Study on heat exchange with low temperature difference for high heat flux by boiling heat transfer enhancement surface with microstructure

2014 Fiscal Year Final Research Report

• Project/Area Number: 24560233
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Thermal engineering
• Research Institution: Kobe University
• Principal Investigator: ASANO Hitoshi 神戸大学, 工学(系)研究科(研究院), 准教授 (10260647)
• Co-Investigator(Kenkyū-buntansha): SUGIMOTO Katsumi 神戸大学, 大学院工学研究科, 助教 (40420468) ; TAKENAKA Nobuyuki 神戸大学, 大学院工学研究科, 教授 (50171658)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 熱交換 / 沸騰熱伝達 / 強制対流 / 限界熱流束 / ドライアウト / 伝熱促進 / 膜沸騰 / ボイド率

Outline of Final Research Achievements

Thermal spray coating with porous structure had been applied for boiling heat transfer enhancement. In this study, two special phenomena that was observed only for the coating, a deterioration in heat transfer coefficient of forced convective boiling flow and an increase in CHF for subcooled flow boiling were examined.
On the 1st subject, it was considered based on liquid hold-up measurements by capacitance method that that the deterioration was caused by large dry patches in the active nucleate boiling field.
On the 2nd subject, it was found that a large pressure fluctuation in synchronization with void fraction fluctuation was observed in DNB. The fluctuation was caused by periodic change in boiling behavior of nucleate and film boiling. During the pressure fluctuation, the wall temperature gradually increased, and then stable vapor film was formed. The effect of the surface structure on the wall temperature at the stable vapor film formation was a little.

Free Research Field

熱工学