Heat transfer in condensing, pulsating flows

The internal heat transfer coefficient in a pulsating circular pipe flow was determined for both dry and condensing surfaces. The fully-reversing flow was driven by a pulse combustion process at a frequency of 34 Hz. The mean Reynolds numbers ranged from approximately 2600 to 4300, while the instantaneous Reynolds number had a maximum of 18,000. The internal heat transfer is noted to increase by up to a factor of 1.8 due to the pulsating flow prior to the onset of condensation, and by up to 12 times after the onset of condensation. At all Reynolds numbers and flow regimes tested, the flow pulsations were observed to enhance heat transfer when compared to steady flow results.