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Hiroshi Honda - One of the best experts on this subject based on the ideXlab platform.

  • examination of Minimum Heat Flux point condition for film boiling on a sphere in terms of the limiting liquid superHeat and the critical vapor film thickness
    International Journal of Heat and Mass Transfer, 2012
    Co-Authors: Osamu Makishi, Hiroshi Honda
    Abstract:

    Abstract Previously proposed theories of the Minimum-Heat-Flux-point (MHF-point) condition were examined using available experimental data obtained from the immersion cooling of spheres in water. The sphere diameter ranged from 9.5 to 30 mm and the liquid subcooling from 0 to 85 K. The limiting liquid superHeat predicted by the Lienhard equation was compared with the liquid–solid interface superHeat at the instant of liquid–solid contact at the MHF-point. The results showed that the liquid–solid interface superHeat was not limited by the limiting liquid superHeat and its value was connected with the collapse mode of vapor film. The collapse mode was a coherent collapse at a low interface superHeat and the mode changed to a propagative collapse as the interface superHeat increased. The critical vapor film thickness obtained from the linear stability analysis of vapor film was compared with the calculated value of average vapor film thickness at the MHF-point. For all data, the ratio of the average vapor film thickness to the critical vapor film thickness was correlated well as a function of liquid subcooling. The ratio decreased with increasing liquid subcooling and tended to about 0.8 to 1 depending on the experiments. This indicated that the MHF-point at a high liquid subcooling was determined by the critical vapor film thickness. A physical consideration was given to the effect of liquid–solid contact that occurred in the film boiling region on the calculated value of the vapor film thickness and the stability of vapor film.

  • the Minimum Heat Flux point condition for film boiling on a sphere examination on the limiting liquid superHeat and the critical vapor film thickness
    Transactions of the Japan Society of Mechanical Engineers. B, 2011
    Co-Authors: Osamu Makishi, Hiroshi Honda
    Abstract:

    Previously proposed theories on the Minimum-Heat-Flux-point (MHF-point) condition were examined using available data obtained from the immersion cooling experiments of spheres in water. The sphere diameter ranged from 9.5 mm to 30mm and the liquid subcooling from 0 K to 85 K. The limiting liquid superHeat predicted by the Lienhard equation was compared with the wall superHeat at the instant of liquid-solid contact at the MHF-point. The results showed that the wall superHeat at the MHF-point was not limited by the limiting liquid superHeat and its value was connected with the collapse mode of vapor film. The collapse mode was a coherent collapse at a low wall superHeat and the mode changed to a propagative collapse as the wall superHeat increased. The critical vapor film thickness obtained from the linear stability analysis of vapor film was compared with the calculated value of average vapor film thickness at the MHF-point. For all data, the ratio of the average vapor film thickness and the critical vapor film thickness was correlated well as a function of liquid subcooling. The ratio decreased with increasing liquid subcooling and tended to 0.8 to 1 depending on the experiments. This indicated that the MHF-point at a high liquid subcooling was determined by the critical vapor film thickness. A physical consideration was given to the effect of liquid-solid contact that occurred in the film boiling region on the calculated value of the vapor film thickness and the stability of vapor film.

  • Effect of the behavior of generated vapor on the Minimum-Heat-Flux point during rapid quenching of a thin horizontal wire
    TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B, 1999
    Co-Authors: Hiroshi Honda, Hiroshi Takamatsu, Hikaru Yamashiro, Kazuo Tanaka
    Abstract:

    Heat transfer characteristics and minumum Heat Flux point (MHF point) condition during rapid quenching of a thin horizontal wire were studied both experimentally and theoretically. Experiments were conducted with ethanol as a quenching liquid. The wire was either fixed or moving downward at a constant speed in an ethanol bath. When the wire was Heated instantly to a high temperature, bead like bubbles were formed along the wire. This was in contrast to the previous results for a Heated wire that was dipped into the ethanol bath at a relatively high velocity, where a vapor sheet was formed in the wake of the wire. Consideration was given to the effect of film boiling mode on the MHF point condition. A linear stability analysis of vapor film for natural convection film boiling on a horizontal cylinder was presented. The theoretical prediction of the critical vapor film thickness compared well with the measured value at the MHF point for the fixed wire.

  • Stability of Vapor Film in Subcooled Forced-Convection Film Boiling on a Horizontal Cylinder : An Analysis Considering the Effect of Periodic Heat Conduction
    TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B, 1998
    Co-Authors: Hiroshi Honda, Hiroshi Takamatsu, Hikaru Yamashiro
    Abstract:

    A linear stability analysis of vapor film in forced-convection film boiling on a horizontal cylinder is presented that considers the effects of liquid inertia, viscosity and compressibility of vapor, and periodic Heat conduction. The theoretical prediction of the critical vaper film thickness compared well with the measured mean vapor film thickness at the Minimum-Heat-Flux point that was obtained from the rapid quenching experiments of thin horizontal wires in water and ethanol. However, while the theoretical prediction was about 20% higher than the experiment for water, the former was about 15% lower than the latter for ethanol. Discussion was given to the cause of this difference between the water and ethanol results.

