Hiroto Sakashita

J-GLOBAL         Last updated: Jan 9, 2020 at 14:50
 
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Name
Hiroto Sakashita
E-mail
sakaeng.hokudai.ac.jp
Affiliation
Hokkaido University

Research Areas

 
 

Published Papers

 
J.Wang, H.Sakashita, F.C.Li, M.Mori
Experimental Thermal and Fluid Science   93 131-138   2018   [Refereed]
Matsumoto Tatsuki, Sakurada Keishi, Miwa Shuichiro, Sakashita Hiroto, Mori Michitsugu
ANNALS OF NUCLEAR ENERGY   108 79-88   Oct 2017   [Refereed]
Miwa Shuichiro, Endo Hiroto, Moribe Takahiro, Sakashita Hiroto, Mori Michitsugu, Hibiki Takashi
APPLIED THERMAL ENGINEERING   109 261-271   Oct 2016   [Refereed]
Hiroto Sakashita
Journal of Thermal Science and Technology   11(2) 1-12   Aug 2016   [Refereed]
Y.Hamada, H.Kokami, S.Miwa, H.Sakashita and M.Mori
Annals of Nuclear Energy   94 223-229   Aug 2016   [Refereed]
Hiroto Sakashita
International Journal of Heat and Mass Transfer   93 1000-1007   2016   [Refereed]
Hiroto Sakashita
Journal of Nuclear Science and Technology   53(6) 797-802   2016   [Refereed]
SAKASHITA HIROTO
Int J Heat Mass Transfer   55(23-24) 7312-7320   Nov 2012
SAKASHITA HIROTO
J Nucl Sci Technol   48(5) 734-743 (J-STAGE)   2011
SAKASHITA HIROTO, ONO AYAKO, NAKABAYASHI YUTA
Int J Heat Mass Transfer   53(7-8) 1554-1562   Mar 2010

