The pressurization smoke control system has been commonly used as a smoke control system at the emergency stairs of high-rise buildings. However, a higher possibility of overpressure between the lobby and the accommod...The pressurization smoke control system has been commonly used as a smoke control system at the emergency stairs of high-rise buildings. However, a higher possibility of overpressure between the lobby and the accommodation or pressure drop in the lobby could lead to failure in achievement of the purpose of pressurization system, particularly when supplying the leakage and supplementary air flow through one air-supply path at a time. To improve this particular issue, the devise configurations, as well as the different ways to supply the leakage and supplementary air flow through the different flow passages have been proposed. The performance of the trial product was evaluated on the test bed, ultimately providing a safe evacuation environment if high-rise buildings fired.展开更多
The volumetric flow rate of smoke generated from the fire in large space often reaches to hundreds of thousands CMH because of extended floor height and as it’s more difficult to isolate the smoke to the limited area...The volumetric flow rate of smoke generated from the fire in large space often reaches to hundreds of thousands CMH because of extended floor height and as it’s more difficult to isolate the smoke to the limited area, comparing to normal-scale building, design and operation of effective smoke control system for large space is more than important. In this study, with the analysis model for such a large space as exhibition hall or conference room in conventional center, design of mechanical smoke exhaust system was conducted based on currently-available design standard which was then followed by numerical analysis of the design using 3D numerical analysis method. For conference room at 2.0 MW heat release rate, 99,173 CMH flow rate is required, if smoke layer is maintained at 60% of the floor height and for exhibition hall at 8.8 MW with 80% of floor height, flow rate required is 219,802 CMH, which are incorporated into the design. In view of 3D numerical analysis, accuracy of the design according to algebraic expression is sufficient.展开更多
At present, with the rapid development of China's economy, the integration of urban and rural areas has been strengthened to ease the tension in the housing field, and the number of high-rise residential buildings...At present, with the rapid development of China's economy, the integration of urban and rural areas has been strengthened to ease the tension in the housing field, and the number of high-rise residential buildings and shopping malls has been increasing, which has brought great difficulties to the fire control work. In the process of design and construction, combined with the requirements of fire control management in the new era, attention should be paid to centralized control of smoke control devices and HVAC fire fighting equipment, so as to ensure the quality of HVAC fire fighting projects, reduce the possibility of fire and other accidents, and protect the safety of people's lives and property.展开更多
Research on the distribution of smoke in tunnels is significant for the fire emergency rescue after an operating metro train catches fire. A dynamic grid technique was adopted to research the law of smoke flow diffusi...Research on the distribution of smoke in tunnels is significant for the fire emergency rescue after an operating metro train catches fire. A dynamic grid technique was adopted to research the law of smoke flow diffusion inside the tunnel when the bottom of a metro train was on fire and to compare the effect of longitudinal ventilation modes on the smoke motion when the burning train stopped. Research results show that the slipstream curves around the train obtained by numerical simulation are consistent with experimental data. When the train decelerates, the smoke flow first extends to the tail of the train. With the decrease of the train's speed, the smoke flow diffuses to the head of the train. After the train stops, the slipstream around the train formed in the process of train operation plays a leading role in the smoke diffusion in the tunnel. The smoke flow quickly diffuses to the domain in front of the train. After forward mechanical ventilation is provided, the smoke flow inside the tunnel continues to diffuse downstream. When reverse mechanical ventilation operates, the smoke in front of the train flows back rapidly and diffuses to the rear of the train.展开更多
The Shenzhen–Zhongshan Bridge is a 24‐km‐long bridge and tunnel system,including a 6.8-km-long super cross section subsea tunnel.To solve the smoke exhaust problem of a super large cross-section subsea tunnel,the t...The Shenzhen–Zhongshan Bridge is a 24‐km‐long bridge and tunnel system,including a 6.8-km-long super cross section subsea tunnel.To solve the smoke exhaust problem of a super large cross-section subsea tunnel,the tunnel has a new smoke exhaust system that combines a horizontal smoke exhaust cross section at the top and sidewall smoke exhaust holes.In order to evaluate the potential fire hazards of this type of tunnel,a 1:30 tunnel model was established and 140 smallscale experiments on underwater tunnel fires were conducted.By changing the fire power,fire location,and fan operation mode,different scenarios of submarine immersed tunnel fire were simulated and the related key parameters such as fire smoke diffusion behavior and smoke temperature distribution were studied.On this basis,the optimal smoke control strategy was proposed for different fire scenarios.The research results indicate that the new smoke exhaust system can fully utilize the smoke flow characteristics,significantly improve smoke exhaust efficiency,and increase available evacuation time,thus further enhancing the fire safety of super large cross-section subsea tunnels.展开更多
