Cu-30Ni-xRE(x=0–0.213 wt.%) alloy was prepared by adding rare earths(RE) in melted Cu-30Ni alloy using metal mould casting method.The effects of RE on corrosion resistance of the alloy in simulated seawater were inve...Cu-30Ni-xRE(x=0–0.213 wt.%) alloy was prepared by adding rare earths(RE) in melted Cu-30Ni alloy using metal mould casting method.The effects of RE on corrosion resistance of the alloy in simulated seawater were investigated using optical microscope,scanning electronic microscope with energy-dispersive spectrometer and electrochemical measurement system.The results showed that the corrosion resistance of Cu-30Ni alloy was greatly improved by adding proper amount of RE,whereas excess addition of RE worsened ...展开更多
To explore the role of biofilm formation on the corrosion of marine concrete structures, we investigated the attachment of biofilm on mortar surfaces in simulated seawater and the influence of biofilm on the microstru...To explore the role of biofilm formation on the corrosion of marine concrete structures, we investigated the attachment of biofilm on mortar surfaces in simulated seawater and the influence of biofilm on the microstructure of mortar surfaces. The results show that the evolution of biofilm on mortar surfaces in simulated seawater is closely related to the corrosion suffered by the mortar, and the process of biofilm attachment and shedding is continuous and cyclical. It is found that the specimens in the absence of biofilm attachment are more severely eroded internally by the corrosive medium in simulated seawater than those in the presence of biofilm attachment. For the specimens without biofilm attachment, after 60 days, gypsum forms,and after 120 days, the number of pores in the mortar is reduced. In contrast, for the specimens in the presence of biofilm attachment, gypsum could only be detected after 90 days, and fewer pores are filled. Therefore, the formation of biofilm could delay the invasion of the corrosive medium into the interior of mortar during the evolution of biofilm on mortar surfaces, mitigating the corrosion of mortars in seawater.展开更多
This study proposes and systematically evaluates an optimized integration of warm surface seawater injection with depressurization for the long-term exploitation of marine natural gas hydrates.By employing comprehensi...This study proposes and systematically evaluates an optimized integration of warm surface seawater injection with depressurization for the long-term exploitation of marine natural gas hydrates.By employing comprehensive multiphysics simulations guided by field data from hydrate production tests in the South China Sea,we pinpoint key operational parameters—such as injection rates,depths,and timings—that notably enhance production efficiency.The results indicate that a 3-phase hydrate reservoir transitions from a free-gas-dominated production stage to a hydrate-decomposition-dominated stage.Moderate warm seawater injection supplies additional heat during the hydrate decomposition phase,thereby enhancing stable production;however,excessively high injection rates can impede the depressurization process.Only injection at an appropriate depth simultaneously balances thermal supplementation and the pressure gradient,leading to higher overall productivity.A“depressurization-driven sensible-heat supply window”is introduced,highlighting that timely seawater injection following initial depressurization prolongs reservoir dissociation dynamics.In this study area,commencing seawater injection at 170 d of depressurization proved optimal.This optimized integration leverages clean and renewable thermal energy,providing essential insights into thermal supplementation strategies with significant implications for sustainable,economically feasible,and efficient commercial-scale hydrate production.展开更多
The hot compression test of 6063 Al alloy was performed on a Gleeble-1500 thermo-simulation machine, and the forming of 6063 rod cxtrudate in low-temperature high-speed extrusion was simulated with extrusion ratio of ...The hot compression test of 6063 Al alloy was performed on a Gleeble-1500 thermo-simulation machine, and the forming of 6063 rod cxtrudate in low-temperature high-speed extrusion was simulated with extrusion ratio of 25 on the platform of DEFORM 2D successfully. From the compression experimental results, the flow stress model of this Al alloy is obtained which could be the constitutive equation in the simulation of low-temperature high-speed extrusion process. From the numerical simulation results, there is a higher strain concentration at the entrance of the die and the exit temperature reaches up to 522 ℃ in low-temperature high-speed extrusion, which approaches to the quenching temperature of the 6063 Al alloy. The results show that the low-temperature high-speed extrusion method as a promsing one can reduce energy consumption effectively.展开更多
In this paper, we report a method by which the ion quantity is estimated rapidly with an accuracy of 4%. This finding is based on the low-temperature ion density theory and combined with the ion crystal size obtained ...In this paper, we report a method by which the ion quantity is estimated rapidly with an accuracy of 4%. This finding is based on the low-temperature ion density theory and combined with the ion crystal size obtained from experiment with the precision of a micrometer. The method is objective, straightforward, and independent of the molecular dynamics （MD） simulation. The result can be used as the reference for the MD simulation, and the method can improve the reliability and precision of MD simulation. This method is very helpful for intensively studying ion crystal, such as phase transition, spatial configuration, temporal evolution, dynamic character, cooling efficiency, and the temperature limit of the ions.展开更多
