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Masanori Monde - One of the best experts on this subject based on the ideXlab platform.

  • Characteristics of Wetting Temperature and Maximum Heat Flux During Spray Cooling of Hot Surface
    2010 14th International Heat Transfer Conference Volume 6, 2010
    Co-Authors: Yuichi Mitsutake, Masanori Monde
    Abstract:

    An experimental investigation has been done to elucidate the effects of mass Flux G, degree of subcooling ΔTsub and initial solid temperature Tb0 on transient spray cooling of a downward facing φ89 mm hot block surface. The spray impact diameter was adjusted to φ110mm and φ36mm which simulate uniform and non-uniform spray cooling of the surface. The block made of copper, brass and carbon steel at an initial temperature of 200–500 °C was cooled with subcooled water and ethanol spray. The subcooling was from 10 to 80 K and the mass Flux was from 1 to 72 kg/m2 s. Surface temperature and surface Heat Flux were evaluated with an axisymmetric 2D inverse Heat conduction analysis. A transient transition regime was characterized with a wetting temperature and a quenching temperature. The wetting and quenching temperatures were correlated fairly with GΔTsub . Effects of G, ΔTsub , Tb0 and a thermal inertia of the solid (ρcλ)s on a Maximum Heat Flux are evaluated.Copyright © 2010 by ASME

  • Maximum Heat Flux propagation velocity during quenching by water jet impingement
    International Journal of Heat and Mass Transfer, 2007
    Co-Authors: Aloke Kumar Mozumder, Peter Woodfield, M A Islam, Masanori Monde
    Abstract:

    Abstract Maximum Heat Flux propagation characteristics during quenching of hot cylindrical blocks with initial temperature 250–600 °C have been investigated experimentally using a subcooled water jet. When the wetted area starts moving towards the circumferential region, the Heat Flux reaches its Maximum value and the position of Maximum Heat Flux follows the visible leading edge of the wetting front. If wetting starts immediately after the jet strikes the surface, the velocity of this Maximum Heat Flux point increases with the increase of jet velocity and subcooling and decreases with the increase of block initial temperature. These trends are opposite if there is a long delay before movement of the front.

  • Maximum Heat Flux propagation velocity during quenching by water jet impingement
    International Journal of Heat and Mass Transfer, 2007
    Co-Authors: Aloke Kumar Mozumder, Peter Woodfield, Md. Ashraful Islam, Masanori Monde
    Abstract:

    Maximum Heat Flux propagation characteristics during quenching of hot cylindrical blocks with initial temperature 250-600 àhave been investigated experimentally using a subcooled water jet. When the wetted area starts moving towards the circumferential region, the Heat Flux reaches its Maximum value and the position of Maximum Heat Flux follows the visible leading edge of the wetting front. If wetting starts immediately after the jet strikes the surface, the velocity of this Maximum Heat Flux point increases with the increase of jet velocity and subcooling and decreases with the increase of block initial temperature. These trends are opposite if there is a long delay before movement of the front.No Full Tex

  • Characteristics of transient Heat transfer during quenching of a vertical hot surface with a falling liquid film
    Heat Transfer—Asian Research, 2007
    Co-Authors: Hiroaki Matsueda, Masanori Monde, Shoichi Matsuda
    Abstract:

    An experimental study has been conducted to elucidate characteristics of transient Heat transfer during quenching of a vertical hot surface with a falling liquid film. The experiment was done at atmospheric pressure for the following conditions: an initial surface temperature from 200 to 400°C, a subcooling of 20– 80 K, average velocity of 0.52– 1.24 m/s, and the block material is copper and carbon steel. The surface temperature and Heat Flux are estimated from the measured temperatures in the block during the quench by a two-dimensional inverse solution. It follows that as the position of wetting advances downward, the position at which the Heat Flux becomes a Maximum also advances downward. The time at which the position of Maximum Heat Flux begins to move is one of the most important parameters and can be predicted by a proposed correlation. In addition, it is revealed that the Maximum Heat Flux for copper depends on the length to which it occurs from the leading edge. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(6): 345– 360, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20167

