The Experts below are selected from a list of 15957 Experts worldwide ranked by ideXlab platform
Yang Yang - One of the best experts on this subject based on the ideXlab platform.
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transport and control of droplets a comparison between two types of Local Ventilation airflows
2019Co-Authors: Yang Yang, Yi Wang, Yingxue Cao, Bingbing Song, Jianing Fan, Mengjie DuanAbstract:Abstract The efficient removal of droplets with different Ventilation systems is a key scientific problem affecting an indoor environment. In this study the transport of monodispersed droplets generated from an open tank with a large length/width ratio was investigated under the influence of an upper-receiving Ventilation (URV) system and a push-pull Ventilation (PPV) system, based on numerical simulation. The movement of droplets under the two systems were compared. The effects of the initial diameters of the droplets and the exhaust airflow velocity on the capture efficiency and removal rate of droplets were evaluated. The results showed that the turbulence dispersion of droplets, gravity acting on the droplets and vortex interaction contributed to the different droplet behaviour under different Local Ventilation modes and exhaust airflow velocities. The PPV system demonstrated faster droplet removal ability than the URV system, for the same size of droplets. The URV system achieved higher capture efficiency with less energy consumption than the PPV system for droplets with an initial diameter of 10–50 μm; for those with an initial diameter of 75–100 μm, the PPV system prevented any droplets from escaping into the occupied zone with less energy cost. The results of this study can contribute to the design and selection of Local Ventilation modes and the operation conditions required to control droplets.
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stability and accuracy of numerical investigation of droplet motion under Local Ventilation airflow
2018Co-Authors: Yang Yang, Yi Wang, Bingbing Song, Jianing Fan, Yingxue CaoAbstract:Abstract It is challenging to predict droplet motion in numerical studies of particulate transport in indoor environment. This paper attempts at providing answers on this topic while using a Eulerian–Lagrangian method. The effect of the droplet release number and evaporation on prediction stability and accuracy was evaluated by modeling the droplet motion for two initial droplets (10 and 100 μm) and three different airflow patterns in an upper-receiving Ventilation system. The results show that the effect of the droplet release number on prediction stability depends on the spatial scale of droplet motion, airflow pattern, and droplet number in a certain domain. Evaporation affected the motion and distribution of droplets, especially for those with an initial diameter of 100 μm. The number of droplets with an initial diameter of 100 μm escaping into the indoor environment was over predicted when ignoring droplet evaporation. The results may contribute to more accurate predictions of droplet transport by numerical simulation.
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an evaluation index for the control effect of the Local Ventilation systems on indoor air quality in industrial buildings
2016Co-Authors: Yi Wang, Yingxue Cao, Bo Liu, Jiaping Liu, Yang YangAbstract:To evaluate the control effect on indoor air quality (IAQ) of the Local Ventilation systems in industrial buildings with centralized contaminant sources, a new index, namely, normalized concentration in the target zone (NC-TZ), was proposed in this paper. According to theoretical analysis, NC-TZ is non-dimensional and ranges from 0 to 1. When NC-TZ tends toward 0, the control effect of the Local Ventilation system on IAQ is more satisfactory. When NC-TZ tends toward 1, the control effect on IAQ is less satisfactory. The numerical simulation on a push–pull Ventilation system with varying exhaust flow rates and varying distances between push and pull hoods was performed. The results demonstrate that for the same capture efficiency, changing the Local Ventilation system characteristics can change the control effect on the Local environment. The results for obstacles at different positions also indicate that NC-TZ can clearly reflect the control effect on IAQ of the Local Ventilation systems in industrial buildings.
