Repeat Problem 6-98 for the same mass flow of atmospheric helium with properties evaluated at 255, 477, and 700 K and comment on the results.
Problem 6-98
It has been noted that convection heat transfer is dependent on fluid properties, which in turn are dependent on temperature. Consider flow of atmospheric air at 0.012 kg/s in a smooth 2.5-cm-diameter tube. Assuming that the Dittus-Boelter relation [Equation (6-4a)] applies, calculate the average heat-transfer coefficient for properties evaluated at 300, 400, 500, and 800 K. Comment on the results.