The storage of hydrogen gas in lined rock caverns(LRCs)may enable the implementation of the firstlarge-scale fossil-free steelmaking process in Sweden,but filling such storage causes joints in the rockmass to open,con...The storage of hydrogen gas in lined rock caverns(LRCs)may enable the implementation of the firstlarge-scale fossil-free steelmaking process in Sweden,but filling such storage causes joints in the rockmass to open,concentrating strains in the lining.The structural interaction between the LRC componentsmust be able to reduce the strain concentration in the sealing steel lining;however,this interaction iscomplex and difficult to predict with analytical methods.In this paper,the strain concentration in LRCsfrom the opening of rock joints is studied using finite element(FE)analyses,where the large-and small-scale deformation behaviors of the LRC are coupled.The model also includes concrete crack initiation anddevelopment with increasing gas pressure and rock joint width.The interaction between the jointed rockmass and the reinforced concrete,the sliding layer,and the steel lining is demonstrated.The results showthat the rock mass quality and the spacing of the rock joints have the greatest influence on the straindistributions in the steel lining.The largest effect of rock joints on the maximum strains in the steellining was observed for geological conditions of“good”quality rock masses.展开更多
The combination of pyrolysis high resolution gas chromatography and pat- tern recognition techniques is a powerful tool for the classification of traditional Chinese drug.A study has been completed on 55 Beimu samples...The combination of pyrolysis high resolution gas chromatography and pat- tern recognition techniques is a powerful tool for the classification of traditional Chinese drug.A study has been completed on 55 Beimu samples of five different geographic origins: Eastern China.Central China.South-western China,North-western China and North-eastern China.Principal component analysis and SIMCA are applied to effectively classifying the samples according to the origin of the plants.The chemical information contained in the high resolution gas chromatographic data is sufficient to characterize the geographic origin of sam- pies.展开更多
The influence of cooling rate on the microstructure of Al0.6CoCrFeNi high entropy alloy（HEA） powders was investigated. The spherical HEA powders（D50≈78.65 μm） were prepared by high pressure gas atomization. The ...The influence of cooling rate on the microstructure of Al0.6CoCrFeNi high entropy alloy（HEA） powders was investigated. The spherical HEA powders（D50≈78.65 μm） were prepared by high pressure gas atomization. The different cooling rates were achieved by adjusting the powder diameter. Based on the solidification model, the relationship between the cooling rate and the powder diameter was developed. The FCC phase gradually disappears as particle size decreases. Further analysis reveals that the phase structure gradually changes from FCC＋BCC dual-phase to a single BCC phase with the increase of the cooling rate. The microstructure evolves from planar crystal to equiaxed grain with the cooling rate increasing from 3.19×10^4 to 1.11×10^6 K/s.展开更多
In 2005, the US passed the Energy Policy Act of 2005 mandating the construction and operation of a high-temperature gas reactor （HTGR） by 2021. This law was passed after a multiyear study by national experts on what...In 2005, the US passed the Energy Policy Act of 2005 mandating the construction and operation of a high-temperature gas reactor （HTGR） by 2021. This law was passed after a multiyear study by national experts on what future nuclear technologies should be developed. As a result of the Act, the US Congress chose to develop the so-called Next-Generation Nuclear Plant, which was to be an HTGR designed to produce process heat for hydrogen production. Despite high hopes and expectations, the current status is that high temperature reactors have been relegated to completing research programs on advanced fuels, graphite and materials with no plans to build a demonstration plant as required by the US Con- gress in 2005. There are many reasons behind this diminution of HTGR development, including but not limited to insufficient government funding requirements for research, unrealistically high temperature requirements for the reactor, the delay in the need for a ＂hydrogen＂ economy, competition from light water small modular light water reactors, little utility interest in new technologies, very low natural gas prices in the US, and a challenging licensing process in the US for non-water reactors.展开更多
