Costs fabrication

Although all of the preceding processes can produce a p—n homojunction, the properties required from the junction and the fabrication costs determine the fabrication method. Methods of making other kinds of junctions are similar to those used to make homojunctions, but the materials on either side of such junctions are dissimilar. 

A. Pikiilik and H. E. Diaz [Chem. Eng., 84, 106-122 (Oct. 10, 1977)] presented a graphical method for estimating the fabricated cost of distillation cohimns and pressnre vessels, storage tanks, fired heaters, pnmps and drivers, compressors and drivers, and vacnnm eqnipment. 

TABLE 14-9 Relative Fabricated Cost for Metals Used in Tray-tower Construction ... 

FIG. 14-81 Fabricated costs and installation time of towers. Costs are for shell with two beads and sldrt, but without trays, packing, or connections. (Peters and Timmerhatis, Plant Design and Economics for Chemical Engineers, 4th ed., McGraw-Hill, New Yoik, 1991. )... 

When designing apparatus with several materials, consider all materials as an integrated entity. More highly resistant materials should be selected for the critical components and for cases in which relatively high fabrication costs are anticipated. Often, a compromise must be made between mechanically advantageous properties and corrosion resistance. 

However, it should always be remembered that it is bad design practice to select materials on the basis of cost per unit weight. In the mass production industries, in particular, die raw material cost is of relatively little importance. It is the in-position cost which is all important. The in-position cost of a component is the sum of several independent factors i.e. raw material costs, fabrication costs and performance costs. 

It is in the second two of these cost components that, in relation to other materials, plastics can offer particular advantages. Fabrication costs include power, labour, consumables, etc and Table 1.10 shows that, in terms of the overall energy consumption, plastics come out much better than metals. Performance costs relate to servicing, warranty claims, etc. On this basis plastics can be very attractive to industries manufacturing consumer products because they can offer advantages such as colour fasmess, resilience, toughness, corrosion resistance and uniform quality - all features which help to ensure a reliable product. 

For the purpose of this design, assume that a cost study has verified the above remarks, and a 2-ft, 6-in. tower will be used. This means that entrainment will be very low on a 15-in. tray spacing. Therefore, a smaller spacing should be considered. From usual fabrication costs, 12-inch spacing is about the closest spacing to consider. 

Trusses may be the best solution for very high-imposed loads. Frame action with columns is not possible with trusses. Although trusses are generally the lightest form of roof construction, they may be the most expensive due to high fabrication cost. A combination of lattices or lattice and truss may form a sawtooth roof profile for incorporation of north lights. 

In terms of photoelectrode material quality, single crystals comprise a rational choice since their bulk properties can be controlled better and their influence on cell performance may be evaluated in a rather accurate manner, as being microstruc-turally well-defined solids. However, the cost and convenience of single-crystal preparation are not suited to the practical requirement of cheap device components. Polycrystalline photoelectrodes are advantageous in terms of fabrication cost, ability to prepare large areas in one operation, and material economy. 

Though the fabrication cost is low, flat ends are not a structurally efficient form, and very thick plates would be required for high pressures or large diameters. 

Provide one large bin wherever possible, rather than multiple small bins. This saves supports, materials, fabrication cost, and conveyors. 

As can be seen from this figure, the heat-resistance was remarkably improved by the drastic changes in the microstructure from amorphous to polycrystalline structure. Another type of SiC-based fiber, SA fiber (2), has a sintered SiC polycrystalline structure and includes very small amounts of aluminum. This fiber exhibits outstanding high temperature strength, coupled with much improved thermal conductivity and thermal stability compared with the Nicalon and Hi-Nicalon fibers. The fabrication cost of the SA fiber is also reduced to near half of that of the Hi-Nicalon Type S [ 17]. The SA fiber makes SiC/SiC composites even more attractive to the many applications [18]. In the next section, the production process, microstructure and physical properties of the SA fiber are explained in detail. 

Although, for other orders of reaction, equal-sized vessels do not correspond to the minimum volume, the difference in total volume is sufficiently small that there is usually no economic benefit to constructing different-sized vessels once fabrication costs are considered. 

In addition to the performance and durability of the fuel cells fabricated, cost is also an extremely important consideration in the decision of whether or not to adopt... 

The (L/D)opt ratio is significantly different from the rule of thumb stated earlier in the example, namely, LID = 3 this difference must be due to the assumptions (perhaps erroneous) regarding vessel geometry and fabrication costs. 

Single crystal silicon (sc-Si), polyciystalline silicon (p-Si), and amorphous silicon (a-Si) can all be used to make solar cells, with fabrication cost and device photoconversion efficiencies decreasing as one moves from single-crystal to amorphous materials. Various properties of these materials are summarized in Table 8.1. Other relatively common solar cell materials include gallium arsenide (GaAs), copper indiirm diselenide (CIS), copper indium-gallium... 

Capital costs of gas treatment system include purchase cost of system components and fabrication costs. 

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