Film turbulent

Kinoshita, E, and Uehera, H., Turbulent Film Condensation of Binary Mixture on a Vertical Plate, ASME/JSME Thermal Engineering Conf., Vol. 2, pp367-373, 1995. 

Clements and Colver developed the modified Nusselt equation to correlate hydrocarbon and hydrocarbon mixtures in turbulent film condensation ... 

Figure 10-77. Turbulent film condensation of light hydrocarbons and their mixtures—up-flow, (used by permission Clements, L. D., and Colver, C. P. AlChE Heat Transfer Symposium V. 131, No. 69, 1973. American Institute of Chemical Engineers. All rights reserved.)...

Rosenow WM, Webber JH and Ling AT (1956) Effect of Velocity on Laminar and Turbulent Film Condensation, Trans ASME, 78 1645. 

Levich (L8, L9) has given an interesting treatment of fully turbulent film flow. In the absence of a flowing gas stream at the interface, Levich deduced that the scale of turbulence and the turbulent velocity normal to the interface must be proportional to the distance from the interface, so that all turbulent pulsations must disappear at the interface itself, leaving there a nonturbulent layer of thickness... 

Nearly all of the remaining treatments of turbulent film flow are based on the assumption that the film can be regarded as smooth, and that some... 

Turbulent Film Flow with an Adjoining Gas Stream... 

Attention in this section will be confined to the analysis of turbulent film flow by Dukler (D12, D13, D14), which includes the effect of a cocurrent downward gas stream. Film heat transfer under these circumstances is also considered. The Dukler analysis was later extended to cover the case of upward cocurrent gas/film flow by Hewitt (H7). 

Fig. 3. Comparison of various correlations for the film thickness in the turbulent film flow regime in the absence of a gas flow.

As noted earlier, the equation for turbulent film flow obtained by Levich (L8) [Eq. (71)] contains an unspecified constant and therefore cannot be readily compared with the other relationships for turbulent films. 

In the case of turbulent film flow with an adjoining gas stream, there is a wealth of experimental studies reported in the literature. Only the briefest review of these can be given here. In general, the difficulty en-... 

There are several reports in the literature of the critical Reynolds number at which turbulent film flow commences. These values of NRe t are usually determined from the breaks which appear in the curves of film thickness, surface velocity of the film, heat or mass transfer coefficients in the film, etc., when plotted against NHe. Some of the numerical values proposed by various investigators are listed in Table I. 

Kutateladze and Styrikovich (K25), 1958 Sections deal with film flow in presence of zero, counter-current, upward and downward cocurrent gas streams, including turbulent film flow. 

Dukler (D12), 1959 Theoretical analysis of turbulent film flow (with and without downward cocurrent gas stream) with extension to film heat transfer. Interfacial disturbances are neglected basic equations are solved by computer giving film thicknesses, velocity profiles, local and mean heat transfer coefficients. Interfacial shear is shown to be of great importance. 

This Rayleigh number corresponds to a turbulent film along the wall, but its value is close to the lower end of turbulent flow. If, for example, the viscosity increases to 1000 mPa s, the Rayleigh criterion is only 108. Moreover, it is not... 

WAVY AND TURBULENT FILM CONDENSATION ON A VERTICAL SURFACE... 

Develop an expression for the total condensate flow in a turbulent film in terms of the fluid properties, the temperature difference, and the dimensions of the plate. 

Killion and Garimella conducted comprehensive critical reviews of analytical and numerical models [44] and experimental investigations [45] of absorption heat and mass transfer. Killion and Garimella [44] found that most of the literature on absorption heat and mass transfer work has focused on the particularly simplified case of absorption in laminar vertical films of LiBr/HjO. Fewer researchers have considered the important situations of wavy films, turbulent films, and films on horizontal tubes. They pointed out that attention must be paid to droplets and waves on horizontal tubes, and to the potential interaction of the heat and mass transfer process on the film hydrodynamics, surface wetting, and heat transfer in the vapor phase. In their review of experimental... 

Nusselt s film condensation theory presumes a laminar film flow. As the amount of condensate increases downstream, the Reynolds number formed with the film thickness increases. The initially flat film becomes wavy and is eventually transformed from a laminar to a turbulent film the heat transfer is significantly better than in the laminar film. The heat transfer in turbulent film condensation was first calculated approximately by Grigull [4.14], who applied the Prandtl analogy for pipe flow to the turbulent condensate film. In addition to the quantities for laminar film condensation the Prandtl number appears as a new parameter. The results can not be represented explicitly. In order to obtain a clear representation, we will now define the Reynolds number of the condensate film... 

Isashenko [4.17], has developed simple formulae, originating from the solution of the momentum and energy equations for turbulent flow, for the turbulent film... 

In the calculation of heat transfer in the transition region between laminar and turbulent film condensation, empirical interpolation formulae are well established. One of these types of formulae is... 

With these estimated values the vapour side heat transfer coefficient aG and the mass transfer coefficient [3G can be calculated. Just as the heat transfer coefficient aL of the condensate film is also known, which in laminar film condensation is yielded from Nusselt s film condensation theory (4.39), and for turbulent film condensation from (4.41). From (4.67) the temperature... 

Turbulent film condensation on vertical or inclined plates and on the inside or outside of vertical tubes. 

Transition region between laminar and turbulent film condensation. 

Turbulent film condensation of vapour flowing in tubes. 

Figure 10.8. Ratio /C12A115 which are elements of the zero-flux matrix of mass transfer coefficients [/c], as a function of the gas-phase Reynolds number. Mass transfer between a gaseous mixture of acetone (l)-benzene (2)-helium (3) and a liquid film containing acetone and benzene. Calculations by Krishna (1982) based on the von Karman turbulent film model and the Chilton-Colburn analogy.

Krishna, R., A Turbulent Film Model for Multicomponent Mass Transfer, Chem. Eng. J., 24, 163-172 (1982). 

Various semiempirical models exist in the literature to predict turbulent film condensation [20-23]. Butterworth [18] recommends the result of Labuntsov [23] for the local coefficient... 

Rohsenow et al. [21] extended the analysis into the turbulent film regime using the heat transfer-momentum analogy. The results for a downward flowing vapor are shown in Fig. 14.7 for Prf = 1.0 and 10.0. At high vapor velocities, as the dimensionless shear stress x increases, the transition to turbulence occurs at smaller values of the film Reynolds number (Eq. 14.31) as represented by the dashed lines. The influence of x on both laminar and turbulent film condensation is evident. 

Dhir and Lienhard [118] studied laminar film condensation on two-dimensional isothermal surfaces for which boundary layer similarity solutions exist and found that a similarity solution exists for body shapes that give g(x) = x". Nakayama and Koyama [119] extended the analysis of arbitrarily shaped bodies to include turbulent film condensation. 

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