Stack design assembly

Table 3.1 Results table for a paper-based analysis of the solenoid assembly stack design...

When the discs are of the shrunk-on design, they are made up individually and stacked onto the shaft by first heating the disc to dilate the bore. They are then allowed to cool and thus attach themselves to the shaft. Keys are normally not used. When the discs are of the stacked design, the discs are equipped with rabbet fit to radially lock the discs to maintain concentricity of assembly. The through-bolts are usually tensioned by stretching hydraulically to a precise value to ensure the mechanical integrity of the assembly. 

Labor and operating costs are low. The system is highly automated allowing for minimal operator intervention. The two major operating costs are power and membrane maintenance. Allied-Signal s commitment and continued research and development of the AQUATECH membranes and stack design ensures longer lifetime on the membrane and even more power efficient units. Membrane replacements are facilitated by cell modules pre-assembled for easy installation. 

Among the many complications of structural testing of membranes is the variety of approaches to membrane stack design proposed by different groups working in the field (1, 8). The necessary service conditions of a membrane are determined not only by the membrane itself but also by the type of spacer employed with it, the flow rate and pressure drop across the face of the membrane, pressure differences which can exist either permanently or temporarily from one side of a membrane to the other, the ease and frequency of disassembly and assembly of the stack, and the way in which it is supported. 

Performance of a stack of cells is limited by performance of the weakest cell in stack. It is therefore important to achieve high uniformity in performance of the individual cells in the stack, through stack design, mass production techniques, quality control, and automated stack assembly process. Optimum flow field design may be obtained by careful Computational Fluid Mechanic techniques and experimental validation including flow visualization techniques. 

Fabrication and characterization of tubular SOFC stacks designed for low temperature operation were shown. Two types of stacks were proposed and demonstrated using the micro tubular SOFC bundles the type A was a vertically assembled stack, four-story cube-type stack with the volume of about 0.8 cm The performance of the type A stack was shown to be 3.6 V OCV and 2 W maximum output power under 500 °C operating temperature. Another type of the stack was also fabricated, which consists of three bundles and fuel manifolds, where the air was applied only by natural convection. Open circuit voltages of the type B stack were shown to be 2.85 and 2.73 V at 450 and 500 C operating temperatures, with the maximum power outputs of 0.91 and 1.54 W. Overall, both types of stacks showed reasonably sufficient performance for application use. 

Because of the relatively thin dimensions and low mechanical strength of GDLs and MEAs versus the gaskets, bipolar plates, and endplates, the most important goal in stack design and assembly is to achieve a proper and uniform pressure distribution in GDLs and MEAs. The endplates that make up each fuel... 

STACK DESIGN AND ASSEMBLY 2.7.1. Hardware of a Fuel Cell Stack... 

Figure 9.7 shows the actual cell stack unit assembly for the fourth-generation 1-kW class module. The individual separator plates are designed... 

An obvious method of increasing the filtration area in the vessel is to stack several plates on top of each other the plates are operated in parallel. One design, known as the plate filter, uses circular plates and a stack that can be removed as one assembly. This allows the stack to be replaced after the filtration period with a clean stack, and the filter can be put back into operation quickly. The filter consists of dimpled plates supporting perforated plates on which filter cloth or paper is placed. The space between the dimpled plates and the cloth is coimected to the filtrate outlet, which is either into the hoUow shaft or into the vessel, the other being used for the feed. When the feed is into the vessel, a scavenger plate may have to be fitted because the vessel will be full of unfiltered slurry at the end of the filtration period. This type of filter is available with filtration areas up to 25 m and cakes up to 50 mm thick. 

Horizontal Vessel, Horizontal Leaf Filters. These filters consist of a horizontal cylindrical vessel with an opening at one end (Fig. 19). A stack of rectangular horizontal trays is mounted inside the vessel the trays can usuaUy be withdrawn for cake discharge, either individuaUy or in the whole assembly. The latter case requires a suitable carriage. One alternative design aUows the tray assembly to be rotated through 90° so that the cake can faU off into the bottom part, designed in the shape of a hopper and fitted with a screw conveyor. 

Design Principles An individual fuel cell will generate an electrical potential of about 1 V or less, as discussed above, and a current that is proportional to the external load demand. For practical apph-cations, the voltage of an individual fuel cell is obviously too small, and cells are therefore stacked up as shown in Fig. 27-61. Anode/ electrolyte/cathode assemblies are electrically connected in series by inserting a bipolar plate between the cathode of one cell and the anode of the next. The bipolar plate must be impervious to the fuel... 

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