Effect of absorption of solar radiation in glass-cover(s) on heat transfer coefficients in upward heat flow in single and double glazed flat-plate collectors

2012 ◽  
Vol 55 (1-3) ◽  
pp. 125-132 ◽  
Author(s):  
Naiem Akhtar ◽  
S.C. Mullick
Keyword(s):  
Heat Transfer ◽  
Heat Flow ◽  
Solar Radiation ◽  
Flat Plate ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Glass Cover

Estimation of Heat-Transfer Coefficients, the Upward Heat Flow, and Evaporation in a Solar Still

1991 ◽  
Vol 113 (1) ◽  
pp. 36-41 ◽  
Author(s):  
V. B. Sharma ◽  
S. C. Mullick
Keyword(s):  
Heat Transfer ◽  
Heat Flow ◽  
Empirical Relation ◽  
Absolute Error ◽  
Solar Still ◽  
Transfer Coefficients ◽  
Maximum Absolute Error ◽  
Heat Transfer Coefficients ◽  
Glass Cover ◽  
The Heat Balance

The present work enables prediction of the performance of a solar still through simple calculations. Estimation of the temperature of the glass cover by an empirical relation developed in this work permits calculation of the heat-transfer coefficients, the upward heat flow, and evaporation. Since some of the heat-transfer coefficients vary substantially and nonlinearly with temperature, the empirical relation developed for glass cover temperature is based on an approximate solution of the heat balance equation. Hence, the overall upward heat flow factor is obtained with a maximum absolute error of three percent compared to the value obtained through a numerical solution of the heat balance equation along with the relations for vapor pressure and latent heat. The fraction of upward heat flow utilized for evaporation is determined with a maximum absolute error of 0.5 percent. The range of variables covered is 30°C to 80°C in water temperature, 5W/m2K to 40W/m2K in wind heat-transfer coefficient, and 5°C to 40°C in ambient temperature.

Heat Transfer and Pressure Distribution in Open Cavity Flow

1967 ◽  
Vol 89 (1) ◽  
pp. 103-108 ◽  
Author(s):  
A. F. Emery ◽  
J. A. Sadunas ◽  
M. Loll
Keyword(s):  
Heat Transfer ◽  
Pressure Distribution ◽  
Flat Plate ◽  
Cavity Flow ◽  
Rectangular Cavity ◽  
Open Cavity ◽  
Transfer Coefficients ◽  
Transient Techniques ◽  
Heat Transfer Coefficients ◽  
Mach 3

The heat transfer and pressure distribution in a rectangular cavity in a Mach 3 flow were investigated for a rectangular and an inverted-wedge recompression step. Noticeable differences between the results for the two steps were found in the recovery factors, but no real differences were detected in the heat-transfer coefficients or the velocity profiles. Heat-transfer coefficients in the cavity were determined by transient techniques and were found to range from 50 to 110 percent of the flat-plate value just prior to the expansion step.

scholarly journals Heat flow and heat transfer coefficient during crystallization under the pressure

2018 ◽  
Vol 157 ◽  
pp. 02036
Author(s):  
Richard Pastirčák ◽  
Ján Ščury ◽  
Tomáš Fecura
Keyword(s):  
Heat Transfer ◽  
Heat Flow ◽  
Solidification Process ◽  
Metal Mold ◽  
Transfer Coefficients ◽  
Microstructure Modeling ◽  
Heat Transfer Coefficients ◽  
Flow And Heat Transfer ◽  
Solidification Processes ◽  
Precise Prediction

Estimation of the heat flow at the metal-mold interface is necessary for accurate simulation of the solidification processes. For the numerical simulation, a precise prediction of boundary conditions is required to determine the temperature distribution during solidification, porosity nucleation, microstructure development, and residual stresses. Determination of the heat transfer coefficients at the metal-mold interface is a critical aspect for simulation of the solidification process and the microstructure modeling of the castings. For crystallization under the pressure and for thin-walled castings, HTC evaluation is important due to the very limited freezing time.