Saltwater Intrusion(SI)poses a significant environmental threat to freshwater resources in coastal aquifers globally.The primary objective of this research is to illustrate the variations in the saltwater-freshwater i...Saltwater Intrusion(SI)poses a significant environmental threat to freshwater resources in coastal aquifers globally.The primary objective of this research is to illustrate the variations in the saltwater-freshwater interface using several established analytical solutions,integrated within a user-friendly web-based tool.Three case studies,including a hypothetical unconfined coastal aquifer,an experimental coastal aquifer,and a real-world coastal aquifer in Gaza,were applied to examine the interface dynamics using the developed tool,built with JavaScript.To simulate variable-density flow within the Gaza coastal aquifer,the public domain code SEAWAT was employed.The resulting lengths of seawater intrusion,as simulated by SEAWAT and the observed toe length,were compared with those obtained from the web-based analytical solutions under both constant head and constant flux boundary conditions.This comparison demonstrated a strong correlation between the experimental results,SEAWAT model outputs,and analytical solutions.This research provides valuable insights into SI in coastal aquifers,with a specific focus on the impact of Sea Level Rise(SLR)on the shifting position of the seawater intrusion toe.The outcomes are presented through an accessible web-based interface,thereby promoting broader dissemination and practical application of the research outcomes.展开更多
The simulation of this process and the effects of protection projects lays the foundation of its effective control and defence. The mathematical model of the problem and upwind splitting alternating direction method w...The simulation of this process and the effects of protection projects lays the foundation of its effective control and defence. The mathematical model of the problem and upwind splitting alternating direction method were presented. Using this method, the numerical simulation of seawater intrusion in Laizhou Bay Area of Shandong Provivce was finished. The numerical results turned out to be identical with the real measurements, so the prediction of the consequences of protection projectects is reasonable.展开更多
Taking the ratio of heat transfer area to net power and heat recovery efficiency into account, a multi-objective mathematical model was developed for organic Rankine cycle （ORC）. Working fluids considered were R123,...Taking the ratio of heat transfer area to net power and heat recovery efficiency into account, a multi-objective mathematical model was developed for organic Rankine cycle （ORC）. Working fluids considered were R123, R134a, R141b, R227ea and R245fa. Under the given conditions, the parameters including evaporating and condensing pressures, working fluid and cooling water velocities were optimized by simulated annealing algorithm. The results show that the optimal evaporating pressure increases with the heat source temperature increasing. Compared with other working fluids, R123 is the best choice for the temperature range of 100--180℃ and R141 b shows better performance when the temperature is higher than 180 ℃. Economic characteristic of system decreases rapidly with the decrease of heat source temperature. ORC system is uneconomical for the heat source temperature lower than 100℃.展开更多
The current research of seawater hydraulic motor mainly focused on piston motor and vane motor, but seldom regarded low speed high torque seawater hydraulic motor. Low speed high torque seawater hydraulic motor as a k...The current research of seawater hydraulic motor mainly focused on piston motor and vane motor, but seldom regarded low speed high torque seawater hydraulic motor. Low speed high torque seawater hydraulic motor as a kind of energy conversion device and actuator plays an important role in seawater hydraulic transmission system. However, the physical and chemical properties of seawater, such as low viscosity, high causticity and poor lubrication, result in numerous problems. In this paper, the flow distribution characteristics of port plate pairs for the seawater hydraulic motor are investigated, and the leakage flow and power loss models of port plate pairs are established. Numerical simulations are carried out to examine the effects of water film, inlet pressure and rotating speed on the pressure distribution and leakage flow. And the friction and wear tests of port plate pairs are also carried out. Moreover, the test system of the seawater hydraulic motor is constructed and the performance of prototype with no-load or loading is conducted. The results indicate that the clearance of port plate pairs and inlet pressure have a significant effect on distribution characteristics, but the effect of rotating speed is not very obvious. The experimental results show that the minimum error rate can be maintained within 0.3% by the proposed flow model and the counter materials of 316 L against carbon-fiber-reinforced polyetheretherketone(CFRPEEK) are suitable for the port plate pairs of seawater hydraulic motor. Finally, based on the seawater hydraulic experiment platform, the volumetric efficiency of no-load and loading are obtained that the maximum can achieve 94.71% and 90.14%, respectively. This research work may improve the flow distribution performance, lubrication and the friction and wear properties, enhance energy converting efficiency of port plate pair and provide theoretical and technical support for the design of highperformance water hydraulic components.展开更多
