Effect of surface configuration on nucleate boiling heat transfer

To investigate in detail the effect of surface configuration on nucleate boiling heat transfer, the experiment of nucleate pool boiling of water at atmospheric pressure from a copper flat plate whose orientation is varied from 0° to 175° from the horizontal plane is performed. The effect of surface orientation is remarkable in the low heat flux region where the heat transfer coefficient increases as the inclination angle is increased. On the contrary there is no marked effect in the high heat flux region. To explain the observed effect of surface orientation for the surfaces facing downwards, two mechanisms of the sensible heat transport by compulsory removal of the thermal layer by the rising bubble and the latent heat transport by evaporation from thin liquid film underneath the rising bubble are proposed. The latter contribution becomes more predominant at large inclination angles.