Variable ballast systems are necessary for manned submersibles to adjust their buoyancy.In this paper,the design of a variable ballast system for a manned submersible is described.The variable ballast system uses a su...Variable ballast systems are necessary for manned submersibles to adjust their buoyancy.In this paper,the design of a variable ballast system for a manned submersible is described.The variable ballast system uses a super high pressure hydraulic seawater system.A super high pressure seawater pump and a deep-sea brushless DC motor are used to pump seawater into or from the variable ballast tank,increasing or decreasing the weight of the manned submersible.A magnetostrictive linear displacement transducer can detect the seawater level in the variable ballast tank.Some seawater valves are used to control pumping direction and control on-off states.The design and testing procedure for the valves is described.Finally,the future development of variable ballast systems and seawater hydraulic systems is projected.展开更多
Energy recovery device （ERD） is an important part of the seawater reverse osmosis （SWRO） desalination system. There are principally two kinds of ERDs, the centrifugal type and the positive displacement （PD） type...Energy recovery device （ERD） is an important part of the seawater reverse osmosis （SWRO） desalination system. There are principally two kinds of ERDs, the centrifugal type and the positive displacement （PD） type. The PD type is of extensive concern and is preferred in large-scale plants. In this article, an innovative fluid switcher was presented and a two-cylinder hydraulic energy recovery unit with a lab-scale fluid switcher was set up. Tap water was used as the working medium instead of the actual seawater and brine in SWRO desalination plants. Under steady state operating conditions, the experimental results were obtained on the variations of the pressure and flow rate to and from the energy recovery unit. The hydraulic recovery efficiency （En） of the energy recovery unit with the fluid switcher reached up to 76.83%.展开更多
In the beach well intake system, heat is transferred from soil to fluid when seawater is filtered through the aquifer, providing higher temperature source water to the seawater source heat pump (SWHP) system in winter...In the beach well intake system, heat is transferred from soil to fluid when seawater is filtered through the aquifer, providing higher temperature source water to the seawater source heat pump (SWHP) system in winter. A 3-D coupled seepage and heat transfer model for studying beach well intake system is established by adopting the computer code FLUENT. Numerical results of this model are compared with the experimental results under the same conditions. Based on the experiment-verified coupled model, numerical simulation of the supply water tem-perature is studied over a heating season. Results show that the minimum temperature of supply water is 275.2 K when this intake system continuously provides seawater with flow rate of 35 m3/h to SWHP. Results also indicate that the supply water temperature is higher than seawater, and that the minimum temperature of supply water lags behind seawater, ensuring effective and reliable operation of SWHP.展开更多
River water plays a key role in human health, and in social and economic development, and is often affected by both natural factors and human activities. An in-depth understanding of the role of these factors can help...River water plays a key role in human health, and in social and economic development, and is often affected by both natural factors and human activities. An in-depth understanding of the role of these factors can help in developing an effective catchment management strategy to protect precious water resources. This study analyzed river water quality, patterns of terrestrial and riparian ecosystems, intensity of agricultural activities, industrial structure, and spatial distribution of pollutant emissions in the Haihe River Basin in China for the year of 2010, identifying the variables that have the greatest impact on river water quality. The area percentage of farmland in study area, the percentage of natural vegetation cover in the 1000-m riparian zone, rural population density, industrial Gross Domestic Product(GDP)/km^2, and industrial amino nitrogen emissions were all significantly correlated with river water quality(P < 0.05). Farming had the largest impact on river water quality, explaining 43.0% of the water quality variance, followed by the coverage of natural vegetation in the 1000-m riparian zone, which explained 36.2% of the water quality variance. Industrial amino nitrogen emissions intensity and rural population density explained 31.6% and 31.4% of the water quality variance, respectively, while industrial GDP/km^2 explained 26.6%. Together, these five indicators explained 67.3% of the total variance in water quality. Consequently, water environmental management of the Haihe River Basin should focus on adjusting agricultural activities, conserving riparian vegetation, and reducing industrial pollutant emissions by optimizing industrial structure. The results demonstrate how human activities drive the spatial pattern changes of river water quality, and they can provide reference for developing land use guidelines and for prioritizing management practices to maintain stream water quality in a large river basin.展开更多
基金Supported by the "863" Foundation under Grant No.2002AA401000
文摘Variable ballast systems are necessary for manned submersibles to adjust their buoyancy.In this paper,the design of a variable ballast system for a manned submersible is described.The variable ballast system uses a super high pressure hydraulic seawater system.A super high pressure seawater pump and a deep-sea brushless DC motor are used to pump seawater into or from the variable ballast tank,increasing or decreasing the weight of the manned submersible.A magnetostrictive linear displacement transducer can detect the seawater level in the variable ballast tank.Some seawater valves are used to control pumping direction and control on-off states.The design and testing procedure for the valves is described.Finally,the future development of variable ballast systems and seawater hydraulic systems is projected.