The aim of this paper is to analyze the change in the active structure of lignite during the process of lowtemperature oxidation by constructing a molecular structure model for lignite. Using quantum computation combi...The aim of this paper is to analyze the change in the active structure of lignite during the process of lowtemperature oxidation by constructing a molecular structure model for lignite. Using quantum computation combined with experimental results of proximate analysis, ultimate analysis, Fourier transform infrared spectroscopy(FTIR) and X-ray photoelectron spectroscopy(XPS), a structural model for the large molecular structure was constructed. By analyzing the bond lengths in the model molecule, the evolution law for the active structure of lignite was predicted for the process of low-temperature oxidation. In low-temperature oxidation,alkanes and hydroxyls are the primary active structures observed in lignite, though ether may also react. These active functional groups react with oxygen to release heat, thereby speeding up the reaction between coal and oxygen. Finally, the content of various functional groups in the process of lignite low-temperature oxidation was analyzed by infrared analysis, and the accuracy of the model was verified.展开更多
On the bisis of determining the there elements of thermocline ( depth [upper bound depth ], thickness and intensity ) and the maximum vertical temperature gradient of the surveying station, the paper calculates the me...On the bisis of determining the there elements of thermocline ( depth [upper bound depth ], thickness and intensity ) and the maximum vertical temperature gradient of the surveying station, the paper calculates the mean temperature of the Nansha deep-water surveying station within the upper-bound depth layer of thermocline and the mean temperature below the lower-bound depth of thermocline between the 300m and 800m layers,respectively. Analysis indicates that the horizontal distribution of mean seawater temperature shows a distinct trend of the low-temperature seawater slowly moving from the northeast to the southeast of Nansha,which seems to have been driven by the Northeast Monsoon. The larger the vertical temperature radient is, the greater is its capability of preventing the heat of the upper seawater from diffusing into the deeper layers on the vertical direction.展开更多
Numerical simulation and theoretical analysis of seawater intrusion is the mathematical basis for modern environmental science. Its mathematical model is the nonlinear coupled system of partial differential equations ...Numerical simulation and theoretical analysis of seawater intrusion is the mathematical basis for modern environmental science. Its mathematical model is the nonlinear coupled system of partial differential equations with initial-boundary problems. For a generic case of a three-dimensional bounded region, two kinds of finite difference fractional steps pro- cedures are put forward. Optimal order estimates in norm are derived for the error in the approximation solution. The present method has been successfully used in predicting the consequences of seawater intrusion and protection projects.展开更多
A series of NiMoO_(4)-nano rod/carbon cloth composite electrodes with different loadings(x)of NiMoO_(4)-NRs was synthesized with a view to implementing an efficient hydrogen evolution reaction(HER).The NiMoO_(4) nano-...A series of NiMoO_(4)-nano rod/carbon cloth composite electrodes with different loadings(x)of NiMoO_(4)-NRs was synthesized with a view to implementing an efficient hydrogen evolution reaction(HER).The NiMoO_(4) nano-rods(NRs)were prepared by growing them directly on carbon cloth(CC)via a simple hydrothermal reaction coupled with an annealing treatment.The resulting NiMoO_(4)-NR/CC-x composites served directly as electrodes for electrolysis of an alkaline medium and a simulated sea water.The results indicated that among the NiMoO_(4)-NR/CC-x composites,the NiMoO_(4)-NR/CC-10 composite possessed the highest HER activity with an overpotential of 244.8 mV at 10 mA/cm^(2),a Tafel slope of 95 mV/dec,the fastest charge transfer rate(R_(ct)<1Ω)and good stability in alkaline media.Even in simulated seawater,the NiMoO_(4)-NR/CC-10 composite showed good stability.The outstanding HER activity and stability may originate from the strong interaction between Ni and Mo in the NiMoO_(4) NRs as well as the efficient charge transfer process and the rate of the HER due to the synergistic effect involving the CC and NiMoO_(4) NRs.展开更多
