Heat Transfer in a Bank of Tubes
This Demonstration shows convective, steady-state heat transfer from a bank of tubes, which are at a constant temperature of 70 °C, to cross-flowing air, which enters at 15 °C. Align or stagger the tubes with buttons. The aligned configuration has flow lanes for the air, whereas the staggered configuration disrupts these flow lanes. When the air velocity increases, the rate of heat transfer increases and the outlet air temperature decreases. An average Nusselt number is calculated for the entire tube bank, and that number is used to calculate the outlet air temperature and the heat transfer rate per length of tube. Radiation is negligible and air properties are assumed independent of temperature. Use sliders to adjust the arrangement of the tubes. Due to ineffective heat transfer, aligned tubes should not be considered for a ratio of transverse pitch to longitudinal pitch less than 0.7. The tube diameter does not change when the tube arrangement changes, but the diameter displayed in the tube configuration figure changes so that all tubes are shown.
Contributed by: Benjamin L. Kee (April 2014)
Additional contributions by: Rachael L. Baumann and John L. Falconer
(University of Colorado Boulder, Department of Chemical and Biological Engineering)
Open content licensed under CC BY-NC-SA