الفهرس 
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Abstract
The objective of the present work is to investigate experimentally the forced convection heat transfer and pressure DROP characteristics of air flow inside a horizontal semi-circular tube. The experiments are carried out on a semi-circular tube (test section) of 23 mm inner radius, 2 mm thickness and 2000 mm length. The thermal boundary condition imposed on the semi-circular tube is a uniform heat flux rate both axially and peripherally. The required amount of heat is generated around the walls of the test section by an electric heater wire wound carefully around the circumference of the semi-circular tube with a constant pitch. The heat generated from the heater is controlled by a voltage regulator (Variac). A uniform flow of air with low turbulence level is drawn in the test section. The flow rate is controlled by a variable area gate mounted at the outlet of the experimental set-up and it is measured by a calibrated orifice-mater .Temperature measurements are made using calibrated thermocouples and digital thermometer. The friction factor is determined by measuring the axial static pressure at different selected axial stations and the resulting experimental data are converted into friction factor via the definition of Darcy friction factor. The pressure measurements are made using liquid manometers specially designed and constructed for this investigation. A preliminary series of experiments are carried out under identical conditions to check the validity of the present experimental set-up and the measuring instruments. The dependence of the heat transfer coefficient and friction factor on Reynolds number has been investigated by carrying out the experimental runs for a wide range of Reynolds number (8242-v Re –v 57794). The obtained experimental data have been presented in charts and tabular from which show the variations of surface and mean air temperatures, local heat transfer coefficient, local Nusselt number, and the friction factor with the axial dimensionless distance. The effect of Reynolds number on both the heat transfer and the friction factor is also presented and discussed.
Empirical correlations for the heat transfer coefficient and friction factor as a function of the Reynolds number are obtained and compared with previous research where good agreement was found.
The objective of the present work is to investigate experimentally the forced convection heat transfer and pressure DROP characteristics of air flow inside a horizontal semi-circular tube. The experiments are carried out on a semi-circular tube (test section) of 23 mm inner radius, 2 mm thickness and 2000 mm length. The thermal boundary condition imposed on the semi-circular tube is a uniform heat flux rate both axially and peripherally. The required amount of heat is generated around the walls of the test section by an electric heater wire wound carefully around the circumference of the semi-circular tube with a constant pitch. The heat generated from the heater is controlled by a voltage regulator (Variac). A uniform flow of air with low turbulence level is drawn in the test section. The flow rate is controlled by a variable area gate mounted at the outlet of the experimental set-up and it is measured by a calibrated orifice-mater .Temperature measurements are made using calibrated thermocouples and digital thermometer. The friction factor is determined by measuring the axial static pressure at different selected axial stations and the resulting experimental data are converted into friction factor via the definition of Darcy friction factor. The pressure measurements are made using liquid manometers specially designed and constructed for this investigation. A preliminary series of experiments are carried out under identical conditions to check the validity of the present experimental set-up and the measuring instruments. The dependence of the heat transfer coefficient and friction factor on Reynolds number has been investigated by carrying out the experimental runs for a wide range of Reynolds number (8242-v Re –v 57794). The obtained experimental data have been presented in charts and tabular from which show the variations of surface and mean air temperatures, local heat transfer coefficient, local Nusselt number, and the friction factor with the axial dimensionless distance. The effect of Reynolds number on both the heat transfer and the friction factor is also presented and discussed.
Empirical correlations for the heat transfer coefficient and friction factor as a function of the Reynolds number are obtained and compared with previous research where good agreement was found.
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