Ventilated Enclosure

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Jean Moureh - One of the best experts on this subject based on the ideXlab platform.

  • Airflow in a slot-Ventilated Enclosure partially filled with porous boxes: Part II Measurements and simulations within porous boxes
    Computers and Fluids, 2009
    Co-Authors: Jean Moureh, Mitoubkieta Tapsoba, D. Flick
    Abstract:

    The present study will give rise to better understanding of the airflow behaviour in a ceiling-slot Ventilated Enclosure partially filled with slotted porous boxes under isothermal conditions. Boxes were filled randomly with spheres of the same diameter. Laser Doppler velocimetry (LDV) measurements and computational fluid dynamics (CFD) predictions were carried out to characterize air velocity inside packed vented boxes. An original approach was also developed to evaluate the internal macroscopic velocities within the boxes by means of thermal sphere-shaped probes. LDV measurements and CFD predictions related to the main turbulent flow developed by the jet above the boxes were presented in the part I. Special attention was paid to the strong aerodynamic interactions observed on the top faces of the slotted boxes, between the external main flow and the return flow which predominate inside the boxes. Numerical and experimental data make it possible to evaluate the air ventilation levels and their heterogeneity for the different boxes. The RSM turbulence model gives reasonable agreement with experiments.

  • Airflow in a slot-Ventilated Enclosure partially filled with porous boxes: Part I Measurements and simulations in the clear region
    Computers and Fluids, 2009
    Co-Authors: Jean Moureh, Mitoubkieta Tapsoba, D. Flick
    Abstract:

    A reduced-scale model and CFD predictions were used to investigate experimentally and numerically the airflow patterns within a ceiling slot-Ventilated Enclosure partially loaded with vented boxes filled by spherical objects. The experiments were carried out using laser Doppler velocimetry. Airflows around and inside porous boxes were predicted taking into account their aerodynamic interactions. This work is divided into two parts. This paper presents part I and concerns the air velocity characteristics within the jet above the boxes, while Part II deals with the air velocity characteristics inside the boxes. The results highlight the confinement effect due to the Enclosure and the influence of load porosity on jet penetration, its development and hence the heterogeneity of ventilation within the Enclosure. The numerical predictions obtained with the computational fluid dynamics Fluent package using the RSM turbulence model show reasonable agreement with experimental data. Predicted velocity profiles were generally within an error of 330% of the measured velocities.

  • Airflow in a slot-Ventilated Enclosure partially filled with porous boxes: Part I – Measurements and simulations in the clear region
    Computers & Fluids, 2009
    Co-Authors: Jean Moureh, Mitoubkieta Tapsoba, Denis Flick
    Abstract:

    Abstract A reduced-scale model and CFD predictions were used to investigate experimentally and numerically the airflow patterns within a ceiling slot-Ventilated Enclosure partially loaded with vented boxes filled by spherical objects. The experiments were carried out using laser Doppler velocimetry. Airflows around and inside porous boxes were predicted taking into account their aerodynamic interactions. This work is divided into two parts. This paper presents part I and concerns the air velocity characteristics within the jet above the boxes, while Part II deals with the air velocity characteristics inside the boxes. The results highlight the confinement effect due to the Enclosure and the influence of load porosity on jet penetration, its development and hence the heterogeneity of ventilation within the Enclosure. The numerical predictions obtained with the computational fluid dynamics Fluent package using the RSM turbulence model show reasonable agreement with experimental data. Predicted velocity profiles were generally within an error of 3–30% of the measured velocities.

  • Airflow in a slot-Ventilated Enclosure partially filled with porous boxes: Part II – Measurements and simulations within porous boxes
    Computers & Fluids, 2009
    Co-Authors: Jean Moureh, Mitoubkieta Tapsoba, Denis Flick
    Abstract:

    Abstract The present study will give rise to better understanding of the airflow behaviour in a ceiling-slot Ventilated Enclosure partially filled with slotted porous boxes under isothermal conditions. Boxes were filled randomly with spheres of the same diameter. Laser Doppler velocimetry (LDV) measurements and computational fluid dynamics (CFD) predictions were carried out to characterize air velocity inside packed vented boxes. An original approach was also developed to evaluate the internal macroscopic velocities within the boxes by means of thermal sphere-shaped probes. LDV measurements and CFD predictions related to the main turbulent flow developed by the jet above the boxes were presented in the part I. Special attention was paid to the strong aerodynamic interactions observed on the top faces of the slotted boxes, between the external main flow and the return flow which predominate inside the boxes. Numerical and experimental data make it possible to evaluate the air ventilation levels and their heterogeneity for the different boxes. The RSM turbulence model gives reasonable agreement with experiments.

  • Airflow and heat transfer in a slot-Ventilated Enclosure apllication to refrigerated trucks
    2008
    Co-Authors: Jean Moureh, M.s. Tapsoba, D. Flick
    Abstract:

    Slot-Ventilated Enclosures are extensively used in many engineering applications such as buildings, animal houses and equipments for food transport and storage. The level and the uniformity of ambiance parameters such as temperature and humidity are highly governed by airflow patterns and in most of the applications different obstacles also interact with airflow. The study concerns a slot Ventilated long Enclosure (L/H=5.3, W/H=1) loaded with porous boxes. This configuration corresponds to a refrigerated truck loaded with crates containing fruit or vegetable. The rectangular inlet section (hi/H=0.056, wi/W=0.4) is near the ceiling and the outlet is located near the floor on the same face. The inlet wall jet is turbulent (Re=1.9 105). Isothermal case and anisothermal case (including heat generation in the boxes and heat losses trough the walls) were simulated and compared. The Reynolds Averaged Navier-Stokes equations were solved using an RSM turbulence closure model. Darcy-Forchheimer terms were added in porous medium zone. Boussinesq approximation was used to take account of mixed convection. The governing equations were solved using the finite volume method. In the isothermal case, velocity is very low at rear part of the Enclosure. In the anisothermal case, a secondary recirculation appears in the rear part of the Enclosure due to free convection and therefore the velocity magnitude is higher. But in the front part, airflow pattern which reflects the wall jet expansion is very similar because flow is governed by forced convection. A different inlet configuration, in which the airflow is blown at three positions along the Enclosure, was also investigated. In this case, ventilation and temperature levels within boxes were found to be more homogeneous.

Denis Flick - One of the best experts on this subject based on the ideXlab platform.

  • Airflow in a slot-Ventilated Enclosure partially filled with porous boxes: Part I – Measurements and simulations in the clear region
    Computers & Fluids, 2009
    Co-Authors: Jean Moureh, Mitoubkieta Tapsoba, Denis Flick
    Abstract:

    Abstract A reduced-scale model and CFD predictions were used to investigate experimentally and numerically the airflow patterns within a ceiling slot-Ventilated Enclosure partially loaded with vented boxes filled by spherical objects. The experiments were carried out using laser Doppler velocimetry. Airflows around and inside porous boxes were predicted taking into account their aerodynamic interactions. This work is divided into two parts. This paper presents part I and concerns the air velocity characteristics within the jet above the boxes, while Part II deals with the air velocity characteristics inside the boxes. The results highlight the confinement effect due to the Enclosure and the influence of load porosity on jet penetration, its development and hence the heterogeneity of ventilation within the Enclosure. The numerical predictions obtained with the computational fluid dynamics Fluent package using the RSM turbulence model show reasonable agreement with experimental data. Predicted velocity profiles were generally within an error of 3–30% of the measured velocities.

  • Airflow in a slot-Ventilated Enclosure partially filled with porous boxes: Part II – Measurements and simulations within porous boxes
    Computers & Fluids, 2009
    Co-Authors: Jean Moureh, Mitoubkieta Tapsoba, Denis Flick
    Abstract:

    Abstract The present study will give rise to better understanding of the airflow behaviour in a ceiling-slot Ventilated Enclosure partially filled with slotted porous boxes under isothermal conditions. Boxes were filled randomly with spheres of the same diameter. Laser Doppler velocimetry (LDV) measurements and computational fluid dynamics (CFD) predictions were carried out to characterize air velocity inside packed vented boxes. An original approach was also developed to evaluate the internal macroscopic velocities within the boxes by means of thermal sphere-shaped probes. LDV measurements and CFD predictions related to the main turbulent flow developed by the jet above the boxes were presented in the part I. Special attention was paid to the strong aerodynamic interactions observed on the top faces of the slotted boxes, between the external main flow and the return flow which predominate inside the boxes. Numerical and experimental data make it possible to evaluate the air ventilation levels and their heterogeneity for the different boxes. The RSM turbulence model gives reasonable agreement with experiments.

  • Airflow patterns inside slotted obstacles in a Ventilated Enclosure
    Computers & Fluids, 2007
    Co-Authors: Mitoubkieta Tapsoba, Jean Moureh, Denis Flick
    Abstract:

    Abstract Laser Doppler measurements and CFD predictions were carried out to characterize air flow pattern, mean velocities and turbulence structure inside slotted boxes stacked within a slot Ventilated Enclosure. Special attention was paid to the strong aerodynamic interactions observed on the top faces of the slotted boxes, between the external main flow and the return flow which predominate inside the boxes. Numerical and experimental data make it possible to evaluate the air ventilation levels and their heterogeneity for the different boxes. The two turbulence models used, RSM and k – e , give quite similar results for the velocity levels in the load and show qualitative agreement with experiments.

  • Airflow characteristics within a slot-Ventilated Enclosure
    International Journal of Heat and Fluid Flow, 2005
    Co-Authors: Jean Moureh, Denis Flick
    Abstract:

    Abstract The objective of this study is to numerically and experimentally investigate velocity characteristics throughout a long slot-Ventilated Enclosure as a function of inlet flow arrangement located on the same side of the exit section. This study focused on the effect of the Enclosure’s confinement on the airflow pattern and more particularly on the wall jet characteristics concerning its decay and its stabilisation. An original approach is also proposed to evaluate the local effect of airflow pattern on ventilation efficiency. To improve the performance and the uniformity of ventilation in the Enclosure, a new configuration with a lateral air inlet section was studied. The results concerning airflow characteristics and air-ventilation efficiency were compared and contrasted with the more common case with a central inlet section. A numerical approach based on computational fluid dynamics (CFD) Fluent code was used to test various turbulence closure models including the high and low Reynolds number form of the two-equation k – e model and the more advanced Reynolds stress model (RSM). Comparisons with experimental data obtained on a scale model under isothermal conditions allow a critical evaluation of the performance of these models in internal flows.

  • wall air jet characteristics and airflow patterns within a slot Ventilated Enclosure
    International Journal of Thermal Sciences, 2003
    Co-Authors: Jean Moureh, Denis Flick
    Abstract:

    Abstract The present study reports on the numerical and experimental characterisation of airflow generated by a wall jet within a long and empty slot-Ventilated Enclosure. In the configuration investigated, blowing and outlet sections are placed in the front of the box. This design is extensively used in refrigerated transport. Experiments were carried out on a scale model ( 1 :3.3 ) of a trailer. Numerical modelling of airflow was performed using the computational fluid dynamics Fluent code. In this study, a second-moment closure, the Reynolds stress model (RSM) and two-equation turbulence models: the standard k–e and a renormalization group (RNG), were tested, contrasted and compared with experimental data. It was demonstrated that only the RSM model enabled detection of the presence and the localisation of separated flow and correctly predicts airflow patterns related to primary and secondary recirculation.

D. Flick - One of the best experts on this subject based on the ideXlab platform.

  • Airflow in a slot-Ventilated Enclosure partially filled with porous boxes: Part II Measurements and simulations within porous boxes
    Computers and Fluids, 2009
    Co-Authors: Jean Moureh, Mitoubkieta Tapsoba, D. Flick
    Abstract:

    The present study will give rise to better understanding of the airflow behaviour in a ceiling-slot Ventilated Enclosure partially filled with slotted porous boxes under isothermal conditions. Boxes were filled randomly with spheres of the same diameter. Laser Doppler velocimetry (LDV) measurements and computational fluid dynamics (CFD) predictions were carried out to characterize air velocity inside packed vented boxes. An original approach was also developed to evaluate the internal macroscopic velocities within the boxes by means of thermal sphere-shaped probes. LDV measurements and CFD predictions related to the main turbulent flow developed by the jet above the boxes were presented in the part I. Special attention was paid to the strong aerodynamic interactions observed on the top faces of the slotted boxes, between the external main flow and the return flow which predominate inside the boxes. Numerical and experimental data make it possible to evaluate the air ventilation levels and their heterogeneity for the different boxes. The RSM turbulence model gives reasonable agreement with experiments.

  • Airflow in a slot-Ventilated Enclosure partially filled with porous boxes: Part I Measurements and simulations in the clear region
    Computers and Fluids, 2009
    Co-Authors: Jean Moureh, Mitoubkieta Tapsoba, D. Flick
    Abstract:

    A reduced-scale model and CFD predictions were used to investigate experimentally and numerically the airflow patterns within a ceiling slot-Ventilated Enclosure partially loaded with vented boxes filled by spherical objects. The experiments were carried out using laser Doppler velocimetry. Airflows around and inside porous boxes were predicted taking into account their aerodynamic interactions. This work is divided into two parts. This paper presents part I and concerns the air velocity characteristics within the jet above the boxes, while Part II deals with the air velocity characteristics inside the boxes. The results highlight the confinement effect due to the Enclosure and the influence of load porosity on jet penetration, its development and hence the heterogeneity of ventilation within the Enclosure. The numerical predictions obtained with the computational fluid dynamics Fluent package using the RSM turbulence model show reasonable agreement with experimental data. Predicted velocity profiles were generally within an error of 330% of the measured velocities.

  • Airflow and heat transfer in a slot-Ventilated Enclosure apllication to refrigerated trucks
    2008
    Co-Authors: Jean Moureh, M.s. Tapsoba, D. Flick
    Abstract:

    Slot-Ventilated Enclosures are extensively used in many engineering applications such as buildings, animal houses and equipments for food transport and storage. The level and the uniformity of ambiance parameters such as temperature and humidity are highly governed by airflow patterns and in most of the applications different obstacles also interact with airflow. The study concerns a slot Ventilated long Enclosure (L/H=5.3, W/H=1) loaded with porous boxes. This configuration corresponds to a refrigerated truck loaded with crates containing fruit or vegetable. The rectangular inlet section (hi/H=0.056, wi/W=0.4) is near the ceiling and the outlet is located near the floor on the same face. The inlet wall jet is turbulent (Re=1.9 105). Isothermal case and anisothermal case (including heat generation in the boxes and heat losses trough the walls) were simulated and compared. The Reynolds Averaged Navier-Stokes equations were solved using an RSM turbulence closure model. Darcy-Forchheimer terms were added in porous medium zone. Boussinesq approximation was used to take account of mixed convection. The governing equations were solved using the finite volume method. In the isothermal case, velocity is very low at rear part of the Enclosure. In the anisothermal case, a secondary recirculation appears in the rear part of the Enclosure due to free convection and therefore the velocity magnitude is higher. But in the front part, airflow pattern which reflects the wall jet expansion is very similar because flow is governed by forced convection. A different inlet configuration, in which the airflow is blown at three positions along the Enclosure, was also investigated. In this case, ventilation and temperature levels within boxes were found to be more homogeneous.

  • Airflow patterns inside slotted obstacles in a Ventilated Enclosure
    Computers and Fluids, 2007
    Co-Authors: Mitoubkieta Tapsoba, Jean Moureh, D. Flick
    Abstract:

    Laser Doppler measurements and CFD predictions were carried out to characterize air flow pattern, mean velocities and turbulence structure inside slotted boxes stacked within a slot Ventilated Enclosure. Special attention was paid to the strong aerodynamic interactions observed on the top faces of the slotted boxes, between the external main flow and the return flow which predominate inside the boxes. Numerical and experimental data make it possible to evaluate the air ventilation levels and their heterogeneity for the different boxes. The two turbulence models used, RSM and k-, give quite similar results for the velocity levels in the load and show qualitative agreement with experiments.

  • Airflow patterns in a slot-Ventilated Enclosure partially loaded with empty slotted boxes
    International Journal of Heat and Fluid Flow, 2007
    Co-Authors: Mitoubkieta Tapsoba, Jean Moureh, D. Flick
    Abstract:

    A reduced-scale model and CFD predictions were used to investigate experimentally and numerically the airflow patterns within a ceiling-slot Ventilated Enclosure loaded by slotted boxes. The experiments were carried out with a laser Doppler anemometer. This paper concerns the air velocity characteristics within the jet and outside the boxes. Results make it possible to highlight the confinement effect due to Enclosure and the influence of load porosity on the jet penetration, its development and hence the heterogeneity of ventilation within the Enclosure. The numerical predictions obtained with the computational fluid dynamics Fluent package using the RSM turbulence model show rather good agreement with experimental data.

Christopher Yu Hang Chao - One of the best experts on this subject based on the ideXlab platform.

  • numerical and experimental study of velocity and temperature characteristics in a Ventilated Enclosure with underfloor ventilation systems
    Indoor Air, 2005
    Co-Authors: Man Pun Wan, Christopher Yu Hang Chao
    Abstract:

    UNLABELLED Airflow and temperature distributions in an Enclosure with heat sources Ventilated by floor supply jets with floor or ceiling air exit vents were investigated using experimental and numerical approaches. These ventilation configurations represent the floor return or the top return underfloor ventilation systems found in real applications. Experiments and numerical simulations were performed on a full-sized environmental chamber. The results reveal that the temperature stratification in the Enclosure highly depended on the thermal length scale of the floor supply jets. When the thermal length scale of the supply jet was >>1, temperature stratification was minor for all tested heat densities and air distribution methods. Significant vertical temperature gradients occurred when the jet thermal length scale was <<1. Changes in air distribution methods also became significant for temperature stratification at small supply jet thermal length scales. Temperature stratification also affected the terminal height of the momentum-dominant region of the vertical buoyant supply jets. The applicability of these results to underfloor ventilation design was also discussed. PRACTICAL IMPLICATIONS In designing underfloor ventilation systems, supply jet conditions and heat load density have to be considered to avoid thermal discomfort because of excessive temperature stratifications. This study demonstrated, by both numerical simulations and experiments, that thermal length scale can be used as a design indicator to predict thermal stratifications under a floor return and a top return underfloor ventilation setting.

  • Numerical and experimental study of velocity and temperature characteristics in a Ventilated Enclosure with underfloor ventilation systems.
    Indoor air, 2005
    Co-Authors: Man Pun Wan, Christopher Yu Hang Chao
    Abstract:

    UNLABELLED Airflow and temperature distributions in an Enclosure with heat sources Ventilated by floor supply jets with floor or ceiling air exit vents were investigated using experimental and numerical approaches. These ventilation configurations represent the floor return or the top return underfloor ventilation systems found in real applications. Experiments and numerical simulations were performed on a full-sized environmental chamber. The results reveal that the temperature stratification in the Enclosure highly depended on the thermal length scale of the floor supply jets. When the thermal length scale of the supply jet was >>1, temperature stratification was minor for all tested heat densities and air distribution methods. Significant vertical temperature gradients occurred when the jet thermal length scale was

Man Pun Wan - One of the best experts on this subject based on the ideXlab platform.

  • numerical and experimental study of velocity and temperature characteristics in a Ventilated Enclosure with underfloor ventilation systems
    Indoor Air, 2005
    Co-Authors: Man Pun Wan, Christopher Yu Hang Chao
    Abstract:

    UNLABELLED Airflow and temperature distributions in an Enclosure with heat sources Ventilated by floor supply jets with floor or ceiling air exit vents were investigated using experimental and numerical approaches. These ventilation configurations represent the floor return or the top return underfloor ventilation systems found in real applications. Experiments and numerical simulations were performed on a full-sized environmental chamber. The results reveal that the temperature stratification in the Enclosure highly depended on the thermal length scale of the floor supply jets. When the thermal length scale of the supply jet was >>1, temperature stratification was minor for all tested heat densities and air distribution methods. Significant vertical temperature gradients occurred when the jet thermal length scale was <<1. Changes in air distribution methods also became significant for temperature stratification at small supply jet thermal length scales. Temperature stratification also affected the terminal height of the momentum-dominant region of the vertical buoyant supply jets. The applicability of these results to underfloor ventilation design was also discussed. PRACTICAL IMPLICATIONS In designing underfloor ventilation systems, supply jet conditions and heat load density have to be considered to avoid thermal discomfort because of excessive temperature stratifications. This study demonstrated, by both numerical simulations and experiments, that thermal length scale can be used as a design indicator to predict thermal stratifications under a floor return and a top return underfloor ventilation setting.

  • Numerical and experimental study of velocity and temperature characteristics in a Ventilated Enclosure with underfloor ventilation systems.
    Indoor air, 2005
    Co-Authors: Man Pun Wan, Christopher Yu Hang Chao
    Abstract:

    UNLABELLED Airflow and temperature distributions in an Enclosure with heat sources Ventilated by floor supply jets with floor or ceiling air exit vents were investigated using experimental and numerical approaches. These ventilation configurations represent the floor return or the top return underfloor ventilation systems found in real applications. Experiments and numerical simulations were performed on a full-sized environmental chamber. The results reveal that the temperature stratification in the Enclosure highly depended on the thermal length scale of the floor supply jets. When the thermal length scale of the supply jet was >>1, temperature stratification was minor for all tested heat densities and air distribution methods. Significant vertical temperature gradients occurred when the jet thermal length scale was