A numerical study on the conjugated heat-mass transfer of helical hollow fiber membrane tube bank(HFMTB)for seawater desalination was carried out.Physical and mathematical models of fluid flow,temperature and humidity...A numerical study on the conjugated heat-mass transfer of helical hollow fiber membrane tube bank(HFMTB)for seawater desalination was carried out.Physical and mathematical models of fluid flow,temperature and humidity distribution were constructed to investigate the influences of flow type,Reynolds number,and temperature on the conjugated heat-mass transfer performance of hollow fibers in the distillation membrane module.The conjugated heat-mass transfer characteristics of HFMTB were discussed by utilizing the friction coefficient,Nusselt number(Nu),and Sherwood number(Sh).Results demonstrate that a distillation efficiency enhancement of 29%compared to the straight HFMTB has been detected for four-helical HFMTB configuration,though the friction coefficient of such a module is about 4 times of their straight counterparts.The values of average Nu and Sh numbers are increasing with tube number,which improves distillation efficiency.The effect of flow type has been studied by employing the upstream and downstream flows to the double-helical HFMTB,demonstrating upstream flow type is more conducive to the heat-mass transfer process.Both the outlet air humidity(ω)and distillation efficiency(η)decrease with the air-side Reynolds number(Rea)and inlet air temperature in the helical HFMTB while increasing with the solution-side Reynolds number(Re_(S))and inlet solution temperature.Overall,the obtained results indicate that helical HFMTB applying upstream flow has great potential to achieve high-performance SGMD for seawater desalination.It is anticipated that the present work can assist in a better understanding of the membrane desalination process in HFMTB and thus provide theoretical suggestions for further optimization and development.展开更多
The corrosion behavior of B10 copper-nickel alloy welded joints in seawater pipeline system was analyzed under local turbulence induced by weld residual height.The corrosion behavior was evaluated by array electrode t...The corrosion behavior of B10 copper-nickel alloy welded joints in seawater pipeline system was analyzed under local turbulence induced by weld residual height.The corrosion behavior was evaluated by array electrode technology,mor-phology and elemental characterization,and COMSOL Multiphysics simulation.The results provide a theoretical basis for the corrosion and leakage of B10 alloy in seawater pipeline under the action of turbulence.The results show that residual height-induced turbulence exhibits a significant effect on the corrosion behavior in different areas of welded joints in B10 alloy.Turbulence can damage some surfaces,causing polarity deflection followed by acceleration of corrosion,or it is easier to form a protective film to slow down corrosion.COMSOL Multiphysics results show that the shear rate and turbulent kinetic energy increase linearly with the increase in residual height and velocity.The corrosion behavior of alloy surface is influenced by controlling the mass transfer rate and surface state.展开更多
A simple diagnostic simulation of the annual cycling of the surface specific photosynthesis rate (SPR) in Jiaozhou Bay is described in this paper. Light intensity, temperature and nutrients (nitrate + ammonia, phospha...A simple diagnostic simulation of the annual cycling of the surface specific photosynthesis rate (SPR) in Jiaozhou Bay is described in this paper. Light intensity, temperature and nutrients (nitrate + ammonia, phosphate) were considered as main factors controlling photosynthesis of phytoplankton and were introduced into the model by different function equations. The simulated variation of specific photosynthesis rate coincided with the measured data. Analysis of the effect of every factor on photosynthesis indicated that the variation of photosynthesis rate was controlled by all these three factors, while temperature showed good correlation with SPR as measurement showed. This diagnostic simulation yielded the values of some parameter relating with the photosynthesis in Jiaozhou Bay.展开更多
MSF seawater desalination has become an important technology to solve the scarce of fresh water resources in the world. But the high energy cost is the bottle-neck of extendibility and application. In this paper, the ...MSF seawater desalination has become an important technology to solve the scarce of fresh water resources in the world. But the high energy cost is the bottle-neck of extendibility and application. In this paper, the principle of MSF is analyzed and the single flash stage is divided into several elementary unit operations. The Aspen Plus is adopted to simulate MSF desalination process. The effect factor of MSF system, such as the feed seawater temperature, the top brine temperature(TBT) and the stage number, is investigated and the optimum operation condition is obtained.展开更多
基金Project Financially supported by Major State Basic Research Development Program of China (2007CB616903)
文摘Cu-30Ni-xRE(x=0–0.213 wt.%) alloy was prepared by adding rare earths(RE) in melted Cu-30Ni alloy using metal mould casting method.The effects of RE on corrosion resistance of the alloy in simulated seawater were investigated using optical microscope,scanning electronic microscope with energy-dispersive spectrometer and electrochemical measurement system.The results showed that the corrosion resistance of Cu-30Ni alloy was greatly improved by adding proper amount of RE,whereas excess addition of RE worsened ...
基金Funded by the National Natural Science Foundation of China (Nos. 52278269, 52278268, 52178264, 52108238)Tianjin Outstanding Young Scholars Science Fund Project (No. 22JCJQJC00020)State Key Laboratory of Green Building Materials Open Foundation (No. 2021GBM08)。
文摘To explore the role of biofilm formation on the corrosion of marine concrete structures, we investigated the attachment of biofilm on mortar surfaces in simulated seawater and the influence of biofilm on the microstructure of mortar surfaces. The results show that the evolution of biofilm on mortar surfaces in simulated seawater is closely related to the corrosion suffered by the mortar, and the process of biofilm attachment and shedding is continuous and cyclical. It is found that the specimens in the absence of biofilm attachment are more severely eroded internally by the corrosive medium in simulated seawater than those in the presence of biofilm attachment. For the specimens without biofilm attachment, after 60 days, gypsum forms,and after 120 days, the number of pores in the mortar is reduced. In contrast, for the specimens in the presence of biofilm attachment, gypsum could only be detected after 90 days, and fewer pores are filled. Therefore, the formation of biofilm could delay the invasion of the corrosive medium into the interior of mortar during the evolution of biofilm on mortar surfaces, mitigating the corrosion of mortars in seawater.
基金supported by the National Key R&D Program of China(No.2024YFB4206700)the Joint Geological Funds of the National Natural Science Foundation of China(No.U2244223)+5 种基金the China Scholarship Council Program(No.202404910533)the Guangdong Major Project of Basic and Applied Basic Research(No.2020B0301030003)the China Geological Survey Project(No.DD20211350)the Key Deployment Program of Chinese Academy of Sciences(Nos.YJKYYQ20190043,ZDBS-LY-DQC003,KFZD-SW-422,and ZDRW-ZS-2021-3-1)the Scientific Research and Technology Development Project of China National Petroleum Corporation(No.2022DJ5503)the Supercomputing Laboratory,IGGCAS.
文摘This study proposes and systematically evaluates an optimized integration of warm surface seawater injection with depressurization for the long-term exploitation of marine natural gas hydrates.By employing comprehensive multiphysics simulations guided by field data from hydrate production tests in the South China Sea,we pinpoint key operational parameters—such as injection rates,depths,and timings—that notably enhance production efficiency.The results indicate that a 3-phase hydrate reservoir transitions from a free-gas-dominated production stage to a hydrate-decomposition-dominated stage.Moderate warm seawater injection supplies additional heat during the hydrate decomposition phase,thereby enhancing stable production;however,excessively high injection rates can impede the depressurization process.Only injection at an appropriate depth simultaneously balances thermal supplementation and the pressure gradient,leading to higher overall productivity.A“depressurization-driven sensible-heat supply window”is introduced,highlighting that timely seawater injection following initial depressurization prolongs reservoir dissociation dynamics.In this study area,commencing seawater injection at 170 d of depressurization proved optimal.This optimized integration leverages clean and renewable thermal energy,providing essential insights into thermal supplementation strategies with significant implications for sustainable,economically feasible,and efficient commercial-scale hydrate production.
基金Project(2008A09030004) supported by the Major Science and Technology Project of Guangdong Province,ChinaProject(30815009) supported by the Foundation of State Key Laboratory of Advanced Design and Manufacture for Vehicle Body
文摘The hot compression test of 6063 Al alloy was performed on a Gleeble-1500 thermo-simulation machine, and the forming of 6063 rod cxtrudate in low-temperature high-speed extrusion was simulated with extrusion ratio of 25 on the platform of DEFORM 2D successfully. From the compression experimental results, the flow stress model of this Al alloy is obtained which could be the constitutive equation in the simulation of low-temperature high-speed extrusion process. From the numerical simulation results, there is a higher strain concentration at the entrance of the die and the exit temperature reaches up to 522 ℃ in low-temperature high-speed extrusion, which approaches to the quenching temperature of the 6063 Al alloy. The results show that the low-temperature high-speed extrusion method as a promsing one can reduce energy consumption effectively.
