An aircraft cabin is a narrow,closed-space environment.To keep the air quality in cabin healthy for passengers,especially during an epidemic such as SARS-CoV-2(or 2019-nCoV)in 2020,a novel aircraft air conditioning sy...An aircraft cabin is a narrow,closed-space environment.To keep the air quality in cabin healthy for passengers,especially during an epidemic such as SARS-CoV-2(or 2019-nCoV)in 2020,a novel aircraft air conditioning system,called the ultra-high-temperature instantaneous sterilization air conditioning system(UHTACS),is proposed.Based on the proposed system,a simulation of the UHT-ACS is analysed in various flight states.In the UHT-ACS,the mixing air temperature of return and bleed air can reach temperature up to 148.8°C,which is high enough to kill bacilli and viruses in 2一8 s.The supply air temperature of the UHT-ACS in a mixing cavity is about 12 C in cooling mode both on the ground and in the air.The supply air temperature is about 42 C in heating mode.Compared with the air conditioning systems(ACS)of traditional aircraft the supply air temperatures of the UHT-ACS in the mixing cavity are in good agreement with those of a traditional ACS with 60%fresh air and 40%return air.Furthermore the air temperature at the turbine outlet of the UHT-ACS is higher than that of a traditional ACS which will help to reduce the risk of icing at the outlet.Therefore the UHT-ACS can operate normally in various flight states.展开更多
Using structured mesh to discretize the calculation region, the wind velocity and pressure distribution in front of the wind barrier under different embankment heights are investigated based on the Detached Eddy Simul...Using structured mesh to discretize the calculation region, the wind velocity and pressure distribution in front of the wind barrier under different embankment heights are investigated based on the Detached Eddy Simulation(DES) with standard SpalartAllmaras(SA) model. The Reynolds number is 4.0×105 in this calculation. The region is three-dimensional. Since the wind barrier and trains are almost invariable cross-sections, only 25 m along the track is modeled. The height of embankment ranges from 1 m to 5 m and the wind barrier is 3 m high. The results show that the wind speed changes obviously before the wind barrier on the horizontal plane, which is 4.5 m high above the track. The speed of wind reduces gradually while approaching the wind barrier. It reaches the minimum value at a distance about 5 m before the wind barrier, and increases dramatically afterwards. The speed of wind at this location is linear with the speed of far field. The train aerodynamic coefficients decrease sharply with the increment of the embankment height. And they take up the monotonicity. Meanwhile, when the height increases from 3 m to 5 m, they just change slightly. It is concluded that the optimum anemometer location is nearly 5 m in front of the wind barrier.展开更多
The need for moving away from traditional energy sources and to find alternate energy sources is undoubtedly one of the primary objectives for a sustainable progress to humankind. The design and construction of buildi...The need for moving away from traditional energy sources and to find alternate energy sources is undoubtedly one of the primary objectives for a sustainable progress to humankind. The design and construction of buildings in hot-humid climates requires high energy consumption typically for air conditioning due to higher thermal loads. In the Gulf Region, there is a rising concern on the current rate of energy consumption due to air conditioning, i.e. two thirds of domestic electrical loads. Considering the wider impacts of carbon emissions on our climate, and the need to reduce these emissions, effective energy efficiency solutions are necessary in order to achieve the overall goal of reducing carbon emissions. This paper presents the performance of the “All in One” fully integrated solar desiccant air conditioning system. The superefficient air conditioning system can provide 1,000 to 2,000 litre/s treated fresh air at supply temperature of 16 °C with 60% reduction in energy consumption compared to conventional systems. The system is locally manufactured and installed.展开更多
