Heat transfer and crisis phenomena at boiling in Freon mixture films falling down the structured tube

摘要

Investigation results on hydrodynamics, heat transfer, and crisis phenomena in laminar-wave liquid films falling down the surfaces of different geometry are presented in this study. Freon mixture R21/R114 with initial concentration of low-boiling component of 4-16. 6 % was used as the working liquid. The film Reynolds number at the inlet to the experimental section varied from 60 to 700. The heat flux density was changed within 0-5 W/cm 2. The images of wave surface of the falling liquid film and formation of dry spots were visualized and recorded by the high-speed video camera. Results of investigation of the wave structure of the film surface, measurements of heat transfer coefficients under the conditions of boiling, and critical heat fluxes in the film flow over the smooth and structured surfaces are presented.