The number of smokers in Chinese rural areas is more than 200 million, which is twice that in cities. It is very significant to carry out tobacco control interventions in rural areas. We performed this community inter...The number of smokers in Chinese rural areas is more than 200 million, which is twice that in cities. It is very significant to carry out tobacco control interventions in rural areas. We performed this community intervention study to evaluate the efficacy of village-based health education of tobacco control on the male current smoking rate in rural areas. The population of this study was the males above 15 years old from 6 villages in rural areas. The villages were randomly assigned to intervention group or control group（3 villages in each group）. Self-designed smoking questionnaire was applied. The intervention group received the village-based health education of tobacco control for one year. The primary outcome measurement was the male current smoking rate. In the baseline investigation, completed surveys were returned by 814 male residents from the control group and 831 male residents from the intervention group. The male current smoking rate in the control group and the intervention group was 61.2% and 58.5%, respectively, before intervention. There was no significant difference between these two groups（P〉0.05）. After one-year intervention, the current smoking rate in the intervention group（51.2%） was significantly lower than that in the control group（62.8%）（P〈0.001）. Our study suggested that the village-based health education of tobacco control was effective in lowering the male current smoking rate in rural areas, which could be a suitable and feasible way for tobacco control in the Chinese rural areas.展开更多
High smoke extraction efficiency and a relatively stable smoke layer stratification are both expected in tunnel ventilation systems.The purpose of this paper is to explore the overall performance of mechanical board-c...High smoke extraction efficiency and a relatively stable smoke layer stratification are both expected in tunnel ventilation systems.The purpose of this paper is to explore the overall performance of mechanical board-coupled shaft under different ventilation strategies.A total of 57 simulations were conducted,and the effects of the distance between the shaft and board(hp)and ventilation velocity on the overall performance were investigated.The results indicate that the performance of smoke extraction and control will be improved by the application of mechanical ventilation and board.Smoke movement patterns under different working conditions were dfferent,for cases of hp≤0.40 m the smoke could propagate through the whole tunnel without backflow,while for cases of hp>0.40 m,the backflow exists and the smoke movement can be separated into three periods(propagation,stagnation,and retraction).The critical criterion of backflow was investigated and a simple model was deduced to estimate the maximum propagation length.Moreover,the dimensionless time for the smoke flow to reach its maximum propagation length was established.Finally,a comprehensive index was proposed to evaluate the synergistic effects of smoke extraction and control performance.These studies may provide positive significance for the ventilation design.展开更多
文摘The pressurization smoke control system has been commonly used as a smoke control system at the emergency stairs of high-rise buildings. However, a higher possibility of overpressure between the lobby and the accommodation or pressure drop in the lobby could lead to failure in achievement of the purpose of pressurization system, particularly when supplying the leakage and supplementary air flow through one air-supply path at a time. To improve this particular issue, the devise configurations, as well as the different ways to supply the leakage and supplementary air flow through the different flow passages have been proposed. The performance of the trial product was evaluated on the test bed, ultimately providing a safe evacuation environment if high-rise buildings fired.
文摘The volumetric flow rate of smoke generated from the fire in large space often reaches to hundreds of thousands CMH because of extended floor height and as it’s more difficult to isolate the smoke to the limited area, comparing to normal-scale building, design and operation of effective smoke control system for large space is more than important. In this study, with the analysis model for such a large space as exhibition hall or conference room in conventional center, design of mechanical smoke exhaust system was conducted based on currently-available design standard which was then followed by numerical analysis of the design using 3D numerical analysis method. For conference room at 2.0 MW heat release rate, 99,173 CMH flow rate is required, if smoke layer is maintained at 60% of the floor height and for exhibition hall at 8.8 MW with 80% of floor height, flow rate required is 219,802 CMH, which are incorporated into the design. In view of 3D numerical analysis, accuracy of the design according to algebraic expression is sufficient.
文摘At present, with the rapid development of China's economy, the integration of urban and rural areas has been strengthened to ease the tension in the housing field, and the number of high-rise residential buildings and shopping malls has been increasing, which has brought great difficulties to the fire control work. In the process of design and construction, combined with the requirements of fire control management in the new era, attention should be paid to centralized control of smoke control devices and HVAC fire fighting equipment, so as to ensure the quality of HVAC fire fighting projects, reduce the possibility of fire and other accidents, and protect the safety of people's lives and property.
