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. The tubes are either aligned or staggered. 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 rate per length of tube. Radiation is negligible and air properties are assumed independent of temperature. The sliders can adjust the arrangement of the tubes, but for a ratio of transverse pitch to longitudinal pitch less than 0.7, aligned tubes should not be considered due to ineffective heat transfer. 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 can be shown.

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