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A study on improvement of wettability on heating surface and boiling heat transfer enhancement by thermal spray coating

Research Project

Project/Area Number 17560187
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Thermal engineering
Research InstitutionKobe University

Principal Investigator

ASANO Hitoshi  Kobe University, Faculty of Engineering Dept. of Mechanical Engineering, Associate Professor, 工学部, 助教授 (10260647)

Co-Investigator(Kenkyū-buntansha) TAKENAKA Nobuyuki  Kobe University, Faculty of Engineering Dept. of Mechanical Engineering, Professor, 工学部, 教授 (50171658)
Project Period (FY) 2005 – 2006
Project Status Completed (Fiscal Year 2006)
Budget Amount *help
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2006: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2005: ¥1,900,000 (Direct Cost: ¥1,900,000)
KeywordsNucleate boiling / Heat transfer enhancement / Thermal spray coating / Pool boiling / Forced convective boiling / Wall superheat at onset of boiling / Critical heat flux / Neutron radiography / 核沸騰熱伝達 / 沸騰開始過熱度 / ボイド率
Research Abstract

Two-phase flow cooling system utilizing latent heat is required to obtain higher cooling heat flux from electro or power equipments. In this case, enhancement of boiling heat transfer, reduction in wall superheat at the onset of boiling, and increase critical heat flux are desired. In the investigator's previous work on pool boiling experiments, it was shown that constant heat transfer enhancement could be obtained by vacuum plasma spray coating over the experimental heat flux range, and wall superheat at the onset of boiling could be reduced. However, critical heat flux on thermal spray coating was almost the same as that on smooth surface. Moreover, from a microgravity experiment during a parabolic trajectory flight of airplane, it was shown that thermal spray coating produced almost the same boiling heat transfer enhancement as that under normal gravity. It could be said that the surface has high wettability due to complex microscopic sub-channels in coatings.
In this study, pool boi … More ling and forced convective boiling heat transfer on thermal spray coatings were evaluated for some coatings with different material and structure. In the pool boiling experiments, a horizontal tube test section was covered by a cylinder with a clearance of 1 to 2 mm in order to clarify the effect of vapor bubble that is hard to depart, and the effect of the cover on the boiling heat transfer was considered. As the result, it was shown that heat transfer was improved by the cover, the effect for smooth surface was larger than for thermal spray coating, and the critical heat flux was decreased by the cover for both surfaces.
On the other hand, for the forced convective boiling experiment, aluminum and copper narrow channels with the conduit width of 20 mm and height of 2 mm were used. For the aluminum test section, vertical upward flows under inlet subcool condition were examined, and wall superheat at the onset of boiling and steady condition were evaluated. Moreover, void fraction distributions in the narrow channel were measured by neutron radiography method. As the results, the thermal spray surface made the wall superheat at the onset of boiling lower and the critical heat flux higher.
For copper coating on copper plate, it was shown from horizontal boiling flow experiments that the coating surface produced 2 to 4 times higher heat transfer coefficient. The enhancement factor increased with increasing heat flux. Hysteresis in heating procedure existed in boiling heat transfer characteristics. Higher heating velocity lead to higher heat transfer coefficient. Less

Report

(3 results)
  • 2006 Annual Research Report   Final Research Report Summary
  • 2005 Annual Research Report
  • Research Products

    (9 results)

All 2006

All Journal Article (9 results)

  • [Journal Article] 溶射皮膜による核沸騰伝熱促進に関する研究(微小重力場でのプール沸騰実験結果)2006

    • Author(s)
      浅野等, 秋田賢二, 黒田陽子, 藤井照重
    • Journal Title

      日本混相流学会誌,混相流研究の進展 I

      Pages: 103-109

    • NAID

      130004488682

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Annual Research Report 2006 Final Research Report Summary
  • [Journal Article] 水平円柱周りのプール沸騰熱伝達に及ぼす重力の影響に関する研究(溶射皮膜による伝熱促進効果の評価)2006

    • Author(s)
      浅野等, 秋田賢二, 藤井照重
    • Journal Title

      日本マイクログラビティ応用学会誌 "JASMA" 23・2

      Pages: 88-92

    • NAID

      10017427645

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Boiling Heat Transfer Enhancement by Spray Coating Surface (Effect of Gravity on Pool Boiling Heat Transfer)2006

    • Author(s)
      Hitoshi Asano, Kenji Akita, Terushige Fujii
    • Journal Title

      Proc. 13th International Heat Transfer Conference, on CD-Rom.

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] A Study on Nucleate Boiling Heat Transfer Enhancement by Thermal Spray Coating (Results of Pool Boiling Experiments under Micro gravity)2006

    • Author(s)
      Hitoshi ASANO, Kenji AKITA, Yoko KURODA, Terushige FUJII
    • Journal Title

      Progress in multiphase flow research I

      Pages: 103-109

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Effect of Gravity on Pool Boiling Heat Transfer around a Horizontal Cylinder (Evaluation of Heat Transfer Enhancement by Thermal Spraying)2006

    • Author(s)
      Hitoshi ASANO, Kenji AKITA, Terushige FUJII
    • Journal Title

      Journal of the Japan Society of Microgravity Application

      Pages: 88-92

    • NAID

      10017427645

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] Boiling Heat Transfer Enhancement by Spray Coating Surface (Effect of Gravity on Pool Boiling Heat Transfer)2006

    • Author(s)
      Hitoshi ASANO, Kenji AKITA, Terushige FUJII
    • Journal Title

      Proc. 13th International Heat Transfer Conference Paper No. BOI-50(on CD-Rom)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2006 Final Research Report Summary
  • [Journal Article] 水平円柱周りのプール沸騰熱伝達に及ぼす重力の影響に関する研究(溶射皮膜による伝熱促進効果の評価)2006

    • Author(s)
      浅野等, 秋田賢二, 藤井照重
    • Journal Title

      日本マイクログラビティ応用学会誌"JASMA" 23・2

      Pages: 88-92

    • NAID

      10017427645

    • Related Report
      2006 Annual Research Report
  • [Journal Article] Boiling Heat Transfer Enhancement by Spray Coating Surface (Effect of Gravity on Pool Boiling Heat Transfer)2006

    • Author(s)
      Hitoshi Asano, Kenji Akita, Terushige Fujii
    • Journal Title

      Proc. 13th International Heat Transfer Conference (on CD-Rom)

    • Related Report
      2006 Annual Research Report
  • [Journal Article] 溶射皮膜による核沸騰伝熱促進に関する研究(微小重力場でのプール沸騰実験結果)2006

    • Author(s)
      浅野等, 秋田賢二, 黒田陽子, 藤井照重
    • Journal Title

      混相流 (印刷中)

    • NAID

      130004488682

    • Related Report
      2005 Annual Research Report

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Published: 2005-04-01   Modified: 2016-04-21  

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