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Homework Help: Engineering heat transfer problem for critical radius

  1. Nov 9, 2015 #1
    1. The problem statement, all variables and given/known data

    A pipe of internal radius r1=0.03 m is built to have conductivity variable with radius: k=ar2, where a=250 Wm/K. 1) Find the critical radius r2 for the maximum heat transfer by convection from its external surface if the heat transfer coefficient is h2=30 W/m2K.

    2. Relevant equations

    3. The attempt at a solution
    I am just wondering do i start differenticate the rate of heat transfer Q equation ? if not can anyone guide me.
  2. jcsd
  3. Nov 10, 2015 #2
    Let's see what you have done so far.

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