The Experts below are selected from a list of 330 Experts worldwide ranked by ideXlab platform

Svendsen, Hallvard Fjøsne - One of the best experts on this subject based on the ideXlab platform.

  • A study of film thickness and Hydrodynamic Entrance Length in liquid laminar film flow along a vertical tube
    'Royal College of Obstetricians & Gynaecologists (RCOG)', 2018
    Co-Authors: Gao Hongxia, Luo Xiao, Cui Ding, Liang Zhiwu, Hu Xiayi, Hartono Ardi, Svendsen, Hallvard Fjøsne
    Abstract:

    The liquid film thickness and Hydrodynamic Entrance Length in a vertical tube was studied experimentally and numerically. Measurements using distilled water, 30 wt % MEA and 40 wt % sugar solutions were carried out to investigate the effects of liquid flow rate on the formation of the liquid film. The experimental results validate the new Navier-Stokes based equation in cylindrical coordinates (Eq. 16) and the volume of fluid (VOF) model giving a competitively high prediction of the liquid film thickness especially in the low Reynolds number region. In addition, a new empiricalmodel and an improved minimal surface model have been first proposed for calculation of the Hydrodynamic Entrance Length, with a relatively reasonable average absolute relative deviation (AARD) of 3.03% and 6.83%, respectively. Furthermore, the effects of the Hydrodynamic entry Length on the gas–liquid interfacial area calculated by the improved minimal surface model were comprehensively studied, and can be ignored if the ratio of the liquid film Length (y) and the Hydrodynamic Entrance Length (kE) is lower than 10. However, it should be noted that the Hydrodynamic Entrance Length cannot be ignored in packed columns in which the liquid flow is very complex due to the packings with different structures and materials

  • A study of film thickness and Hydrodynamic Entrance Length in liquid laminar film flow along a vertical tube
    Wiley, 2018
    Co-Authors: Gao Hongxia, Luo Xiao, Cui Ding, Liang Zhiwu, Hu Xiayi, Hartono Ardi, Svendsen, Hallvard Fjøsne
    Abstract:

    The liquid film thickness and Hydrodynamic Entrance Length in a vertical tube was studied experimentally and numerically. Measurements using distilled water, 30 wt % MEA and 40 wt % sugar solutions were carried out to investigate the effects of liquid flow rate on the formation of the liquid film. The experimental results validate the new Navier-Stokes based equation in cylindrical coordinates (Eq. 16) and the volume of fluid (VOF) model giving a competitively high prediction of the liquid film thickness especially in the low Reynolds number region. In addition, a new empiricalmodel and an improved minimal surface model have been first proposed for calculation of the Hydrodynamic Entrance Length, with a relatively reasonable average absolute relative deviation (AARD) of 3.03% and 6.83%, respectively. Furthermore, the effects of the Hydrodynamic entry Length on the gas–liquid interfacial area calculated by the improved minimal surface model were comprehensively studied, and can be ignored if the ratio of the liquid film Length (y) and the Hydrodynamic Entrance Length (kE) is lower than 10. However, it should be noted that the Hydrodynamic Entrance Length cannot be ignored in packed columns in which the liquid flow is very complex due to the packings with different structures and materials.submittedVersionThis is the pre-peer reviewed version of an article, which has been published in final form at https://doi.org/10.1002/aic.16081. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving

Michael W. Patterson - One of the best experts on this subject based on the ideXlab platform.

  • thermal hydraulic performance testing of printed circuit heat exchangers in a high temperature helium test facility
    Applied Thermal Engineering, 2014
    Co-Authors: Sai K Mylavarapu, Richard E Glosup, R N Christensen, Michael W. Patterson
    Abstract:

    Abstract In high-temperature gas-cooled reactors, such as a very high temperature reactor (VHTR), an intermediate heat exchanger (IHX) is required to efficiently transfer the core thermal output to a secondary fluid for electricity generation with an indirect power cycle and/or process heat applications. Currently, there is no proven high-temperature (750–800 °C or higher) compact heat exchanger technology for high-temperature reactor design concepts. In this study, printed circuit heat exchanger (PCHE), a potential IHX concept for high-temperature applications, has been investigated for their heat transfer and pressure drop characteristics under high operating temperatures and pressures. Two PCHEs, each having 10 hot and 10 cold plates with 12 channels (semicircular cross-section) in each plate are fabricated using Alloy 617 plates and tested for their performance in a high-temperature helium test facility (HTHF). The PCHE inlet temperature and pressure were varied from 85 to 390 °C/1.0–2.7 MPa for the cold side and 208–790 °C/1.0–2.7 MPa for the hot side, respectively, while the mass flow rate of helium was varied from 15 to 49 kg/h. This range of mass flow rates corresponds to PCHE channel Reynolds numbers of 950 to 4100 for the cold side and 900 to 3900 for the hot side (corresponding to the laminar and laminar-to-turbulent transition flow regimes). The obtained experimental data have been analyzed for the pressure drop and heat transfer characteristics of the heat transfer surface of the PCHEs and compared with the available models and correlations in the literature. In addition, a numerical treatment of Hydrodynamically developing and Hydrodynamically fully-developed laminar flow through a semicircular duct is presented. Relations developed for determining the Hydrodynamic Entrance Length in a semicircular duct and the friction factor (or pressure drop) in the Hydrodynamic entry Length region for laminar flow through a semicircular duct are given. Various Hydrodynamic Entrance region parameters, such as incremental pressure drop number, apparent Fanning friction factor, and Hydrodynamic Entrance Length in a semicircular duct have been numerically estimated.

Xin Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Lattice Boltzmann Simulation of the Hydrodynamic Entrance Region of Rectangular Microchannels in the Slip Regime
    Micromachines, 2018
    Co-Authors: Zhipeng Duan, Xiaoru Ning, Peng Liang, Xin Zhang
    Abstract:

    Developing a three-dimensional laminar flow in the Entrance region of rectangular microchannels has been investigated in this paper. When the Hydrodynamic development Length is the same magnitude as the microchannel Length, Entrance effects have to be taken into account, especially in relatively short ducts. Simultaneously, there are a variety of non-continuum or rarefaction effects, such as velocity slip and temperature jump. The available data in the literature appearing on this issue is quite limited, the available study is the semi-theoretical approximate model to predict pressure drop of developing slip flow in rectangular microchannels with different aspect ratios. In this paper, we apply the lattice Boltzmann equation method (LBE) to investigate the developing slip flow through a rectangular microchannel. The effects of the Reynolds number (1 < Re < 1000), channel aspect ratio (0 < e < 1), and Knudsen number (0.001 < Kn < 0.1) on the dimensionless Hydrodynamic Entrance Length, and the apparent friction factor, and Reynolds number product, are examined in detail. The numerical solution of LBM can recover excellent agreement with the available data in the literature, which proves its accuracy in capturing fundamental fluid characteristics in the slip-flow regime.

  • Lattice Boltzmann Simulation of the Hydrodynamic Entrance Region of Rectangular Microchannels in the Slip Regime
    MDPI AG, 2018
    Co-Authors: Zhipeng Duan, Xiaoru Ning, Peng Liang, Xin Zhang
    Abstract:

    Developing a three-dimensional laminar flow in the Entrance region of rectangular microchannels has been investigated in this paper. When the Hydrodynamic development Length is the same magnitude as the microchannel Length, Entrance effects have to be taken into account, especially in relatively short ducts. Simultaneously, there are a variety of non-continuum or rarefaction effects, such as velocity slip and temperature jump. The available data in the literature appearing on this issue is quite limited, the available study is the semi-theoretical approximate model to predict pressure drop of developing slip flow in rectangular microchannels with different aspect ratios. In this paper, we apply the lattice Boltzmann equation method (LBE) to investigate the developing slip flow through a rectangular microchannel. The effects of the Reynolds number (1 < Re < 1000), channel aspect ratio (0 < ε < 1), and Knudsen number (0.001 < Kn < 0.1) on the dimensionless Hydrodynamic Entrance Length, and the apparent friction factor, and Reynolds number product, are examined in detail. The numerical solution of LBM can recover excellent agreement with the available data in the literature, which proves its accuracy in capturing fundamental fluid characteristics in the slip-flow regime

Gao Hongxia - One of the best experts on this subject based on the ideXlab platform.

  • A study of film thickness and Hydrodynamic Entrance Length in liquid laminar film flow along a vertical tube
    'Royal College of Obstetricians & Gynaecologists (RCOG)', 2018
    Co-Authors: Gao Hongxia, Luo Xiao, Cui Ding, Liang Zhiwu, Hu Xiayi, Hartono Ardi, Svendsen, Hallvard Fjøsne
    Abstract:

    The liquid film thickness and Hydrodynamic Entrance Length in a vertical tube was studied experimentally and numerically. Measurements using distilled water, 30 wt % MEA and 40 wt % sugar solutions were carried out to investigate the effects of liquid flow rate on the formation of the liquid film. The experimental results validate the new Navier-Stokes based equation in cylindrical coordinates (Eq. 16) and the volume of fluid (VOF) model giving a competitively high prediction of the liquid film thickness especially in the low Reynolds number region. In addition, a new empiricalmodel and an improved minimal surface model have been first proposed for calculation of the Hydrodynamic Entrance Length, with a relatively reasonable average absolute relative deviation (AARD) of 3.03% and 6.83%, respectively. Furthermore, the effects of the Hydrodynamic entry Length on the gas–liquid interfacial area calculated by the improved minimal surface model were comprehensively studied, and can be ignored if the ratio of the liquid film Length (y) and the Hydrodynamic Entrance Length (kE) is lower than 10. However, it should be noted that the Hydrodynamic Entrance Length cannot be ignored in packed columns in which the liquid flow is very complex due to the packings with different structures and materials

  • A study of film thickness and Hydrodynamic Entrance Length in liquid laminar film flow along a vertical tube
    Wiley, 2018
    Co-Authors: Gao Hongxia, Luo Xiao, Cui Ding, Liang Zhiwu, Hu Xiayi, Hartono Ardi, Svendsen, Hallvard Fjøsne
    Abstract:

    The liquid film thickness and Hydrodynamic Entrance Length in a vertical tube was studied experimentally and numerically. Measurements using distilled water, 30 wt % MEA and 40 wt % sugar solutions were carried out to investigate the effects of liquid flow rate on the formation of the liquid film. The experimental results validate the new Navier-Stokes based equation in cylindrical coordinates (Eq. 16) and the volume of fluid (VOF) model giving a competitively high prediction of the liquid film thickness especially in the low Reynolds number region. In addition, a new empiricalmodel and an improved minimal surface model have been first proposed for calculation of the Hydrodynamic Entrance Length, with a relatively reasonable average absolute relative deviation (AARD) of 3.03% and 6.83%, respectively. Furthermore, the effects of the Hydrodynamic entry Length on the gas–liquid interfacial area calculated by the improved minimal surface model were comprehensively studied, and can be ignored if the ratio of the liquid film Length (y) and the Hydrodynamic Entrance Length (kE) is lower than 10. However, it should be noted that the Hydrodynamic Entrance Length cannot be ignored in packed columns in which the liquid flow is very complex due to the packings with different structures and materials.submittedVersionThis is the pre-peer reviewed version of an article, which has been published in final form at https://doi.org/10.1002/aic.16081. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving

Sai K Mylavarapu - One of the best experts on this subject based on the ideXlab platform.

  • thermal hydraulic performance testing of printed circuit heat exchangers in a high temperature helium test facility
    Applied Thermal Engineering, 2014
    Co-Authors: Sai K Mylavarapu, Richard E Glosup, R N Christensen, Michael W. Patterson
    Abstract:

    Abstract In high-temperature gas-cooled reactors, such as a very high temperature reactor (VHTR), an intermediate heat exchanger (IHX) is required to efficiently transfer the core thermal output to a secondary fluid for electricity generation with an indirect power cycle and/or process heat applications. Currently, there is no proven high-temperature (750–800 °C or higher) compact heat exchanger technology for high-temperature reactor design concepts. In this study, printed circuit heat exchanger (PCHE), a potential IHX concept for high-temperature applications, has been investigated for their heat transfer and pressure drop characteristics under high operating temperatures and pressures. Two PCHEs, each having 10 hot and 10 cold plates with 12 channels (semicircular cross-section) in each plate are fabricated using Alloy 617 plates and tested for their performance in a high-temperature helium test facility (HTHF). The PCHE inlet temperature and pressure were varied from 85 to 390 °C/1.0–2.7 MPa for the cold side and 208–790 °C/1.0–2.7 MPa for the hot side, respectively, while the mass flow rate of helium was varied from 15 to 49 kg/h. This range of mass flow rates corresponds to PCHE channel Reynolds numbers of 950 to 4100 for the cold side and 900 to 3900 for the hot side (corresponding to the laminar and laminar-to-turbulent transition flow regimes). The obtained experimental data have been analyzed for the pressure drop and heat transfer characteristics of the heat transfer surface of the PCHEs and compared with the available models and correlations in the literature. In addition, a numerical treatment of Hydrodynamically developing and Hydrodynamically fully-developed laminar flow through a semicircular duct is presented. Relations developed for determining the Hydrodynamic Entrance Length in a semicircular duct and the friction factor (or pressure drop) in the Hydrodynamic entry Length region for laminar flow through a semicircular duct are given. Various Hydrodynamic Entrance region parameters, such as incremental pressure drop number, apparent Fanning friction factor, and Hydrodynamic Entrance Length in a semicircular duct have been numerically estimated.