Great quantities of light oil and gas are produced from deep buried hill reservoirs at depths of 5,641 m to 6,027 m and 190 ℃ to 201 ℃ in the Niudong-1 Well, representing the deepest and hottest commercial hydrocarb...Great quantities of light oil and gas are produced from deep buried hill reservoirs at depths of 5,641 m to 6,027 m and 190 ℃ to 201 ℃ in the Niudong-1 Well, representing the deepest and hottest commercial hydrocarbons discovered in the Bohai Bay Basin in eastern China. This discovery suggests favorable exploration prospects for the deep parts of the basin. However, the discovery raises questions regarding the genesis and accumulation of hydrocarbons in deep reservoirs. Based on the geochemical features of the hydrocarbons and characteristics of the source rocks as well as thermal simulation experiments of hydrocarbon generation, we conclude that the oil and gas were generated from the highly mature Sha-4 Member （Es4） source rocks instead of thermal cracking of crude oils in earlier accumulations. The source kitchen with abnormal pressures and karsted carbonate reservoirs control the formation of high-maturity hydrocarbon accumulations in the buried hills （i.e., Niudong-1） in conjunction with several structural-lithologic traps in the ES4 reservoirs since the deposition of the upper Minghuazhen Formation. This means the oil and gas exploration potential in the deep parts of the Baxian Depression is probably high.展开更多
This study numerically simulated and investigated the flow field characteristics of a typical dual-pulse solid rocket motor with a soft pulse separation device through thermal insulation ablation under high-temperatur...This study numerically simulated and investigated the flow field characteristics of a typical dual-pulse solid rocket motor with a soft pulse separation device through thermal insulation ablation under high-temperature dual-pulse erosion.The ablation rate of ethylene-propylene-diene monomer(EPDM)insulator was measured after the experiment.Experimental results were analyzed through scanning electron microscopy and microcomputed tomography.The ablation mechanism of the EPDM insulator under the operation conditions of a dual-pulse solid rocket motor was evaluated by analyzing the results.The results reveal that the internal flow field of the motor with a soft pulse separation device is uniform.The original charred layer existing on the EPDM insulator surface in the first pulse combustor is the decisive factor affecting the final ablation rate of the dual-pulse motor during the second pulse operation,and the ablation characteristic region is easily formed with the exfoliation of the charred layer.The ablation rate difference of the insulator increases with gas velocity.展开更多
As the classical transient flow model cannot simulate the water hammer effect of gas well, a transient flow mathematical model of multiphase flow gas well is established based on the mechanism of water hammer effect a...As the classical transient flow model cannot simulate the water hammer effect of gas well, a transient flow mathematical model of multiphase flow gas well is established based on the mechanism of water hammer effect and the theory of multiphase flow. With this model, the transient flow of gas well can be simulated by segmenting the curved part of tubing and calculating numerical solution with the method of characteristic curve. The results show that the higher the opening coefficient of the valve when closed, the larger the peak value of the wellhead pressure, the more gentle the pressure fluctuation, and the less obvious the pressure mutation area will be. On the premise of not exceeding the maximum shut-in pressure of the tubing, adopting large opening coefficient can reduce the impact of the pressure wave. The higher the cross-section liquid holdup, the greater the pressure wave speed, and the shorter the propagation period will be. The larger the liquid holdup, the larger the variation range of pressure, and the greater the pressure will be. In actual production, the production parameters can be adjusted to get the appropriate liquid holdup, control the magnitude and range of fluctuation pressure, and reduce the impact of water hammer effect. When the valve closing time increases, the maximum fluctuating pressure value of the wellhead decreases, the time of pressure peak delays, and the pressure mutation area gradually disappears. The shorter the valve closing time, the faster the pressure wave propagates. Case simulation proves that the transient flow model of gas well can optimize the reasonable valve opening coefficient and valve closing time, reduce the harm of water hammer impact on the wellhead device and tubing, and ensure the integrity of the wellbore.展开更多
Heat and mass transfer of a porous permeable wall in a high temperature gas dynamical flow is considered. Numerical simulation is conducted on the ground of the conjugate mathematical model which includes filtration a...Heat and mass transfer of a porous permeable wall in a high temperature gas dynamical flow is considered. Numerical simulation is conducted on the ground of the conjugate mathematical model which includes filtration and heat transfer equations in a porous body and boundary layer equations on its surface. Such an approach enables one to take into account complex interaction between heat and mass transfer in the gasdynamical flow and in the structure subjected to this flow. The main attention is given to the impact of the intraporous heat transfer intensity on the transpiration cooling efficiency.展开更多
