Condensate turbulent

It must also be realized that this thin surface region is in a very turbulent state. Since the liquid is in equilibrium with its vapor, then, clearly, there is a two-way and balanced traffic of molecules hitting and condensing on the surface from the vapor phase and of molecules evaporating from the surface into the vapor phase. From the gas kinetic theory, the number of moles striking 1 cm of surface per second is... 

Vertical In-Shell Condensers Condensers are often designed so that condensation occurs on the outside of vertical tubes. Equation (5-88) is valid as long as the condensate film is laminar. When it becomes turbulent. Fig. 5-10 or Colburns equation [Tran.s. Am. Jn.st. Chem. Ertg., 30, 187 (1933-1934) maybe used. 

Spirai Compact, concentric plates no bypassing, high turbulence. Cross-flow, condensing, heating. Process corrosion, suspended materials. 0.8-1.5... 

This corrosion is most pronounced in locations of high velocity, turbulence, and impingement, such as at elbows, weld reinforcements, pump impellers, steam injection nozzles, and locations where freshly condensed fractions drip upon or run down metal surfaces. 

Braun, M., and Renz, U., Investigation of Multicomponent Diffusion Models in Turbulent Flow, Procc. Engineering Foundation Conf. on Condensation and Condenser Design, pp81- 92, 1993. 

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. 

GASFLOW models geometrically complex containments, buildings, and ventilation systems with multiple compartments and internal structures. It calculates gas and aerosol behavior of low-speed buoyancy driven flows, diffusion-dominated flows, and turbulent flows dunng deflagrations. It models condensation in the bulk fluid regions heat transfer to wall and internal stmetures by convection, radiation, and condensation chemical kinetics of combustion of hydrogen or hydrocarbon.s fluid turbulence and the transport, deposition, and entrainment of discrete particles. 

As the water and steam interacted, the turbulence sealed off a pocket of steam, which quickly condensed, lowering the pressure in the pocket and creating a void. 

Figure 10-67B. Correlation of McAdams representing the condensing film coefficient on the outside of vertical tubes, integrated for the entire tube length. This represents the streamline transition and turbulent flow conditions for Prandtl numbers 1 and 5. Do not extrapolate Prandtl numbers, Pr beyond 5. (Used by permission Engineering Data Book II 1984, Wolverine Tube, Inc.)...

Devore has presented useful charts for solving a multi-tuhe condenser design as shown in Figures 10-68,10-69, and 10-70. Figure 10-71 is useful for condensing steam. The charts all follow Nusselt s basic presentation however, a correction for turbulence of the film and other deviations is included. 

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.)...

The tube-side inlet to an exchanger, i.e. the tube ends, is a highly turbulent region and nylon ferrules in the tube ends of the inlet pass have been used in cupro-nickel-tubed condensers to prevent erosion. Where the flow is two phase the same rules will apply except that an erosion velocity limit is more difficult to specify. 

Operated in this manner, the shell-and-tube type is a flooded evaporator (see Figure 7.3) and has oil drainage pots if using ammonia, or a mixture bleed system if the refrigerant is one of the halocarbons. The speed of the liquid within the tubes should be about 1 m/ s or more, to promote internal turbulence for good heat transfer. End cover baffles will constrain the flow to a number of passes, as with the shell-and-tube condenser. (See Section 6.4.)... 

Under conditions of high vapour velocity Carpenter and Colburn 9 have shown that turbulence may occur with low values of the Reynolds number, in the range 200-400. When the vapour velocity is high, there will be an appreciable drag on the condensate him and the expression obtained for the heat transfer coefficient is difficult to manage. 

If Re is greater than 2100 during condensation on a vertical tube the mean coefficient hm will increase as a result of turbulence. The data of Kirkbride 62 and Badger 63,645 for the condensation of diphenyl vapour and Dowtherm on nickel tubes are expressed in the form ... 

Comparing equation 9.176 for streamline flow of condensate and equation 9.179 for turbulent flow, it is seen that, with increasing Reynolds number, hm decreases with streamline flow but increases with turbulent flow. These results are shown in Figure 9.49. 

For conditions of turbulent flow the transfer coefficient for the water side, hi = u<>. Ri the scale resistance is constant, and h the coefficient for the condensate film is almost independent of the water velocity. Thus, equation 9.201 reduces to ... 

The cluster reactor is attached to the pulsed cluster source s condensation channel, as shown in Figure 6. (16) To it is attached a high-pressure nozzle from which a helium/hydrocarbon mixture is pulsed into the reactor at a time selected with respect to the production and arrival of the clusters. The effect of turbulent mixing with the reactant pulse perturbs the beam, but clusters and reaction products which survive the travel from the source to the photoionization regime ( 600y sec) and the photoionization process are easily detected. 

The basic equations for filmwise condensation were derived by Nusselt (1916), and his equations form the basis for practical condenser design. The basic Nusselt equations are derived in Volume 1, Chapter 9. In the Nusselt model of condensation laminar flow is assumed in the film, and heat transfer is assumed to take place entirely by conduction through the film. In practical condensers the Nusselt model will strictly only apply at low liquid and vapour rates, and where the flowing condensate film is undisturbed. Turbulence can be induced in the liquid film at high liquid rates, and by shear at high vapour rates. This will generally increase the rate of heat transfer over that predicted using the Nusselt model. The effect of vapour shear and film turbulence are discussed in Volume 1, Chapter 9, see also Butterworth (1978) and Taborek (1974). 

Above a Reynolds number of around 2000, the condensate film becomes turbulent. The effect of turbulence in the condensate film was investigated by Colburn (1934) and Colburn s results are generally used for condenser design, Figure 12.43. Equation 12.51 is also shown on Figure 12.43. The Prandtl number for the condensate film is given by ... 

COLBURN, A. P. (1934) Trans. Am. Inst. Chem. Eng. 30, 187. Note on the calculation of condensation when a portion of the condensate layer is in turbulent motion. 

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

The spacer grid in a rod bundle is also a turbulence promoter that enhances liquid-vapor exchange and bubble condensation. The local intensity of such turbulence is a function of the grid pressure loss coefficient, K, and the distance from the grid, t D. Thus an empirical spacer factor, Fs, can be defined as... 

These different approaches are complementary to each other in basic concept. However, these analyses have not provided clear insight information of the bubble layer at the CHF about the bubble shape (spherical or flat elliptical), bubble population and its effect on turbulent mixing, and bubble behavior. The bubble behavior in a bubble layer could involve bubble rotation caused by flow shear, normal bubble velocity fluctuation, and bubble condensation in the bubble layer caused by the subcooled water coming from the core. Further visual study and measurements in this area may be desired. 

Blake, T. R., Gas Jets in Fluidized Media, Turbulent Diffusion Flames, and Condensing Vapor Jets in Liquids, Powder Technology (1996)... 

---