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visits member for 3 years, 7 months
seen May 1 at 5:33

Mechanical Engineering Student at Georgia Tech

EMail:Gharrington44@gmail.com


Feb
26
comment In what situations do I use the characteristic length of a fin to find the surface area?
He didnt use that rigorous one. I looked at the solution and he used $$\eta_{f}=\frac{tanh(mL_{c})}{mL_{c}}$$ and $$A_{f}=2(w+t)L+wt$$ Essentially, he is using the corrected length for one equation but not for the other which, like you said, is inconsistent. But what if he used the area equation without the corrected length but use the other equation for the efficiency by using the temperature distribution. Would that theoretically yield the same result or would it be different? Pretty much does it matter which method you use as long as you stay consistent with which 'type' of length you use?
Feb
26
asked At what point can we assume the tip of a fin is adiabatic?
Feb
25
comment In what situations do I use the characteristic length of a fin to find the surface area?
Here's why I ask. I just had an exam the other day where there was a rectangular fin attached to the wall the protruded a distance L=8mm and exposed ta fluid. It's width was 10mm and it's thickness was 1mm. We had to determine the resistance and efficiency of the fin. He said $$A_{f}=PL+A_{c}=2(w+t)L+wt=186mm^{2}$$ whereas I said $$A_{f}=2wL_{c}=2w(L+\frac{t}{2})=170mm^{2}$$ Now there is a $16mm^{2}$ difference between the two areas. So which way is correct?
Feb
25
accepted In what situations do I use the characteristic length of a fin to find the surface area?
Feb
25
asked In what situations do I use the characteristic length of a fin to find the surface area?
Feb
20
comment What's the temperature distribution of a plane wall insulated on one side with no internal heat gen.?
So my intuition is wrong, but is my derivation correct in this case? Would the temperature of the wall be a constant temperature that is equal to the temperature of the flowing hot/cold liquid? And yes this problem was assuming that it is not insulated on the top or bottom. There is only insulation on one side and the other side is exposed to the fluid. I guess you could say it is an infinitely long/high wall
Feb
20
accepted What's the temperature distribution of a plane wall insulated on one side with no internal heat gen.?
Feb
20
asked What's the temperature distribution of a plane wall insulated on one side with no internal heat gen.?
Feb
16
revised Is the $mL_c$ value for triangular and rectangular fins the same value?
added 34 characters in body
Feb
16
revised Is the $mL_c$ value for triangular and rectangular fins the same value?
added 206 characters in body
Feb
16
accepted When to use Heat Diffusivity eqn and when to use Fourier's law to find temperature distribution?
Feb
16
accepted How do I find average temperature given a temperature distribution?
Feb
16
asked Is the $mL_c$ value for triangular and rectangular fins the same value?
Feb
13
comment How do I find average temperature given a temperature distribution?
I edited the formula above, sorry about that
Feb
13
revised How do I find average temperature given a temperature distribution?
changed formula
Feb
13
reviewed Reject suggested edit on How do I find average temperature given a temperature distribution?
Feb
13
asked How do I find average temperature given a temperature distribution?
Feb
1
asked When to use Heat Diffusivity eqn and when to use Fourier's law to find temperature distribution?
Jan
25
comment When do I know if energy stored in an object is 0 or nonzero? (Heat transfer)
@dmckee when it says "steady-state", does that mean that there is or is not energy storage? and if it doesnt explicitly say steady state, how do i determine if there is energy storage or not?
Jan
25
asked When do I know if energy stored in an object is 0 or nonzero? (Heat transfer)