Aiming at acute characteristics of flammability,explosibility,causticity and leakiness of high sour natural gas,giving full consideration to local natural conditions in Sichuan Province and starting with purification ...Aiming at acute characteristics of flammability,explosibility,causticity and leakiness of high sour natural gas,giving full consideration to local natural conditions in Sichuan Province and starting with purification process,the paper analyzed process configurations,energy utilization and conservation,safety and environment protection measures. The integrated technology and engineering scheme for high sour natural gas purification was established and successfully used in industrial application.展开更多
The desulfurization performance of the UDS solvents was investigated at an industrial side-stream plant and was compared with that of MDEA solvent.A mass transfer performance model was employed for explaining the COS ...The desulfurization performance of the UDS solvents was investigated at an industrial side-stream plant and was compared with that of MDEA solvent.A mass transfer performance model was employed for explaining the COS absorption into different solvents.Meanwhile,the regeneration performance of the UDS solvents was evaluated in side-stream tests.Results indicate that under the conditions covering an absorption temperature of 40℃,a pressure of 8.0 MPa,and a gas to liquid volume ratio(V/L)of around 230,the H2S content in purified gas can be reduced to 4.2 mg/m3 and 0 by using solvents UDS-II and UDS-III,respectively.Moreover,the total sulfur content in both purified gases is less than 80 mg/m3.As a result,the UDS-III solvent shows by 30 percentage points higher in COS removal efficiency than MDEA.In addition,the total volume mass transfer coefficient of UDS solvent is found to be twice higher than that of MDEA.Furthermore,the UDS solvents exhibit satisfactory thermal stability and regeneration performance.展开更多
High energy gas fracturing provides a new way for economic and high efficient development of the low permeability reservoir.By the end of 1993,it is tested and used in more:than 50 oil production and water injection w...High energy gas fracturing provides a new way for economic and high efficient development of the low permeability reservoir.By the end of 1993,it is tested and used in more:than 50 oil production and water injection wells in Changqing Oilfield with treatment success rate of more than 92%,and treatment effective rate of 86%,with average increase of oil production 3.4 times and somewhat increase.of water iniectivity in the water wells,cumulative increment of oil produc-tion and water injection had reached 11660 tons and 39220 cubic meters respectively.The test was undertaken by 0il Drilling&Production Tech-nology Research Institute in collaboration with Oil Production Plant,both are subordinated to Changqing Petroleum Exploration Bureau.展开更多
Ti-6 Al-4 V alloy powder was processed by electrode induction melting gas atomization(EIGA)at high gas pressure(5.5-7.0 MPa).The effects of atomizing gas pressure on the powder characteristics and the microstructure,a...Ti-6 Al-4 V alloy powder was processed by electrode induction melting gas atomization(EIGA)at high gas pressure(5.5-7.0 MPa).The effects of atomizing gas pressure on the powder characteristics and the microstructure,along with the mechanical properties of the as-fabricated block by laser melting deposition(LMD),were investigated.The results indicate that the diameters of powders are distributed in a wide range of sizes from 1 to 400μm,and the median powder size(d50)decreases with increasing gas pressure.The powders with a size fraction of 100-150μm obtained at gas pressures of 6.0 and 6.5 MPa have better flowability.The oxygen content is consistent with the change trend of gas pressure within a low range of 0.06%-0.20%.Specimens fabricated by LMD are mainly composed ofα+βgrains with a fine lamellar Widmanstatten structures and have the ultimate tensile strength(UTS)and yield strength of approximately 1100 and 1000 MPa,respectively.Furthermore,the atomized powders have a favorable 3 D printing capability,and the mechanical properties of Ti-6 Al-4 V alloys manufactured by LMD typically exceed those of their cast or wrought counterparts.展开更多