基金supported by the National Basic Research Program of China(Grant Nos.2012CB821301 and 2010CB832803)the National Natural Science Foundation of China(Grant Nos.11004222 and 91121016)the Chinese Academy of Sciences
文摘In this paper, we report a method by which the ion quantity is estimated rapidly with an accuracy of 4%. This finding is based on the low-temperature ion density theory and combined with the ion crystal size obtained from experiment with the precision of a micrometer. The method is objective, straightforward, and independent of the molecular dynamics （MD） simulation. The result can be used as the reference for the MD simulation, and the method can improve the reliability and precision of MD simulation. This method is very helpful for intensively studying ion crystal, such as phase transition, spatial configuration, temporal evolution, dynamic character, cooling efficiency, and the temperature limit of the ions.
基金funded by the Science and Technology Development Fund(STDF)-Egypt(Grant number#46278).
文摘Saltwater Intrusion(SI)poses a significant environmental threat to freshwater resources in coastal aquifers globally.The primary objective of this research is to illustrate the variations in the saltwater-freshwater interface using several established analytical solutions,integrated within a user-friendly web-based tool.Three case studies,including a hypothetical unconfined coastal aquifer,an experimental coastal aquifer,and a real-world coastal aquifer in Gaza,were applied to examine the interface dynamics using the developed tool,built with JavaScript.To simulate variable-density flow within the Gaza coastal aquifer,the public domain code SEAWAT was employed.The resulting lengths of seawater intrusion,as simulated by SEAWAT and the observed toe length,were compared with those obtained from the web-based analytical solutions under both constant head and constant flux boundary conditions.This comparison demonstrated a strong correlation between the experimental results,SEAWAT model outputs,and analytical solutions.This research provides valuable insights into SI in coastal aquifers,with a specific focus on the impact of Sea Level Rise(SLR)on the shifting position of the seawater intrusion toe.The outcomes are presented through an accessible web-based interface,thereby promoting broader dissemination and practical application of the research outcomes.
文摘The simulation of this process and the effects of protection projects lays the foundation of its effective control and defence. The mathematical model of the problem and upwind splitting alternating direction method were presented. Using this method, the numerical simulation of seawater intrusion in Laizhou Bay Area of Shandong Provivce was finished. The numerical results turned out to be identical with the real measurements, so the prediction of the consequences of protection projectects is reasonable.
基金Project(2009GK2009) supported by Science and Technology Department Funds of Hunan Province,ChinaProject(08C26224302178) supported by Innovation Fund for Technology Based Firms of China
文摘Taking the ratio of heat transfer area to net power and heat recovery efficiency into account, a multi-objective mathematical model was developed for organic Rankine cycle （ORC）. Working fluids considered were R123, R134a, R141b, R227ea and R245fa. Under the given conditions, the parameters including evaporating and condensing pressures, working fluid and cooling water velocities were optimized by simulated annealing algorithm. The results show that the optimal evaporating pressure increases with the heat source temperature increasing. Compared with other working fluids, R123 is the best choice for the temperature range of 100--180℃ and R141 b shows better performance when the temperature is higher than 180 ℃. Economic characteristic of system decreases rapidly with the decrease of heat source temperature. ORC system is uneconomical for the heat source temperature lower than 100℃.
