(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Heated air at 1 atmosphere and 35 deg. Celsius is to be transported in a 150 meter long circular plastic duct (smooth) at a rate of 0.35 cubic meters/sec. If the head loss in the pipe is not to exceed 20 meters, determine the minimum diameter of the duct.

2. Relevant equations

hlt (total head loss) = hl + hlm (major and minor head loss)

there is no minor head loss

hl=f*(L/d)*[(v^2)/2] - (friction factor times length over diameter times velocity squared over 2)

V=Q/A

Re= ro*v*d / meu

3. The attempt at a solution

Okay so first I tried to calculate diameter using a combination of the major head loss equation and the Q=VA eq. I got a huge mess involving large calculations to the 1/5th power. I don't that that was the right approach.

I also got the density and dynamic viscosity of air at 35 deg-

ro(air@35deg.C)=1.15kg/m^3

meu(air@35deg.C)=1.88E-5

Okay so then I thought I could get the Reynolds # but I am missing velocity and diameter.

NEXT- I figured- there is no head loss because (being that the pipe is smooth) there are no losses to friction and there are no components (valves, elbows etc) so there are no major or minor head losses. Where would they come from if not from friction? So now I am a little lost with this one. Am I applying the wrong formula? Not having the velocity OR diameter is really messing me up. Any help is appreciated. Thanks

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# Homework Help: Fluids - Head Loss complicated

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