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movement and control of evaporating droplets released from an open surface tank in the push pull Ventilation system
2016Co-Authors: Yi Wang, Yang Yang, Yan Zou, Xinyu Zhang, Xiaofen RenAbstract:Push–pull Ventilation systems are effective Local Ventilation methods to control airborne contaminants generated in industrial buildings, among which droplets are typical. In this paper, the numerical simulations of water droplets released from an open surface tank into the push–pull flow field are carried out and the effects of ambient relative humidity and the pull-flow velocity on the Ventilation system performance are discussed based on the droplet evaporation and movement. It was found that the movement and evaporation of droplets were closely related to the push–pull flow mechanism and the droplet initial diameter. When the control effect was good due to the presence of air closure in the flow field (pull-flow velocity ranging from 1.5 m/s to 3.0 m/s), droplets were unlikely to move away from the closure and the evaporation of droplets smaller than 40 μm was obvious. Whereas when the control effect was poor (pull-flow velocity equaling 1.0 m/s), large droplets still moved around the tank surface but small droplets were subject to dispersing, and in such a case droplets smaller than 60 μm evaporated obviously. Moreover, the effect of ambient relative humidity (ranging from 0 to 80%) on controlling droplets was rather limited and no more than ±6%. In addition, the system could save airflow rate and energy consumption by reducing the pull-flow velocity which was excessive originally in Ventilation design. Finally, the paper put forward a new index to evaluate the control effect from another standpoint based on whether the droplets did harm to the environment.
Hao Shao - One of the best experts on this subject based on the ideXlab platform.
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information fusion of plume control and personnel escape during the emergency rescue of external caused fire in a coal mine
2016Co-Authors: Kai Wang, Shuguang Jiang, Weiqing Zhang, Hao Shao, Chuanbo CuiAbstract:Abstract After a fire occurred in a coal mine, compared with putting out the fire, organizing the miners’ safe escape was especially important. We established a Local Ventilation system model using TEPS (Thunderhead Engineering PyroSim) and set up control measures for fire smoke. The change rule of fire parameters, such as temperature, concentration of smoke, and visibility, was analyzed based on the results of FDS (Fire Dynamics Simulator). Without the control measures for fire smoke, the coal face and the intake airflow roadway were all polluted by smoke at 541 s after the fire broke out; at this time, personnel escape would be almost impossible in the coal face. Thus, the personnel escape conditions and routes are determined by the parameters of fire smoke flow. Evac was used to simulate the escape behavior of a miner who encounters an accident in a coal mine. After taking the fire smoke control measures into account, we performed simulation calculation to determine the best and fastest way for miners’ escape. We exploited the hardware and software, and the belt fire emergency rescue system of the No. 1 plate in the Da Liu-ta coal mine was established. The emergency rescue system successfully fused fire plume control and personnel escape information into one platform. Through simulating a fire drill three times, the air quantity of the key branches changed to within reasonable limits while the air-door's opening area was 2 m 2 , field tests proved the reliability and feasibility of the system.
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study of the destruction of Ventilation systems in coal mines due to gas explosions
2015Co-Authors: Kai Wang, Shuguang Jiang, Weiqing Zhang, Hao ShaoAbstract:Abstract Gas explosions presented a serious safety threat in the mining industry worldwide. Many coal miners had been killed due to explosions in mining. The malfunction of a Ventilation system caused by a gas explosion was the primary reason for casualties in coal mines. In this study, two models were built to simulate Ventilation systems in which gas explosions often occur. The models consisted of a pipe incorporating weak panels. Using each model, the propagation of the overpressure shock wave and the distribution on the Ventilation system were verified. According to the characteristics of multiple Ventilation facilities in a Local Ventilation system, the combined effects of bends and bifurcations and the destruction of Ventilation facilities in the Local network model due to an overpressure wave were analyzed. By analyzing the distribution of the methane/air mixture explosion overpressure wave in the pipe models, the effect of a weak panel on the explosion shock wave and the degree of explosion damage were characterized by the statistical results from the sizes of the fragments. The explosion wave peak overpressure in the forward direction was higher than the peak overpressure in the elbow bend direction. After explosion, the production gas was immediately extracted and the composition was analyzed. The destruction order for different Ventilation facilities in the Local Ventilation system was determined according to the pipe model experimental results. The disaster of gas explosion for Ventilation network and workers was analyzed, and the spare door was designed to recover the Ventilation system after gas explosion.
Yi Wang - One of the best experts on this subject based on the ideXlab platform.