  • Maximum Heat Flux in relation to quenching of a high temperature surface with liquid jet impingement
    International Journal of Heat and Mass Transfer, 2006
    Co-Authors: Aloke Kumar Mozumder, Peter Woodfield, Masanori Monde, Ashraful Islam
    Abstract:

    Abstract Experimental investigation has been conducted for quenching of hot cylindrical blocks made of copper, brass and steel with initial block temperature 250–400 °C by a subcooled water jet of diameter of 2 mm. The subcooling was from 5 to 80 K and the jet velocity was from 3 to 15 m/s. After impingement, the jet stagnates for a certain period of time in a small region near the centre and then the wetting front starts moving outwards. During this movement, when the surface temperature at the wetting front drops to 120–200 °C, the surface Heat Flux reaches its Maximum value due to forced convection nucleation boiling. The Maximum Heat Flux is a strong function of the position on the hot surface, jet velocity, block material properties and jet subcooling. A new correlation for Maximum Heat Flux is proposed.

Aloke Kumar Mozumder - One of the best experts on this subject based on the ideXlab platform.

  • Jet quenching phenomena during emergency cooling of high temperature solid surface
    Energy Procedia, 2019
    Co-Authors: Aloke Kumar Mozumder, Mousumi Ahmed
    Abstract:

    Abstract In the case of loss of coolant accident, LOCA in nuclear reactor, Heat removal can be successful only when water rewets the surface. Jet impingement is a highly potential technique of Heat removal from high temperature solid surface. After the impingement of liquid jet on hot solid surface it is not capable to wet the surface immediately, it takes time (wetting delay) to get a favorable condition by the liquid to wet and then propagate over the surface. Generation of vapor and its explosion creates the barrier for the liquid front to move. An experimental investigation has been conducted during sub-cooled water jet impingement quenching of three different cylindrical blocks of copper, brass and steel. The jet velocity varied from 3 to15 m/s, jet sub-cooling was 5-80 K and initial block temperature was 250 to 600 oC. The study was conducted to determine the dominating parameters of Maximum Heat Flux, wetting delay, quench front movement, boiling region size and finally developed a correlation of Maximum Heat Flux for steel. After elapsing the wetting delay period, a visible smaller boiling region was observed to move radially from the impinged centre. The leading edge of this boiling region is designated as the quench front. The boiling region is a vital region as the Maximum Heat Flux occurred at this region during cooling. The boiling region increases with the movement of the quench front and therefore the position of Maximum Heat Flux moves accordingly. The boiling region width increases with material conductivity and decreases with liquid sub-cooling and liquid velocity. The Maximum Heat Flux increases with jet velocity, liquid sub-cooling, solid material conductivity and it is almost independent of solid initial temperature. Wetting delay increases with block initial temperature and decreases with jet velocity and liquid sub-cooling.

  • Maximum Heat Flux propagation velocity during quenching by water jet impingement
    International Journal of Heat and Mass Transfer, 2007
    Co-Authors: Aloke Kumar Mozumder, Peter Woodfield, M A Islam, Masanori Monde
    Abstract:

    Abstract Maximum Heat Flux propagation characteristics during quenching of hot cylindrical blocks with initial temperature 250–600 °C have been investigated experimentally using a subcooled water jet. When the wetted area starts moving towards the circumferential region, the Heat Flux reaches its Maximum value and the position of Maximum Heat Flux follows the visible leading edge of the wetting front. If wetting starts immediately after the jet strikes the surface, the velocity of this Maximum Heat Flux point increases with the increase of jet velocity and subcooling and decreases with the increase of block initial temperature. These trends are opposite if there is a long delay before movement of the front.

