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Thermodynamics? number crunching thermal conductivity

  1. Feb 5, 2014 #1
    I am working on some basic calcs for heat transfer from polyethylene pipe. My numbers are not working out right so I need a little refresher.

    The PE pipe would have a TC of about .46 W/(m.*C). to get to BTU/(hr.ft.*F), I mult by .5779 to get .266.

    Assuming 10sf of PE pipe, and lets say a dT of 10*F, how do I arrive at my BTU/hr? Wall thickness of piping is .120" but I am told that does not matter. IIRC, the unit is actualy per sf PER ft so I might actually divide by my thickness which gets me closer at around 2.22 BTU/hr/sf*F of pipe?
  2. jcsd
  3. Feb 5, 2014 #2
    The formula for the heat load Q (BTU/hr) is:
    where d is the wall thickness.
  4. Feb 5, 2014 #3
    I guess I am second guessing the units here. Would you mind applying the math to my above figures? Would this indeed be


    k/d = 2.22BTU?
  5. Feb 5, 2014 #4
    You need to use d expressed in feet. How many inches are there in 1 ft?
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