Flat plate configuration

The cost of a PV device is determined by several factors. These include the kind of materials used and the amount of materials requited, choice of substrates, device design, and fabrication processes. Crystalline devices ate generally mote efficient, but thin-film devices ate anticipated to cost less in flat-plate configurations. The use of concentrated light permits retention of efficiency with simultaneous reduction in cost. 

To develop a laboratory reactor that permits the easiest solution of the RTE employing the DOM (Cabrera etal, 1994). It consists of a flat plate configuration (a cylinder irradiated from one of its circular surfaces). 

Figure 2.18 Vapor jet configuration f or boiling on a horizontal flat-plate heater, as postulated by Zuber (1959). Adapted from Leinhard and Dhir, 1973. Reprinted with permission of U.S. Department of Energy.)...

The value of the Reynolds number which approximately separates laminar from turbulent flow depends, as previously mentioned, on the particular configuration of the system. Thus the critical value is around 50 for a film of liquid or gas flowing down a flat plate, around 500 for flow around a sphere, and around 2500 for flow through a pipe. The characteristic length in the definition of the Reynolds number is, for example, the diameter of the sphere or of the pipe in two of these examples. 

The electric mass filter is the basis for the electrodynamic trap used for studies of the spectroscopy of atomic ions that earned Paul and Dehmelt the 1989 Nobel Prize in Physics. A wide variety of electrode configurations can be used to trap particles, and a particularly simple design was proposed by Straubel (1956). His dc electrodes were flat plates, and the ac electrode was a simple torus or washer placed at the midplane between the endplates. 

Flat Plates. In this case, the hepatocytes are cultured on multilayered solid sheets, between which the blood is passed through narrow channels. This configuration, with direct blood-cell contact, somewhat resembles that ofthe human liver. However, scale-up is not easy because of the possible maldistribution of blood, and the existence of large dead spaces. 

The drive system of a rotational rheometer is likely to be optimized in one of two ways depending upon its preferred mode of operation. The most common form of rheometer is a controlled-rate (controlled-speed) device. This configuration is also used in most viscometers and has been around for decades. A shear rate is applied to a rotor by the motor controlling the viscometer s speed. The rotor is normally a flat plate or cylindrical cup. The stator is thus a cone or plate for the first two geometries or a cylindrical bob for the third (Figure HI. 1.1). The stator is linked to the rotor via the sample, which acts to couple the input signal like an automobile transmission. Thus, the torque on the stator when measured by a transducer is used to derive the shear stress in the sample. 

The bipolar plate design is illustrated in Fig. 47. It consists of a cross-flow arrangement where the gas-tight separation is achieved by dense ceramic or metallic plates with grooves for air and fuel supply to the appropriate electrodes. A porous cathode, a dense and thin electrolyte and a porous anode form a composite flat layer placed at the top of the interconnected grooves. The deposition of the porous electrodes can be achieved by mass production methods. Moreover, the bipolar plate configuration technology makes it possible to check for defaults, independently and prior to assembly of the interconnection plate and the anode-electrolyte-cathode structure. 

A drawback to the rectangular cell design is that the hydrodynamic description of fluid flow is much more complicated than in the cylindrical cell. Though it is beyond the intent of this discussion to go into full detail, analytical solutions to the Navier-Stokes equation for steady laminar fluid flow have been derived that can be used for calculation of electro-osmosis at flat plates in the rectangular cell configuration where electro-osmosis may differ at the upper, lower, and side chamber walls [ 15). 

This, in essence, is what is done in explosive welding. The technique looks very simple, but in mechanism is quite complex. Figure 30.13 shows the two most conunon welding setup configurations, for welding or cladding flat plates. 

Different photocatalytic reactor configurations are reported in the literature including annular reactor with a small thin film of catalyst coated on the iimer surface of the outer annulus, flat-plate fluidized beds, annular packed beds, and catalyst coated on honeycombed monoliths, porous fibrous mesh, and optical fiber bundles (31,32). 

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