Misc

 
Sakashita Hiroto
Proceedings of National Heat Transfer Symposium   2011(0) 168-168   2011
液体中にナノ粒子を分散させたナノ流体を沸騰の作動媒体として用いると,限界熱流束(CHF)は大きく促進される.本研究では,CHF促進機構を検討するために,直径25nmのTiO2ナノ粒子を析出させた上向き伝熱面上の水のプール沸騰を対象として導電プローブを用いて伝熱面近傍の気液挙動を測定し,伝熱面と蒸気塊の間に存在する液層厚さ(マクロ液膜厚さ)を特定した.その結果,TiO2析出面で形成されるマクロ液膜は,清浄面に比べて厚くなることが判明した.この厚いマクロ液膜の形成が,ナノ流体によるCHF促進の...
SAKASHITA Hiroto
伝熱 : journal of the Heat Transfer Society of Japan   49(209) 53-62   Oct 2010
CHIKAHISA Takemi, OSONE Yasuo, KURODA Akiyoshi, KUWAHARA Fujio, SAKASHITA Hiroto, TOTANI Tsuyoshi, NAKAMURA Yuji, YAMADA Masahiko, TABE Yutaka
Journal of the Heat Transfar Society of Japan   49(208) 19-28   Jul 2010
Sakashita Hiroto
Proceedings of National Heat Transfer Symposium   2010(0) 222-222   2010
2-プロパノール水溶液のプール沸騰における限界熱流束は水に比べて大幅に促進される.この要因は,伝熱面近傍の気液構造が水の沸騰とは大きく異なることによる,この違いをもたらす要因を検討するため,直径12mmの上向き伝熱面近傍の温度場を微細熱電対を用いて測定した.その結果,2-プロパノール水溶液の沸騰では,液の飽和温度が空間的に大きな不均一を持つことが判明した.得られた飽和温度の分布から濃度分布を算出した結果,2-プロパノールの濃度は径方向で大きく異なり,伝熱面中央部で大幅に低下していることが判...
Sakashita Hiroto, Ono Ayako
Proceedings of National Heat Transfer Symposium   2009(0) 14-14   2009
2-プロパノール水溶液による限界熱流束促進機構を検討するため,上向き面の飽和プール沸騰において伝熱面近傍の気液挙動を触針法で測定した.その結果, 2-プロパノール水溶液では,蒸気塊下の液層厚さが伝熱面中央部で著しく厚く周辺部で薄くなっていることが判明した.一方,表面活性剤(SDS)を添加した水溶液では,伝熱面中央部は乾燥状態にあり周辺部のみで沸騰を生じるなど,気液構造は全く異なる.したがって,2-プロパノール添加による限界熱流束の促進は,気泡微細化や表面張力の低下だけでは説明できない.
nakabayashi Yuta, Ono Ayakko, Sakashita Hiroto
Proceedings of National Heat Transfer Symposium   2008(0) 265-265   2008
前報において,水に微量の2-プロパノールを添加することで,上向き面上のプール沸騰の限界熱流束(CHF)が大幅に促進されることを明らかにした.本研究は,伝熱面近傍の気液構造を導電プローブによって測定し,水と2-プロパノールの沸騰でどのような違いが生じるかを検討した.また,表面張力や伝熱面周囲の構造の違いがCHFに与える影響を調べ,マランゴニ効果とCHF促進との関連性を検討した.
ONO Ayako, SAKASHITA Hiroto
Procee[d]ings of Thermal Engineering Conference   2007 131-132   Nov 2007
This paper summarizes the results of our researches that we have performed to clarify the mechanism of critical heat flux (CHF) for saturated and subcooled pool boiling on an upward surface with high heat capacity. The reasons why the macrolayer d...
ONO Ayako, SAKASHITA Hiroto
Transactions of the Japan Society of Mechanical Engineers. B   73(725) 283-290   Jan 2007
The authors have conducted measurements of liquid-vapor behavior in the vicinity of a heating surface for saturated and subcooled pool boiling on an upward-facing copper surface by using a conductance probe method. The previous paper (Transactions...
ONO Ayako, SAKASHITA Hiroto
Procee[d]ings of Thermal Engineering Conference   2006 179-180   Nov 2006
A macrolayer formation model in saturated and subcooled pool boiling is presented. It is assumed that the spatial distributions of nucleation sites are described by the Poisson distribution. Active nucleation site density is calculated by consider...
ONO Ayako, SAKASHITA Hiroto
Procee[d]ings of Thermal Engineering Conference   2005 41-42   Nov 2005
For the purpose of clarifying the mechanism of CHF for saturated and subcooled pool boiling, boiling behaviors close to a heating surface were investigated with micro-sensors. Dryout process of the heating surface appearing near the CHF was measur...
SAKASHITA Hiroto
Transactions of the Japan Society of Mechanical Engineers. B   71(702) 552-558   Feb 2005
Observation of boiling behavior and measurement of critical heat flux (CHF) were carried out for saturated water boiling on a horizontal, upward-facing plate at pressures from atmospheric to 7MPa. The heating surface was made of nichrom with 20μm ...
ONO Ayako, SAKASHITA Hiroto
Transactions of the Japan Society of Mechanical Engineers. B   70(699) 2951-2958   Nov 2004
A conductance probe method with high accuracy was developed to measure liquid-vapor structure at high heat flux in the vicinity of boiling surface. The probe with tip diameter below 5μm was made using electro-polishing technique. Measurements were...
ONO Ayako, SAKASHITA Hiroto
Procee[d]ings of Thermal Engineering Conference   2004 127-128   Nov 2004
Dryout process appearing near critical heat flux for water boiling on an upward heating surface was investigated with conductance probes with tip diameter below 5μm. 2-D distribution of dryout void fraction was obtained by analyzing the dryout sig...
SAKASHITA Hiroto, ONO Ryujiro, ONO Ayako
年次大会講演論文集 : JSME annual meeting   2003(6) 263-264   Aug 2003
A conductance probe method and a capacitance probe method were developed to measure liquid-vapor behavior in the vicinity of boiling surface with high accuracy. With the conductance probe, liquid macrolayer thicknesses formed beneath the large coa...
Cherif Ould Lahoucine, Sakashita Hiroto, Kumada Toshiaki
Jpn. J. Thermophys. Prop.   15(3) 176-181   2001
A thermistor probe method is developed for measuring the thermal conductivity of buffer materials used in the repository of high level radioactive wastes. The two-dimensional heat conduction model including a thermistor probe is developed and calc...
CHERIF Ould Lahoucine, SAKASHITA Hiroto, KUMADA Toshiaki
Transactions of the Atomic Energy Society of Japan   43(9) 924-930   2001
The paper concerns the measurement of thermal conductivity of buffer materials and the evaluation of existing correlations predicting thermal conductivity of them. The thermistor probe method developed by the authors was used to measure the therma...
SAKASHITA Hiroto, KUMADA Toshiaki
Transactions of the Atomic Energy Society of Japan   40(3) 235-240   1998
A mechanistic heat transfer model of highly compacted bentonite is developed to derive equations predicting the thermal conductivity. In the model clearances between molecular layers in the montmorillonite particles and spaces among the particles ...
坂下 弘人, 熊田 俊明
Bulletin of the Faculty of Engineering,Hokkaido University   (150) p91-97   May 1990
熊田 俊明, 坂下 弘人, 山岸 英明
Bulletin of the Faculty of Engineering,Hokkaido University   (144) p67-74   Dec 1988