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transport and control of droplets a comparison between two types of Local Ventilation airflows
2019Co-Authors: Yang Yang, Yi Wang, Yingxue Cao, Bingbing Song, Jianing Fan, Mengjie DuanAbstract:Abstract The efficient removal of droplets with different Ventilation systems is a key scientific problem affecting an indoor environment. In this study the transport of monodispersed droplets generated from an open tank with a large length/width ratio was investigated under the influence of an upper-receiving Ventilation (URV) system and a push-pull Ventilation (PPV) system, based on numerical simulation. The movement of droplets under the two systems were compared. The effects of the initial diameters of the droplets and the exhaust airflow velocity on the capture efficiency and removal rate of droplets were evaluated. The results showed that the turbulence dispersion of droplets, gravity acting on the droplets and vortex interaction contributed to the different droplet behaviour under different Local Ventilation modes and exhaust airflow velocities. The PPV system demonstrated faster droplet removal ability than the URV system, for the same size of droplets. The URV system achieved higher capture efficiency with less energy consumption than the PPV system for droplets with an initial diameter of 10–50 μm; for those with an initial diameter of 75–100 μm, the PPV system prevented any droplets from escaping into the occupied zone with less energy cost. The results of this study can contribute to the design and selection of Local Ventilation modes and the operation conditions required to control droplets.
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stability and accuracy of numerical investigation of droplet motion under Local Ventilation airflow
2018Co-Authors: Yang Yang, Yi Wang, Bingbing Song, Jianing Fan, Yingxue CaoAbstract:Abstract It is challenging to predict droplet motion in numerical studies of particulate transport in indoor environment. This paper attempts at providing answers on this topic while using a Eulerian–Lagrangian method. The effect of the droplet release number and evaporation on prediction stability and accuracy was evaluated by modeling the droplet motion for two initial droplets (10 and 100 μm) and three different airflow patterns in an upper-receiving Ventilation system. The results show that the effect of the droplet release number on prediction stability depends on the spatial scale of droplet motion, airflow pattern, and droplet number in a certain domain. Evaporation affected the motion and distribution of droplets, especially for those with an initial diameter of 100 μm. The number of droplets with an initial diameter of 100 μm escaping into the indoor environment was over predicted when ignoring droplet evaporation. The results may contribute to more accurate predictions of droplet transport by numerical simulation.
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an evaluation index for the control effect of the Local Ventilation systems on indoor air quality in industrial buildings
2016Co-Authors: Yi Wang, Yingxue Cao, Bo Liu, Jiaping Liu, Yang YangAbstract:To evaluate the control effect on indoor air quality (IAQ) of the Local Ventilation systems in industrial buildings with centralized contaminant sources, a new index, namely, normalized concentration in the target zone (NC-TZ), was proposed in this paper. According to theoretical analysis, NC-TZ is non-dimensional and ranges from 0 to 1. When NC-TZ tends toward 0, the control effect of the Local Ventilation system on IAQ is more satisfactory. When NC-TZ tends toward 1, the control effect on IAQ is less satisfactory. The numerical simulation on a push–pull Ventilation system with varying exhaust flow rates and varying distances between push and pull hoods was performed. The results demonstrate that for the same capture efficiency, changing the Local Ventilation system characteristics can change the control effect on the Local environment. The results for obstacles at different positions also indicate that NC-TZ can clearly reflect the control effect on IAQ of the Local Ventilation systems in industrial buildings.
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movement and control of evaporating droplets released from an open surface tank in the push pull Ventilation system
2016Co-Authors: Yi Wang, Yang Yang, Yan Zou, Xinyu Zhang, Xiaofen RenAbstract:Push–pull Ventilation systems are effective Local Ventilation methods to control airborne contaminants generated in industrial buildings, among which droplets are typical. In this paper, the numerical simulations of water droplets released from an open surface tank into the push–pull flow field are carried out and the effects of ambient relative humidity and the pull-flow velocity on the Ventilation system performance are discussed based on the droplet evaporation and movement. It was found that the movement and evaporation of droplets were closely related to the push–pull flow mechanism and the droplet initial diameter. When the control effect was good due to the presence of air closure in the flow field (pull-flow velocity ranging from 1.5 m/s to 3.0 m/s), droplets were unlikely to move away from the closure and the evaporation of droplets smaller than 40 μm was obvious. Whereas when the control effect was poor (pull-flow velocity equaling 1.0 m/s), large droplets still moved around the tank surface but small droplets were subject to dispersing, and in such a case droplets smaller than 60 μm evaporated obviously. Moreover, the effect of ambient relative humidity (ranging from 0 to 80%) on controlling droplets was rather limited and no more than ±6%. In addition, the system could save airflow rate and energy consumption by reducing the pull-flow velocity which was excessive originally in Ventilation design. Finally, the paper put forward a new index to evaluate the control effect from another standpoint based on whether the droplets did harm to the environment.