In the last several decades, circulating fluidized bed reactors have been studied in many aspects including hydrodynamics, heat and mass transfer and gas–solid two phase contacting. However, despite the abundance of ...In the last several decades, circulating fluidized bed reactors have been studied in many aspects including hydrodynamics, heat and mass transfer and gas–solid two phase contacting. However, despite the abundance of review papers on hydrodynamics, there is no summary paper on gas–solid contact efficiency to date, especially on high density circulating fluidized beds(CFBs). This paper gives an introduction to, and a review of the measurement of contact efficiency in circulating fluidized bed riser. Firstly, the popular testing method of contact efficiency including the method of heating transfer experiment and hot model reaction are discussed, then previous published papers are reviewed based on the discussed methods. Some key results of the experimental work are described and discussed. Gas–solid contact efficiency is affected by the operating conditions as well as the particle size distribution. The result of the contact efficiency shows that the CFB riser is far away from an ideal plug flow reactor due to the characteristics of hydrodynamics in the riser. Lacunae in the available literature have been delineated and recommendations have been made for further work.展开更多
For a low permeability single coal seam prone to gas outbursts, pre-drainage of gas is difficult and inefficient, seriously restricting the safety and efficiency of production. Radical measures of increasing gas extra...For a low permeability single coal seam prone to gas outbursts, pre-drainage of gas is difficult and inefficient, seriously restricting the safety and efficiency of production. Radical measures of increasing gas extraction efficiency are pressure relief and infrared antireflection. We have analyzed the effect of mining conditions and the regularity of mine pressure distribution in front of the working face of a major coal mine of the Jiaozuo Industrial （Group） Co. as our test area, studied the width of the depressurization zone in slice mining and analyzed gas efficiency and fast drainage in the advanced stress relaxation zone. On that basis, we further investigated and practiced the exploitation technology of shallow drilling, fan dril- ling and grid shape drilling at the working face. Practice and our results show that the stress relaxation zone is the ideal region for quick and efficient extraction of gas. By means of an integrated extraction technology, the amount of gas emitted into the zone was greatly reduced, while the risk of dangerous outbursts of coal and gas was lowered markedly. This exploration provides a new way to control for gas in working faces of coal mines with low permeability and risk of gas outbursts of single coal seams in the Jiaozuo mining area.展开更多
The effects of plastic deformation and H2 S on fracture toughness of high strength casing steel（C110 steel） were investigated. The studied casing specimens are as follows： original casing, plastic deformation（PD）...The effects of plastic deformation and H2 S on fracture toughness of high strength casing steel（C110 steel） were investigated. The studied casing specimens are as follows： original casing, plastic deformation（PD） casing and PD casing after being immersed in NACE A solution saturated with H2S（PD＋H2S）. Instrumented impact method was employed to evaluate the impact behaviors of the specimens, meanwhile, dynamic fracture toughness（JId） was calculated by using Rice model and Schindler model. The experimental results show that dynamic fracture toughness of the casing decreases after plastic deformation. Compared with that of the original casing and PD casing, the dynamic fracture toughness decreases further when the PD casing immersed in H2 S, moreover, there are ridge-shaped feature and many secondary cracks present on the fracture surface of the specimens. Impact fracture mechanism of the casing is proposed as follows： the plastic deformation results in the increase of defect density of materials where the atomic hydrogen can accumulate in reversible or irreversible traps and even recombine to form molecular hydrogen, subsequently, the casing material toughness decreases greatly.展开更多
High-performance gas sensing materials operated at room temperature(RT) are attractive for a variety of real-time gas monitoring applications,especially with the excellent durability and flexibility of wearable sensor...High-performance gas sensing materials operated at room temperature(RT) are attractive for a variety of real-time gas monitoring applications,especially with the excellent durability and flexibility of wearable sensor.The constructing heterostructure is one of the significant approaches in design strategies of sensing materials.This heterostructure effectively increases the active site for improving sensing performance and decreasing energy consumption.Herein,the heterostructure of Au nanoparticles modified CeO_(2)@carbon-quantum-dots(Au/CeO_(2)@CQDs) with a three-dimensional(3D) scaffold structure are successfully synthesized by an effective strategy,which can apply for preparing flexible gas sensor.The gas sensing properties of Au/CeO_(2)@CQDs based on flexible substrate are obtained under long-term repeated NO_(2) exposure at RT.Meanwhile,the long-term mechanical stability of this gas sensing device is also detected after different bending cycles.The Au/CeO_(2)@CQDs based on flexible substrate sensor exhibits excellent performance,including higher sensitivity(47.2),faster response(18 s)and recovery time(22 s) as well as longer-term stability than performance of pure materials.The obtained sensor also reveals outstanding mechanical flexibility,which is only a tiny response fluctuation(8.1%) after 500 bending/relaxing cycles.Therefore,our study demonstrates the enormous potential of this sensing materials for hazardous gas monitoring in future portable and wearable sensing platform.展开更多