  • Theoretical analysis of the stability of vapor film in subcooled film boiling on a horizontal wire
    Heat Transfer - Japanese Research, 1997
    Co-Authors: Hiroshi Takamatsu, Hikaru Yamashiro, Hiroshi Honda
    Abstract:

    Linear stability analysis of a thin vapor film in subcooled film boiling on a horizontal cylinder is reported. The effects of liquid inertia, vapor viscosity and compressibility, and Heat transfer were taken into account. Theoretical predictions of the Heat transfer coefficient at the neutral stability point were compared with experimental data at the Minimum-Heat-Flux point that was obtained during rapid quenching of thin horizontal wires in water and ethanol. At high liquid subcooling, the experimental value was 60% of the theoretical prediction irrespective of the wire diameter and quenching liquid. This difference was considered to be due to the nonuniformity of the vapor film which was neglected in the theoretical analysis.

Hikaru Yamashiro - One of the best experts on this subject based on the ideXlab platform.

  • Effect of the behavior of generated vapor on the Minimum-Heat-Flux point during rapid quenching of a thin horizontal wire
    TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B, 1999
    Co-Authors: Hiroshi Honda, Hiroshi Takamatsu, Hikaru Yamashiro, Kazuo Tanaka
    Abstract:

    Heat transfer characteristics and minumum Heat Flux point (MHF point) condition during rapid quenching of a thin horizontal wire were studied both experimentally and theoretically. Experiments were conducted with ethanol as a quenching liquid. The wire was either fixed or moving downward at a constant speed in an ethanol bath. When the wire was Heated instantly to a high temperature, bead like bubbles were formed along the wire. This was in contrast to the previous results for a Heated wire that was dipped into the ethanol bath at a relatively high velocity, where a vapor sheet was formed in the wake of the wire. Consideration was given to the effect of film boiling mode on the MHF point condition. A linear stability analysis of vapor film for natural convection film boiling on a horizontal cylinder was presented. The theoretical prediction of the critical vapor film thickness compared well with the measured value at the MHF point for the fixed wire.

  • Stability of Vapor Film in Subcooled Forced-Convection Film Boiling on a Horizontal Cylinder : An Analysis Considering the Effect of Periodic Heat Conduction
    TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B, 1998
    Co-Authors: Hiroshi Honda, Hiroshi Takamatsu, Hikaru Yamashiro
    Abstract:

    A linear stability analysis of vapor film in forced-convection film boiling on a horizontal cylinder is presented that considers the effects of liquid inertia, viscosity and compressibility of vapor, and periodic Heat conduction. The theoretical prediction of the critical vaper film thickness compared well with the measured mean vapor film thickness at the Minimum-Heat-Flux point that was obtained from the rapid quenching experiments of thin horizontal wires in water and ethanol. However, while the theoretical prediction was about 20% higher than the experiment for water, the former was about 15% lower than the latter for ethanol. Discussion was given to the cause of this difference between the water and ethanol results.

  • Theoretical analysis of the stability of vapor film in subcooled film boiling on a horizontal wire
    Heat Transfer - Japanese Research, 1997
    Co-Authors: Hiroshi Takamatsu, Hikaru Yamashiro, Hiroshi Honda
    Abstract:

    Linear stability analysis of a thin vapor film in subcooled film boiling on a horizontal cylinder is reported. The effects of liquid inertia, vapor viscosity and compressibility, and Heat transfer were taken into account. Theoretical predictions of the Heat transfer coefficient at the neutral stability point were compared with experimental data at the Minimum-Heat-Flux point that was obtained during rapid quenching of thin horizontal wires in water and ethanol. At high liquid subcooling, the experimental value was 60% of the theoretical prediction irrespective of the wire diameter and quenching liquid. This difference was considered to be due to the nonuniformity of the vapor film which was neglected in the theoretical analysis.

  • Minimum Heat-Flux point and liquid-solid contact during rapid quenching of thin wires
    Heat Transfer - Japanese Research, 1995
    Co-Authors: Hiroshi Honda, Hiroshi Takamatsu, Hikaru Yamashiro
    Abstract:

    Rapid quenching of thin horizontal platinum wires falling at a constant speed was studied experimentally using pure water and ethanol as the quenching liquids. The transient boiling curve obtained from the cooling curve had two local Minimum Heat-Flux (MHF) points. Measurements of liquid-solid contact and observations of boiling patterns showed that a marked liquid-solid contact began at the first (higher wall superHeat) MHF point M1. The Heat-transfer results indicated that the M1 point corresponded to the Minimum vapor film thickness for stable film boiling. The effects of liquid subcooling and falling velocity on the average vapor film thickness and the wall superHeat at the M1 point were explained. The wall superHeat at the second MHF point M2 was almost constant for each liquid regardless of the liquid subcooling and the falling velocity.

