Cross-flow conditions

For shell-and-tube heat exchangers with cross-flow baffles, the preceding methods assume that an adequate number of baffles has been provided. If the shell-side fluid makes less than eight passes across the tube bundle, the mean temperature difference may need to be corrected for this cross-flow condition. Appropriate curves are presented in Caglayan and Buthod [20]. The curves in this reference may also be used to determine correction factors for cross-flow exchangers with one shell pass and more than two tube passes. 

Dynamic membranes are formed on microporous supports under appropriate pressure and cross-flow conditions by deposition of solute components contained in a feed solution. The formation steps are ... 

Simple equations can be derived to estimate the mendirane area for a given gas separation separation problem. Here it is assumed that the penneability coefficients remain constant and the separation occurs under isothermal condition. The calculations are dependent on the flow pattern in the module. The most simple equations are obtained by assuming complete mixing both in feed and penneate. This concept may be found in systems which operate at low recovery. Most gas separation systems resembles cross-flow conditions, i.e. plug flow at the feed side and complete mixing at the permeate side. These two concepts will be discussed here. In case of counter-current and co-current flow conditions the equations are somewhat different and the (terivations applicable for these systems can be found in literature. For vapour penneation the same approach can be used, however the... 

VIll. 16.2 Gas separation under cross-flow conditions... 

As shown in Eqn. (6), the drag coefficient of a cylindrical fiber imder cross flow condition is a function of the Reynolds Number, which is generally expressed as Re = pUp,hd/p (i.e. the ratio of inertial force to viscous force). This definition holds true for Newtonian fluids, where shear stress < shear rate. However, the fluids that are often utilized in fiber sweep applications are non-Newtonian. Hence, the Reynolds Number must be redefined using the apparent viscosity function as Re = pUp>d/papp. The viscosity for Newtonian fluids is independent of the shear rate. However, for non-Newtonian fluids, the apparent viscosity varies with shear rate. Applying the Yield Power Law (YPL) rheology model, the apparent viscosity is expressed as ... 

A Microsoft Office Excel spreadsheet can dehver answers based on Mulder s analytical solution for binary gas system under cross-flow condition [5]. 

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