Design ratio

The factor 0.48 in Eq. (21) is valid for a rotating disc in infinite space. As is shown by a comparison of the Ne numbers found experimentally, Ne = 0.52/Re°-, with Schlichting s data [65], this condition is obviously satisfied very well for the design ratios chosen here (hg/d = 0.7 with H/D = 1). 

Whatever parameter of a specific material one is evaluating, a required value for the material must be found using a design model, and an allowable value for the material must be determined by a test method. The allowable value divided by the required value yields the design ratio (DR), or the resulting FS. This design-by-function concept is necessary to design and evaluate new materials that are both feasible and safe for a variety of situations. 

Relative density of the upstream particles Design ratio Factor of safety Height... 

Pneumatic conveying dense phase No jJow or flow < design plugged line/mal-function of line boosters because of stuck check valve/high humidity. Solids fed to conveying line < design ratio of air to fluidize in the blow tank relative to convey is too small/fault in control system. 

Stripper reflux flow rate is ratioed to stripper feed flow rate using molar flow rates. The reflux flow controller is on cascade with its set point coming from a multiplier whose one input is the stripper feed flow rate and the other is a constant 0.01097 (the steady-state design ratio). 

As with hydrogen partial pressure, the recycle gas/feed ratio should be maintained at the design ratio. The actual calculation for the gas-to-oil ratio, can be defined as ... 

Absorption is not a refining operation and is rarely the last operation conducted on a product. Consequently, close control of the concentration of either effluent stream is not paramount, and on-line analyzers are not often used. More importance is placed on minimizing losses (such as Vy) or total operating costs, for which the simple optimizing feedforward system was designed at the close of Chap. 8. In that example, as in the control equation (12.8), maintenance of a designated ratio of L/F applies. 

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