Abstract
A digital photographic study of pool boiling with binary mixture R11-R113 was performed on a horizontal transparent heater at pressure of 0.1 MPa. A high-speed digital camera was applied to record the bubble behaviors of boiling process. Strong effects of composition on bubble departure diameter, departure time, nucleation density were observed, which was attributed to the nature of the activation of the boiling surface and mass diffusion effects. The bubble departure diameter, departure period and nucleation density as functions of composition for binary mixtures R11-R113 were presented respectively. From the video images, it can be concluded that evaporation of microlayer is very important to the growth of bubble. It is also observed that there is not any liquid recruited into the microlayer below the bubble. At last, based on microlayer model for pure substance, considering the mass diffusion effect, a theoretical model was presented in this paper. The curve between the heat transfer coefficients and the composition for binary mixtures was predicted by using this model. As a result, the agreement between the predictions and the experiment data is good at high heat flux.
