HEAT TRANSFER FROM A HORIZONTAL BUBBLING SURFACE TO AN OVERLYING WATER POOL†

An experimenl was performed to study the effects of bubbling from a circular, horizontal, fiat plate on the heat transfer to an overlying water pool. The plate had drilled orifices through which nitrogen was injected into an overlying pool of water at atmospheric pressure. For “deep” pools, the heat transfer coefficient was found to increase only about 20% over a range of superficial gas velocities from 0.6 to 8.5cm/s, A turbulent heat transfer model developed by Konsetov was found to agree well with the data from this experiment. This model and the experimental data suggest that under certain conditions the heat transfer coefficient is similar for both horizontal and vertical surfaces. These conditions are, that the bubbles only contribute to the stirring action in the pool and only when the bubbling pool is considered “deep”. When the pool height fell below 60% of its diameter, the heat transfer coefficient decreased almost linearly with pool height. This suggests that there occurs a reduction in the turbulent fluctuations or in the characteristic length scale based on the average turbulent eddy size as the pool height decreases.