Seven in-situ tests were carried out in far field to study the blast mitigation effect of a kind of water filled plastic wall. Test results show that the mitigation effect of water filled plastic wall is remarkable. T...Seven in-situ tests were carried out in far field to study the blast mitigation effect of a kind of water filled plastic wall. Test results show that the mitigation effect of water filled plastic wall is remarkable. The maximum reduction of peak reflected overpressure reaches up to 94.53%, as well as 36.3% of the minimum peak reflected overpressure reduction in the scaled distance ranging from 1.71 m/kg1/3 to 3.42 m/kg1/3. Parametric studies were also carried out. The effects of the scaled gauge height, water/charge scaled distance(the distance between the explosive charge and the water wall), water wall scaled height and water/structure scaled distance(the distance between the water wall and the structure) were systematically investigated and compared with the usual rigid anti-blast wall. It is concluded that these parameters affect the mitigation effects of plastic water wall on blast loadings significantly, which is basically consistent to the trend of usual rigid anti-blast wall. Some formulae are also derived based on the numerical and test results, providing a simple but reliable prediction model to evaluate the peak overpressure of mitigated blast loadings on the structures.展开更多
The water wall is an important part of the passive natural circulation residual heat removal system in a high temperature gas-cooled reactor. The maximum temperatures of the pressure shell and the water wall are calcu...The water wall is an important part of the passive natural circulation residual heat removal system in a high temperature gas-cooled reactor. The maximum temperatures of the pressure shell and the water wall are calcu- lated using annular vertical closed cavity model. Fine particles can deposit on the water wall due to the thermophore- sis effect. This deposit can affect heat transfer. The thermophoretic deposit efficiency is calculated by using Batch and Shen’s formula fitted for both laminar flow and turbulent flow. The calculated results indicate that natural convection is turbulent in the closed cavity. The transient thermophoretic deposit efficiency rises with the increase of the pressure shell’s temperature. Its maximum value is 14%.展开更多
This paper aims to evaluate the Pottery Water Wall in a hot arid climate using CFD simulation.The Pottery Water Wall is a passive system and an upgrade to the Water Wall.The Pottery Water Wall is a combination of a Wa...This paper aims to evaluate the Pottery Water Wall in a hot arid climate using CFD simulation.The Pottery Water Wall is a passive system and an upgrade to the Water Wall.The Pottery Water Wall is a combination of a Water Wall and Porous Ceramic Pipes for evaporative cooling.First,the study will evaluate the efficiency of the Pottery Water Wall in cooling and heating in the most extreme climatic conditions of winter and summer in Luxor,Egypt.This study will aid determining the ability of the Pottery Water Wall to cool and heat buildings and its ability to achieve thermal comfort.The study found that the Pottery Water Wall’s cooling ability ranges between 4oC to 10oC,while its heating ability ranges between 4oC to 15oC.The Pottery Water Wall achieved thermal comfort for 62.5%of a day resembling extreme summer and achieved thermal comfort 62.5%of a day resembling extreme winter.In conclusion,the Pottery Water Wall can reduce cooling and heating demand by 88%at the extreme climatic conditions of Luxor,Egypt.展开更多
This paper presented a coupled heat transfer model combining the combustion in the furnace and the ultra-supercritical(USC) heat transfer in the water wall tubes. The thermal analysis of the spiral water wall in a 100...This paper presented a coupled heat transfer model combining the combustion in the furnace and the ultra-supercritical(USC) heat transfer in the water wall tubes. The thermal analysis of the spiral water wall in a 1000 MW double reheat USC boiler was conducted by the coupled heat transfer simulations. The simulation results show that there are two peak heat flux regions on each wall of spiral water wall, where the primary combustion zone and burnt-out zone locate respectively. In the full load condition, the maximal heat flux of the primary combustion zone is close to 500 kW/m^2, which is higher than that in the conventional single reheat USC boilers. The heat flux along the furnace width presents a parabolic shape that the values in the furnace center are much higher than that in the corner regions. The distribution of water wall temperature has a perfect accordance with the heat flux distribution of the parabolic shape curves, which can illustrate the distribution of water wall temperature is mainly determined by heat flux on the water wall. The maximal water wall temperature occurs at the middle width of furnace wall and approaches 530°C, which can be allowed by the metal material of water wall tube 12Cr1MoVG. In the primary combustion zone, the wall temperatures in half load are almost close to the values in 75% load condition, caused by the heat transfer deterioration of the subcritical pressure fluid under the high heat flux condition. The simulation results in this study are beneficial to the better design and operational optimization for the double reheat USC boilers.展开更多
