1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Temperature distribution with heat generation

  1. Nov 9, 2015 #1
    hey i really need help with solving this question.

    1. The problem statement, all variables and given/known data

    the problem is in one dimention x ( 2 plates with diffrent K joined together)
    for x=0 T=500 ( constat temp)
    0<x<L - electric wire is generating heat that maintane the constant temp in x=0 ,it has K=40W/mK.
    L<x<2L - there is rubber preventing electriciution and heat loss Ki= 0.2 W/Km , where T(2L)=300K(constant).

    how do i find the tempreture distribiotion in the 0<x<2L? (q* gen should be unknown but expressed in the finle answer)
    plz help :(

    2. Relevant equations
    foriers' law of conduction & Qin-Qout+Qgen=Qacc

    3. The attempt at a solution

    i can find the distribution using the heat balance integral.. but im not sure about the temperature at x=L..
  2. jcsd
  3. Nov 9, 2015 #2
    Let's see what you've done so far?

  4. Nov 9, 2015 #3
    well , i found the general form of the distribution of the electric wire area(0<x<L) but im missing a constant because im not sure what's the temprature in the middle.
    i was asked to find the distribution from 0<x<2L ..so i dont know if what i did is right..

    here's what i did (image ) :http://www.imageurlhost.com/di/NME6/-.png
  5. Nov 10, 2015 #4
  6. Nov 10, 2015 #5
    The flux has to be continuous at the interface.

  7. Nov 10, 2015 #6
    i know that..
  8. Nov 10, 2015 #7
    If the electrical wire is generating just enough heat to maintain the boundary at x = 0 constant at 500 K, to me that means that the boundary at x = 0 is essentially insulated (i.e., no external heat flux required). What does that mean with regard to the constant C2 in your equation?

    Last edited: Nov 10, 2015
  9. Nov 10, 2015 #8
    i know that constant i wrote in my answer that it is equal to T0. problem is the c1. i have no idea how to calculate it becase the other side of it has a diffrent k and has no heat generation.even if i compere heat flux. what shall i do ? i've tried everything!
  10. Nov 10, 2015 #9
    Oh. Sorry. I meant C1 in post #7, not C2.

  11. Nov 10, 2015 #10
    C1 = 0. With this new added information, do you think you will be able to complete the solution?
    Last edited: Nov 10, 2015
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted