The Experts below are selected from a list of 15 Experts worldwide ranked by ideXlab platform

Zhipeng Duan - 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

  • slip flow in the Hydrodynamic Entrance Region of circular and noncircular microchannels
    Journal of Fluids Engineering-transactions of The Asme, 2010
    Co-Authors: Zhipeng Duan, Y S Muzychka
    Abstract:

    Microscale fluid dynamics has received intensive interest due to the emergence of microelectro-mechanical systems (MEMS) technology. When the mean free path of the gas is comparable to the channel’s characteristic dimension, the continuum assumption is no longer valid and a velocity slip may occur at the duct walls. Noncircular cross sections are common channel shapes that can be produced by microfabrication. The noncircular microchannels have extensive practical applications in MEMS. The paper deals with issues of Hydrodynamic flow development. Slip flow in the Entrance of circular and parallel plate microchannels is first considered by solving a linearized momentum equation. It is found that slip flow is less sensitive to analytical linearized approximations than continuum flow and the linearization method is an accurate approximation for slip flow. Also, it is found that the Entrance friction factor Reynolds product is of finite value and dependent on the Kn and tangential momentum accommodation coefficient but independent of the cross-sectional geometry. Slip flow and continuum flow in the Hydrodynamic Entrance of noncircular microchannels has been examined and a model is proposed to predict the friction factor and Reynolds product f Re for developing slip flow and continuum flow in most noncircular microchannels. It is shown that the complete problem may be easily analyzed by combining the asymptotic results for short and long ducts. Through the selection of a characteristic length scale, the square root of cross-sectional area, the effect of duct shape has been minimized. The proposed model has an approximate accuracy of 10% for most common duct shapes. ! DOI: 10.1115/1.4000692"

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

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.

Richard E Glosup - 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.