Flow factors

If most of the particles are less than ca 0.6 cm in size, flow obstmctions can occur by physical, chemical, or electrical bonds between particles. This cohesiveness is characterized by the bulk material s flow function. The forces acting to overcome a cohesive arch and cause flow are described by a hopper s flow factor, which can be obtained from the design charts (see Fig. 7). The minimum opening size required to prevent a cohesive arch from forming can be calculated from the comparison of the flow factor and flow function. 

A useful approximation of B for a conical hopper is B = 22f/a, where a is the bulk density of the stored product. The apparatus for determining the properties of solids has been developed and is offered for sale by the consulting firm of Jenike and Johansen, Winchester, Massachusetts, which also performs these tests on a contract basis. The flow-factor FF tester, a constant-rate-of-strain, direct-shear-type machine, gives the locus of points for the FF cui ve as well as ( ), the... 

Moisture content is another common and controllable flow factor. Most materials can safely absorb moisture up to a certain point further addition of moisture can cause significant flow problems. Specifications can control the amount of moisture content present in purchased raw materials. Moisture content can be lowered in the plant by including a drying operation in the process line. The costs incurred in drying may be offset by more efficient flow, lower shipping cost, and control of deterioration losses. 

Figure 2 shows 2201h/hr steam flow at 150 psi for a flow factor of 1. For the trap in question ... 

ASME Code default resistance to flow factor = 2.4. 

The flow factor for equation 7.6.2, v , is dependant on the flow regime as follows For subsonic flows... 

K, = vapor or gas flow factor for variable back pressures for balanced sea] ralves only (see Figure 7-27A and Figure 7-27B). 

Determine no-load flow factor, Figure 14-30. Determine 10 /(full load steam rate) (rpm). Read no-load factor corresponding to the general size of turbine. 

Determine no-load flow factor from Figure 14-30. Calculate lOV (steam rate at net hp) (reduced rpm). 

Figure 14-30. No-load flow factors for single-stage general-purpose turbine. (Used by permission Westinghouse Eiectric Corp., Steam Division.)...

The pressure flow factors describe how the surface roughness would affect the lubricant flow driven by the pressure gradient. It is defined as the ratio of pressure flow in an... 

The shear flow factor represents additional flow transport introduced by the roughness in relative sliding. It is defined as the mean flow in an element bearing where the two surfaces are in relative sliding, but the mean pressure gradient would be zero. 

The liquid-vapour flow factor FLV in Figure 11.27 is given by ... 

The values of the flow factor FLV given in Figure 11.44 covers the range that will generally give satisfactory column performance. 

The theory of the thermodynamics of irreversible systems (Prigogine, 1979 Prigogine and Stengers, 1986) shows that the differential quotient of entropy with time (the change of entropy with time) can be expressed as the sum of products, the terms of which contain a force factor and a flow factor. In chemical systems, the... 

Table 7-1 Laminar Flow Factors for Noncircular Conduits...

Fig. 13 shows typical results in a plot of pressure drop per unit length against the gas flow factor Fs (= vp°5). Four types of REUs were identified and simulated, and correlations were developed. The pressure drop arising from criss-crossing elements was the largest contribution to pressure drop of the four. The total pressure drop predicted from the individual contributions was in excellent agreement with literature data. 

Flow-loss factor. The flow factor, x0, is the ratio of out-flow to airflow ... 

Podczeck, F., Miah, Y. The influence of particle size and shape on the angle of internal friction and the flow factor of unlubricated and lubricated powders. Int. J. Pharm., 144, 1996, 187-194. 

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