The Experts below are selected from a list of 42 Experts worldwide ranked by ideXlab platform

Hideo Nakamura - One of the best experts on this subject based on the ideXlab platform.

  • Upward air–water bubbly flow characteristics in a vertical square Duct
    Journal of Nuclear Science and Technology, 2013
    Co-Authors: Haomin Sun, Tomoaki Kunugi, Xiuzhong Shen, Hideo Nakamura
    Abstract:

    In nuclear engineering fields, gas–liquid bubbly flows exist in channels with various shape and size cross-sections. Although many experiments have been carried out especially in circular pipes, those in a Noncircular Duct are very limited. To contribute to the development of gas–liquid bubbly flow model for a Noncircular Duct, detail measurements for the air–water bubbly flow in a square Duct (side length: 0.136 m) were carried out by an X-type hot-film anemometry and a multi-sensor optical probe. Local flow parameters of the void fraction, bubble diameter, bubble frequency, axial liquid velocity and turbulent kinetic energy were measured in 11 two-phase flow conditions. These flow conditions covered bubbly flow with the area-averaged void fraction ranging from 0.069 to 0.172. A pronounced corner peak of the void fraction was observed in a quarter square area of a measuring cross-section. Due to a high bubble concentration in the corner, the maximum values of both axial liquid velocity and turbulent kine...

Haomin Sun - One of the best experts on this subject based on the ideXlab platform.

  • Upward air–water bubbly flow characteristics in a vertical square Duct
    Journal of Nuclear Science and Technology, 2013
    Co-Authors: Haomin Sun, Tomoaki Kunugi, Xiuzhong Shen, Hideo Nakamura
    Abstract:

    In nuclear engineering fields, gas–liquid bubbly flows exist in channels with various shape and size cross-sections. Although many experiments have been carried out especially in circular pipes, those in a Noncircular Duct are very limited. To contribute to the development of gas–liquid bubbly flow model for a Noncircular Duct, detail measurements for the air–water bubbly flow in a square Duct (side length: 0.136 m) were carried out by an X-type hot-film anemometry and a multi-sensor optical probe. Local flow parameters of the void fraction, bubble diameter, bubble frequency, axial liquid velocity and turbulent kinetic energy were measured in 11 two-phase flow conditions. These flow conditions covered bubbly flow with the area-averaged void fraction ranging from 0.069 to 0.172. A pronounced corner peak of the void fraction was observed in a quarter square area of a measuring cross-section. Due to a high bubble concentration in the corner, the maximum values of both axial liquid velocity and turbulent kine...

Tomoaki Kunugi - One of the best experts on this subject based on the ideXlab platform.

  • Upward air–water bubbly flow characteristics in a vertical square Duct
    Journal of Nuclear Science and Technology, 2013
    Co-Authors: Haomin Sun, Tomoaki Kunugi, Xiuzhong Shen, Hideo Nakamura
    Abstract:

    In nuclear engineering fields, gas–liquid bubbly flows exist in channels with various shape and size cross-sections. Although many experiments have been carried out especially in circular pipes, those in a Noncircular Duct are very limited. To contribute to the development of gas–liquid bubbly flow model for a Noncircular Duct, detail measurements for the air–water bubbly flow in a square Duct (side length: 0.136 m) were carried out by an X-type hot-film anemometry and a multi-sensor optical probe. Local flow parameters of the void fraction, bubble diameter, bubble frequency, axial liquid velocity and turbulent kinetic energy were measured in 11 two-phase flow conditions. These flow conditions covered bubbly flow with the area-averaged void fraction ranging from 0.069 to 0.172. A pronounced corner peak of the void fraction was observed in a quarter square area of a measuring cross-section. Due to a high bubble concentration in the corner, the maximum values of both axial liquid velocity and turbulent kine...

Xiuzhong Shen - One of the best experts on this subject based on the ideXlab platform.

  • Upward air–water bubbly flow characteristics in a vertical square Duct
    Journal of Nuclear Science and Technology, 2013
    Co-Authors: Haomin Sun, Tomoaki Kunugi, Xiuzhong Shen, Hideo Nakamura
    Abstract:

    In nuclear engineering fields, gas–liquid bubbly flows exist in channels with various shape and size cross-sections. Although many experiments have been carried out especially in circular pipes, those in a Noncircular Duct are very limited. To contribute to the development of gas–liquid bubbly flow model for a Noncircular Duct, detail measurements for the air–water bubbly flow in a square Duct (side length: 0.136 m) were carried out by an X-type hot-film anemometry and a multi-sensor optical probe. Local flow parameters of the void fraction, bubble diameter, bubble frequency, axial liquid velocity and turbulent kinetic energy were measured in 11 two-phase flow conditions. These flow conditions covered bubbly flow with the area-averaged void fraction ranging from 0.069 to 0.172. A pronounced corner peak of the void fraction was observed in a quarter square area of a measuring cross-section. Due to a high bubble concentration in the corner, the maximum values of both axial liquid velocity and turbulent kine...

M.a. Ebadian - One of the best experts on this subject based on the ideXlab platform.

