An electric current of 200 A is passed through a stainless steel wire having a radius R of 0.001268 m. The wire is L = 0.91 m long and has a resistance R of 0.126 Ohm. The outer surface temperature Tw is held at 422.1 K. The average thermal conductivity is K = 22.5 W/mK. Calculate the center temperature. Power = I^2R (Watts) Where I = current in nmps and R = Resistance in ohms I^2R (Watts) = q pi(Radius)^2L

Respuesta :

Answer:

The value is   [tex]T_m  =  435.2 \  K[/tex]

Explanation:

From the question we are told that  

   The  current is  [tex]I  =  200 \ A[/tex]

   The radius is  [tex]R =  0.001268 \  m[/tex]

   The  length of the wire is  [tex]L  =  0.91 \  m[/tex]\

    The  resistance is  [tex]R  =  0.126 \  \Omega[/tex]

    The  outer surface temperature is  [tex]T _o  =  422.1 \  K[/tex]

    The average thermal conductivity is  [tex]\sigma  =  22.5 W/mK[/tex]

   

Generally the heat generated in the stainless steel wire is mathematically represented as  

    [tex]Q =  \frac{Power}{ \pi r^2L}[/tex]

     [tex]Q =  \frac{I^2 R}{ \pi r^2L}[/tex]

=>   [tex]Q =  \frac{200^2 * 0.126}{3.142 *  (0.001268)^2 * 0.91}[/tex]

=>   [tex]Q =  1.096*10^{9}\  W/m^3[/tex]

Generally the middle temperature is mathematically represented as

      [tex]T_m  =  T_o  + \frac{Q * r^2 }{ 6  * \sigma }[/tex]

       [tex]T_m  =  422.1  +  \frac{1.096*10^{-9} * 0.001268^2}{6 * 22.5}[/tex]

       [tex]T_m  =  435.2 \  K[/tex]