基金Supported by National Natural Science Foundation of China(Grant Nos.51505111,51805125)Zhejiang Provincial National Natural Science Foundation of China(Grant No.LQ16E050003)+1 种基金Hebei Provincial National Natural Science Foundation of China(Grant No.E2015203006)Open Foundation of State Key Laboratory of Fluid Power and Mechatronic Systems(Grant No.GZKF-201519)
文摘The current research of seawater hydraulic motor mainly focused on piston motor and vane motor, but seldom regarded low speed high torque seawater hydraulic motor. Low speed high torque seawater hydraulic motor as a kind of energy conversion device and actuator plays an important role in seawater hydraulic transmission system. However, the physical and chemical properties of seawater, such as low viscosity, high causticity and poor lubrication, result in numerous problems. In this paper, the flow distribution characteristics of port plate pairs for the seawater hydraulic motor are investigated, and the leakage flow and power loss models of port plate pairs are established. Numerical simulations are carried out to examine the effects of water film, inlet pressure and rotating speed on the pressure distribution and leakage flow. And the friction and wear tests of port plate pairs are also carried out. Moreover, the test system of the seawater hydraulic motor is constructed and the performance of prototype with no-load or loading is conducted. The results indicate that the clearance of port plate pairs and inlet pressure have a significant effect on distribution characteristics, but the effect of rotating speed is not very obvious. The experimental results show that the minimum error rate can be maintained within 0.3% by the proposed flow model and the counter materials of 316 L against carbon-fiber-reinforced polyetheretherketone(CFRPEEK) are suitable for the port plate pairs of seawater hydraulic motor. Finally, based on the seawater hydraulic experiment platform, the volumetric efficiency of no-load and loading are obtained that the maximum can achieve 94.71% and 90.14%, respectively. This research work may improve the flow distribution performance, lubrication and the friction and wear properties, enhance energy converting efficiency of port plate pair and provide theoretical and technical support for the design of highperformance water hydraulic components.
基金Supported by the Fundamental Research Funds for the Central Universities(2017XKQY066)
文摘The aim of this paper is to analyze the change in the active structure of lignite during the process of lowtemperature oxidation by constructing a molecular structure model for lignite. Using quantum computation combined with experimental results of proximate analysis, ultimate analysis, Fourier transform infrared spectroscopy(FTIR) and X-ray photoelectron spectroscopy(XPS), a structural model for the large molecular structure was constructed. By analyzing the bond lengths in the model molecule, the evolution law for the active structure of lignite was predicted for the process of low-temperature oxidation. In low-temperature oxidation,alkanes and hydroxyls are the primary active structures observed in lignite, though ether may also react. These active functional groups react with oxygen to release heat, thereby speeding up the reaction between coal and oxygen. Finally, the content of various functional groups in the process of lignite low-temperature oxidation was analyzed by infrared analysis, and the accuracy of the model was verified.
基金The paper is financially supported by the China National Key Basic Research Project (G1999043810) Guangdong Science and Technology Innovation Project (99B07102G) Chinese Academy of Sciences Innovation Project (KZCX2-206 and CXjj-28) and Chinese Natio
文摘On the bisis of determining the there elements of thermocline ( depth [upper bound depth ], thickness and intensity ) and the maximum vertical temperature gradient of the surveying station, the paper calculates the mean temperature of the Nansha deep-water surveying station within the upper-bound depth layer of thermocline and the mean temperature below the lower-bound depth of thermocline between the 300m and 800m layers,respectively. Analysis indicates that the horizontal distribution of mean seawater temperature shows a distinct trend of the low-temperature seawater slowly moving from the northeast to the southeast of Nansha,which seems to have been driven by the Northeast Monsoon. The larger the vertical temperature radient is, the greater is its capability of preventing the heat of the upper seawater from diffusing into the deeper layers on the vertical direction.
文摘Numerical simulation and theoretical analysis of seawater intrusion is the mathematical basis for modern environmental science. Its mathematical model is the nonlinear coupled system of partial differential equations with initial-boundary problems. For a generic case of a three-dimensional bounded region, two kinds of finite difference fractional steps pro- cedures are put forward. Optimal order estimates in norm are derived for the error in the approximation solution. The present method has been successfully used in predicting the consequences of seawater intrusion and protection projects.
文摘A series of NiMoO_(4)-nano rod/carbon cloth composite electrodes with different loadings(x)of NiMoO_(4)-NRs was synthesized with a view to implementing an efficient hydrogen evolution reaction(HER).The NiMoO_(4) nano-rods(NRs)were prepared by growing them directly on carbon cloth(CC)via a simple hydrothermal reaction coupled with an annealing treatment.The resulting NiMoO_(4)-NR/CC-x composites served directly as electrodes for electrolysis of an alkaline medium and a simulated sea water.The results indicated that among the NiMoO_(4)-NR/CC-x composites,the NiMoO_(4)-NR/CC-10 composite possessed the highest HER activity with an overpotential of 244.8 mV at 10 mA/cm^(2),a Tafel slope of 95 mV/dec,the fastest charge transfer rate(R_(ct)<1Ω)and good stability in alkaline media.Even in simulated seawater,the NiMoO_(4)-NR/CC-10 composite showed good stability.The outstanding HER activity and stability may originate from the strong interaction between Ni and Mo in the NiMoO_(4) NRs as well as the efficient charge transfer process and the rate of the HER due to the synergistic effect involving the CC and NiMoO_(4) NRs.
