Heat loss from a rectangular fin calculates the heat loss from a rectangular fin (see Fig. 10.7-1) for the following conditions: 

Air temperature                       350°F 

Wall temperature                     500°F 

Thermal conductivity of fin    60 Btu / hr ∙ ft ∙ F  

Thermal conductivity of air    0.0022 Btu/hr ∙ ft ∙ F 

Heat transfer coefficient         120 Btu/hr ∙ ft² ∙ F 

Length of fin                              0.2 ft 

Width of fin                               1.0 ft 

Thickness of fin                         0.16 in