Frost Formation on Vertical Cylinders in Free Convection

1982 ◽  
Vol 104 (1) ◽  
pp. 3-7 ◽  
Author(s):  
C. J. Cremers ◽  
V. K. Mehra
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Growth Rates ◽  
Convective Flow ◽  
Vertical Cylinder ◽  
Free Convective Flow ◽  
Frost Formation ◽  
Vertical Cylinders ◽  
Frost Growth

Frost growth on a cooled vertical cylinder in free convective flow was studied experimentally. A correlation that is based on heat transfer considerations was found to be effective in predicting frost growth rates particularly at relative humidities equal to or greater than 65 percent and growing times equal to or greater than 60 min.

scholarly journals Влияние периодической макрошероховатости на развитие турбулентной свободной конвекции у внезапно нагреваемой вертикальной пластины

2022 ◽  
Vol 48 (3) ◽  
pp. 47
Author(s):  
А.М. Левченя ◽  
Е.М. Смирнов ◽  
С.Н. Трунова
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Free Convection ◽  
Convective Flow ◽  
Heated Plate ◽  
Checkerboard Pattern ◽  
Free Convective Flow ◽  
Differential Model ◽  
Significant Intensification ◽  
Range Of Variation

The results of numerical simulation of unsteady free convection developing near a suddenly heated plate, on which protrusions in the form of adiabatic cylinders of double height with respect to the diameter are arranged in a checkerboard pattern, are presented. The calculations were performed according to the Reynolds equations using a differential model of turbulent stresses. The range of variation of the Grashof number (plotted according to the thickness of the free convective flow), in which a significant intensification of heat transfer can be achieved, has been determined. It is shown that the best conditions for intensification are created if the longitudinal pitch in the array of protrusions is approximately twenty times the diameter of the latter.

Transient Free Convective Flow of CNT Water Nanofluid with Heat Transfer from a Moving Cylinder

2020 ◽  
Vol 10 ◽  
Author(s):  
C. Sridevi ◽  
A. Sailakumari
Keyword(s):  
Carbon Nanotubes ◽  
Heat Generation ◽  
Convective Flow ◽  
Volume Fraction ◽  
Vertical Cylinder ◽  
Single Wall Carbon Nanotubes ◽  
Free Convective Flow ◽  
Multi Wall Carbon Nanotubes ◽  
Moving Cylinder ◽  
Variable Surface

Background: In this paper, transient two-dimensional laminar boundary layer viscous incompressible free convective flow of water based nanofluid with carbon nanotubes (CNTs) past a moving vertical cylinder with variable surface temperature is studied numerically in the presence of thermal radiation and heat generation. Methods: The prevailing partial differential equations which model the flow with initial and boundary conditions are solved by implicit finite difference method of Crank Nicolson type which is unconditionally stable and convergent. Results: Influence of Grashof number (Gr), nanoparticle volume fraction ( ), heat generation parameter (Q), temperature exponent (m), radiation parameter (N) and time (t) on velocity and temperature profiles are sketched graphically and elaborated comprehensively. Conclusion: Analysis of Nusselt number and Skin friction coefficient are also discussed numerically for both single wall carbon nanotubes (SWCNTs) and multi wall carbon nanotubes (MWCNTs).

scholarly journals Free convection flow of power law fluid in a vertical cylinder of finite height

1995 ◽  
Vol 17 (2) ◽  
pp. 34-39
Author(s):  
Nguyen Van Que
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Power Law ◽  
Average Velocity ◽  
Vertical Cylinder ◽  
Convection Flow ◽  
Power Law Fluid ◽  
Free Convection Flow ◽  
Finite Height ◽  
Good Agreement

A numerical solution has been presented for free convection flow of power law fluid in a vertical cylinder of finite height. The average velocity along the channel and the heat transfer have been calculated. Graphs of velocities and temperature are shown. The results show good agreement with analytic one in the asymptotic case.

Study on Properties and Growth Rate of Frost Layers on Cold Surfaces

1983 ◽  
Vol 105 (4) ◽  
pp. 895-901 ◽  
Author(s):  
I. Tokura ◽  
H. Saito ◽  
K. Kishinami
Keyword(s):  
Experimental Study ◽  
Growth Rate ◽  
Growth Rates ◽  
Formation Process ◽  
Convective Flow ◽  
Vertical Plate ◽  
Growth Data ◽  
Free Convective Flow ◽  
Dimensionless Parameters ◽  
Frost Layer

An experimental study was carried out on the properties and growth rate of the frost layer which developed on a cooled vertical plate in free convective flow. Dimensionless parameters introduced by dimensional analysis were found to be effective in predicting frost densities, its thermal conductivities and growth rates. It was also found that the frost formation process can be divided into two periods if the frost growth data are correlated with the dimensionless parameters presented.

The Effect of Longitudinal Oscillations on Free Convection From Vertical Surfaces

1965 ◽  
Vol 32 (1) ◽  
pp. 183-191 ◽  
Author(s):  
Siavash Eshghy ◽  
V. S. Arpaci ◽  
J. A. Clark
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Shear Stress ◽  
Steady State ◽  
Free Convection ◽  
Classical Problem ◽  
Vertical Cylinder ◽  
Convection Flow ◽  
Fluid Temperature ◽  
Average Coefficient

The free-convection flow along a vertical plate oscillating in its own plane is given analytical treatment. The basic equations of boundary-layer flow and heat transfer are linearized and the first three approximations are considered. The first approximation, being the case of steady-state free convection, is the classical problem of Schmidt and Beckman extended by Ostrach. The second approximation is the frequency response of the fluid temperature and velocity for which limiting solutions are obtained in two regions; namely, the regions of small and large ω* = ωδ2/ν where ω is the circular frequency, δ the steady-state velocity boundary-layer thickness, and ν the fluid kinematic viscosity. The approximate range of validity of the asymptotic solution is estimated in terms of parameter ω0* which is a function only of Prandtl number. Part of the third approximation is time independent and gives rise to a net change in the steady values of the wall heat flux and shear stress. It is found that within the domain of laminar flow this net change is a decrease for the rate of heat transfer and an increase for the shear stress both evaluated for large values of ω0*. Heat-transfer measurements are made for a vertical cylinder in air. It is found that in the laminar regime the average coefficient of heat transfer experiences a slight decrease relative to its measured steady state value. For higher values of oscillatory velocity amplitude the average coefficient of heat transfer undergoes an increase over its measured steady-state value. This reversal in the behavior of average coefficient of heat transfer appears to be due to flow transition which is confirmed by smoke studies along a vertical cylinder.

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