Some crude oils with high water cut have the capability to flow below the oil gel point, while the oil particles adhere to the pipe wall in the form of paste, also called "wall sticking". Wall sticking is a ...Some crude oils with high water cut have the capability to flow below the oil gel point, while the oil particles adhere to the pipe wall in the form of paste, also called "wall sticking". Wall sticking is a serious problem during the pipeline transportation, leading to partial or total blockage of the pipeline and energy wastage. In this paper, a series of laboratory flow loop experiments were conducted to observe the wall sticking characteristics of crude oil with high water cut, high viscosity and high gel point at low transportation temperatures. The effects of shear stress and water cut on the wall sticking rate and occurrence temperature were investigated. Experimental results indicated that the wall sticking rate and occurrence temperature were lower under stronger shear stress and higher water cut conditions. A criterion of wall sticking occurrence temperature(WSOT) and a regression model of wall sticking rate were then established. Finally, the software was developed to calculate the pressure drop along the pipelines of crude oils with high water-cut. It was able to predict the wall sticking thickness of gelled oil and then calculate the pressure drop along the pipelines. A typical case study indicated that the prediction results obtained from the software were in agreement with actual measured values.展开更多
A local thermal stress model of water-cooled-wall pulverized-coal gasifier was built, and ANSYS was used to simulate the stress field in the gasifier operation to research the damage of refractories and slag layer cau...A local thermal stress model of water-cooled-wall pulverized-coal gasifier was built, and ANSYS was used to simulate the stress field in the gasifier operation to research the damage of refractories and slag layer caused by the thermal stress. The results reveal that:（1） the maximum stress of water-cooled-wall gasifier appears at the interface between anchor nails and refractories as well as the interface between refractories and the slag layer, and the maximum stress of slag layer appears on the surface of the slag layer;（2） the increase of slag layer thickness can significantly reduce the thermal stress at the interface between anchor nails and refractories, but increase the thermal stress between slag layer and refractories;（3） when the therma I conductivity is 2-6 W · m-1 · K-1, the thermal stress increases rapidly with the increase of the thermal conductivity, but when the thermal conductivity is 6-10 W · m-1 · K-1, the thermal stress is basically stable;（4） the higher the cooling rate, the faster the decreasing speed of the temperature and thermal stress.展开更多
In this paper, we report that an electromotive force （EMF） can be induced in a rope of aligned single-walled carbon nanotubes （SWNTs） when water droplets fall on this rope. The magnitude of this EMF depends sensit...In this paper, we report that an electromotive force （EMF） can be induced in a rope of aligned single-walled carbon nanotubes （SWNTs） when water droplets fall on this rope. The magnitude of this EMF depends sensitively on the slant angle of the SWNTs. Most interestingly, both the magnitude and the direction of the induced EFM can be modulated by applying a current to the SWNTs. The concepts of electrical slip and no-slip are proposed and can be quantitatively described by ＂electrical slip resistance＂. This kind of generator does not need any magnet, rotor, etc and shows quite a different operating mechanism and design compared with a conventional large scale hydroelectric power generator.展开更多
