Water at 290 K and 0.25 kg/s flows through a Teflon tube of inner and outer radii equal to 10 and 14 mm, respectively. A thin electrical heating tape wrapped around the outer su…

asked Sep 14, 2021 179k views

Water at 290 K and 0.25 kg/s flows through a Teflon tube of inner and outer radii equal to 10 and 14 mm, respectively. A thin electrical heating tape wrapped around the outer surface of the tube delivers a uniform surface heat flux of 2500 W/m2 , while a convection coefficient of 25 W/m2 ·K is maintained on the outer surface of the tape by ambient air at 300 K. What is the fraction of the power dissipated by the tape, which is transferred to the water? What is the outer surface temperature of the Teflon tube? (Hint: draw a thermal circuit and consider where the various "currents" are flowing.)