In China, coal mine spoils have traditionally been dumped in cone-shaped heaps that have the potential to pollute air, soil and water environments. The coal waste pile occupies lots of arable land and endangers the ec...In China, coal mine spoils have traditionally been dumped in cone-shaped heaps that have the potential to pollute air, soil and water environments. The coal waste pile occupies lots of arable land and endangers the ecological system in the coal mine district. Vegetation restoration is an efficient approach for controlling the environment pollution of coal waste pile, and is also a topic of current interest in restoration ecology and degradation system ecology. This study focused on the distribu- tion pattern and limiting factors of vegetation in coal waste pile of Xinzhuangzi Coal Mine in Huainan. The results show that two stable plant communities （Synodon dactylon＋Erigeron bonariensis.L＋Setaria viridis community and Humulus scan- den＋Erigeron bonariensis. L community） exist at the bottom of the pile. Synodon dactylon and Erigeron bonariensis. L have much higher values of summed dominance ratio, which denote that these two species can be used for restoration of coal waste piles. The high levels of pH （8.77） and salinity, low levels of total P and total K in coal mine spoil can be the limiting factors for the residence and growth of vegetation.展开更多
Air content, spacing factor and specific surface of fresh concrete and hardened concrete with different air contents, slumps and mineral admixtures (fly ash, slag, fly ash + slag, fly ash + slag + silica fume composit...Air content, spacing factor and specific surface of fresh concrete and hardened concrete with different air contents, slumps and mineral admixtures (fly ash, slag, fly ash + slag, fly ash + slag + silica fume composite) were studied by the air-void analyzer (AVA) method and the microscopical method. The correlations between the test results obtained from different methods were analyzed. The results show that, there is a close correlation of air content and spacing factor between the fresh concrete and the hardened concrete, but the specific surface correlation is weak. The air content of concrete measured by the AVA method is smaller than that of the pressure method and the microscopical method, because AVA device captures only the air voids with the size smaller than 3 mm. Spacing factor of the fresh concrete measured by the AVA method is greater than that of the hardened concrete measured by the microscopical method, while the specific surface is smaller. When the criterion of 4%-7% air content measured by the pressure method and microscopical method is acceptable for concrete freezing-thawing (F-T) durability in cold weather, the air content measured by the AVA method should be 2.4%-4.6%. For the concrete F-T durability, when the criterion of the spacing factor measured by the microscopical method is 300 μm, the spacing factor measured by the AVA method should be 360 μm.展开更多
In this article, a new kind of solar fresh air system is designed in order to realize the improvement of thermal efficiency by the integrated application of the PCMs and heat pipe technology. Under the adequate sunshi...In this article, a new kind of solar fresh air system is designed in order to realize the improvement of thermal efficiency by the integrated application of the PCMs and heat pipe technology. Under the adequate sunshine condition, the fresh air is directly delivered into the indoor environment after being heated by the solar collector. When the sun radiation is reduced, the heated air temperature can not satisfy the need of supply of air temperature.The main heat source is changed to phase change heat storage equipment instead of solar energy. The system adopt heat pipe for a high-efficiency and isothermal heat transfer which recover the shortcomings of PCMs such as： low coefficient of thermal conductivity and poor thermal efficiency. This article establishes the physical model of phase change solar energy fresh air thermal storage system and creates the mathematical model of its unsteady heat transfer to simulate and analyse the operation process by using Fluent software. The results of the study show that, compared to normal fresh air system, the phase change solar energy fresh air thermal storage system has a significant improvement in energy saving and indoor comfort level and will play an important role in the energy sustainable development.展开更多
The Regional Atmospheric Modeling System (RAMS) has been used to investigate the effects of varied giant cloud condensation nuclei (GCCN) concentrations on precipitation characteristics of the spring hailstorms in a s...The Regional Atmospheric Modeling System (RAMS) has been used to investigate the effects of varied giant cloud condensation nuclei (GCCN) concentrations on precipitation characteristics of the spring hailstorms in a semi-arid region. The simulation result shows that this variation has significant effects on the storm microphysical processes as well as on the surface precipitation. The coverage of hail and hail mixing ratio maxima in cloud increases with greater GCCN concentrations. The accumulation zone structure benefits the growth of hail particles. Higher GCCN concentrations lead to more supercooled rain water and cloud water available for freezing. This simulation also shows that increasing GCCN concentrations may produce more rainfall on the surface but less hail precipitation, and the total accumulated precipitation increases while the ice phase precipitation decreases. This effect is stronger in polluted air than in clean air. The surface flow field changes with different GCCN concentrations. The identification index of spring hailstorm is different from that of summer hailstorm with a different aerosol background.展开更多
