thermodynamics question

[dowxp]

i never took thermo since i went went another route in college, but do any of you know how to solve this problem?

1 foot long, 1" carbon steel pipe filled with water, capped, and heated to 600F at one end. assuming normal ambient conditions, say 80F, 5mph winds, what would the temperature be at the other end assuming the heated end stays constant at 600F?

 

[jpeyton]

42

 

[jaha2000]

Thats more of a heat transfer problem then a thermo problem....
How thick is the pipe? SCH40, SCH80?

 

[dowxp]

sch80. i guess i just need a direction in what theory to read.

 

[Fritzo]

We will not break the laws of thermodynamics in THIS forum!

 

[LordMorpheus]

It's a heat transfer problem, not a thermo problem. Find a textbook with an example problem similar to the one given, and see how they solved it.

 

[dullard]

That isn't an easy problem. And you definately don't give enough information. I'd have to do some calculations first, but it may be possible that the steam inside the pipe is undergoing natural convection. The answer will depend on the direction of the pipe. Is it vertical and heated from the top? Or is it vertical and heated from the bottom? Is it horizontal? Although, you'd have to calculate if these effects are significant or not.

I'd personally make a bunch of assumptions. I'd ignore the steam effects. Then I'd assume the temperature is approximately constant on the surface (that is, assume it is 600°F everywhere). Then look up the equation for heat transfer for forced convection on the outside of a tube/pipe (empirical and theoretical equations exist which depend on the pipe's orientation). With that equation and assumptions, you'd find that heat is approximately linearly lost to the wind. Thus, the temperature would be approximately linearly dropping from 600°F to the temperature at the free end of this steam pipe bomb. If you calculate that the free end temperature is near 600°F, then you are done and the assumptions were correct. If not, the assumptions are incorrect and you'd have to solve this with the full method.

Note: be sure to see if radiation is important in this problem.

Page 373 will tell you most of what you need.