Steam in a heating system flows through tubes whose outer diameter is D1= 3 cm and whose walls are maintained at a temperature of 125oC. Circular aluminium fins ( k = 180 W/moC ) of outer diameter D2= 6 cm and constant thickness t = 2mm are attached to the tube, as shown in the Figure. The space between the fins is 3mm, and thus there are 200 fins per meter length of the tube. Heat is transferred to the surrounding air at 
=27oC, with a combined heat transfer coefficient of h = 60 W/m2 oC. Determine the increase n heat transfer from the tube per meter of its length as a result of adding fins.