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reduced scale experimental investigation on Ventilation performance of a Local exhaust hood in an industrial plant
2015Co-Authors: Yanqiu Huang, Yi Wang, Li Liu, Peter V Nielsen, Rasmus Lund Jensen, Fanliao YanAbstract:Abstract Local Ventilation systems are widely used in industrial production processes to capture heat release and/or gaseous/particulate contaminants. The primary objective of this study was to determine important empirical factors on Local pollutant capture efficiency and characteristics of thermal stratification in the working areas of industrial plants. Investigated factors were confined airflow boundaries, flow rates of the exhaust hoods, source strengths, airflow obstacles and distances between sources and exhaust hoods. Reduced-scale experiments were conducted with a geometric scale of 1:15 corresponding to a portion of the blast furnace workshop of a steel plant. The dependency of capture efficiency on Archimedes numbers was established. The results showed that confined airflow boundaries, flow rates of the exhaust hoods and source strengths were important empirical factors on pollutant capture efficiency. Hood performance was also evaluated by thermal stratification heights in the plants. This study could help improve the capture efficiency of Local Ventilation systems used in industrial plants. Safe operation heights are recommended in the upper space of industrial plants based on the thermal stratification in the plants.
Yingxue Cao - One of the best experts on this subject based on the ideXlab platform.
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transport and control of droplets a comparison between two types of Local Ventilation airflows
2019Co-Authors: Yang Yang, Yi Wang, Yingxue Cao, Bingbing Song, Jianing Fan, Mengjie DuanAbstract:Abstract The efficient removal of droplets with different Ventilation systems is a key scientific problem affecting an indoor environment. In this study the transport of monodispersed droplets generated from an open tank with a large length/width ratio was investigated under the influence of an upper-receiving Ventilation (URV) system and a push-pull Ventilation (PPV) system, based on numerical simulation. The movement of droplets under the two systems were compared. The effects of the initial diameters of the droplets and the exhaust airflow velocity on the capture efficiency and removal rate of droplets were evaluated. The results showed that the turbulence dispersion of droplets, gravity acting on the droplets and vortex interaction contributed to the different droplet behaviour under different Local Ventilation modes and exhaust airflow velocities. The PPV system demonstrated faster droplet removal ability than the URV system, for the same size of droplets. The URV system achieved higher capture efficiency with less energy consumption than the PPV system for droplets with an initial diameter of 10–50 μm; for those with an initial diameter of 75–100 μm, the PPV system prevented any droplets from escaping into the occupied zone with less energy cost. The results of this study can contribute to the design and selection of Local Ventilation modes and the operation conditions required to control droplets.
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stability and accuracy of numerical investigation of droplet motion under Local Ventilation airflow
2018Co-Authors: Yang Yang, Yi Wang, Bingbing Song, Jianing Fan, Yingxue CaoAbstract:Abstract It is challenging to predict droplet motion in numerical studies of particulate transport in indoor environment. This paper attempts at providing answers on this topic while using a Eulerian–Lagrangian method. The effect of the droplet release number and evaporation on prediction stability and accuracy was evaluated by modeling the droplet motion for two initial droplets (10 and 100 μm) and three different airflow patterns in an upper-receiving Ventilation system. The results show that the effect of the droplet release number on prediction stability depends on the spatial scale of droplet motion, airflow pattern, and droplet number in a certain domain. Evaporation affected the motion and distribution of droplets, especially for those with an initial diameter of 100 μm. The number of droplets with an initial diameter of 100 μm escaping into the indoor environment was over predicted when ignoring droplet evaporation. The results may contribute to more accurate predictions of droplet transport by numerical simulation.