The structures of water inside and outside （6,6）, （8,8）, and （10,10） single- walled carbon nanotubes （SWCNTs） under an electric field perpendicular to the tube axis are investigated by molecular dynamics simul...The structures of water inside and outside （6,6）, （8,8）, and （10,10） single- walled carbon nanotubes （SWCNTs） under an electric field perpendicular to the tube axis are investigated by molecular dynamics simulations. The results show that dipole reorientation induced by electric field plays a significant role on the structures of confined water inside and outside SWCNTs. Inside SWCNTs, the average water occupancy and the average number of hydrogen bonds （H-bonds） per water molecule decrease as the electric intensity increases. Because the field intensity is sufficiently strong, the initial water structures inside the SWCNTs are destroyed, and the isolated water clusters are found. Outside SWCNTs, the azimuthal distributions of the density and the average number of H-bonds per water molecule around the solid walls become more and more asymmetric as the electric intensity increases. The percentages of water molecules involved in 0-5 H-bonds for all the three types of SWCNTs under different field intensities are displayed. The results show that those water molecules involved with most H-bonds are the most important to hold the original structures. When the electric field direction is parallel with the original preferred orientation, the density and the H-bond connections in water will be increased; when the electric field direction is perpendicular to the original preferred orientation, the density and the H-bond connections in water will be decreased.展开更多
Reported for the first the in this paper are the results of simulating experimnts on theγ-irradiation-induced oxidation of Fe2+ under the physicochemical conditions tr= 200℃,P= 50 MPa,Eh= -0.1V, PH=7.2) similar to t...Reported for the first the in this paper are the results of simulating experimnts on theγ-irradiation-induced oxidation of Fe2+ under the physicochemical conditions tr= 200℃,P= 50 MPa,Eh= -0.1V, PH=7.2) similar to tfor under which moderate-low temperature hydrothermal uraniumdeposits are formed . Evdence shows that the effect of groundwater radiolysis m to be the majormechanism of wall-rock alteration (hematitizaton ) of hydrothermal uranium deposits.Moreover, adiscussion was made of possible dets of radiolyss of the waterrock system on wall-rock alterationsincluding argillization and decoloration of uranium ore deposits on the basis of the experimentalresults.展开更多
This paper reports the results of separation and identification of the pigments from ice algae in the adjacent waters (62°12′30″S～62°14′30″S, 58°53′W～ 58°57′W) of Great Wall Station, Antarc...This paper reports the results of separation and identification of the pigments from ice algae in the adjacent waters (62°12′30″S～62°14′30″S, 58°53′W～ 58°57′W) of Great Wall Station, Antarctica during the icing Pened (from June 1988～ December 1988) and the discussion is also made on the composition and seasonal variations of the pigments of ice algae in that area as well as their roles in marine ecosystems. The results indicate that 15 kinds of pigments have been separated from ice algae, of which 13 kinds can be identified. They are respeCtively: carotene, pheophytin-a, chlorophyll-a, -b, -c, xanthophyll, fucoxanthin, chlorophyllide-a, violaxanthin, pheophorbide-a, chlorophyllin-a, derivative of chlorophyll-c (diadinoxanthin), but two kinds of pigments can not be identified. There are distinct seasonal variations in the pigments of ice algae at that sea area.展开更多
基金Projects(2015CB058003,2012CB026204)supported by the National Basic Research Program of ChinaProjects(51238007,51210012)supported by the National Natural Science Foundation of China
文摘Seven in-situ tests were carried out in far field to study the blast mitigation effect of a kind of water filled plastic wall. Test results show that the mitigation effect of water filled plastic wall is remarkable. The maximum reduction of peak reflected overpressure reaches up to 94.53%, as well as 36.3% of the minimum peak reflected overpressure reduction in the scaled distance ranging from 1.71 m/kg1/3 to 3.42 m/kg1/3. Parametric studies were also carried out. The effects of the scaled gauge height, water/charge scaled distance(the distance between the explosive charge and the water wall), water wall scaled height and water/structure scaled distance(the distance between the water wall and the structure) were systematically investigated and compared with the usual rigid anti-blast wall. It is concluded that these parameters affect the mitigation effects of plastic water wall on blast loadings significantly, which is basically consistent to the trend of usual rigid anti-blast wall. Some formulae are also derived based on the numerical and test results, providing a simple but reliable prediction model to evaluate the peak overpressure of mitigated blast loadings on the structures.
基金Supported by the Special Funds for Major State Basic Research Projects of China (No.2002CB211604) and the National Key Projects in the Ninth Five –Year Plan (96-G01-02-05).