基金Project(U1134203)supported by the Major Program of the National Natural Science Foundation of ChinaProject(51105384)supported by the National Natural Science Foundation of China
文摘Research on the distribution of smoke in tunnels is significant for the fire emergency rescue after an operating metro train catches fire. A dynamic grid technique was adopted to research the law of smoke flow diffusion inside the tunnel when the bottom of a metro train was on fire and to compare the effect of longitudinal ventilation modes on the smoke motion when the burning train stopped. Research results show that the slipstream curves around the train obtained by numerical simulation are consistent with experimental data. When the train decelerates, the smoke flow first extends to the tail of the train. With the decrease of the train's speed, the smoke flow diffuses to the head of the train. After the train stops, the slipstream around the train formed in the process of train operation plays a leading role in the smoke diffusion in the tunnel. The smoke flow quickly diffuses to the domain in front of the train. After forward mechanical ventilation is provided, the smoke flow inside the tunnel continues to diffuse downstream. When reverse mechanical ventilation operates, the smoke in front of the train flows back rapidly and diffuses to the rear of the train.
基金National Natural Science Foundation of China,Grant/Award Numbers:72091512,52104198,52374210。
文摘The Shenzhen–Zhongshan Bridge is a 24‐km‐long bridge and tunnel system,including a 6.8-km-long super cross section subsea tunnel.To solve the smoke exhaust problem of a super large cross-section subsea tunnel,the tunnel has a new smoke exhaust system that combines a horizontal smoke exhaust cross section at the top and sidewall smoke exhaust holes.In order to evaluate the potential fire hazards of this type of tunnel,a 1:30 tunnel model was established and 140 smallscale experiments on underwater tunnel fires were conducted.By changing the fire power,fire location,and fan operation mode,different scenarios of submarine immersed tunnel fire were simulated and the related key parameters such as fire smoke diffusion behavior and smoke temperature distribution were studied.On this basis,the optimal smoke control strategy was proposed for different fire scenarios.The research results indicate that the new smoke exhaust system can fully utilize the smoke flow characteristics,significantly improve smoke exhaust efficiency,and increase available evacuation time,thus further enhancing the fire safety of super large cross-section subsea tunnels.
文摘The number of smokers in Chinese rural areas is more than 200 million, which is twice that in cities. It is very significant to carry out tobacco control interventions in rural areas. We performed this community intervention study to evaluate the efficacy of village-based health education of tobacco control on the male current smoking rate in rural areas. The population of this study was the males above 15 years old from 6 villages in rural areas. The villages were randomly assigned to intervention group or control group（3 villages in each group）. Self-designed smoking questionnaire was applied. The intervention group received the village-based health education of tobacco control for one year. The primary outcome measurement was the male current smoking rate. In the baseline investigation, completed surveys were returned by 814 male residents from the control group and 831 male residents from the intervention group. The male current smoking rate in the control group and the intervention group was 61.2% and 58.5%, respectively, before intervention. There was no significant difference between these two groups（P〉0.05）. After one-year intervention, the current smoking rate in the intervention group（51.2%） was significantly lower than that in the control group（62.8%）（P〈0.001）. Our study suggested that the village-based health education of tobacco control was effective in lowering the male current smoking rate in rural areas, which could be a suitable and feasible way for tobacco control in the Chinese rural areas.
基金supported by the National Natural Science Foundation of China(Grant No.51906030)the National Key R&D Program of China(Grant No.2021YFB4000904)the Opening Fund of State Key Laboratory of Fire Science(Grant Nos.HZ2019-KF07 and HZ2020-KF03).
文摘High smoke extraction efficiency and a relatively stable smoke layer stratification are both expected in tunnel ventilation systems.The purpose of this paper is to explore the overall performance of mechanical board-coupled shaft under different ventilation strategies.A total of 57 simulations were conducted,and the effects of the distance between the shaft and board(hp)and ventilation velocity on the overall performance were investigated.The results indicate that the performance of smoke extraction and control will be improved by the application of mechanical ventilation and board.Smoke movement patterns under different working conditions were dfferent,for cases of hp≤0.40 m the smoke could propagate through the whole tunnel without backflow,while for cases of hp>0.40 m,the backflow exists and the smoke movement can be separated into three periods(propagation,stagnation,and retraction).The critical criterion of backflow was investigated and a simple model was deduced to estimate the maximum propagation length.Moreover,the dimensionless time for the smoke flow to reach its maximum propagation length was established.Finally,a comprehensive index was proposed to evaluate the synergistic effects of smoke extraction and control performance.These studies may provide positive significance for the ventilation design.
