1. The following is an empiricalequation describing the loss of pressure through

Question

1. The following is an empiricalequation describing the loss of pressure through a packedcolumn:

P=2.15(0.15N0.85v1.85/D1.15)

where: P = Pressure loss, N /m2

= Fluid viscosity, kg / (ms)

N = Packing height,m

= Fluid density kg /m3

= Fluid speed, m /s

D = Packing diameter,m

a) What are the units of thenumerical quantity, 2.15?

b) It is assumed that the terms, N, , and D are in imperial units (mass inlbm, length in ft, time in s), andthat we want to use the formula directly without converting eachterm into metric units (SI) before substituting them into theformula. Modify the formula so that the calculated pressure lossremains in N / m2, but that the other terms remainin imperial units.

Explanation / Answer

P=2.15(0.15N0.85v1.85/D1.15)

(0.15N0.85v1.85/D1.15)has units of(kg0.15m-0.15s-0.15*m1*kg0.85m-3*0.85*m1.85s-1.85m-1.15)

ORkg1*m-1s-2 , which is a unit ofNewton (N)

If P = Pressure loss, N / m2 then, 2.15 must haveunits of m-2

b)

2.15m-2 *(1 m/ 3.28ft)2 = 0.1998 ft-2

P= 0.1998ft-2(0.15N0.85v1.85/D1.15)

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