Chapter 3, Problem 3.20P

The $t=4\text{-mm-thick}$ glass windows of an automobile have a surface area of $A=2.6{\text{m}}^{\text{2}}.$ The outside temperature is $T_{\infty ,o}=32°\text{C}$ while the passenger compartment is maintained at $T_{\infty ,i}=22°\text{C}\text{.}$ The convection heat transfer coefficient on the exterior window surface is $h_o=90{\text{W/m}}^{\text{2}}\cdot \text{K}\text{.}$ Determine the heat gain through the windows when the interior convection heat transfer coefficient is $h_i=15{\text{W/m}}^{\text{2}}\cdot \text{K}\text{.}$ By controlling the air-flow in the passenger compartment the interior heat transfer coefficient can be reduced to $h_i=5{\text{W/m}}^{\text{2}}\cdot \text{K}$ without sacrificing passenger comfort. Determine the heat gain through the window for the reduced inside heat transfer coefficient.