angles of incidence 0 [les ] ϕ [les ] 30°, and Rayleigh numbers 100 < Ra cos ϕ < 10000, are studied experimentally. Results of both heat-transfer measurements and flow-visualization studies are reported. The purpose of the study was to investigate the fact, first noted by Hollands et al. (1976), that the experimental heat-transfer data, for ϕ > 20°, is not a function of the product Ra cos ϕ only, as expected from theoretical consideration. This discrepancy between theory and experiment is here attributed to a hypothesized secondary transition in the convective motion, due primarily to perturbation velocities in the upslope direction. This secondary transition appears to be the same as that predicted theoretically by Clever & Busse (1977); qualitative agreement with their theory is observed.

Material design of a film cooling system using experimental heat transfer data

2012 ◽  
Vol 55 (21-22) ◽  
pp. 6278-6284 ◽  
Author(s):  
Kyung Min Kim ◽  
Jiwoon Song ◽  
Jun Su Park ◽  
Sanghoon Lee ◽  
Hyung Hee Cho
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Cooling System ◽  
Material Design ◽  
Transfer Data ◽  
Experimental Heat ◽  
Experimental Heat Transfer

Using Artificial Neural Networks to Develop a Predictive Method From Complex Experimental Heat Transfer Data

2001 ◽  
Author(s):  
Matthew D. Kelleher ◽  
Thomas J. Cronley ◽  
K. T. Yang ◽  
Mihir Sen
Keyword(s):  
Heat Transfer ◽  
Neural Networks ◽  
Artificial Neural Networks ◽  
Complex Situation ◽  
Transfer Data ◽  
Predictive Algorithm ◽  
Experimental Heat ◽  
Predictive Method ◽  
Experimental Heat Transfer ◽  
Artificial Neural

Abstract Artificial neural networks are employed to develop a predictive algorithm using experimental heat transfer data for a complex situation. The data of Marto and Anderson has used to illustrate the process. This data is from a series of experiments investigating the boiling heat transfer from a vertical bank of tubes in refrigerant 114 with variable amounts of oil present. Both finned and unfinned tubes were investigated. The network was trained with a partial set of the available data. The prediction obtained using the trained network was then compared to the remaining experimental data. The artificial neural network provided an excellent predictive method.

Laminar Combined Convection From a Rotating Cone

1963 ◽  
Vol 85 (1) ◽  
pp. 29-34 ◽  
Author(s):  
R. G. Hering ◽  
R. J. Grosh
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Free Convection ◽  
Numerical Solutions ◽  
Temperature Fields ◽  
Boundary Layer Equations ◽  
Experimental Heat ◽  
Experimental Heat Transfer ◽  
Cone Apex ◽  
Rotating Cone

The effect of free convection on heat transfer and on the flow field about a rotating cone is studied. A similar solution for the laminar boundary-layer equations is found to exist when the cone surface temperature varies linearly with distance from the cone apex. The transformed boundary-layer equations contain the important parameter Gr/Re2. This parameter determines the relative importance of the free convection motions on forced convection. Numerical solutions of the transformed equations for aiding flows have been carried out for Prandtl number 0.7 and different values of Gr/Re2. Results are reported for the heat transfer, shear stress, shaft moment, and velocity and temperature fields. Criteria are given for subdividing the regimes of flow as purely free, purely forced, and combined flow. Preliminary experimental heat-transfer results are reported which indicate the trends predicted by theory.

Condensation Heat Transfer Inside Multi-Port Minichannels

2004 ◽  
Author(s):  
A. Cavallini ◽  
D. Del Col ◽  
L. Doretti ◽  
M. Matkovic ◽  
L. Rossetto ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Research ◽  
Air Conditioning ◽  
Transfer Coefficients ◽  
Air Conditioners ◽  
Transfer Data ◽  
Heat Transfer Coefficients ◽  
Experimental Heat ◽  
Experimental Heat Transfer ◽  
Residential Air Conditioning

In this paper the experimental heat transfer coefficients measured during condensation of R134a and R410A inside multiport minichannels are presented. The need for experimental research on condensation inside multiport minichannels comes from the wide use of those channels in automotive air-conditioners. The perspective for the adoption of similar channels in the residential air conditioning applications also calls for experimental research on new high pressure refrigerants, such as R410A. Heat transfer data are compared against models to show the accuracy of the models in the prediction of heat transfer coefficients inside minichannels.

Laminar Natural Convection Heat Transfer in a Horizontal Cavity with Different End Temperatures

1978 ◽  
Vol 100 (4) ◽  
pp. 641-647 ◽  
Author(s):  
A. Bejan ◽  
C. L. Tien
Keyword(s):  
Heat Transfer ◽  
Convection Heat Transfer ◽  
Regime Theory ◽  
Heat Transfer Mechanism ◽  
Intermediate Regime ◽  
Experimental Heat ◽  
Experimental Heat Transfer ◽  
Horizontal Cavity ◽  
Laminar Natural Convection ◽  
Rayleigh Numbers

The heat transfer by free convection in a horizontal cavity with adiabatic horizontal walls and differentially heated end walls is studied analytically. The paper develops three models for explaining and predicting the heat transfer mechanism in a cavity with the height/length aspect ratio considerably smaller than one. The three models are: 1) the regime of vanishing Rayleigh numbers, 2) the intermediate regime, and 3) the boundary layer regime. The transition from one model to the next occurs as the Rayleigh number increases. The Nusselt number prediction based on the three-regime theory agrees very well with available numerical and experimental heat transfer data.

scholarly journals Heat Transfer to the Highly Accelerated Turbulent Boundary Layer With and Without Mass Addition

1970 ◽  
Vol 92 (3) ◽  
pp. 499-505 ◽  
Author(s):  
W. M. Kays ◽  
R. J. Moffat ◽  
W. H. Thielbahr
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Boundary Layers ◽  
Stanton Number ◽  
Temperature Profiles ◽  
Transfer Data ◽  
Experimental Heat ◽  
Prediction Scheme ◽  
Experimental Heat Transfer ◽  
Impermeable Wall

Experimental heat transfer data are presented for a series of asymptotic accelerated turbulent boundary layers for the case of an impermeable wall, and several cases of blowing, and suction. The data are presented as Stanton number versus enthalpy thickness Reynolds number. As noted by previous investigators, acceleration causes a depression in Stanton number when the wall is impermeable. Suction increases this effect, while blowing suppresses it. The combination of mild acceleration and strong blowing results in Stanton numbers which lie above the correlation for the same blowing but no acceleration. Velocity and temperature profiles are presented, from which it is possible to deduce explanations for the observed behavior of the Stanton number. A prediction scheme is proposed which is demonstrated to quite adequately reproduce the Stanton number results, using correlations derived from the profiles.

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