基金the Seawater Desalination Research Programs of Tianjin(043185211-4)
文摘Energy recovery device （ERD） is an important part of the seawater reverse osmosis （SWRO） desalination system. There are principally two kinds of ERDs, the centrifugal type and the positive displacement （PD） type. The PD type is of extensive concern and is preferred in large-scale plants. In this article, an innovative fluid switcher was presented and a two-cylinder hydraulic energy recovery unit with a lab-scale fluid switcher was set up. Tap water was used as the working medium instead of the actual seawater and brine in SWRO desalination plants. Under steady state operating conditions, the experimental results were obtained on the variations of the pressure and flow rate to and from the energy recovery unit. The hydraulic recovery efficiency （En） of the energy recovery unit with the fluid switcher reached up to 76.83%.
基金Supported by Tianjin Construction Committee Technology Project (No2007-37)
文摘In the beach well intake system, heat is transferred from soil to fluid when seawater is filtered through the aquifer, providing higher temperature source water to the seawater source heat pump (SWHP) system in winter. A 3-D coupled seepage and heat transfer model for studying beach well intake system is established by adopting the computer code FLUENT. Numerical results of this model are compared with the experimental results under the same conditions. Based on the experiment-verified coupled model, numerical simulation of the supply water tem-perature is studied over a heating season. Results show that the minimum temperature of supply water is 275.2 K when this intake system continuously provides seawater with flow rate of 35 m3/h to SWHP. Results also indicate that the supply water temperature is higher than seawater, and that the minimum temperature of supply water lags behind seawater, ensuring effective and reliable operation of SWHP.
基金Under the auspices of National Natural Science Foundation of China(No.41371538)Independent Project of State Key Laboratory of Urban and Regional Ecology,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences(No.SKLURE2008-1-02)
文摘River water plays a key role in human health, and in social and economic development, and is often affected by both natural factors and human activities. An in-depth understanding of the role of these factors can help in developing an effective catchment management strategy to protect precious water resources. This study analyzed river water quality, patterns of terrestrial and riparian ecosystems, intensity of agricultural activities, industrial structure, and spatial distribution of pollutant emissions in the Haihe River Basin in China for the year of 2010, identifying the variables that have the greatest impact on river water quality. The area percentage of farmland in study area, the percentage of natural vegetation cover in the 1000-m riparian zone, rural population density, industrial Gross Domestic Product(GDP)/km^2, and industrial amino nitrogen emissions were all significantly correlated with river water quality(P < 0.05). Farming had the largest impact on river water quality, explaining 43.0% of the water quality variance, followed by the coverage of natural vegetation in the 1000-m riparian zone, which explained 36.2% of the water quality variance. Industrial amino nitrogen emissions intensity and rural population density explained 31.6% and 31.4% of the water quality variance, respectively, while industrial GDP/km^2 explained 26.6%. Together, these five indicators explained 67.3% of the total variance in water quality. Consequently, water environmental management of the Haihe River Basin should focus on adjusting agricultural activities, conserving riparian vegetation, and reducing industrial pollutant emissions by optimizing industrial structure. The results demonstrate how human activities drive the spatial pattern changes of river water quality, and they can provide reference for developing land use guidelines and for prioritizing management practices to maintain stream water quality in a large river basin.
