In high-rise building fires, the most immediate threat to passenger life and safety evacuation is the smoke inhalation. Some traditional models for smoke prevention and exhaust are analyzed and compared with the smoke...In high-rise building fires, the most immediate threat to passenger life and safety evacuation is the smoke inhalation. Some traditional models for smoke prevention and exhaust are analyzed and compared with the smoke-preventing air curtain. The rationality and the feasibility of the air curtain are theoretically expounded. The air volume, tuyere width and jet velocity in the air curtain experiment are designed according to the theoreti- cal calculation model. Experimental results indicate that the effect of air curtain to prevent smoke diffusion is re- markable as the volume ratio of air-smoke is about 0. 6, the jet angle is between 25^o and 35^o, and the jet thickness is between 25 mm and 45 mm. The efficiency of air curtain can reach 98% on the entraining effect. Meanwhile, experiments verify the theorectical calculation.展开更多
Performances and efficiencies of displacement ventilation(DV) and partial ventilation(PV) for industrial halls of different configurations as well as the heat and mass transports within the industrial halls were numer...Performances and efficiencies of displacement ventilation(DV) and partial ventilation(PV) for industrial halls of different configurations as well as the heat and mass transports within the industrial halls were numerically investigated. Three levels of Rayleigh number(5.8×1010, 1.0×1012 and 2.1×1012) and two values of source contaminant flux(5 mg/s and 50 mg/s) were considered. The inlet Reynolds numbers were 2×104, 5×104, 1.5×105 and 4.5×105 for DV and 5×105, 1×106, 2×106 and 4×106 for PV, respectively. From the results, it is concluded that the above parameters have very complex impacts on the conjugated heat and mass transports. From points of view of acceptable indoor air quality and ventilation efficiency, PV at Re=1×106 with side-located sources and 65% of the supply air extracted through floor level outlets is the best choice when Ra=5.8×1010. However, DVs at Re=5×104 and Re=1.5×105with center-located sources and floor-mounted air suppliers are the best choices for Ra=1.0×1012 and Ra=2.1×1012, respectively. When source contaminant flux reaches 50 mg/s, local extraction as a supplement of general ventilation is recommended. The results can be a first approximation to 3D numerical investigation and preliminary ventilation system design guidelines for high-rise industrial halls.展开更多
An emerging issue in Denmark is passive smoking in residential buildings where non-smokers are exposed to smoke from their neighbours. There are various ways that smoke is transferred from one flat to another. The air...An emerging issue in Denmark is passive smoking in residential buildings where non-smokers are exposed to smoke from their neighbours. There are various ways that smoke is transferred from one flat to another. The air transfer rate between two flats in a multi-storey building depends on its construction, tightness and age. This paper presents results of a study on the transfer of ultrafine particles and tracer gas in an older multi-storey building in Copenhagen. The aim of the study was to quantify the transfer ofultrafine particles and gases from one flat to another fiat before and after sealing the floor. A new floor-sealing method was applied to seal the floor between the two flats. The sealing method was developed by a firm specialising in sealing. Indoor ultrafine particle concentrations and tracer gas were measured continuously in the two fiats during the measuring periods. In the unoccupied fiat, the gas source was N20 and the particle source was burning cigarettes. Reduction of the concentration of ultrafine particles and tracer gas by sealing the floor with polyethylene and joint filler made of bitumen was studied. It was evaluated how the sealing performed with regard to decreasing the amount of ultrafine particles and a tracer gas transferred between two fiats separated by a floor. When the floor between the flats was not sealed, the results showed that about 4% of the ultraflne particles and 14% of the tracer gas were transferred. After sealing, the amount transferred was reduced to 1.6% and 5%, respectively.展开更多
文摘In high-rise building fires, the most immediate threat to passenger life and safety evacuation is the smoke inhalation. Some traditional models for smoke prevention and exhaust are analyzed and compared with the smoke-preventing air curtain. The rationality and the feasibility of the air curtain are theoretically expounded. The air volume, tuyere width and jet velocity in the air curtain experiment are designed according to the theoreti- cal calculation model. Experimental results indicate that the effect of air curtain to prevent smoke diffusion is re- markable as the volume ratio of air-smoke is about 0. 6, the jet angle is between 25^o and 35^o, and the jet thickness is between 25 mm and 45 mm. The efficiency of air curtain can reach 98% on the entraining effect. Meanwhile, experiments verify the theorectical calculation.
基金Project(2011BAJ03B07)supported by National Twelve Five-year Science and Technology Support Program of ChinaProject supported by the China Scholarship Council+1 种基金Project(51276057,51376198)supported by the National Natural Science Foundation of ChinaProject(CX2014B064)supported by Hunan Provincial Innovation Foundation for Postgraduate,China
文摘Performances and efficiencies of displacement ventilation(DV) and partial ventilation(PV) for industrial halls of different configurations as well as the heat and mass transports within the industrial halls were numerically investigated. Three levels of Rayleigh number(5.8×1010, 1.0×1012 and 2.1×1012) and two values of source contaminant flux(5 mg/s and 50 mg/s) were considered. The inlet Reynolds numbers were 2×104, 5×104, 1.5×105 and 4.5×105 for DV and 5×105, 1×106, 2×106 and 4×106 for PV, respectively. From the results, it is concluded that the above parameters have very complex impacts on the conjugated heat and mass transports. From points of view of acceptable indoor air quality and ventilation efficiency, PV at Re=1×106 with side-located sources and 65% of the supply air extracted through floor level outlets is the best choice when Ra=5.8×1010. However, DVs at Re=5×104 and Re=1.5×105with center-located sources and floor-mounted air suppliers are the best choices for Ra=1.0×1012 and Ra=2.1×1012, respectively. When source contaminant flux reaches 50 mg/s, local extraction as a supplement of general ventilation is recommended. The results can be a first approximation to 3D numerical investigation and preliminary ventilation system design guidelines for high-rise industrial halls.
文摘An emerging issue in Denmark is passive smoking in residential buildings where non-smokers are exposed to smoke from their neighbours. There are various ways that smoke is transferred from one flat to another. The air transfer rate between two flats in a multi-storey building depends on its construction, tightness and age. This paper presents results of a study on the transfer of ultrafine particles and tracer gas in an older multi-storey building in Copenhagen. The aim of the study was to quantify the transfer ofultrafine particles and gases from one flat to another fiat before and after sealing the floor. A new floor-sealing method was applied to seal the floor between the two flats. The sealing method was developed by a firm specialising in sealing. Indoor ultrafine particle concentrations and tracer gas were measured continuously in the two fiats during the measuring periods. In the unoccupied fiat, the gas source was N20 and the particle source was burning cigarettes. Reduction of the concentration of ultrafine particles and tracer gas by sealing the floor with polyethylene and joint filler made of bitumen was studied. It was evaluated how the sealing performed with regard to decreasing the amount of ultrafine particles and a tracer gas transferred between two fiats separated by a floor. When the floor between the flats was not sealed, the results showed that about 4% of the ultraflne particles and 14% of the tracer gas were transferred. After sealing, the amount transferred was reduced to 1.6% and 5%, respectively.