The poppet valves two-stroke(PV2S)aircraft engine fueled with sustainable aviation fuel is a promising option for general aviation and unmanned aerial vehicle propulsion due to its high power-to-weight ratio,uniform t...The poppet valves two-stroke(PV2S)aircraft engine fueled with sustainable aviation fuel is a promising option for general aviation and unmanned aerial vehicle propulsion due to its high power-to-weight ratio,uniform torque output,and flexible valve timings.However,its high-altitude gas exchange performance remains unexplored,presenting new opportunities for optimization through artificial intelligence(AI)technology.This study uses validated 1D+3D models to evaluate the high-altitude gas exchange performance of PV2S aircraft engines.The valve timings of the PV2S engine exhibit considerable flexibility,thus the Latin hypercube design of experiments(DoE)methodology is employed to fit a response surface model.A genetic algorithm(GA)is applied to iteratively optimize valve timings for varying altitudes.The optimization process reveals that increasing the intake duration while decreasing the exhaust duration and valve overlap angles can significantly enhance high-altitude gas exchange performance.The optimal valve overlap angle emerged as 93°CA at sea level and 82°CA at 4000 m altitude.The effects of operating parameters,including engine speed,load,and exhaust back pressure,on the gas exchange process at varying altitudes are further investigated.The higher engine speed increases trapping efficiency but decreases the delivery ratio and charging efficiency at various altitudes.This effect is especially pronounced at elevated altitudes.The increase in exhaust back pressure will significantly reduce the delivery ratio and increase the trapping efficiency.This study demonstrates that integrating DoE with AI algorithms can enhance the high-altitude performance of aircraft engines,serving as a valuable reference for further optimization efforts.展开更多
Labeled polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs)were extracted by three different methods,i.e.,soxhlet extraction,hot extraction and accelerated solvent extraction(ASE).The PCDD/Fs were detected by...Labeled polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs)were extracted by three different methods,i.e.,soxhlet extraction,hot extraction and accelerated solvent extraction(ASE).The PCDD/Fs were detected by high resolution gas chromatography-high resolution mass spectrometry.Comparisons of the three methods were carried out by recovery of PCDD/Fs,solvent consumption and extraction time.The results showed that all of the method could extract labeled PCDD/Fs efficiently.ASE was a time saving procedure with lowest consumption of solvents compared with the other two methods.展开更多
A rapid pretreatment method of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in soil and analysis by high resolution gas chromatograph-high resolution mass spectrometry was present.The extraction and a...A rapid pretreatment method of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in soil and analysis by high resolution gas chromatograph-high resolution mass spectrometry was present.The extraction and alumina clean up of PCDD/Fs in soil was achieved by accelerated solvent extractor.Then the multi-layer silica-gel column was used for further clean up.The whole method has been evaluated on certified reference soil and farm soil.Accuracy and precision of this method was tested with satisfactory results.展开更多
Stable austenitic structure in medical stainless steels is basically required for surgical implantation. A weak magnetism was found in a high nitrogen nickel-free austenitic stainless steel for cardiovascular stent ap...Stable austenitic structure in medical stainless steels is basically required for surgical implantation. A weak magnetism was found in a high nitrogen nickel-free austenitic stainless steel for cardiovascular stent application. This magnetic behavior in high nitrogen stainless steel was investigated by optical microscopy, X-ray diffraction （XRD）, electron probe microanalysis （EPMA） and superconducting quantum interference device （SQUID）. The results showed that the magnetism came from the composition segregation of ferrite formation elements such as Cr and Mo in the steel and some 6-ferrites were locally formed during the pressurized electroslag remelting process. The magnetism of high nitrogen stainless steel could be eliminated by a proper high temperature gas nitriding （HTGN）.展开更多
基金supported by the Swedish Energy Agency(Grant Nos.42684-2,P2022-00209).