  • convective heat transfer in the thermal entrance region of parallel flow Noncircular Duct heat exchanger arrays
    Wärme - und Stoffübertragung, 1992
    Co-Authors: H.y. Zhang, M.a. Ebadian
    Abstract:

    Convective heat transfer properties of a hydrodynamically fully developed flow, thermally developing flow in a parallel-flow, and Noncircular Duct heat exchanger passage subject to an insulated boundary condition are analyzed. In fact, due to the complexity of the geometry, this paper investigates in detail heat transfer in a parallel-flow heat exchanger of equilateral-triangular and semicircular Ducts. The developing temperature field in each passage in these geometries is obtained seminumerically from solving the energy equation employing the method of lines (MOL). According to this method, the energy equation is reformulated by a system of a first-order differential equation controlling the temperature along each line. Temperature distribution in the thermal entrance region is obtained utilizing sixteen lines or less, in the cross-stream direction of the Duct. The grid pattern chosen provides drastic savings in computing time. The representative curves illustrating the isotherms, the variation of the bulk temperature for each passage, and the total Nusselt number with pertinent parameters in the entire thermal entry region are plotted. It is found that the log mean temperature difference (ΔT LM), the heat exchanger effectiveness, and the number of transfer units (NTU) are 0.247, 0.490, and 1.985 for semicircular Ducts, and 0.346, 0.466, and 1.345 for equilateral-triangular Ducts.

  • Convective heat transfer in the thermal entrance region of parallel-flow Noncircular Duct heat exchanger arrays
    Wärme - und Stoffübertragung, 1992
    Co-Authors: H.y. Zhang, M.a. Ebadian
    Abstract:

    Die Untersuchung bezieht sich auf das konvektive Wärmeübertragungsverhalten eines Gleichstromwärmetauschers mit nichtkreisförmigen Strömungskanälen bei hydraulisch ausgebildetet, thermisch einlaufender Strömung unter Aufprägung einer adiabaten Randbedingung. Zwei Fälle komplizierter Geometrie, nämlich Kanäle mit gleichseitig dreieckigen und halbkreisförmigen Querschnitten, werden bezüglich des Wärmeübergangsverhaltens bei Gleichstromführung eingehend analysiert. Das sich entwickelnde Temperaturfeld in jedem Kanal von der eben spezifizierten Querschnittsform wird halbnumerisch durch Lösung der Energiegleichung unter Einsatz der Linienmethode (MOL) erhalten. Dieser Methode entsprechend erfolgt eine Umformung der Energiegleichung in ein System von Differentialgleichungen erster Ordnung, welches die Temperaturverteilung auf jeder Linie bestimmt. Die Temperaturverteilung im Einlaufgebiet wird unter Vorgabe von 16 oder weniger Linien über dem Kanalquerschnitt erhalten, wobei die gewählte Gitteranordnung drastische Einsparung an Rechenzeit ergibt. Repräsentative Kurven für das Isothermalfeld, den Verlauf der Mischtemperatur für jeden Kanal und die Gesamt-Nusseltzahl als Funktion relevanter Parameter im gesamten Einlaufgebiet sind in Diagrammform dargestellt. Es zeigt sich, daß die mittlere logarithmische Temperaturdifferenz (Δ T _LM), der Wärmetauscherwirkungsgrad und die Anzahl der Übertragungseinheiten (NTU) folgende Werte annehmen: 0,247, 0,490 und 1,985 für halbkreisförmige Kanäle sowie 0,346, 0,466 und 1,345 für gleichseitig dreieckige Kanäle. Convective heat transfer properties of a hydrodynamically fully developed flow, thermally developing flow in a parallel-flow, and Noncircular Duct heat exchanger passage subject to an insulated boundary condition are analyzed. In fact, due to the complexity of the geometry, this paper investigates in detail heat transfer in a parallel-flow heat exchanger of equilateral-triangular and semicircular Ducts. The developing temperature field in each passage in these geometries is obtained seminumerically from solving the energy equation employing the method of lines (MOL). According to this method, the energy equation is reformulated by a system of a first-order differential equation controlling the temperature along each line. Temperature distribution in the thermal entrance region is obtained utilizing sixteen lines or less, in the cross-stream direction of the Duct. The grid pattern chosen provides drastic savings in computing time. The representative curves illustrating the isotherms, the variation of the bulk temperature for each passage, and the total Nusselt number with pertinent parameters in the entire thermal entry region are plotted. It is found that the log mean temperature difference (Δ T _LM), the heat exchanger effectiveness, and the number of transfer units (NTU) are 0.247, 0.490, and 1.985 for semicircular Ducts, and 0.346, 0.466, and 1.345 for equilateral-triangular Ducts.

  • Convective heat transfer in the thermal entrance region of parallel-flow Noncircular Duct heat exchanger arrays
    Wärme- und Stoffübertragung, 1992
    Co-Authors: H.y. Zhang, M.a. Ebadian
    Abstract:

    Convective heat transfer properties of a hydrodynamically fully developed flow, thermally developing flow in a parallel-flow, and Noncircular Duct heat exchanger passage subject to an insulated boundary condition are analyzed. In fact, due to the complexity of the geometry, this paper investigates in detail heat transfer in a parallel-flow heat exchanger of equilateral-triangular and semicircular Ducts. The developing temperature field in each passage in these geometries is obtained seminumerically from solving the energy equation employing the method of lines (MOL). According to this method, the energy equation is reformulated by a system of a first-order differential equation controlling the temperature along each line.