In a combined heat and power (CHP) generation process, by-product heat is used for domestic or industrial heating purposes. Hot steam is carried from a CHP generation plant by a tube with diameter of 127 mm centered at a square cross section solid bar made of concrete with thermal conductivity of 1.7 W/m · K. The surface temperature of the tube is constant at 120°C, while the square concrete bar is exposed to air with temperature of –5°C and convection heat transfer coefficient of 20 W/m² · K. If the temperature difference between the outer surface of the square concrete bar and the ambient air is to be maintained at 5°C, determine the width of the square concrete bar and the rate of heat loss per meter length.

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Air, -5°C h = 20 W/m².K T₁ = 120°C D = 127 mm T₂ W Concrete bar k = 1.7 W/m-K