The surface of a 50-mm-diameter, thin-walled tube is maintained at 100°c. in one case air is in cross flow over the tube with a temperature of 25°c and a velocity of 30 m/s. (extternal flow ) in another case air is in fully developed flow through the tube with a temperature of 25°c and a mean velocity of 30 m/s. (internalflow ) compare the heat flux from the tube to the air for the two cases.

Aspherical thermocouple measurement errors a spherical thermocouple made of constantin transfer coefficient between the gas and the thermocouple is h used to measure the temperature of a gas. the heat 400 w/m2 k. calculate the maximum diameter d of the thermocouple if the thermocouple's measurement error should be w 23 within 5% of the initial temperature difference in 5 seconds. for constantin, k 8920 kg/m3, and c 410 j/kg. k.