Heat Transfer Ehancement and Pressure Drop in the Flow Boiling Field with the Bubble Movement Restricted by a Screen Sheet

摘要

A unique method, which was previously propose by the authors in the pool boiling cases, was experimentally investigated udner flow boiling conditions. A screen sheet was used in this method. It was set parallel to the horizontal heated wall with a very small separation. When nucleate boiling occurred on the wall, the vapor bubbles generated were trapped by the screen and became flat. Then they moved downstream along the heated surface in the gap between the scrren and the wall. This movement caused the heat transfer augmentation. Although the pressure drop was increased considerably, the resutls showed that the ehat transfer enhancement seen in pool boiling also occurred under the flow boiling situation within the present experimental range.