The Experts below are selected from a list of 174 Experts worldwide ranked by ideXlab platform

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

  • Experimental study of ventilation performance and contaminant distribution of underfloor ventilation systems vs. traditional ceiling-based ventilation system.
    Indoor air, 2004
    Co-Authors: Christopher Yu Hang Chao, Man Pun Wan
    Abstract:

    UNLABELLED Ventilation performance and pollutant distribution in a traditional ceiling-type ventilation system, a top-return (TR)-type and a floor-return (FR)-type underfloor ventilation systems were performed in a controlled experimental room. Tracer gas method was utilized to determine the age of air and the contaminant removal effectiveness. Tobacco smoke was also introduced to study the particle-phase pollutant distribution. The TR system delivered conditioned air more efficiently in the occupied zone and exhibited higher gaseous contaminant removal effectiveness. It also showed the lowest smoke particle concentration compared with the other two systems. The FR system showed better ventilation performance over the mixing system at the space that was close to the floor Supply Outlet and at the lower height level. The FR system was less effective than the TR system in removing buoyant tobacco smoke particles at the upper part of the room indicating its highly localized characteristics. Differences in experimental conditions between the present and the previous studies and their effects on the experimental results are discussed. In general, the experimental data suggested that both types of the underfloor ventilation systems have the potential of improving air quality at the breathing zone over the ceiling-based mixing system with suitable designs. PRACTICAL IMPLICATIONS This study shows the possibility of improving indoor air quality using underfloor ventilation systems compared with the traditional ceiling-based ventilation system. However, different configurations of the underfloor ventilation system show various ventilation characteristics. The engineers should consider these features when implementing an underfloor ventilation design. The top-return (TR) configuration improves indoor air quality by creating a displacement-like flow pattern while the floor-return (FR) configuration shows highly localized ventilation characteristics. The FR configuration improved the indoor air quality at spaces near the floor diffusers and up to certain heights.

  • Airflow and air temperature distribution in the occupied region of an underfloor ventilation system
    Building and Environment, 2004
    Co-Authors: Christopher Yu Hang Chao, Man Pun Wan
    Abstract:

    Measurements were carried out in an office-type experimental room ventilated by a floor return-type underfloor ventilation system to investigate the distributions of airflow velocity and air temperature. A fan-powered floor air unit (FAU) with rectangular Supply and return air Outlets covered by straight-profile linear bar-type air diffusers was installed to deliver the conditioned air in the experimental room. Turbulence intensity and draught rate distributions inside the room were also calculated by using the measured data. From the experimental results, it is found that undesirable high air velocities and high draught rates were created within a small region near the Supply Outlet of the FAU. Temperature differences between different height levels were maintained within an acceptable comfort level under the tested Supply air conditions and heat loads. The results indicated that the temperature stratification could be maintained at an acceptable comfort level by designing the Supply air conditions properly. A clearance zone is suggested as a design consideration for locating the FAUs and occupants to avoid undesirable draught discomfort to the occupants.

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

  • Experimental study of ventilation performance and contaminant distribution of underfloor ventilation systems vs. traditional ceiling-based ventilation system.
    Indoor air, 2004
    Co-Authors: Christopher Yu Hang Chao, Man Pun Wan
    Abstract:

    UNLABELLED Ventilation performance and pollutant distribution in a traditional ceiling-type ventilation system, a top-return (TR)-type and a floor-return (FR)-type underfloor ventilation systems were performed in a controlled experimental room. Tracer gas method was utilized to determine the age of air and the contaminant removal effectiveness. Tobacco smoke was also introduced to study the particle-phase pollutant distribution. The TR system delivered conditioned air more efficiently in the occupied zone and exhibited higher gaseous contaminant removal effectiveness. It also showed the lowest smoke particle concentration compared with the other two systems. The FR system showed better ventilation performance over the mixing system at the space that was close to the floor Supply Outlet and at the lower height level. The FR system was less effective than the TR system in removing buoyant tobacco smoke particles at the upper part of the room indicating its highly localized characteristics. Differences in experimental conditions between the present and the previous studies and their effects on the experimental results are discussed. In general, the experimental data suggested that both types of the underfloor ventilation systems have the potential of improving air quality at the breathing zone over the ceiling-based mixing system with suitable designs. PRACTICAL IMPLICATIONS This study shows the possibility of improving indoor air quality using underfloor ventilation systems compared with the traditional ceiling-based ventilation system. However, different configurations of the underfloor ventilation system show various ventilation characteristics. The engineers should consider these features when implementing an underfloor ventilation design. The top-return (TR) configuration improves indoor air quality by creating a displacement-like flow pattern while the floor-return (FR) configuration shows highly localized ventilation characteristics. The FR configuration improved the indoor air quality at spaces near the floor diffusers and up to certain heights.

  • Airflow and air temperature distribution in the occupied region of an underfloor ventilation system
    Building and Environment, 2004
    Co-Authors: Christopher Yu Hang Chao, Man Pun Wan
    Abstract:

    Measurements were carried out in an office-type experimental room ventilated by a floor return-type underfloor ventilation system to investigate the distributions of airflow velocity and air temperature. A fan-powered floor air unit (FAU) with rectangular Supply and return air Outlets covered by straight-profile linear bar-type air diffusers was installed to deliver the conditioned air in the experimental room. Turbulence intensity and draught rate distributions inside the room were also calculated by using the measured data. From the experimental results, it is found that undesirable high air velocities and high draught rates were created within a small region near the Supply Outlet of the FAU. Temperature differences between different height levels were maintained within an acceptable comfort level under the tested Supply air conditions and heat loads. The results indicated that the temperature stratification could be maintained at an acceptable comfort level by designing the Supply air conditions properly. A clearance zone is suggested as a design consideration for locating the FAUs and occupants to avoid undesirable draught discomfort to the occupants.

Anatolijs Borodinecs - One of the best experts on this subject based on the ideXlab platform.

  • Impact of impinging jet ventilation on thermal comfort and indoor air quality in office buildings
    Energy and Buildings, 1
    Co-Authors: Arturs Staveckis, Anatolijs Borodinecs
    Abstract:

    Abstract This paper is dedicated to research of impinging jet (IJV) air distribution method. This system provides the desired indoor climate in office buildings. This paper describes the experimental requirements and boundary conditions for the CFD simulation and experiment in the climate chamber. The necessary modelling scenarios were developed to review the operation of the ventilation system according to different climatic conditions (winter, summer), human positions in the room and the shape of the Supply duct. It is concluded that the shape of the air opening has little effect on the contaminant and heat removal effectiveness, 114%–122% and 1.12–1.16 respectively. At the same time, there is a large impact on the air exchange effectiveness (0.74–0.91). It was experimentally noted that in terms of contaminant removal and air exchange effectiveness, the circular opening provides better results. The human position depends on the Supply temperature and flow velocity. By analyzing different scenarios, it was determined that the minimum acceptable distance to maintain thermal comfort within the standard requirements from the Supply Outlet is 1.7 m. As the distance from the air opening increases, the vertical air temperature difference at the height of 0.1–1.1 m decreases more than 2 times – from 1.9K/m to 0.7K/m. It is concluded that impinging jet ventilation has a great potential for use in office spaces both in winter and summer scenarios. This system significantly improves thermal comfort and indoor air quality. Applying impinging jet ventilation (IJV), limitations and peculiarities of the system such as Supply air velocity, temperature and shape of the air duct must be carefully evaluated.

Arturs Staveckis - One of the best experts on this subject based on the ideXlab platform.

  • Impact of impinging jet ventilation on thermal comfort and indoor air quality in office buildings
    Energy and Buildings, 1
    Co-Authors: Arturs Staveckis, Anatolijs Borodinecs
    Abstract:

    Abstract This paper is dedicated to research of impinging jet (IJV) air distribution method. This system provides the desired indoor climate in office buildings. This paper describes the experimental requirements and boundary conditions for the CFD simulation and experiment in the climate chamber. The necessary modelling scenarios were developed to review the operation of the ventilation system according to different climatic conditions (winter, summer), human positions in the room and the shape of the Supply duct. It is concluded that the shape of the air opening has little effect on the contaminant and heat removal effectiveness, 114%–122% and 1.12–1.16 respectively. At the same time, there is a large impact on the air exchange effectiveness (0.74–0.91). It was experimentally noted that in terms of contaminant removal and air exchange effectiveness, the circular opening provides better results. The human position depends on the Supply temperature and flow velocity. By analyzing different scenarios, it was determined that the minimum acceptable distance to maintain thermal comfort within the standard requirements from the Supply Outlet is 1.7 m. As the distance from the air opening increases, the vertical air temperature difference at the height of 0.1–1.1 m decreases more than 2 times – from 1.9K/m to 0.7K/m. It is concluded that impinging jet ventilation has a great potential for use in office spaces both in winter and summer scenarios. This system significantly improves thermal comfort and indoor air quality. Applying impinging jet ventilation (IJV), limitations and peculiarities of the system such as Supply air velocity, temperature and shape of the air duct must be carefully evaluated.

Ru-he Xie - One of the best experts on this subject based on the ideXlab platform.