Local velocities inside the gas phase during counter-current two-phase flow in a narrow vertical channel

New data are reported on local axial velocities inside the gas phase a vertical rectangular channel with an 8-mm gap between its main parallel plates, during counter-current air/water flow. Such a flow is considered to Simulate, though in a simplified manner, a single flow 'element' of a compact condenser. Mean local velocities, velocity spectra, turbulent intensities and other statistical information have been obtained by analysing the instantaneous velocity records of the gas phase acquired in presence of the liquid film, for relatively low gas Reynolds numbers. A computational fluid dynamics code (CFV(R)) was employed to obtain the velocity profiles and the values calculated are found to be in good agreement with those obtained experimentally. The data suggest that for gas Reynolds numbers in the range of 500-1300 the gas motion resembles the behaviour of turbulent flow.