Chapter 12, Problem 12.3P

Interpretation Introduction

Interpretation:

The overall heat transfer coefficient based on the inside area of the pipe and the heat flux based on the outside area is to be calculated.

Concept introduction:

The heat transfer coefficient is calculated using an appropriate Nusselt correlation.

For high Reynolds number in the straight round tubes and pipes, the following correlation is used to calculate the heat transfer coefficient:

  $h_i=0.023{\mathrm{Re}}^{-0.2}{\mathrm{Pr}}^{-2/3}{C}_{p}G$

The overall heat transfer coefficient based on the inside area of the pipe is calculated using the following equation:

  $U_i=\frac{1}{1/h_i+x_w/k_m\frac{D_i}{D_L}+1/h_o\frac{D_i}{D_o}}$

The relationship between overall heat transfer coefficient based on inside and outside area is given by the following expression:

  ${\text{U}}_o{D}_o=U_i{D}_i$

The heat flux based on the outside area is calculated using the following equation:

  $\frac{q}{A}=U_o\left(T_1-T_2\right)$