抄録
Pool nucleate boiling heat transfer experiments were performed for water using heat transfer surfaces having unified cavities. Cylindrical holes of 10 μm in diameter and 40 μm in depth were formed on a mirror-finished silicon wafer of 0.2 mm in thickness using Micro-Electro Mechanical Systems (MEMS) technology. This silicon plate was used as the heat transfer surface. The test heat transfer surface was heated by a semiconductor laser beam. Experiments were conducted in the range of up to 1.35 × 105 W⁄m2. When a single cavity was formed, the vertical coalescence of bubbles above the cavity was 60 % and no coalescence was 40 %. The ratios of the convection and the phase change were 80 % and 20 %, respectively. When the number of cavities were increased to three, the coalescence of bubbles on the heat transfer surface became important. When the role of the convection and the phase change in nucleate boiling is considered, it is appropriate to examine the bubble departure from the vapor mass on the heat transfer surface not from cavities.
