Mass transfer between a flow core and a boundary liquid film in tubes with nonuniform in length heating

The results of experimental study of liquid flow rate in a film at a disperse circular flow of freon-12 in tubes with nonuniform longitudinal heat release are presented. The selection of a liquid film has been carried out on a 8 mm internal diameter tube at heat flux step-by-step and linear change in length at 1.06 MPa pressure and mass rate 1000 kg/m2s. In tubes with the decreasing to the outlet heat flux the intensity of liquid mass transfer from a flow core into the liquid film is higher than at a uniform heating. This can lead to the fact that at a certain combination of mode parameters the heat transfer crisis arises up the flow and is characterized by a higher value of critical capacity than for a uniformly heated channel of the same length. The heat transfer crisis over the whole region of investigated parameters is practically caused by a complete exhaustion of the film of the liquid flowing over the heated surface