Find the temperature of the bar (made of aluminum, k = 202.4 W/m*k) with a rectangular cross-section at the center point. The Left end of rectangular is 80 c, the right end is 40 c and side walls convection boundary layer (steam temperature 22 c) and convection coefficient is 15 W/m^(2)K. Length is 10 mm, height 10 mm and width 100 mm. Please show working out.

Respuesta :

Explanation:

As it is given that no heat is generating and the system is present in steady state.

As we know that,

    [tex]\frac{\partial^{2}T}{\partial x^{2}} + \frac{Q}{k}[/tex] = [tex]\frac{1}{\alpha} \frac{\partial T}{\partial t}[/tex]

So, according to the given conditions, [tex]\frac{Q}{k}[/tex] = 0, and [tex]\frac{1}{\alpha} \frac{\partial T}{\partial t}[/tex] = 0

So,     [tex]\frac{\partial^{2}T}{\partial x^{2}}[/tex] = 0 , [tex]\frac{\partial T}{\partial x}[/tex] = [tex]C_{1}[/tex]

               T = [tex]C_{1}x + C_{2}[/tex]

Hence, boundary conditions will be as follows.

At x = 0, T = [tex]80^{o}C[/tex]

At x = L, T = [tex]40^{o}C[/tex]

Applying boundary condition is [tex]T_{0} = C_{2}[/tex]

Therefore, [tex]T_{0} = C_{2}[/tex] = [tex]80^{o}C[/tex]

       [tex]T_{L} = C_{1}x + 80[/tex]

               40 = [tex]C_{1} (100 \times 10^{-3}) + 80[/tex]

          [tex]\frac{-40}{100 \times 10^{-3}} = C_{1}[/tex]

                 [tex]C_{1}[/tex] = -400

Hence, temperature distribution in a block will be as follows.

                  T = -400x + 80

At center, x = [tex]50 \times 10^{-3}[/tex]

Therefore,  T = [tex]-400 \times 50 \times 10^{-3} + 80[/tex]

                      = [tex]60^{o}C[/tex]

Thus, we can conclude that the temperature of block at the center point is [tex]60^{o}C[/tex].