- #1
williamcarter
- 153
- 4
Homework Statement
Problem data:[/B]
http://imgur.com/a/hEz16
Homework Equations
Rconduction=ln(rout/rin)/2*pi*Length*thermal conduct
Rconvection=1/2*pi*Length*routside*convective heat transfer outside
=>Qconduct=2*pi*Length*thermal conduct*(Tin-Tout)/ln(rout/rin)
=>Qconv=2*pi*Length*routside*convective heat transfer outside*(Tout-Tair)
The Attempt at a Solution
Solution:
a)[/B]
http://imgur.com/a/cH9hV
b)
For a)
I do not understand why we need to find Toutside by equating Qcond=Qconv?
And why we need to calculate Q from the pipe just as Qconvection instead of Q total?
Why we cannot do Q=delta T/Resistance Total
where:
Rtotal=Rconduction+Rconvection,because we do not need temperatures in those 2 R formulas
and delta T=(Tin-Tair) specifficaly 300 and 5 degrees celsius
As for b) They do Rtotal and then Qtotal=delta T/Rtotal
and then they do Qtotal=Qconv and they get T2.
Why we cannot proceed the same for a)?
Last edited: