The Experts below are selected from a list of 3249 Experts worldwide ranked by ideXlab platform

Walid Chakroun - One of the best experts on this subject based on the ideXlab platform.

  • Effectiveness of contaminant confinement in office spaces equipped with ceiling personalized ventilation system
    Building Simulation, 2018
    Co-Authors: Sorour Alotaibi, Walid Chakroun, Charbel Habchi, Kamel Ghali, Nesreen Ghaddar
    Abstract:

    Creating a micro-environment around infected occupants constitutes an effective strategy in reducing contaminants spread insuring a relatively clean macroclimate decreasing the risk of infection for occupants circulating in an office space. In this work, the ability of ceiling personalized ventilation (CPV) system assisted by desk fans (DF) or chair fans (CF) was studied with respect to confining contaminants spread in typical office space while considering possible occupant shift. A 3D computational fluid dynamics (CFD) model was developed to simulate particle spread. The developed model was validated experimentally with respect to concentration values using a thermal manikin in a climatic chamber with controlled particle generation. A parametric study was followed to determine the effect of the occupant shift from CPV design position, the CPV+DF or CF configuration, and the canopy angle on confinement performance for minimal particle spread in the space. The CPV jet and diffusers’ flow canopy favored particle deposition within the Microclimate Region leading to their removal from indoor air. For no occupant shift, assisting the CPV jet by DF or CF was very efficient in particle confinement. However, in the cases of critical backward occupant shift, flow asymmetry was formed around the occupant leading to particle spread and leading to asymmetry attenuation when operated with CF. The highest particle confinement was obtained for a canopy angle of 45° for the case of CPV assisted by CF due to forming a recirculation zone between the CPV and jet diffusers; hence trapping particles and reducing their spread to the macroclimate. It was found that a total supply flow rate of 60 L/s for MV is required compared to 43.5 L/s for the optimal CPV design, for equivalent average particle concentration within the macroclimate zone at the critical generation plane, leading to 62% reduction in power consumption of the supply fan.

  • Investigation of particle transport in offices equipped with ceiling-mounted personalized ventilators
    Building and Environment, 2013
    Co-Authors: Abdallah Makhoul, Kamel Ghali, Nesreen Ghaddar, Walid Chakroun
    Abstract:

    The performance of ceiling-mounted personalized ventilators (PV) in reducing particle migration between office stations was assessed. The PV nozzles were integrated with peripheral diffusers that were able to form a canopy of conditioned air around the occupant. A numerical CFD model was developed to simulate the flow, temperature and particle concentration fields. Validation against experimental measurements and published experimental data was performed. The canopy was effective in reducing the migration of particles from the macroclimate to the Microclimate Region and low intake fractions of 1.90 × 10−4 and 5.9 × 10−4 were achieved for particle sizes of 1 μm and 0.01 μm, respectively. The PV jet was capable of maintaining an intake fraction of 3.6 × 10−4 for fine particle sizes (1 μm) and 2.95 × 10−4 for ultrafine particles (0.01 μm) when the particle-emitting source is in the proximity of the occupant. However, in spite of the good inhaled air quality achieved by the PV nozzle, the particle deposition rate on solid surfaces that are easily reached by the occupant is high when the source is placed in the Microclimate.

Abdallah Makhoul - One of the best experts on this subject based on the ideXlab platform.

  • Performance of coaxial ceiling-mounted personalized ventilator for comfort and good air quality
    ASME 2013 Heat Transfer Summer Conf. Collocated with the ASME 2013 7th Int. Conf. on Energy Sustainability and the ASME 2013 11th Int. Conf. on Fuel C, 2013
    Co-Authors: Nesreen Ghaddar, Kamel Ghali, Abdallah Makhoul
    Abstract:

    The aim of this work is to study the performance of a novel ceiling mounted coaxial personalized ventilator that can be used as an add on to the conventional ceiling diffuser in providing the thermal comfort and air quality needs to occupants in office building. A detailed 3D CFD model is coupled to a bioheat model to improve prediction of the microenvironment conditions around the human and the associated local and overall thermal comfort. Extensive simulations were performed to assess the effect of nozzle supply temperature and flow rate on the performance of the cooling system and on occupant comfort. The localized air conditioning system reduced the energy consumption by up to 34% when compared with conventional mixing systems providing the same level of thermal comfort. The proposed system also achieved high air quality in the occupant breathing zone with 45% ventilation effectiveness at fresh airflow rate of 10 L/s/person and attained 2C between the occupant's comfortable microenvironment and the rest of the space. In addition, the canopy of the angled diffuser was effective in reducing the migration of particles from the macroclimate to the Microclimate Region and low intake fractions of 1.90×10-4 were achieved Copyright © 2013 by ASME.

  • Investigation of particle transport in offices equipped with ceiling-mounted personalized ventilators
    Building and Environment, 2013
    Co-Authors: Abdallah Makhoul, Kamel Ghali, Nesreen Ghaddar, Walid Chakroun
    Abstract:

    The performance of ceiling-mounted personalized ventilators (PV) in reducing particle migration between office stations was assessed. The PV nozzles were integrated with peripheral diffusers that were able to form a canopy of conditioned air around the occupant. A numerical CFD model was developed to simulate the flow, temperature and particle concentration fields. Validation against experimental measurements and published experimental data was performed. The canopy was effective in reducing the migration of particles from the macroclimate to the Microclimate Region and low intake fractions of 1.90 × 10−4 and 5.9 × 10−4 were achieved for particle sizes of 1 μm and 0.01 μm, respectively. The PV jet was capable of maintaining an intake fraction of 3.6 × 10−4 for fine particle sizes (1 μm) and 2.95 × 10−4 for ultrafine particles (0.01 μm) when the particle-emitting source is in the proximity of the occupant. However, in spite of the good inhaled air quality achieved by the PV nozzle, the particle deposition rate on solid surfaces that are easily reached by the occupant is high when the source is placed in the Microclimate.

Kamel Ghali - One of the best experts on this subject based on the ideXlab platform.

  • Effectiveness of contaminant confinement in office spaces equipped with ceiling personalized ventilation system
    Building Simulation, 2018
    Co-Authors: Sorour Alotaibi, Walid Chakroun, Charbel Habchi, Kamel Ghali, Nesreen Ghaddar
    Abstract:

    Creating a micro-environment around infected occupants constitutes an effective strategy in reducing contaminants spread insuring a relatively clean macroclimate decreasing the risk of infection for occupants circulating in an office space. In this work, the ability of ceiling personalized ventilation (CPV) system assisted by desk fans (DF) or chair fans (CF) was studied with respect to confining contaminants spread in typical office space while considering possible occupant shift. A 3D computational fluid dynamics (CFD) model was developed to simulate particle spread. The developed model was validated experimentally with respect to concentration values using a thermal manikin in a climatic chamber with controlled particle generation. A parametric study was followed to determine the effect of the occupant shift from CPV design position, the CPV+DF or CF configuration, and the canopy angle on confinement performance for minimal particle spread in the space. The CPV jet and diffusers’ flow canopy favored particle deposition within the Microclimate Region leading to their removal from indoor air. For no occupant shift, assisting the CPV jet by DF or CF was very efficient in particle confinement. However, in the cases of critical backward occupant shift, flow asymmetry was formed around the occupant leading to particle spread and leading to asymmetry attenuation when operated with CF. The highest particle confinement was obtained for a canopy angle of 45° for the case of CPV assisted by CF due to forming a recirculation zone between the CPV and jet diffusers; hence trapping particles and reducing their spread to the macroclimate. It was found that a total supply flow rate of 60 L/s for MV is required compared to 43.5 L/s for the optimal CPV design, for equivalent average particle concentration within the macroclimate zone at the critical generation plane, leading to 62% reduction in power consumption of the supply fan.

  • Performance of coaxial ceiling-mounted personalized ventilator for comfort and good air quality
    ASME 2013 Heat Transfer Summer Conf. Collocated with the ASME 2013 7th Int. Conf. on Energy Sustainability and the ASME 2013 11th Int. Conf. on Fuel C, 2013
    Co-Authors: Nesreen Ghaddar, Kamel Ghali, Abdallah Makhoul
    Abstract:

    The aim of this work is to study the performance of a novel ceiling mounted coaxial personalized ventilator that can be used as an add on to the conventional ceiling diffuser in providing the thermal comfort and air quality needs to occupants in office building. A detailed 3D CFD model is coupled to a bioheat model to improve prediction of the microenvironment conditions around the human and the associated local and overall thermal comfort. Extensive simulations were performed to assess the effect of nozzle supply temperature and flow rate on the performance of the cooling system and on occupant comfort. The localized air conditioning system reduced the energy consumption by up to 34% when compared with conventional mixing systems providing the same level of thermal comfort. The proposed system also achieved high air quality in the occupant breathing zone with 45% ventilation effectiveness at fresh airflow rate of 10 L/s/person and attained 2C between the occupant's comfortable microenvironment and the rest of the space. In addition, the canopy of the angled diffuser was effective in reducing the migration of particles from the macroclimate to the Microclimate Region and low intake fractions of 1.90×10-4 were achieved Copyright © 2013 by ASME.

  • Investigation of particle transport in offices equipped with ceiling-mounted personalized ventilators
    Building and Environment, 2013
    Co-Authors: Abdallah Makhoul, Kamel Ghali, Nesreen Ghaddar, Walid Chakroun
    Abstract:

    The performance of ceiling-mounted personalized ventilators (PV) in reducing particle migration between office stations was assessed. The PV nozzles were integrated with peripheral diffusers that were able to form a canopy of conditioned air around the occupant. A numerical CFD model was developed to simulate the flow, temperature and particle concentration fields. Validation against experimental measurements and published experimental data was performed. The canopy was effective in reducing the migration of particles from the macroclimate to the Microclimate Region and low intake fractions of 1.90 × 10−4 and 5.9 × 10−4 were achieved for particle sizes of 1 μm and 0.01 μm, respectively. The PV jet was capable of maintaining an intake fraction of 3.6 × 10−4 for fine particle sizes (1 μm) and 2.95 × 10−4 for ultrafine particles (0.01 μm) when the particle-emitting source is in the proximity of the occupant. However, in spite of the good inhaled air quality achieved by the PV nozzle, the particle deposition rate on solid surfaces that are easily reached by the occupant is high when the source is placed in the Microclimate.

Nesreen Ghaddar - One of the best experts on this subject based on the ideXlab platform.

  • Effectiveness of contaminant confinement in office spaces equipped with ceiling personalized ventilation system
    Building Simulation, 2018
    Co-Authors: Sorour Alotaibi, Walid Chakroun, Charbel Habchi, Kamel Ghali, Nesreen Ghaddar
    Abstract:

    Creating a micro-environment around infected occupants constitutes an effective strategy in reducing contaminants spread insuring a relatively clean macroclimate decreasing the risk of infection for occupants circulating in an office space. In this work, the ability of ceiling personalized ventilation (CPV) system assisted by desk fans (DF) or chair fans (CF) was studied with respect to confining contaminants spread in typical office space while considering possible occupant shift. A 3D computational fluid dynamics (CFD) model was developed to simulate particle spread. The developed model was validated experimentally with respect to concentration values using a thermal manikin in a climatic chamber with controlled particle generation. A parametric study was followed to determine the effect of the occupant shift from CPV design position, the CPV+DF or CF configuration, and the canopy angle on confinement performance for minimal particle spread in the space. The CPV jet and diffusers’ flow canopy favored particle deposition within the Microclimate Region leading to their removal from indoor air. For no occupant shift, assisting the CPV jet by DF or CF was very efficient in particle confinement. However, in the cases of critical backward occupant shift, flow asymmetry was formed around the occupant leading to particle spread and leading to asymmetry attenuation when operated with CF. The highest particle confinement was obtained for a canopy angle of 45° for the case of CPV assisted by CF due to forming a recirculation zone between the CPV and jet diffusers; hence trapping particles and reducing their spread to the macroclimate. It was found that a total supply flow rate of 60 L/s for MV is required compared to 43.5 L/s for the optimal CPV design, for equivalent average particle concentration within the macroclimate zone at the critical generation plane, leading to 62% reduction in power consumption of the supply fan.

  • Performance of coaxial ceiling-mounted personalized ventilator for comfort and good air quality
    ASME 2013 Heat Transfer Summer Conf. Collocated with the ASME 2013 7th Int. Conf. on Energy Sustainability and the ASME 2013 11th Int. Conf. on Fuel C, 2013
    Co-Authors: Nesreen Ghaddar, Kamel Ghali, Abdallah Makhoul
    Abstract:

    The aim of this work is to study the performance of a novel ceiling mounted coaxial personalized ventilator that can be used as an add on to the conventional ceiling diffuser in providing the thermal comfort and air quality needs to occupants in office building. A detailed 3D CFD model is coupled to a bioheat model to improve prediction of the microenvironment conditions around the human and the associated local and overall thermal comfort. Extensive simulations were performed to assess the effect of nozzle supply temperature and flow rate on the performance of the cooling system and on occupant comfort. The localized air conditioning system reduced the energy consumption by up to 34% when compared with conventional mixing systems providing the same level of thermal comfort. The proposed system also achieved high air quality in the occupant breathing zone with 45% ventilation effectiveness at fresh airflow rate of 10 L/s/person and attained 2C between the occupant's comfortable microenvironment and the rest of the space. In addition, the canopy of the angled diffuser was effective in reducing the migration of particles from the macroclimate to the Microclimate Region and low intake fractions of 1.90×10-4 were achieved Copyright © 2013 by ASME.

  • Investigation of particle transport in offices equipped with ceiling-mounted personalized ventilators
    Building and Environment, 2013
    Co-Authors: Abdallah Makhoul, Kamel Ghali, Nesreen Ghaddar, Walid Chakroun
    Abstract:

    The performance of ceiling-mounted personalized ventilators (PV) in reducing particle migration between office stations was assessed. The PV nozzles were integrated with peripheral diffusers that were able to form a canopy of conditioned air around the occupant. A numerical CFD model was developed to simulate the flow, temperature and particle concentration fields. Validation against experimental measurements and published experimental data was performed. The canopy was effective in reducing the migration of particles from the macroclimate to the Microclimate Region and low intake fractions of 1.90 × 10−4 and 5.9 × 10−4 were achieved for particle sizes of 1 μm and 0.01 μm, respectively. The PV jet was capable of maintaining an intake fraction of 3.6 × 10−4 for fine particle sizes (1 μm) and 2.95 × 10−4 for ultrafine particles (0.01 μm) when the particle-emitting source is in the proximity of the occupant. However, in spite of the good inhaled air quality achieved by the PV nozzle, the particle deposition rate on solid surfaces that are easily reached by the occupant is high when the source is placed in the Microclimate.

Sorour Alotaibi - One of the best experts on this subject based on the ideXlab platform.

  • Effectiveness of contaminant confinement in office spaces equipped with ceiling personalized ventilation system
    Building Simulation, 2018
    Co-Authors: Sorour Alotaibi, Walid Chakroun, Charbel Habchi, Kamel Ghali, Nesreen Ghaddar
    Abstract:

    Creating a micro-environment around infected occupants constitutes an effective strategy in reducing contaminants spread insuring a relatively clean macroclimate decreasing the risk of infection for occupants circulating in an office space. In this work, the ability of ceiling personalized ventilation (CPV) system assisted by desk fans (DF) or chair fans (CF) was studied with respect to confining contaminants spread in typical office space while considering possible occupant shift. A 3D computational fluid dynamics (CFD) model was developed to simulate particle spread. The developed model was validated experimentally with respect to concentration values using a thermal manikin in a climatic chamber with controlled particle generation. A parametric study was followed to determine the effect of the occupant shift from CPV design position, the CPV+DF or CF configuration, and the canopy angle on confinement performance for minimal particle spread in the space. The CPV jet and diffusers’ flow canopy favored particle deposition within the Microclimate Region leading to their removal from indoor air. For no occupant shift, assisting the CPV jet by DF or CF was very efficient in particle confinement. However, in the cases of critical backward occupant shift, flow asymmetry was formed around the occupant leading to particle spread and leading to asymmetry attenuation when operated with CF. The highest particle confinement was obtained for a canopy angle of 45° for the case of CPV assisted by CF due to forming a recirculation zone between the CPV and jet diffusers; hence trapping particles and reducing their spread to the macroclimate. It was found that a total supply flow rate of 60 L/s for MV is required compared to 43.5 L/s for the optimal CPV design, for equivalent average particle concentration within the macroclimate zone at the critical generation plane, leading to 62% reduction in power consumption of the supply fan.