  • Maximum Heat Flux propagation velocity during quenching by water jet impingement
    International Journal of Heat and Mass Transfer, 2007
    Co-Authors: Aloke Kumar Mozumder, Peter Woodfield, Md. Ashraful Islam, Masanori Monde
    Abstract:

    Maximum Heat Flux propagation characteristics during quenching of hot cylindrical blocks with initial temperature 250-600 àhave been investigated experimentally using a subcooled water jet. When the wetted area starts moving towards the circumferential region, the Heat Flux reaches its Maximum value and the position of Maximum Heat Flux follows the visible leading edge of the wetting front. If wetting starts immediately after the jet strikes the surface, the velocity of this Maximum Heat Flux point increases with the increase of jet velocity and subcooling and decreases with the increase of block initial temperature. These trends are opposite if there is a long delay before movement of the front.No Full Tex

  • Maximum Heat Flux in relation to quenching of a high temperature surface with liquid jet impingement
    International Journal of Heat and Mass Transfer, 2006
    Co-Authors: Aloke Kumar Mozumder, Peter Woodfield, Masanori Monde, Ashraful Islam
    Abstract:

    Abstract Experimental investigation has been conducted for quenching of hot cylindrical blocks made of copper, brass and steel with initial block temperature 250–400 °C by a subcooled water jet of diameter of 2 mm. The subcooling was from 5 to 80 K and the jet velocity was from 3 to 15 m/s. After impingement, the jet stagnates for a certain period of time in a small region near the centre and then the wetting front starts moving outwards. During this movement, when the surface temperature at the wetting front drops to 120–200 °C, the surface Heat Flux reaches its Maximum value due to forced convection nucleation boiling. The Maximum Heat Flux is a strong function of the position on the hot surface, jet velocity, block material properties and jet subcooling. A new correlation for Maximum Heat Flux is proposed.

  • quenching of high temperature cylindrical surface with an impinging jet Maximum Heat Flux
    Transactions of the Japan Society of Mechanical Engineers. B, 2006
    Co-Authors: Masanori Monde, Aloke Kumar Mozumder, Peter Woodfield, Yuichi Mitsutake
    Abstract:

    An experimental study has been conducted to understand characteristics of transient Heat transfer during quenching a hot cylindrical block with an impinging water jet. The experiment was done at atmospheric pressure for the following condition : an initial block temperature of 250 and 400°C, a subcooling of 20-80 K, a jet velocity of 3-15 m/s, and a nozzle diameter of 2 mm. The surface temperature and Heat Flux are estimated by applying two-dimensional inverse solution to the measured temperatures in the block during the quench. The surface Heat Flux is greatly influenced by the position of the wetting front. It reveals that the Maximum Heat Flux appears slightly far from the wetting front and its value decreases with a distance from the jet. The experiment shows that the Maximum Heat Flux in the quecnching is smaller than the critical Heat Flux (CHF) in the corresponding steady condition depending on a cooling situation, but the trend is similar between the Maximum Heat Flux and the CHF. An equation is proposed to predict the Maximum Heat Flux on a basis of the CHF correlation.

Igor Pioro - One of the best experts on this subject based on the ideXlab platform.

  • Thermal Aspects of Using Uranium Mononitride Fuel in a SuperCritical Water-Cooled Reactor at Maximum Heat Flux Conditions
    18th International Conference on Nuclear Engineering: Volume 2, 2010
    Co-Authors: Ashley Milner, Wargha Peiman, Caleb Pascoe, Hemal Patel, Graham Richards, Igor Pioro
    Abstract:

    Generation IV nuclear reactor technology is increasing in popularity worldwide. One of the six Generation-IV-reactor types are SuperCritical Water-cooled Reactors (SCWRs). The main objective of SCWRs is to increase substantially thermal efficiency of Nuclear Power Plants (NPPs) and thus, to reduce electricity costs. This reactor type is developed from concepts of both Light Water Reactors (LWRs) and supercritical fossil-fired steam generators. The SCWR is similar to a LWR, but operates at a higher pressure and temperature. The coolant used in a SCWR is light water, which has supercritical pressures and temperatures during operation. Typical light water operating parameters for SCWRs are a pressure of 25 MPa, an inlet temperature of 280–350°C, and an outlet temperature up to 625°C. Currently, NPPs have thermal efficiency about of 30–35%, whereas SCW NPPs will operate with thermal efficiencies of 45–50%. Furthermore, since SCWRs have significantly higher water parameters than current water-cooled reactors, they are able to support co-generation of hydrogen. Studies conducted on fuel-channel options for SCWRs have shown that using uranium dioxide (UO2 ) as a fuel at supercritical-water conditions might be questionable. The industry accepted limit for the fuel centerline temperature is 1850°C and using UO2 would exceed this limit at certain conditions. Because of this problem, there have been other fuel options considered with a higher thermal conductivity. A generic 43-element bundle for an SCWR, using uranium mononitride (UN) as the fuel, is discussed in this paper. The material for the sHeath is Inconel-600, because it has a high resistance to corrosion and can adhere to the Maximum sHeath-temperature design limit of 850°C. For the purpose of this paper, the bundle will be analyzed at its Maximum Heat Flux. This will verify if the fuel centerline temperature does not exceed 1850°C and that the sHeath temperature remains below the limit of 850°C.Copyright © 2010 by ASME

  • Thermal Aspects of Using Uranium Dicarbide Fuel in an SCWR at Maximum Heat-Flux Conditions
    18th International Conference on Nuclear Engineering: Volume 2, 2010
    Co-Authors: Caleb Pascoe, Wargha Peiman, Ashley Milner, Hemal Patel, Graham Richards, Lisa Grande, Igor Pioro
    Abstract:

    There are 6 prospective Generation-IV nuclear reactor conceptual designs. SuperCritical Water-cooled nuclear Reactors (SCWRs) are one of these design options. The reactor coolant in SCWRs will be light water operating at 25 MPa and up to 625°C, actually at conditions above the critical point of water (22.1 MPa and 374°C, respectively). Current Nuclear Power Plants (NPPs) around the world operate at sub-critical pressures and temperatures achieving thermal efficiencies within the range of 30–35%. One of the major advantages of SCWRs is increased thermal efficiency up to 45–50% by utilizing the elevated temperatures and pressures. SuperCritical Water (SCW) behaves as a single-phase fluid. This prevents the occurrence of “dryout” phenomena. Additionally, operating at SCW conditions allows for a direct cycle to be utilized, thus simplifying the steam-flow circuit. The components required for steam generation and drying can be eliminated. Also, SCWRs have the ability to support hydrogen co-generation through thermochemical cycles. There are two main types of SCWR concepts being investigated, Pressure-Vessel (PV) and Pressure-Tube (PT) or Pressure-Channel (PCh) reactors. The current study models a single fuel channel from a 1200-MWel generic PT-type reactor with a pressure of 25 MPa, an inlet temperature of 350°C and an outlet temperature of 625°C. Since, SCWRs are presently in the design phase there are many efforts in determining fuel and sHeath combinations suited for SCWRs. The design criterion to determine feasible material combinations is restricted by the following constraints: 1) The industry accepted limit for fuel centreline temperature is 1850°C, and 2) sHeath-material-temperature design limit is 850°C. The primary candidate fuel is uranium dioxide. However; previous studies have shown that the fuel centreline temperature of an UO2 pellet might exceed the industry accepted limit for the fuel centreline temperature. Therefore, investigation on alternative fuels with higher thermal conductivities is required to respect the fuel centreline temperature limit. SHeath (clad) materials must be able to withstand the aggressive SCW conditions. Ideal sHeath properties are a high-corrosion resistance and high-temperature mechanical strength. Uranium dicarbide (UC2 ) is selected as a choice fuel, because of its high thermal conductivity compared to that of conventional nuclear fuels such as UO2 , Mixed OXide (MOX) and Thoria (ThO2 ). The chosen sHeath material is Inconel-600. This Ni-based alloy has high-yield strength and maintains its integrity beyond the design limit of 850°C. This paper utilizes a generic SCWR fuel channel containing a continuous 43-element bundle string. The bulk-fluid, sHeath and fuel-centreline temperature profiles together with Heat Transfer Coefficient (HTC) profile were calculated along the Heated length of a fuel channel at the Maximum Axial Heat Flux Profiles (AHFPs).Copyright © 2010 by ASME