Books etc

 
Boiling: Research and Advances
Hiroto Sakashita (Part:Contributor, 3.1 Critical heat flux and near-wall boiling behaviors in pool boiling)
Elsevier   2017   

Conference Activities & Talks

 
CHF and Near-Wall Boiling Behaviors in Flow boiling on a Vertical Surface
Hiroto Sakashita
17 Dec 2019   
Estimation of local concentrations and visualization of boiling behaviors at high heat fluxes in saturated pool boiling of 2-propanol/water mixtures
Hiroto Sakashita
16th International Heat Transfer Conference   Aug 2018   
Macrolayer Formation Model for Prediction of Critical Heat Flux in Saturated and Subcooled Pool Boiling
Ayako Ono and Hiroto Sakashita
10th International Conference on Boiling and Condensation Heat Transfer   Mar 2018   
Boiling behaviors on a vertical surface in saturated pool boiling at high pressures
Hiroto Sakashita
15th International Heat Transfer Conference, IHTC15-9772 (12pages)   Aug 2014   
Mechanism of CHF enhancement in pool boiling of nanofluids
Hiroto Sakashita
The 8th KSME-JSME Thermal and Fluids Engineering Conference   2012   

Research Grants & Projects

 
Ministry of Education, Culture, Sports, Science and Technology: Grants-in-Aid for Scientific Research(基盤研究(C))
Project Year: 2010 - 2012    Investigator(s): Hiroto SAKASHITA
This study investigated the saturated pool boiling of water on a 12mm diameter horizontal heating surface coated with TiO2 nanoparticles under atmospheric pressure. The CHF for the TiO2 coated surface increased up to about 2 times the CHF for the ...
Ministry of Education, Culture, Sports, Science and Technology: Grants-in-Aid for Scientific Research(基盤研究(C))
Project Year: 2006 - 2007    Investigator(s): Hiroto SAKASHITA
A purpose of the present study is to develop an effective method to drastically enhance the critical heat flux (CHF) in pool boiling. The present study focused on the method by using positive mixtures; binary aqueous solutions where less volatile ...
Ministry of Education, Culture, Sports, Science and Technology: Grants-in-Aid for Scientific Research(基盤研究(C))
Project Year: 2001 - 2002    Investigator(s): Hiroto SAKASHITA
In subcooled pool boiling on heating surfaces with high thermal capacity, large coalesced bubbles are formed and detach repeatedly and rest thin liquid-rich layer (termed liquid macrolayer) on their bottom. Critical heat flux occurs when the liqui...