Answer:
Heat is lost at the rate of 750 J/s or W
The thermal resistance is 1 K/W
Explanation:
interior temperature [tex]T_{2}[/tex] = 900 °C
wall thickness t = 60 cm = 0.6 m
width = 1 m
breadth = 1.5 m
thermal conductivity k = 0.4 W/m-K
outside temperature [tex]T_{1}[/tex] = 150 °C
heat through the wall = ?
The area of the wall A = w x b = 1 x 1.5 = 1.5 m^2
Temperature difference [tex]dt[/tex] = [tex]T_{2}[/tex] - [tex]T_{1}[/tex] = 900 - 150 = 750 °C
note that [tex]dt[/tex] is also equal to 750 K since to convert from °C to K we'll have to add 273 to both temperature, which will still cancel out when we subtract the two temperatures.
To get the heat that escapes through the wall, we use the equation
Q = Ak[tex]\frac{dt}{t}[/tex]
substituting values, we have
Q = 1.5 x 0.4 x [tex]\frac{750}{0.6}[/tex] = 750 J/s or W
Thermal resistance [tex]R_{t}[/tex] = [tex]\frac{dt}{Q}[/tex]
[tex]R_{t}[/tex] = 750/750 = 1 K/W