  • Maximum Heat Flux to antifreeze boiling in a two-phase thermosiphon
    Heat Transfer Research, 1992
    Co-Authors: S. A. Tikhonovskiy, Igor Pioro
    Abstract:

    Experimental results on the Maximum Heat Flux to water-ethanol and water-ethylene glycol mixtures boiling in two-phase thermosiphons are presented. Relationships correcting for the effect of evaporator geometry and thermosiphon slope are derived

  • Maximum Heat transferring capacity of two phase thermosiphons with separate vapor and condensate streams
    Heat Transfer Research, 1992
    Co-Authors: Igor Pioro
    Abstract:

    Experimental results on the effects of the geometry of the evaporator, the slope of the thermosiphon and the circulation velocity on the Maximum Heat Flux in boiling of water in two-phase straight-through thermosiphons, and also photographs of the boiling of water in a rectangular channel are presented

Peter Woodfield - One of the best experts on this subject based on the ideXlab platform.

  • Maximum Heat Flux propagation velocity during quenching by water jet impingement
    International Journal of Heat and Mass Transfer, 2007
    Co-Authors: Aloke Kumar Mozumder, Peter Woodfield, M A Islam, Masanori Monde
    Abstract:

    Abstract Maximum Heat Flux propagation characteristics during quenching of hot cylindrical blocks with initial temperature 250–600 °C have been investigated experimentally using a subcooled water jet. When the wetted area starts moving towards the circumferential region, the Heat Flux reaches its Maximum value and the position of Maximum Heat Flux follows the visible leading edge of the wetting front. If wetting starts immediately after the jet strikes the surface, the velocity of this Maximum Heat Flux point increases with the increase of jet velocity and subcooling and decreases with the increase of block initial temperature. These trends are opposite if there is a long delay before movement of the front.

  • Maximum Heat Flux propagation velocity during quenching by water jet impingement
    International Journal of Heat and Mass Transfer, 2007
    Co-Authors: Aloke Kumar Mozumder, Peter Woodfield, Md. Ashraful Islam, Masanori Monde
    Abstract:

    Maximum Heat Flux propagation characteristics during quenching of hot cylindrical blocks with initial temperature 250-600 àhave been investigated experimentally using a subcooled water jet. When the wetted area starts moving towards the circumferential region, the Heat Flux reaches its Maximum value and the position of Maximum Heat Flux follows the visible leading edge of the wetting front. If wetting starts immediately after the jet strikes the surface, the velocity of this Maximum Heat Flux point increases with the increase of jet velocity and subcooling and decreases with the increase of block initial temperature. These trends are opposite if there is a long delay before movement of the front.No Full Tex

  • Maximum Heat Flux in relation to quenching of a high temperature surface with liquid jet impingement
    International Journal of Heat and Mass Transfer, 2006
    Co-Authors: Aloke Kumar Mozumder, Peter Woodfield, Masanori Monde, Ashraful Islam
    Abstract:

    Abstract Experimental investigation has been conducted for quenching of hot cylindrical blocks made of copper, brass and steel with initial block temperature 250–400 °C by a subcooled water jet of diameter of 2 mm. The subcooling was from 5 to 80 K and the jet velocity was from 3 to 15 m/s. After impingement, the jet stagnates for a certain period of time in a small region near the centre and then the wetting front starts moving outwards. During this movement, when the surface temperature at the wetting front drops to 120–200 °C, the surface Heat Flux reaches its Maximum value due to forced convection nucleation boiling. The Maximum Heat Flux is a strong function of the position on the hot surface, jet velocity, block material properties and jet subcooling. A new correlation for Maximum Heat Flux is proposed.

