Condensation horizontal cylinders

It will be noted that the above equation is identical to the equation for condensation on a single horizontal cylinder, i.e., Eq. (11.55), except that D is replaced with nD. 

Using an analysis similar to Nusselt s theory on filmwisc condensation presented in the next section, Bromley developed a theory for the prediction of heat flux for stable film boiling on the outside of a horizontal cylinder. The heat Ilux for film boiling on a horizontal cylinder or sphere of diameter D is given by... 

Studies have been reported on condensation in a rotating horizontal disk [265], a rotating vertical cylinder [266], and a rotating horizontal cylinder [267]. Improvements are several hundred percent above the stationary case for water and organic liquids. 

An extension of this model to take account of turbulence is described by Klimenko [194], Horizontal Cylinders. The horizontal cylinder has been the most widely studied case of film boiling. Again, there is a strong analogy with condensation (see Fig. 15.76ft) and the classical expression for this case is that due to Bromley [190] as follows ... 

Figure 5.3 illustrates a process to manufacture acetylene from calcium carbide. The carbide is introduced by a screw conveyor into a perforated horizontal cylinder housed in a concentric envelope. Water is sprayed inside the internal shell. The acetylene formed passes upstream through the screw conveyor to a scrubbing tower, where, a new water spray carries off most, of the solids conveyed by the gas. The residual lime and carbide impurities are removed by a screw conveyor to a sludge receiver. The acetylene is cooled to — 10°C to condense most of the water. It is then purified by contact with dilute sulfuric acid in a liquid liquid absorber, and then with sodium hypochlorite prepared by the action of chlorine on caustic soda, to. remove impurities. The acetylene is then cooled to 0°C for the more complete separation of moisture. The final product nevertheless still contains 0.4 per cent by weight of water, which is suitable for most uses. More intensive dehydratation can be achieved by passage over silicagel. 

The Standard Messo multistage vacuum crystallizer Figure 8.52) provides a number of cooling stages in one vessel. The horizontal cylinder is divided into several compartments by vertical baffles that permit underflow of magma from one section to another but isolate the vapour spaces. Each vapour space is kept at its operating pressure by a thermocompressor, which discharges to a barometric condenser. 

Film-condensation coefficients outside horizontal cylinders. The analysis of Nusselt can also be extended to the practical case of condensation outside a horizontal tube. For a single tube the film starts out with zero thickness at the top of the tube and increases in thickness as it flows around to the bottom and then drips off. If there is a... 

Evaporators, Horizontal-Tube Type - The basic horizontal-tube evaporator is illustrated in Figure 12. The body of this evaporator is the liquor compartment and is in the form of a vertical cylinder. It is closed, top and bottom, with dished heads, although the bottom may be conical. The lower body ring is provided on opposite sides with steam compartments, closed on the outside by cover plates and on the inside by tube sheets. Between these tube sheets are fastened a number of horizontal tubes. The two steam chests with their connecting mbes form the steam compartment, and the tube wall heating surface. Steam is introduced into one steam chest and as it flows through the tubes it washes non-condensed gases and condensate ahead of it, so that these are withdrawn from the opposite steam chest. 

A certain pressure cooker is designed to operate at 20 lb/in2 gauge. It is well known that an item of food will cook faster in such a device because of the higher steam temperature at the higher pressure. Consider a certain item of food as a horizontal 4-in-diameter cylinder at a temperature of 95°F when placed in the cooker. Calculate the percentage increase in heat transfer to this cylinder for the 20-lb/in2-gauge condition compared with condensation on the cylinder at standard atmospheric pressure. 

B Calculate the heat flux associated with condensation on inclined and horizontal plates, vertical and hoiizonlal cylinders or spheres, and tube bundles,... 

In this paper, we now report measurements of heat transfer coefficients for three systems at a variety of compositions near their lower consolute points. The first two, n-pentane--CO2 and n-decane--C02 are supercritical. The third is a liquid--liquid mixture, triethylamine (TEA)--H20, at atmospheric pressure. It seems to be quite analogous and exhibits similar behavior. All measurements were made using an electrically heated, horizontal copper cylinder in free convection. An attempt to interpret the results is given based on a scale analysis. This leads us to the conclusion that no attempt at modeling the observed condensation behavior will be possible without taking into account the possibility of interfacial tension-driven flows. However, other factors, which have so far eluded definition, appear to be involved. 

Film condensation on a horizontal tube. For a curvilinear surface, in particular, for a horizontal circular cylinder along which a condensate film flows, the angle 6 is a nonconstant variable. By taking into account the fact that 6(6) d, where d is the diameter of a circular cylinder, and proceeding by analogy with (5.7.7), one can readily obtain the following formula for the heat transfer coefficient averaged over the external surface of the tube provided that the flow in the condensate film is laminar [200] ... 

R. M. Singer and G. W. Preckshot, The Condensation of Vapor on a Horizontal Rotating Cylinder, Proc. 1963 Heat Transfer Fluid Mech. Inst., Stanford University Press, Stanford, CA, pp. 205-221, 1963. 

Karimi [120] and Fieg and Roetzel [121] extended the Nusselt-type analysis of Hassan and Jakob [109] to include condensation on horizontal and inclined elliptical cylinders of various eccentricities. Memory et al. [122] studied both free and forced convection on horizontal elliptical cylinders. 

---