Abstract
Diffuse ceiling ventilation is a novel air distribution concept, where the space above a suspended ceiling is used as a plenum and fresh air is supplied into the occupied zone through perforations in the suspended ceiling panels. Due to the low momentum supply, the airflow in the room is driven by buoyancy force generated by heat sources. The previous studies indicate that the diffuse ceiling ventilation system can effectively eliminate the draught risk in the occupied zone and provide a comfortable indoor environment even with low-temperature
supply. However, the effectiveness of diffuse ceiling ventilation in term of air quality has not been studied systematically. It is essential to investigate whether the ventilation system could remove the air-borne contaminants in an efficient way. This study was based on experimental measurement in a full-scale test room simulated an office condition. Contaminant removal effectiveness were measured with N2O tracer gas by step-up method. Two different contaminant sources were analysed, one was occupants also served as heat sources, and the
other was a point source located at floor level and 1.1 m height simulated the contaminant from floor finish and furniture. The measurements were conducted with different heat loads and air flow rates, which represented typical office operating scenario in the summer. When the contaminant released from occupants, mixing has been reached between contaminant and room air. In addition, the stronger the heat load, the higher mixing level was observed. When
the passive contaminant source was located on the floor, due to lack of buoyancy it was trapped in the lower zone and high CRE was observed in the occupied zone (above 0.6 m height). However, the thermal plume around occupant created an upward movement and brought the containment to the breathing zone. This local disturbance of the concentration distribution may affect the personal exposure significantly. Finally, the contaminant concentration was measured in the plenum, and the results indicated that no reverse flow from
occupied zone to the plenum occurred in all cases.
supply. However, the effectiveness of diffuse ceiling ventilation in term of air quality has not been studied systematically. It is essential to investigate whether the ventilation system could remove the air-borne contaminants in an efficient way. This study was based on experimental measurement in a full-scale test room simulated an office condition. Contaminant removal effectiveness were measured with N2O tracer gas by step-up method. Two different contaminant sources were analysed, one was occupants also served as heat sources, and the
other was a point source located at floor level and 1.1 m height simulated the contaminant from floor finish and furniture. The measurements were conducted with different heat loads and air flow rates, which represented typical office operating scenario in the summer. When the contaminant released from occupants, mixing has been reached between contaminant and room air. In addition, the stronger the heat load, the higher mixing level was observed. When
the passive contaminant source was located on the floor, due to lack of buoyancy it was trapped in the lower zone and high CRE was observed in the occupied zone (above 0.6 m height). However, the thermal plume around occupant created an upward movement and brought the containment to the breathing zone. This local disturbance of the concentration distribution may affect the personal exposure significantly. Finally, the contaminant concentration was measured in the plenum, and the results indicated that no reverse flow from
occupied zone to the plenum occurred in all cases.
| Original language | English |
|---|---|
| Title of host publication | Proceedings of the 39th AIVC Conference, 7th TightVent Conference and 5th venticool Conference : Smart Ventilation for buildings |
| Number of pages | 7 |
| Place of Publication | Antibes Juan-Les-Pins, France |
| Publication date | Sept 2018 |
| Pages | 990-996 |
| Publication status | Published - Sept 2018 |
| Event | 39th AIVC Conference: "Smart ventilation for buildings" - Antibes Juan-Les-Pins, France Duration: 18 Sept 2018 → 19 Sept 2018 Conference number: 39 http://aivc2018conference.org/ |
Conference
| Conference | 39th AIVC Conference: "Smart ventilation for buildings" |
|---|---|
| Number | 39 |
| Country/Territory | France |
| City | Antibes Juan-Les-Pins |
| Period | 18/09/2018 → 19/09/2018 |
| Internet address |
Keywords
- Diffuse ceiling ventilation
- Ventilation effectiveness
- Contaminant removal effectiveness
- Experimental study