Current Collection

There are four basic variations of the linear MHD channel (Fig. 5) which differ primarily in their method of electrical loading. The simplest is the two-terrninal Faraday or continuous electrode generator, Figure 5a, where a single pair of current-collecting electrodes spans the channel in the axial direction, short-circuiting the channel from end to end. Hence, for this configuration, = 0, andj can be obtained from equations 21 and 22 ... 

All data recorded in the data base have been acquired from plant records. Statistical reductions of data for generation of reports or specific end use are available. Data are currently collected from four operating plants (eight units). Time clocks have been installed on components, to record actual exposure time. Event data are available on a broad variety of safety and commercial grade components including pumps, valves, transformers, diesels, filters, tanks (vessels), and heat exchangers. 

Production costs for biodiesel from soybean oil exceeds 2.00 per gal ( 0.53 per 1), compared to 0.55 to 0.65 per gal ( 0.15 to 0.17 per 1) for conventional diesel. The main cost in biodiesel is in the raw material. It takes about 7.7 lb (3.5 kg) of soybean oil valued at about 0.25 per lb (0.36 per kg) to make 1 gal (3.81) of biodiesel. Waste oils, valued at 1 per gal ( 3.79 per 1) or less, have the potential to provide low feedstock cost. However, much waste oil" is currently collected, reprocessed as yellow and white greases, and used for industrial purposes and as an animal feed supplement. Production of biodiesel... 

The central current-collecting spine produces uniform current flow across the active material. 

II. Ease of electrical connection Here the main problem is that of efficient electrical current collection, ideally with only two electrical leads entering the reactor and without an excessive number of interconnects, as in fuel cells. This is because the competitor of an electrochemically promoted chemical reactor is not a fuel cell but a classical chemical reactor. The main breakthrough here is the recent discovery of bipolar or wireless NEMCA,8 11 i.e. electrochemical promotion induced on catalyst films deposited on a solid electrolyte but not directly connected to an electronic conductor (wire). 

Figure 2. Total positive ion current collected on blanked-off first electrode variation caused by interposing collimating slit d is the height of the center of the slit over the level of the sampling leak...

The above predictions will now be compared with the experimental results. The high probability volume agrees well with the movable slit observations above. The predicted low collection efficiency for electrons is also observed. Figure 5 (bottom) shows the ratio of negative to positive ion current collected on the blanked-off conical electrode for different gases. For the rare gases this ratio is small especially at low pressures while... 

The current collection of the Mg anodes is achieved through the magnesium itself, without using additional current collectors. This type of... 

LDs usually give also an approximate reading of the total pressure (ion current collected by the diaphragm electrodes of Fig. 1.34). 

FIGURE 6.6 High power density (HPD) SOFC, consisting of a flattened tube with two flat faces. The vertical struts between the two flat faces provide shorter paths for the electronic current collection, eliminating the need for all of the electronic current to travel around the circumference of the cathode, as in the standard tubular cell design shown in Figure 6.5 [48], Reprinted from [48] with permission from Elsevier. 

Recently, the planar structures using bipolar current collection have received more consideration for SOFCs because of new gas sealing and fabrication techniques. 

Schematic of the Si-nMEA fabrication process (a) sputter Au layer on double-side polished wafer (b) pattern Au layer with liftoff process (c) spincoat and cure a polyimide layer (d) perform the double-sided photolithography to pattern etch pits (e) etch Si in ICP-DRIE to form Au/Si electrode (f) dice the wafer into a single die (g) RIE etch the polyimide layer with a shadow mask to expose current collecting region (h) electroplate Pt black on Au layer (i) sandwich both electrodes with Nafion 112 in a hot-press bonder. (Reprinted from J. Yeom et al. Sensors Actuators B107 (2005) 882-891. With permission from Elsevier.)...

DL thicknesses on overall fuel cell performance and concluded fhaf fhe performance of DLs wifh MPL increased considerably when the MPL thickness was increased from 7.5 to 17.5 pm. Their explanation was that very thin MPLs provide poor electrical contact between the CL and the current-collecting FF plate because the electrical resistance is increased due to the roughness of fhe carbon clofh DL. If fhe MPL is too fhin, fhe amount of carbon/PTFE is insufficienf to provide good elecfrical confacf for the collection of fhe currenf generated in fhe fhree-phase reaction zone of fhe catalyst layer. 

Diffusion medium properties for the PEFC system were most recently reviewed by Mathias et al. The primary purpose of a diffusion medium or gas diffusion layer (GDL) is to provide lateral current collection from the catalyst layer to the current collecting lands as well as uniform gas distribution to the catalyst layer through diffusion. It must also facilitate the transport of water out of the catalyst layer. The latter function is usually fulfilled by adding a coating of hydrophobic polymer such as poly(tet-rafluoroethylene) (PTFE) to the GDL. The hydrophobic polymer allows the excess water in the cathode catalyst layer to be expelled from the cell by gas flow in the channels, thereby alleviating flooding. It is known that the electric conductivity of GDL is... 

Accurate modeling of the temperature distribution in a PEFC requires accurate information in four areas heat source, thermal properties of various components, thermal boundary conditions, and experimental temperature-distribution data for model validation. The primary mechanism of heat removal from the catalyst layers is through lateral heat conduction along the in-plane direction to the current collecting land (like a heat sink). Heat removed by gas convection inside the gas channel accounts for less than 5% under typical PEFC operating conditions. 

In most countries, solid waste containing metals such as neutralization sludge from the plating industry and flue dust from the metal and steel industries is currently collected and dumped in landfill, where it constitutes a perpetual toxic threat to the environment and a waste of resources. The alternatives to this landfill disposal are either to reduce the rate of discharge at source by an individually designed recovery process or to separate and recover the metals from the collected waste in a centrally located facility. A presumption for a centrally located facility would be that companies with metals in their effluents require treatment of their total wastewater streams. This could be accomplished through the relatively simple process of neutralization, which requires minor investment in sedimentation tanks and dewatering equipment and involves relatively modest operation costs. 

It comprises an axially mounted W filament and three cylindrical collectors Ci,Ci, and Ci. All collectors are maintained at the same positive potential with respect to the W filament, but only the emission current collected from Ci is recorded. In the region of C2 the temperature and the surface concentration of adsorbate on the emitter are assumed to be uniform. 

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