文摘The water wall is an important part of the passive natural circulation residual heat removal system in a high temperature gas-cooled reactor. The maximum temperatures of the pressure shell and the water wall are calcu- lated using annular vertical closed cavity model. Fine particles can deposit on the water wall due to the thermophore- sis effect. This deposit can affect heat transfer. The thermophoretic deposit efficiency is calculated by using Batch and Shen’s formula fitted for both laminar flow and turbulent flow. The calculated results indicate that natural convection is turbulent in the closed cavity. The transient thermophoretic deposit efficiency rises with the increase of the pressure shell’s temperature. Its maximum value is 14%.
文摘This paper aims to evaluate the Pottery Water Wall in a hot arid climate using CFD simulation.The Pottery Water Wall is a passive system and an upgrade to the Water Wall.The Pottery Water Wall is a combination of a Water Wall and Porous Ceramic Pipes for evaporative cooling.First,the study will evaluate the efficiency of the Pottery Water Wall in cooling and heating in the most extreme climatic conditions of winter and summer in Luxor,Egypt.This study will aid determining the ability of the Pottery Water Wall to cool and heat buildings and its ability to achieve thermal comfort.The study found that the Pottery Water Wall’s cooling ability ranges between 4oC to 10oC,while its heating ability ranges between 4oC to 15oC.The Pottery Water Wall achieved thermal comfort for 62.5%of a day resembling extreme summer and achieved thermal comfort 62.5%of a day resembling extreme winter.In conclusion,the Pottery Water Wall can reduce cooling and heating demand by 88%at the extreme climatic conditions of Luxor,Egypt.
基金the financial support of the National Key Research & Development Program of China (Grant No.:2017YFB0602102)
文摘This paper presented a coupled heat transfer model combining the combustion in the furnace and the ultra-supercritical(USC) heat transfer in the water wall tubes. The thermal analysis of the spiral water wall in a 1000 MW double reheat USC boiler was conducted by the coupled heat transfer simulations. The simulation results show that there are two peak heat flux regions on each wall of spiral water wall, where the primary combustion zone and burnt-out zone locate respectively. In the full load condition, the maximal heat flux of the primary combustion zone is close to 500 kW/m^2, which is higher than that in the conventional single reheat USC boilers. The heat flux along the furnace width presents a parabolic shape that the values in the furnace center are much higher than that in the corner regions. The distribution of water wall temperature has a perfect accordance with the heat flux distribution of the parabolic shape curves, which can illustrate the distribution of water wall temperature is mainly determined by heat flux on the water wall. The maximal water wall temperature occurs at the middle width of furnace wall and approaches 530°C, which can be allowed by the metal material of water wall tube 12Cr1MoVG. In the primary combustion zone, the wall temperatures in half load are almost close to the values in 75% load condition, caused by the heat transfer deterioration of the subcritical pressure fluid under the high heat flux condition. The simulation results in this study are beneficial to the better design and operational optimization for the double reheat USC boilers.
基金the support from the projects of the National Natural Science Foundation of China(No.51374224)for this research
文摘Some crude oils with high water cut have the capability to flow below the oil gel point, while the oil particles adhere to the pipe wall in the form of paste, also called "wall sticking". Wall sticking is a serious problem during the pipeline transportation, leading to partial or total blockage of the pipeline and energy wastage. In this paper, a series of laboratory flow loop experiments were conducted to observe the wall sticking characteristics of crude oil with high water cut, high viscosity and high gel point at low transportation temperatures. The effects of shear stress and water cut on the wall sticking rate and occurrence temperature were investigated. Experimental results indicated that the wall sticking rate and occurrence temperature were lower under stronger shear stress and higher water cut conditions. A criterion of wall sticking occurrence temperature(WSOT) and a regression model of wall sticking rate were then established. Finally, the software was developed to calculate the pressure drop along the pipelines of crude oils with high water-cut. It was able to predict the wall sticking thickness of gelled oil and then calculate the pressure drop along the pipelines. A typical case study indicated that the prediction results obtained from the software were in agreement with actual measured values.