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an evaluation index for the control effect of the Local Ventilation systems on indoor air quality in industrial buildings
2016Co-Authors: Yi Wang, Yingxue Cao, Bo Liu, Jiaping Liu, Yang YangAbstract:To evaluate the control effect on indoor air quality (IAQ) of the Local Ventilation systems in industrial buildings with centralized contaminant sources, a new index, namely, normalized concentration in the target zone (NC-TZ), was proposed in this paper. According to theoretical analysis, NC-TZ is non-dimensional and ranges from 0 to 1. When NC-TZ tends toward 0, the control effect of the Local Ventilation system on IAQ is more satisfactory. When NC-TZ tends toward 1, the control effect on IAQ is less satisfactory. The numerical simulation on a push–pull Ventilation system with varying exhaust flow rates and varying distances between push and pull hoods was performed. The results demonstrate that for the same capture efficiency, changing the Local Ventilation system characteristics can change the control effect on the Local environment. The results for obstacles at different positions also indicate that NC-TZ can clearly reflect the control effect on IAQ of the Local Ventilation systems in industrial buildings.
Kai Wang - One of the best experts on this subject based on the ideXlab platform.
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information fusion of plume control and personnel escape during the emergency rescue of external caused fire in a coal mine
2016Co-Authors: Kai Wang, Shuguang Jiang, Weiqing Zhang, Hao Shao, Chuanbo CuiAbstract:Abstract After a fire occurred in a coal mine, compared with putting out the fire, organizing the miners’ safe escape was especially important. We established a Local Ventilation system model using TEPS (Thunderhead Engineering PyroSim) and set up control measures for fire smoke. The change rule of fire parameters, such as temperature, concentration of smoke, and visibility, was analyzed based on the results of FDS (Fire Dynamics Simulator). Without the control measures for fire smoke, the coal face and the intake airflow roadway were all polluted by smoke at 541 s after the fire broke out; at this time, personnel escape would be almost impossible in the coal face. Thus, the personnel escape conditions and routes are determined by the parameters of fire smoke flow. Evac was used to simulate the escape behavior of a miner who encounters an accident in a coal mine. After taking the fire smoke control measures into account, we performed simulation calculation to determine the best and fastest way for miners’ escape. We exploited the hardware and software, and the belt fire emergency rescue system of the No. 1 plate in the Da Liu-ta coal mine was established. The emergency rescue system successfully fused fire plume control and personnel escape information into one platform. Through simulating a fire drill three times, the air quantity of the key branches changed to within reasonable limits while the air-door's opening area was 2 m 2 , field tests proved the reliability and feasibility of the system.
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study of the destruction of Ventilation systems in coal mines due to gas explosions
2015Co-Authors: Kai Wang, Shuguang Jiang, Weiqing Zhang, Hao ShaoAbstract:Abstract Gas explosions presented a serious safety threat in the mining industry worldwide. Many coal miners had been killed due to explosions in mining. The malfunction of a Ventilation system caused by a gas explosion was the primary reason for casualties in coal mines. In this study, two models were built to simulate Ventilation systems in which gas explosions often occur. The models consisted of a pipe incorporating weak panels. Using each model, the propagation of the overpressure shock wave and the distribution on the Ventilation system were verified. According to the characteristics of multiple Ventilation facilities in a Local Ventilation system, the combined effects of bends and bifurcations and the destruction of Ventilation facilities in the Local network model due to an overpressure wave were analyzed. By analyzing the distribution of the methane/air mixture explosion overpressure wave in the pipe models, the effect of a weak panel on the explosion shock wave and the degree of explosion damage were characterized by the statistical results from the sizes of the fragments. The explosion wave peak overpressure in the forward direction was higher than the peak overpressure in the elbow bend direction. After explosion, the production gas was immediately extracted and the composition was analyzed. The destruction order for different Ventilation facilities in the Local Ventilation system was determined according to the pipe model experimental results. The disaster of gas explosion for Ventilation network and workers was analyzed, and the spare door was designed to recover the Ventilation system after gas explosion.
