SINGLE BUBBLE GROWTH OF PURE FLUIDS AND BINARY MIXTURES WITH A CONSTANT WALL TEMPERATURE CONDITION

摘要

Nucleate pool boiling experiments with constant wall temperatures were performed using pure R11, R113, and mixtures of R11 and R113. A microscale heater array and Wheatstone bridge circuits were used to maintain a constant wall temperature condition and to obtain measurements with high temporal and spatial resolution. The measured heat flow rate showed a discernible peak in the initial growth stage, and reached an almost constant value. Images of the bubble growth were captured using a high-speed CCD camera synchronized with the heat flow rate measurements. In the asymptotic growth region, the bubble showed a growth rate that was proportional to t~(1/5). The bubble growth behavior was analyzed using a new dimensionless parameter to permit comparisons with previous results at the same scale. The comparisons showed good agreement in the asymptotic growth region. A non-dimensional correlation for the bubble radius that can predict the bubble growth and the heat flow rate, simultaneously, was suggested. The required heat flow rate for the volume change of the observed bubble was larger than the instantaneous heat flow rate supplied from the wall.