文摘A local thermal stress model of water-cooled-wall pulverized-coal gasifier was built, and ANSYS was used to simulate the stress field in the gasifier operation to research the damage of refractories and slag layer caused by the thermal stress. The results reveal that:（1） the maximum stress of water-cooled-wall gasifier appears at the interface between anchor nails and refractories as well as the interface between refractories and the slag layer, and the maximum stress of slag layer appears on the surface of the slag layer;（2） the increase of slag layer thickness can significantly reduce the thermal stress at the interface between anchor nails and refractories, but increase the thermal stress between slag layer and refractories;（3） when the therma I conductivity is 2-6 W · m-1 · K-1, the thermal stress increases rapidly with the increase of the thermal conductivity, but when the thermal conductivity is 6-10 W · m-1 · K-1, the thermal stress is basically stable;（4） the higher the cooling rate, the faster the decreasing speed of the temperature and thermal stress.
基金Project supported by the National Basic Research Program of China (Grant No.2006CB932402)the National Natural Science Foundation of China (Grant Nos.50702015,10574034,and 10774032)
文摘In this paper, we report that an electromotive force （EMF） can be induced in a rope of aligned single-walled carbon nanotubes （SWNTs） when water droplets fall on this rope. The magnitude of this EMF depends sensitively on the slant angle of the SWNTs. Most interestingly, both the magnitude and the direction of the induced EFM can be modulated by applying a current to the SWNTs. The concepts of electrical slip and no-slip are proposed and can be quantitatively described by ＂electrical slip resistance＂. This kind of generator does not need any magnet, rotor, etc and shows quite a different operating mechanism and design compared with a conventional large scale hydroelectric power generator.
基金Project supported by the National Natural Science Foundation of China(Nos.11372175 and 11272197)the Doctoral Fund of Ministry of Education of China(No.20103108110004)the Innovation Program of Shanghai Municipality Education Commission(No.14ZZ095)
文摘The structures of water inside and outside （6,6）, （8,8）, and （10,10） single- walled carbon nanotubes （SWCNTs） under an electric field perpendicular to the tube axis are investigated by molecular dynamics simulations. The results show that dipole reorientation induced by electric field plays a significant role on the structures of confined water inside and outside SWCNTs. Inside SWCNTs, the average water occupancy and the average number of hydrogen bonds （H-bonds） per water molecule decrease as the electric intensity increases. Because the field intensity is sufficiently strong, the initial water structures inside the SWCNTs are destroyed, and the isolated water clusters are found. Outside SWCNTs, the azimuthal distributions of the density and the average number of H-bonds per water molecule around the solid walls become more and more asymmetric as the electric intensity increases. The percentages of water molecules involved in 0-5 H-bonds for all the three types of SWCNTs under different field intensities are displayed. The results show that those water molecules involved with most H-bonds are the most important to hold the original structures. When the electric field direction is parallel with the original preferred orientation, the density and the H-bond connections in water will be increased; when the electric field direction is perpendicular to the original preferred orientation, the density and the H-bond connections in water will be decreased.
文摘Reported for the first the in this paper are the results of simulating experimnts on theγ-irradiation-induced oxidation of Fe2+ under the physicochemical conditions tr= 200℃,P= 50 MPa,Eh= -0.1V, PH=7.2) similar to tfor under which moderate-low temperature hydrothermal uraniumdeposits are formed . Evdence shows that the effect of groundwater radiolysis m to be the majormechanism of wall-rock alteration (hematitizaton ) of hydrothermal uranium deposits.Moreover, adiscussion was made of possible dets of radiolyss of the waterrock system on wall-rock alterationsincluding argillization and decoloration of uranium ore deposits on the basis of the experimentalresults.
文摘This paper reports the results of separation and identification of the pigments from ice algae in the adjacent waters (62°12′30″S～62°14′30″S, 58°53′W～ 58°57′W) of Great Wall Station, Antarctica during the icing Pened (from June 1988～ December 1988) and the discussion is also made on the composition and seasonal variations of the pigments of ice algae in that area as well as their roles in marine ecosystems. The results indicate that 15 kinds of pigments have been separated from ice algae, of which 13 kinds can be identified. They are respeCtively: carotene, pheophytin-a, chlorophyll-a, -b, -c, xanthophyll, fucoxanthin, chlorophyllide-a, violaxanthin, pheophorbide-a, chlorophyllin-a, derivative of chlorophyll-c (diadinoxanthin), but two kinds of pigments can not be identified. There are distinct seasonal variations in the pigments of ice algae at that sea area.