基金the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)and the Foundation of Jiangsu Postdoctoral(No.2019K126)。
文摘An aircraft cabin is a narrow,closed-space environment.To keep the air quality in cabin healthy for passengers,especially during an epidemic such as SARS-CoV-2(or 2019-nCoV)in 2020,a novel aircraft air conditioning system,called the ultra-high-temperature instantaneous sterilization air conditioning system(UHTACS),is proposed.Based on the proposed system,a simulation of the UHT-ACS is analysed in various flight states.In the UHT-ACS,the mixing air temperature of return and bleed air can reach temperature up to 148.8°C,which is high enough to kill bacilli and viruses in 2一8 s.The supply air temperature of the UHT-ACS in a mixing cavity is about 12 C in cooling mode both on the ground and in the air.The supply air temperature is about 42 C in heating mode.Compared with the air conditioning systems(ACS)of traditional aircraft the supply air temperatures of the UHT-ACS in the mixing cavity are in good agreement with those of a traditional ACS with 60%fresh air and 40%return air.Furthermore the air temperature at the turbine outlet of the UHT-ACS is higher than that of a traditional ACS which will help to reduce the risk of icing at the outlet.Therefore the UHT-ACS can operate normally in various flight states.
基金Projects(51075401,U1334205)supported by the National Natural Science Foundation of ChinaProject(NCET-10-0833)supported by the New Century Excellent Talents in University,China+2 种基金Project supported by the Scholarship Award for Excellent Innovative Doctoral Student granted by Central South University,ChinaProject(2012T002-E)supported by the Science and Technology Research and Development Program of Ministry of Railway,ChinaProject(14JJ1003)supported by the Natural Science Foundation of Hunan Province,China
文摘Using structured mesh to discretize the calculation region, the wind velocity and pressure distribution in front of the wind barrier under different embankment heights are investigated based on the Detached Eddy Simulation(DES) with standard SpalartAllmaras(SA) model. The Reynolds number is 4.0×105 in this calculation. The region is three-dimensional. Since the wind barrier and trains are almost invariable cross-sections, only 25 m along the track is modeled. The height of embankment ranges from 1 m to 5 m and the wind barrier is 3 m high. The results show that the wind speed changes obviously before the wind barrier on the horizontal plane, which is 4.5 m high above the track. The speed of wind reduces gradually while approaching the wind barrier. It reaches the minimum value at a distance about 5 m before the wind barrier, and increases dramatically afterwards. The speed of wind at this location is linear with the speed of far field. The train aerodynamic coefficients decrease sharply with the increment of the embankment height. And they take up the monotonicity. Meanwhile, when the height increases from 3 m to 5 m, they just change slightly. It is concluded that the optimum anemometer location is nearly 5 m in front of the wind barrier.
文摘The need for moving away from traditional energy sources and to find alternate energy sources is undoubtedly one of the primary objectives for a sustainable progress to humankind. The design and construction of buildings in hot-humid climates requires high energy consumption typically for air conditioning due to higher thermal loads. In the Gulf Region, there is a rising concern on the current rate of energy consumption due to air conditioning, i.e. two thirds of domestic electrical loads. Considering the wider impacts of carbon emissions on our climate, and the need to reduce these emissions, effective energy efficiency solutions are necessary in order to achieve the overall goal of reducing carbon emissions. This paper presents the performance of the “All in One” fully integrated solar desiccant air conditioning system. The superefficient air conditioning system can provide 1,000 to 2,000 litre/s treated fresh air at supply temperature of 16 °C with 60% reduction in energy consumption compared to conventional systems. The system is locally manufactured and installed.