基金This work was supported by the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(GML2019ZD0108)Science and Technology Planning Project of Guangdong Province,China(2017A050501046)+1 种基金Natural Science Foundation of Guangdong Province(2017A030310185)Science and Technology Program of Guangzhou,China(202102021199).
文摘A numerical study on the conjugated heat-mass transfer of helical hollow fiber membrane tube bank(HFMTB)for seawater desalination was carried out.Physical and mathematical models of fluid flow,temperature and humidity distribution were constructed to investigate the influences of flow type,Reynolds number,and temperature on the conjugated heat-mass transfer performance of hollow fibers in the distillation membrane module.The conjugated heat-mass transfer characteristics of HFMTB were discussed by utilizing the friction coefficient,Nusselt number(Nu),and Sherwood number(Sh).Results demonstrate that a distillation efficiency enhancement of 29%compared to the straight HFMTB has been detected for four-helical HFMTB configuration,though the friction coefficient of such a module is about 4 times of their straight counterparts.The values of average Nu and Sh numbers are increasing with tube number,which improves distillation efficiency.The effect of flow type has been studied by employing the upstream and downstream flows to the double-helical HFMTB,demonstrating upstream flow type is more conducive to the heat-mass transfer process.Both the outlet air humidity(ω)and distillation efficiency(η)decrease with the air-side Reynolds number(Rea)and inlet air temperature in the helical HFMTB while increasing with the solution-side Reynolds number(Re_(S))and inlet solution temperature.Overall,the obtained results indicate that helical HFMTB applying upstream flow has great potential to achieve high-performance SGMD for seawater desalination.It is anticipated that the present work can assist in a better understanding of the membrane desalination process in HFMTB and thus provide theoretical suggestions for further optimization and development.
基金support from the National Natural Science Foundation of China(Grant No.42176209)the Natural Science Foundation of Shandong Province(Grant No.ZR2021MD064)the Fundamental Research Funds for the Central Universities(Grant No.19CX05001A).
文摘The corrosion behavior of B10 copper-nickel alloy welded joints in seawater pipeline system was analyzed under local turbulence induced by weld residual height.The corrosion behavior was evaluated by array electrode technology,mor-phology and elemental characterization,and COMSOL Multiphysics simulation.The results provide a theoretical basis for the corrosion and leakage of B10 alloy in seawater pipeline under the action of turbulence.The results show that residual height-induced turbulence exhibits a significant effect on the corrosion behavior in different areas of welded joints in B10 alloy.Turbulence can damage some surfaces,causing polarity deflection followed by acceleration of corrosion,or it is easier to form a protective film to slow down corrosion.COMSOL Multiphysics results show that the shear rate and turbulent kinetic energy increase linearly with the increase in residual height and velocity.The corrosion behavior of alloy surface is influenced by controlling the mass transfer rate and surface state.
文摘A simple diagnostic simulation of the annual cycling of the surface specific photosynthesis rate (SPR) in Jiaozhou Bay is described in this paper. Light intensity, temperature and nutrients (nitrate + ammonia, phosphate) were considered as main factors controlling photosynthesis of phytoplankton and were introduced into the model by different function equations. The simulated variation of specific photosynthesis rate coincided with the measured data. Analysis of the effect of every factor on photosynthesis indicated that the variation of photosynthesis rate was controlled by all these three factors, while temperature showed good correlation with SPR as measurement showed. This diagnostic simulation yielded the values of some parameter relating with the photosynthesis in Jiaozhou Bay.
文摘MSF seawater desalination has become an important technology to solve the scarce of fresh water resources in the world. But the high energy cost is the bottle-neck of extendibility and application. In this paper, the principle of MSF is analyzed and the single flash stage is divided into several elementary unit operations. The Aspen Plus is adopted to simulate MSF desalination process. The effect factor of MSF system, such as the feed seawater temperature, the top brine temperature(TBT) and the stage number, is investigated and the optimum operation condition is obtained.