  • quenching of high temperature cylindrical surface with an impinging jet Maximum Heat Flux
    Transactions of the Japan Society of Mechanical Engineers. B, 2006
    Co-Authors: Masanori Monde, Aloke Kumar Mozumder, Peter Woodfield, Yuichi Mitsutake
    Abstract:

    An experimental study has been conducted to understand characteristics of transient Heat transfer during quenching a hot cylindrical block with an impinging water jet. The experiment was done at atmospheric pressure for the following condition : an initial block temperature of 250 and 400°C, a subcooling of 20-80 K, a jet velocity of 3-15 m/s, and a nozzle diameter of 2 mm. The surface temperature and Heat Flux are estimated by applying two-dimensional inverse solution to the measured temperatures in the block during the quench. The surface Heat Flux is greatly influenced by the position of the wetting front. It reveals that the Maximum Heat Flux appears slightly far from the wetting front and its value decreases with a distance from the jet. The experiment shows that the Maximum Heat Flux in the quecnching is smaller than the critical Heat Flux (CHF) in the corresponding steady condition depending on a cooling situation, but the trend is similar between the Maximum Heat Flux and the CHF. An equation is proposed to predict the Maximum Heat Flux on a basis of the CHF correlation.

  • Maximum Heat Flux in relation to quenching of a high temperature surface with liquid jet impingement
    International Journal of Heat and Mass Transfer, 2006
    Co-Authors: Aloke Kumar Mozumder, Peter Woodfield, Masanori Monde, M A Islam
    Abstract:

    Experimental investigation has been conducted for quenching of hot cylindrical blocks made of copper, brass and steel with initial block temperature 250-400 àby a subcooled water jet of diameter of 2 mm. The subcooling was from 5 to 80 K and the jet velocity was from 3 to 15 m/s. After impingement, the jet stagnates for a certain period of time in a small region near the centre and then the wetting front starts moving outwards. During this movement, when the surface temperature at the wetting front drops to 120-200 ì the surface Heat Flux reaches its Maximum value due to forced convection nucleation boiling. The Maximum Heat Flux is a strong function of the position on the hot surface, jet velocity, block material properties and jet subcooling. A new correlation for Maximum Heat Flux is proposed.No Full Tex

Zengyao Li - One of the best experts on this subject based on the ideXlab platform.

  • numerical simulation of solar radiation transmission process for the solar tower power plant from the heliostat field to the pressurized volumetric receiver
    Applied Thermal Engineering, 2013
    Co-Authors: Ya-ling He, Ze-dong Cheng, Zengyao Li
    Abstract:

    Abstract In the present work, a concentrating and collecting subsystem optical model for the solar tower power plant is fully developed and the corresponding solar radiation transmission process from heliostat field to the pressurized volumetric receiver (PVR) is simulated by the in-house developed Monte Carlo Ray Tracing (MCRT) code. Based on the above model, the optical efficiency of heliostat field and the local Heat Flux distribution within the SiC absorber are calculated, and then the influences of time and date, receiver mounting height and heliostats tracking error on the radiation transmission and absorption process are also investigated. The computation results show that, the Heat Flux distribution within the SiC absorber exhibits a great non-uniform characteristic, while the Maximum Heat Flux density at the top area of the absorber is up to 2.58 × 109 W/m3. The variation tendencies of the field efficiency and the Maximum Heat Flux density of the absorber are similar to that of the solar altitude angle during a day or a year. Furthermore, the annual mean field efficiency and the Maximum Heat Flux of the absorber exhibit a rapid decreasing trend as the tracking error increases, but show a little increasing trend as the receiver mounting height increases.