Heat Transfer Characteristics of Impinging Two-Dimensional Air Jets

1966 ◽  
Vol 88 (1) ◽  
pp. 101-107 ◽  
Author(s):  
Robert Gardon ◽  
J. Cahit Akfirat
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Two Dimensional ◽  
Heat Transfer Characteristics ◽  
Transfer Coefficients ◽  
Average Heat ◽  
Heat Transfer Coefficients ◽  
Transfer Characteristics ◽  
Air Jets

Local as well as average heat transfer coefficients between an isothermal flat plate and impinging two-dimensional jets were measured for both single jets and arrays of jets. For a large and technologically important range of variables the results have been correlated in relatively simple terms, and their application to design is briefly considered.

Angular Dependency on Film Boiling Heat Transfer From Relatively Long Inclined Flat Plates

2013 ◽  
Vol 135 (12) ◽  
Author(s):  
Chan Soo Kim ◽  
Kune Y. Suh
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Boiling Heat Transfer ◽  
Flow Direction ◽  
Film Boiling ◽  
Transfer Coefficients ◽  
Flat Plates ◽  
Heat Transfer Coefficients ◽  
Inclination Angles ◽  
Angular Dependency

The effect of inclination angle of the downward facing flat plate on the interfacial wavy motion is investigated utilizing the water quenching test apparatus downward ebullient laminar transition apparatus flat surface (DELTA-FS) in a quasi-steady state. Film boiling heat transfer coefficients are obtained on the relatively long surface in the flow direction. Interfacial velocities at the various inclination angles and wall superheat conditions are determined through the analysis of the visualized continuous snapshots with 1000 fps. Visualization of the vapor film reveals that the interfacial wavelength increases and the interfacial velocity decreases as the flat plate moves from the vertical to downward facing locations. A new semi-empirical correlation is developed from the measured heat transfer coefficients and interfacial velocities. The correlation shows good agreement with the previous water test results on vertical plates. In the case of the previous other fluid experimental results on the vertical plates, the correlation overpredicts the film boiling heat transfer coefficients at the experimental condition.

Temperature Distributions in Laminar Flat Plate Shear Flow

1968 ◽  
Vol 90 (1) ◽  
pp. 32-36 ◽  
Author(s):  
A. F. Emery ◽  
K. F. Brettman
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Transfer Coefficients ◽  
Shearing Flow ◽  
Heat Transfer Coefficients ◽  
Temperature Distributions ◽  
High Shearing ◽  
The Heat Transfer Coefficient

An approximate solution to the heat transfer coefficient on a flat plate in a linear shearing flow is given. It is shown that high shearing rates may significantly increase the local heat transfer coefficients.

Short Duration Heat Transfer Studies at High Free-Stream Temperatures

1982 ◽  
Author(s):  
D. M. Kercher ◽  
R. E. Sheer ◽  
R. M. C. So
Keyword(s):  
Heat Transfer ◽  
Shock Tube ◽  
Flat Plate ◽  
Short Duration ◽  
Free Stream ◽  
Convex Surface ◽  
Surface Heat ◽  
Shock Tunnel ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

This paper describes short duration heat transfer measurements on a flat plate and a gas turbine nozzle airfoil at high free-stream temperatures. A shock tube generated the high temperature and pressure air flow. Thin-film heat gages recorded the surface heat flux. The flat plate was tested both in the shock tube and in a shock tunnel placed aft of the tube. Shock tunnel tests on the nozzle airfoil measured the local heat transfer distribution. The flat plate free-stream temperatures varied from 830 °R (460 K) to 3190 °R (1770 K) for a Tw/TT,g temperature ratio of 0.17 to 0.64 at Mach numbers from 0.12 to 1.34. The nozzle measurements at a Tw/TT,g of 0.35 to 0.39 generally indicate that pressure (concave) surface heat transfer coefficients are high, whereas the suction (convex) surface shows much lower heat transfer coefficients than a turbulent flat plate correlation.

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