scholarly journals Discussion: “Developing Flow with Combined Forced–Free Convection in an Isothermal Vertical Tube” (Zeldin, B., and Schmidt, F. W., 1972, ASME J. Heat Transfer, 94, pp. 211–221)

1972 ◽  
Vol 94 (2) ◽  
pp. 221-221
Author(s):  
Stuart W. Churchill
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Vertical Tube ◽  
Developing Flow

Free Convection, Forced Convection, and Acoustic Vibrations in a Constant Temperature Vertical Tube

1959 ◽  
Vol 81 (1) ◽  
pp. 68-74 ◽  
Author(s):  
T. W. Jackson ◽  
W. B. Harrison ◽  
W. C. Boteler
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Sound Pressure ◽  
Experimental Studies ◽  
Experimental System ◽  
Vertical Tube ◽  
Acoustic Vibrations ◽  
Average Temperature ◽  
Comparison Of The Results ◽  
The Heat Transfer Coefficient

Experimental studies of heat transfer to air with superposed forced and free convection were reported in a previous paper [1]. In studies reported in this paper, the same experimental system was employed, but a complication was added in the form of acoustic vibrations in the flow field. By comparison of the results with and without acoustic vibrations under conditions which were otherwise the same, an effort has been made to determine the effect of acoustic vibrations on heat transfer. The Nusselt modulus, based on the log mean temperature difference, ranged from 17.2 to 50.6; the Graetz modulus, based on the bulk or average temperature of the air, ranged from 40.2 to 1633; and the Grashof-Prandtl D/L modulus, based on properties of air at the wall temperature, ranged from 0.967 × 105 to 1.26 × 106. The results indicated that sound pressure levels below approximately 118 decibels had little effect on the heat-transfer coefficient. Below 118 decibels free convection forces were evident. Above 118 decibels free convection forces were apparently negligible and the effect of sound appeared to be considerable.

Developing Flow with Combined Forced–Free Convection in an Isothermal Vertical Tube

1972 ◽  
Vol 94 (2) ◽  
pp. 211-221 ◽  
Author(s):  
B. Zeldin ◽  
F. W. Schmidt
Keyword(s):  
Numerical Analysis ◽  
Free Convection ◽  
Velocity Profiles ◽  
Vertical Tube ◽  
Test Fluid ◽  
Nusselt Numbers ◽  
Numerical Predictions ◽  
Test Conditions ◽  
Developing Flow ◽  
Entrance Velocity

The influence of gravity on developing forced, laminar flow in a vertical isothermal tube was investigated by means of a numerical analysis and an associated experiment. Numerically predicted velocity profiles and Nusselt numbers for combined forced–free convection with Gr/Re = −30 are compared with their counterparts for pure forced convection, Gr/Re = 0, for air with Re = 500. The analysis was performed for both the uniform irrotational and the fully developed velocity entrance models. Velocity profiles were measured in a vertical-tube apparatus designed to provide an approximately uniform entrance velocity using air as the test fluid. These are compared with numerical predictions based on test conditions.

The study of heat transfer coefficient while flow unsaturated liquid through the tube at pressure below critical

2020 ◽  
Vol 34 (27) ◽  
pp. 2050299
Author(s):  
J. R. Mammadova ◽  
A. P. Abdullayev ◽  
R. M. Rzayev ◽  
S. H. Mammadova ◽  
R. A. Sultanov
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Free Convection ◽  
Transfer Coefficient ◽  
Temperature Regime ◽  
Vertical Tube ◽  
Criterion Equation

This work studies the temperature regime of the wall while up and down moving of the unsaturated liquid in the vertical tube at pressure below critical and influence of free convection on the heat transfer. The boundary of influence free convection on heat transfer is determined and summarized as a criterion equation.

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