Determine the heat lost by radiation per metre length of a 75 mm oxidised steel pipe at 327°C if (a) located in a large room with red brick walls at a temperature of 27°C, (b) enclosed in a 150 mm...

Determine the heat lost by radiation per metre length of a 75 mm oxidised steel pipe at 327°C if (a) located in a large room with red brick walls at a temperature of 27°C, (b) enclosed in a 150 mm
 150 mm red brick walls at a temperature of 27°C. Emissivities of oxidised steel and red brick are 0.79 and 0.93 respectively.