Temperature profiles and fluctuations in combined free- and forced-convection flows

Brown, C. K.; Gauvin, W. H.

doi:10.1016/0009-2509(66)85093-5

Cited by 9 publications

(2 citation statements)

References 5 publications

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“…The fluid is flowing upward and the Boussinesq approximation is used. The momentum and energy equations can be written as follows: __ 4 (2) where T c is the cooled wall temperature and dp/dx = (dpjdx) + pg, where p s is the static pressure. The eddy diffusivities V T and a T for momentum and heat transfer, respectively, appearing in Eqs.…”

Section: Governing Equationsmentioning

confidence: 99%

“…15 k m = 0.4[(0.974 -(20.77/d + -5.48)](13) In the region near the heated wall, i.e., 6 < y < b, y and d + are replaced by b -y and (b + -d + )z = (b% -d£) for the preceding equations where z is the correction factor to normalize the variable by means of the respective wall parameters of the cooled wall.The boundary conditions for Eq. (1),(2), and (the wall parameters at the cooled wall, Eqs. (1), (2), and (5) are normalized as -…”

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confidence: 99%

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Turbulent mixed flow of free and forced convection between vertical parallel plates

Chen

Chiu

Lee

1989

Journal of Thermophysics and Heat Transfer

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In predicting the fully developed turbulent mixed flow of forced and natural convection, the one-equation model of turbulence for low Reynolds number flows is adopted. Finite-element solutions are carried out in the upward turbulent flow between vertical parallel plates at different wall temperatures. In this condition, the aiding and opposing flows arise simultaneously on the heated and cooled sides, respectively, and a fully developed condition is established. The solutions with and without the effect of buoyancy force are predicted and the comparisons are discussed. In these two situations, the mean velocity and temperature profiles, the locations of the maximum velocity, eddy diffusivities of momentum, Nusselt number, friction factor, and turbulence kinetic energy are presented. The substantial effects of the buoyancy force are also confirmed.eddy diffusivity for heat 8 = global source vector b = distance between parallel plates bj = element of global source vector b + = dimensionless distance between parallel plates = bu*/v c p = specific heat at constant pressure f c -friction factor = 2 t c \/p (u >? f H = friction factor = 2 i; H \/p <« >Ĝ + = buoyancy parameter = gf$(T H -T c )v/u* 3 Gr -Grashof number based on temperature difference = *gp(T H -T c )b 3 /v 2 g = gravitational acceleration K = turbulence kinetic energy K + = dimensionless turbulence kinetic energy = K/u* 2 k = von Karman constant / = element length / 1Z) = mixing length in dissipation ID -dimensionless mixing length in dissipation = /i jD w*/v £ lv = mixing length in diffusivity £i~v = dimensionless mixing length in diffusivity = £ lv u*/v N f = shape function Nu c = Nusselt number = 4|#|<5/«r> c -rjM Nu H = Nusselt number = 4\q\(b -d)/(T H -P = turbulence production P u = viscous production P 0 = buoyancy production Pr = Prandtl number p = real pressure p s = static pressure p + = dimensionless pressure =

/pw* 2 q = heat flux -Reynolds number = 2£/v = local turbulent Reynolds number = dimensionless local turbulent Reynolds number = temperature = dimensionless temperature normalized by the cooled-wall parameter = (T -T c )pc p u*/\q\ = dimensionless temperature normalized by the heated-wall parameter = (T H -T)pc p Uff/\q\ = time-averaged velocity in the x direction = dimensionless velocity = u/u* = friction velocity = ^/\r c \/p = velocity in y direction = coordinate in the flow direction = dimensionless coordinate in the flow direction = xu*/v = distance from the cooled wall = dimensionless distance from the cooled = correction factor defined by Eq. (40) = thermal expansion coefficient = distance from the cooled wall to the maximum velocity location = dimensionless distance = du*/v = turbulent dissipation = dimensionless temperature = (r -T c )j(T H -T c ) = thermal conductivity = kinematic viscosity = eddy diffusivity for momentum = dimensionless eddy diffusivity for momentum = V T /V = density = turbulent Prandtl number = shear stress Subscripts c H m o = at the cooled wall = at the heated wall = momentum = forced convection < )...

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Section: Governing Equationsmentioning

confidence: 99%

mentioning

confidence: 99%

Turbulent mixed flow of free and forced convection between vertical parallel plates

Chen

Chiu

Lee

1989

Journal of Thermophysics and Heat Transfer

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A novel approach to spray drying using plasmas of water vapour

Gauvin¹

1981

Can J Chem Eng

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The technical feasibility of drying an aqueous solution in the form of a fine spray of droplets in contact with the water vapor generated by the evaporation of the solution has been amply demonstrated in the course of the extensive experimental work which accompanied the development of the Atomized Suspension Technique (AST). In the present paper, it is proposed to replace the external heating formerly used in an AST system by a stream of plasma‐generated superheated steam as the sole source of heat. The ratio of plasma steam required to total evaporation (circa 1 to 24) is extremely low. Based on a computer program developed in this laboratory, a simulation of the proposed operation is presented for an industrial installation. The calculations indicate that a considerable reduction in equipment size should result. No gas compression is required and operation under pressure is now possible. Most important is the considerable saving in energy resulting from the recovery of the heat in the exhaust steam from the process. An approximate estimate of capital and operating costs is presented.

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The effect of buoyancy on flow and heat transfer for a gas passing down a vertical pipe at low turbulent reynolds numbers

Easby

1978

International Journal of Heat and Mass Transfer

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Temperature profiles and fluctuations in combined free- and forced-convection flows

Cited by 9 publications

References 5 publications

Turbulent mixed flow of free and forced convection between vertical parallel plates

Turbulent mixed flow of free and forced convection between vertical parallel plates

A novel approach to spray drying using plasmas of water vapour

The effect of buoyancy on flow and heat transfer for a gas passing down a vertical pipe at low turbulent reynolds numbers

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