文摘In China, coal mine spoils have traditionally been dumped in cone-shaped heaps that have the potential to pollute air, soil and water environments. The coal waste pile occupies lots of arable land and endangers the ecological system in the coal mine district. Vegetation restoration is an efficient approach for controlling the environment pollution of coal waste pile, and is also a topic of current interest in restoration ecology and degradation system ecology. This study focused on the distribu- tion pattern and limiting factors of vegetation in coal waste pile of Xinzhuangzi Coal Mine in Huainan. The results show that two stable plant communities （Synodon dactylon＋Erigeron bonariensis.L＋Setaria viridis community and Humulus scan- den＋Erigeron bonariensis. L community） exist at the bottom of the pile. Synodon dactylon and Erigeron bonariensis. L have much higher values of summed dominance ratio, which denote that these two species can be used for restoration of coal waste piles. The high levels of pH （8.77） and salinity, low levels of total P and total K in coal mine spoil can be the limiting factors for the residence and growth of vegetation.
基金Project(50908229) supported by the National Natural Science Foundation of ChinaProjects(2008G031-N, 50908229, 10125C131) supported by Technological Research and Development Programs of the Ministry of Railways, China
文摘Air content, spacing factor and specific surface of fresh concrete and hardened concrete with different air contents, slumps and mineral admixtures (fly ash, slag, fly ash + slag, fly ash + slag + silica fume composite) were studied by the air-void analyzer (AVA) method and the microscopical method. The correlations between the test results obtained from different methods were analyzed. The results show that, there is a close correlation of air content and spacing factor between the fresh concrete and the hardened concrete, but the specific surface correlation is weak. The air content of concrete measured by the AVA method is smaller than that of the pressure method and the microscopical method, because AVA device captures only the air voids with the size smaller than 3 mm. Spacing factor of the fresh concrete measured by the AVA method is greater than that of the hardened concrete measured by the microscopical method, while the specific surface is smaller. When the criterion of 4%-7% air content measured by the pressure method and microscopical method is acceptable for concrete freezing-thawing (F-T) durability in cold weather, the air content measured by the AVA method should be 2.4%-4.6%. For the concrete F-T durability, when the criterion of the spacing factor measured by the microscopical method is 300 μm, the spacing factor measured by the AVA method should be 360 μm.
文摘In this article, a new kind of solar fresh air system is designed in order to realize the improvement of thermal efficiency by the integrated application of the PCMs and heat pipe technology. Under the adequate sunshine condition, the fresh air is directly delivered into the indoor environment after being heated by the solar collector. When the sun radiation is reduced, the heated air temperature can not satisfy the need of supply of air temperature.The main heat source is changed to phase change heat storage equipment instead of solar energy. The system adopt heat pipe for a high-efficiency and isothermal heat transfer which recover the shortcomings of PCMs such as： low coefficient of thermal conductivity and poor thermal efficiency. This article establishes the physical model of phase change solar energy fresh air thermal storage system and creates the mathematical model of its unsteady heat transfer to simulate and analyse the operation process by using Fluent software. The results of the study show that, compared to normal fresh air system, the phase change solar energy fresh air thermal storage system has a significant improvement in energy saving and indoor comfort level and will play an important role in the energy sustainable development.
基金supported by National Natural Science Foundation of China (Grant Nos. 40875080 and 40875002)Ministry of Science and Technology of China (Grant No. 2006BAC12B01-01)
文摘The Regional Atmospheric Modeling System (RAMS) has been used to investigate the effects of varied giant cloud condensation nuclei (GCCN) concentrations on precipitation characteristics of the spring hailstorms in a semi-arid region. The simulation result shows that this variation has significant effects on the storm microphysical processes as well as on the surface precipitation. The coverage of hail and hail mixing ratio maxima in cloud increases with greater GCCN concentrations. The accumulation zone structure benefits the growth of hail particles. Higher GCCN concentrations lead to more supercooled rain water and cloud water available for freezing. This simulation also shows that increasing GCCN concentrations may produce more rainfall on the surface but less hail precipitation, and the total accumulated precipitation increases while the ice phase precipitation decreases. This effect is stronger in polluted air than in clean air. The surface flow field changes with different GCCN concentrations. The identification index of spring hailstorm is different from that of summer hailstorm with a different aerosol background.
