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Heat transfer rate to heating time

  1. Aug 6, 2008 #1
    i have set up an equation to get the heat transfer rate Q for a combined system where heat is transfered from a cylindrical outer wall set at 500 C. the wall heats a gas, which in turn heats a solid block of cylindrical metal positioned in the centre of the heated walls with a starting temperature of 20 C.

    the equation i have is

    Q=[1]\frac{}{}[/(A0/(h*Alm1))+((r*A0)/(k*A2))+(A0/(h*Alm3))+((r*A0)/(k*A4))+(A0/(h*Alm5))]*A0*[tex]\Delta[/tex]T

    and it give a result of 11.3213 Watts or the situation above.

    but too me this seems small?? am i right in thinking this?

    also can anyone tell me how i can relate this heat transfer to time. ie. know how long it would take to heat the central metal part.

    Thank you in advance.
     
  2. jcsd
  3. Aug 10, 2008 #2
    could you fix the latex?
     
  4. Aug 11, 2008 #3
    i could not get the equation editor to work properly (probaly the user to be fair) but i am included a hand written version as an attachment. i have managed to modifie it a bit which is giving me more sensible answers. But to get a value for time (in seconds#) i am using the below equation to get a value for q in joulse and then dividing q by Q.

    q=cm[tex]\Delta[/tex]T

    c = specific heat of the gas
    m = mass of gas
    delta T = the change in temperature

    Thanks
     

    Attached Files:

  5. Oct 17, 2008 #4
    Hi, can you send me eveything about this equation including details the of model, description of the variable and sketch, I will look into this.....
    My email address is riscy00@googlemail.com
     
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