DEVELOPMENT OF BUBBLY BOILING IN CHANNEL FLOW

The development of bubbly boiling in a tubular channel is investigated experimentally. Boiling conditions are achieved by decreasing the pressure and mass flux density of the medium flowing in the channel. It is found that under certain favorable circumstances at the outlet from the heated channel, that is, at the place of the highest liquid superheat, a boiling front is formed and then propagates upstream. The boiling front propagation velocity depends on, among other factors, the void fraction, the pressure drop giving rise to the boiling, and the heat flux density at the channel wall. Based on the acquired experimental data, a correlation is elaborated in the form of nondimensional criterial numbers describing the development of bubbly boiling in channel flow. The investigations also indicate the wave character of bubbly boiling in channel flow.