Study on Bubble Departure Frequency in Subcooled Boiling Flow under Narrow Rectangular Channel

A visual study on forced convection subcooled water boiling experiments was conducted in vertical upward narrow rectangular channels by using the high-speed digital video camera.The results show that the increasing of mass flux or subcooled inlet causes the decreasing of bubble frequency,and the increas-ing of the heat flux causes the increasing of bubble frequency.Existing models were compared with the ex-perimental data of bubble frequency.The correlations developed for the pool boiling or saturated boiling do not work well for subcooled boiling flow.A dimensionless bubble departure frequency correlation has been sought for the influence of mass flux,subcooled flow and heat flux by using the dimensionless number of Reynolds number,Jacob number and dimensionless nucleate boiling heat flux.The proposed model agreed with the experimental data within the averaged relative deviation of ±17.1%.