  • Heat-transfer characteristics during rapid quenching of a thin wire in water
    Heat Transfer - Japanese Research, 1992
    Co-Authors: Hiroshi Honda, Hiroshi Takamatsu, Hikaru Yamashiro, Shintaro Kobayashi
    Abstract:

    Rapid quenching of thin horizontal platinum wires (0.3 and 0.5 mm in diameter) was studied experimentally using pure water as the quenching liquid. The cooling curve was obtained in the ranges of water temperature of 0 to 50° C, falling velocity of the wire of 0.1 to 1.5 m/s, and initial wire temperature of 600 to 1400° C. Boiling curves for the rapid quenching process were obtained from the cooling curve. The degree of superHeat at the Minimum Heat Flux point was around 350 K irrespective of the water temperature, the falling velocity, and the wire diameter. The Heat Fluxes in the film, transition, and nucleate boiling regions increased with increasing degree of subcooling and falling velocity

Hiroshi Takamatsu - One of the best experts on this subject based on the ideXlab platform.

  • Effect of the behavior of generated vapor on the Minimum-Heat-Flux point during rapid quenching of a thin horizontal wire
    TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B, 1999
    Co-Authors: Hiroshi Honda, Hiroshi Takamatsu, Hikaru Yamashiro, Kazuo Tanaka
    Abstract:

    Heat transfer characteristics and minumum Heat Flux point (MHF point) condition during rapid quenching of a thin horizontal wire were studied both experimentally and theoretically. Experiments were conducted with ethanol as a quenching liquid. The wire was either fixed or moving downward at a constant speed in an ethanol bath. When the wire was Heated instantly to a high temperature, bead like bubbles were formed along the wire. This was in contrast to the previous results for a Heated wire that was dipped into the ethanol bath at a relatively high velocity, where a vapor sheet was formed in the wake of the wire. Consideration was given to the effect of film boiling mode on the MHF point condition. A linear stability analysis of vapor film for natural convection film boiling on a horizontal cylinder was presented. The theoretical prediction of the critical vapor film thickness compared well with the measured value at the MHF point for the fixed wire.

  • Stability of Vapor Film in Subcooled Forced-Convection Film Boiling on a Horizontal Cylinder : An Analysis Considering the Effect of Periodic Heat Conduction
    TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B, 1998
    Co-Authors: Hiroshi Honda, Hiroshi Takamatsu, Hikaru Yamashiro
    Abstract:

    A linear stability analysis of vapor film in forced-convection film boiling on a horizontal cylinder is presented that considers the effects of liquid inertia, viscosity and compressibility of vapor, and periodic Heat conduction. The theoretical prediction of the critical vaper film thickness compared well with the measured mean vapor film thickness at the Minimum-Heat-Flux point that was obtained from the rapid quenching experiments of thin horizontal wires in water and ethanol. However, while the theoretical prediction was about 20% higher than the experiment for water, the former was about 15% lower than the latter for ethanol. Discussion was given to the cause of this difference between the water and ethanol results.

  • Theoretical analysis of the stability of vapor film in subcooled film boiling on a horizontal wire
    Heat Transfer - Japanese Research, 1997
    Co-Authors: Hiroshi Takamatsu, Hikaru Yamashiro, Hiroshi Honda
    Abstract:

    Linear stability analysis of a thin vapor film in subcooled film boiling on a horizontal cylinder is reported. The effects of liquid inertia, vapor viscosity and compressibility, and Heat transfer were taken into account. Theoretical predictions of the Heat transfer coefficient at the neutral stability point were compared with experimental data at the Minimum-Heat-Flux point that was obtained during rapid quenching of thin horizontal wires in water and ethanol. At high liquid subcooling, the experimental value was 60% of the theoretical prediction irrespective of the wire diameter and quenching liquid. This difference was considered to be due to the nonuniformity of the vapor film which was neglected in the theoretical analysis.

  • Minimum Heat-Flux point and liquid-solid contact during rapid quenching of thin wires
    Heat Transfer - Japanese Research, 1995
    Co-Authors: Hiroshi Honda, Hiroshi Takamatsu, Hikaru Yamashiro
    Abstract:

    Rapid quenching of thin horizontal platinum wires falling at a constant speed was studied experimentally using pure water and ethanol as the quenching liquids. The transient boiling curve obtained from the cooling curve had two local Minimum Heat-Flux (MHF) points. Measurements of liquid-solid contact and observations of boiling patterns showed that a marked liquid-solid contact began at the first (higher wall superHeat) MHF point M1. The Heat-transfer results indicated that the M1 point corresponded to the Minimum vapor film thickness for stable film boiling. The effects of liquid subcooling and falling velocity on the average vapor film thickness and the wall superHeat at the M1 point were explained. The wall superHeat at the second MHF point M2 was almost constant for each liquid regardless of the liquid subcooling and the falling velocity.

