Collector Geometry

A first attempt at organizing collected nanofibers into yam using SEM stubs as collectors was reported by Dalton et al. (2005). A pair of grounded stubs placed 6 cm apart were used as collectors to obtain a quantity of oriented poly(e-caprolactone) (PCL) fibers between them. One of the grounded stubs was rotated at 2500 rpm to obtain samples of nanofibrous yarn 5 cm in length with an average diameter of 4.7 jjim. 

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In the general case, when arbitrary interaction profiles prevail, the particle deposition rate must be obtained by solving the complete transport equations. The first numerical solution of the complete convective diffusional transport equations, including London-van der Waals attraction, gravity, Brownian diffusion and the complete hydrodynamical interactions, was obtained for a spherical collector [89]. Soon after, numerical solutions were obtained for a panoplea of other collector geometries... 

Several studies have been conducted on particle capture by collectors of different shapes. Among the first studies were those of Albrecht (6), and Kaufman (7), who investigated the capture of airborne particles flowing past simple collector geometries. In packed columns, particle capture can be quantified in terms of the filter coefficient, X, defined by ... 

When the Bom, double-layer, and van der Waals forces act over distances that are short compared to the diffusion boundary-layer thickness, and when the e forces form an energy hairier, the adsorption and desorption rates may be calculated by lumping the effect of the interactions into a boundary condition on the usual ccm-vective-diffusion equation. This condition takes the form of a first-order, reversible reaction on the collector s surface. The apparent rate constants and equilibrium collector capacity are explicitly related to the interaction profile and are shown to have the Arrhenius form. They do not depend on the collector geometry or flow pattern. 

As discussed in the previous section, one type of solar collector geometry that has been foimd to be very advantageous for solar photocatalysis is based on CPC (Blanco et. al., 1999), which are a type of nonimaging optical devices. 

A similar approach could be applied to different current-collector geometries and lead to new technological solutions aimed at optimizing MCFC performance. 

Figure 13. Schematic of reactor collection of direct and scattered ( diffuse) near UV radiation for flat plate (left) and parabolic trough collector geometries (right). Plate collects Ip=I(j+Is, whereas trough reactor collects...

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