  • Heat-transfer characteristics during rapid quenching of a thin wire in water
    Heat Transfer - Japanese Research, 1992
    Co-Authors: Hiroshi Honda, Hiroshi Takamatsu, Hikaru Yamashiro, Shintaro Kobayashi
    Abstract:

    Rapid quenching of thin horizontal platinum wires (0.3 and 0.5 mm in diameter) was studied experimentally using pure water as the quenching liquid. The cooling curve was obtained in the ranges of water temperature of 0 to 50° C, falling velocity of the wire of 0.1 to 1.5 m/s, and initial wire temperature of 600 to 1400° C. Boiling curves for the rapid quenching process were obtained from the cooling curve. The degree of superHeat at the Minimum Heat Flux point was around 350 K irrespective of the water temperature, the falling velocity, and the wire diameter. The Heat Fluxes in the film, transition, and nucleate boiling regions increased with increasing degree of subcooling and falling velocity

Shoichrou Fukusako - One of the best experts on this subject based on the ideXlab platform.

  • Experimental study on the critical Heat Flux of ice accretion along a fine wire immersed in a cold air flow with water spray
    Lecture Notes in Physics, 1
    Co-Authors: Koji Fumoto, Hideaki Yamagishi, Shoichrou Fukusako
    Abstract:

    An experimental study was carried out on the critical Heat Flux of ice accretion along a horizontal wire immersed in a cold air stream with water spray. The critical Heat Flux was defined as the Minimum Heat Flux, which could maintain de-icing along a wire. The air stream velocity and temperature range were from about 3 to 8 ms−1 and from −5 to −15 deg. C, respectively, and the average droplet diameter of the water-spray range was from 140 to 640 µm. In order to determine the effect of the wire diameter on the critical Heat Flux, three diameters, namely, 0.5, 0.8 and 1.0 mm were selected. The critical Heat Flux was determined from the profile of the variation of the wire temperature with the loading electric power on the wire. It was found for the conditions of the present experiments that the critical Heat Flux showed a linear increase with an increase in the air stream temperature and velocity. Moreover, the effects of the profile of droplet and wire diameter on the critical Heat Flux were examined.

Ashok Kumar Satapathy - One of the best experts on this subject based on the ideXlab platform.

  • Rewetting of an Infinite Slab With Uniform Heating Under Quasi-Steady Conditions
    Journal of Heat Transfer, 2002
    Co-Authors: Ashok Kumar Satapathy, Ranjit K. Sahoo
    Abstract:

    The two-dimensional quasi-steady conduction equation governing conduction controlled rewetting of an infinite slab, with one side flooded and the other side subjected to a constant Heat Flux, has been solved by Wiener-Hopf technique. The solution yields the quench front temperature as a function of various model parameters such as Peclet number, Riot number and dimensionless Heat Flux. Also, the critical (dryout) Heat Flux is obtained by setting the Peclet number equal to zero, which gives the Minimum Heat Flux required to prevent the hot surface being rewetted.

  • Rewetting of an infinite tube with internal Heating
    International Journal of Numerical Methods for Heat & Fluid Flow, 2001
    Co-Authors: Ashok Kumar Satapathy, Ranjit K. Sahoo
    Abstract:

    A numerical study has been made to investigate the effect of internal Heating and precursory cooling during quenching of an infinite tube. The finite difference solution gives the quench front temperature as a function of various model parameters such as Peclet number, Biot number and dimensionless Heat Flux. The parametric dependence of the rewetting rate is obtained by the condition that the surface can only be wetted when its temperature is below the quench front temperature. Also, the critical Heat Flux is obtained by setting Peclet number equal to zero, which gives the Minimum Heat Flux required to prevent the hot surface being rewetted. The numerical model is validated by comparing the results with known closed form solutions.

  • Rewetting of an infinite slab with boundary Heat Flux
    Numerical Heat Transfer Part A-applications, 2000
    Co-Authors: Ashok Kumar Satapathy
    Abstract:

    This paper deals with a numerical solution of the two-dimensional quasi-static conduction equation, governing conduction controlled rewetting of an infinitely long slab with one side flooded and the other side subjected to a constant Heat Flux. The solution gives the quench front temperature as a function of various model parameters such as Peclet number, Biot number, and dimensionless boundary Heat Flux. Also, the critical boundary Heat Flux is obtained by setting the Peclet number equal to zero, which gives the Minimum Heat Flux required to prevent the hot surface being rewetted.