文摘The storage of hydrogen gas in lined rock caverns(LRCs)may enable the implementation of the firstlarge-scale fossil-free steelmaking process in Sweden,but filling such storage causes joints in the rockmass to open,concentrating strains in the lining.The structural interaction between the LRC componentsmust be able to reduce the strain concentration in the sealing steel lining;however,this interaction iscomplex and difficult to predict with analytical methods.In this paper,the strain concentration in LRCsfrom the opening of rock joints is studied using finite element(FE)analyses,where the large-and small-scale deformation behaviors of the LRC are coupled.The model also includes concrete crack initiation anddevelopment with increasing gas pressure and rock joint width.The interaction between the jointed rockmass and the reinforced concrete,the sliding layer,and the steel lining is demonstrated.The results showthat the rock mass quality and the spacing of the rock joints have the greatest influence on the straindistributions in the steel lining.The largest effect of rock joints on the maximum strains in the steellining was observed for geological conditions of“good”quality rock masses.
文摘The combination of pyrolysis high resolution gas chromatography and pat- tern recognition techniques is a powerful tool for the classification of traditional Chinese drug.A study has been completed on 55 Beimu samples of five different geographic origins: Eastern China.Central China.South-western China,North-western China and North-eastern China.Principal component analysis and SIMCA are applied to effectively classifying the samples according to the origin of the plants.The chemical information contained in the high resolution gas chromatographic data is sufficient to characterize the geographic origin of sam- pies.
基金Project(51471035)supported by the National Natural Science Foundation of China
文摘The influence of cooling rate on the microstructure of Al0.6CoCrFeNi high entropy alloy（HEA） powders was investigated. The spherical HEA powders（D50≈78.65 μm） were prepared by high pressure gas atomization. The different cooling rates were achieved by adjusting the powder diameter. Based on the solidification model, the relationship between the cooling rate and the powder diameter was developed. The FCC phase gradually disappears as particle size decreases. Further analysis reveals that the phase structure gradually changes from FCC＋BCC dual-phase to a single BCC phase with the increase of the cooling rate. The microstructure evolves from planar crystal to equiaxed grain with the cooling rate increasing from 3.19×10^4 to 1.11×10^6 K/s.
文摘In 2005, the US passed the Energy Policy Act of 2005 mandating the construction and operation of a high-temperature gas reactor （HTGR） by 2021. This law was passed after a multiyear study by national experts on what future nuclear technologies should be developed. As a result of the Act, the US Congress chose to develop the so-called Next-Generation Nuclear Plant, which was to be an HTGR designed to produce process heat for hydrogen production. Despite high hopes and expectations, the current status is that high temperature reactors have been relegated to completing research programs on advanced fuels, graphite and materials with no plans to build a demonstration plant as required by the US Con- gress in 2005. There are many reasons behind this diminution of HTGR development, including but not limited to insufficient government funding requirements for research, unrealistically high temperature requirements for the reactor, the delay in the need for a ＂hydrogen＂ economy, competition from light water small modular light water reactors, little utility interest in new technologies, very low natural gas prices in the US, and a challenging licensing process in the US for non-water reactors.
文摘Great quantities of light oil and gas are produced from deep buried hill reservoirs at depths of 5,641 m to 6,027 m and 190 ℃ to 201 ℃ in the Niudong-1 Well, representing the deepest and hottest commercial hydrocarbons discovered in the Bohai Bay Basin in eastern China. This discovery suggests favorable exploration prospects for the deep parts of the basin. However, the discovery raises questions regarding the genesis and accumulation of hydrocarbons in deep reservoirs. Based on the geochemical features of the hydrocarbons and characteristics of the source rocks as well as thermal simulation experiments of hydrocarbon generation, we conclude that the oil and gas were generated from the highly mature Sha-4 Member （Es4） source rocks instead of thermal cracking of crude oils in earlier accumulations. The source kitchen with abnormal pressures and karsted carbonate reservoirs control the formation of high-maturity hydrocarbon accumulations in the buried hills （i.e., Niudong-1） in conjunction with several structural-lithologic traps in the ES4 reservoirs since the deposition of the upper Minghuazhen Formation. This means the oil and gas exploration potential in the deep parts of the Baxian Depression is probably high.
基金financially supported by the National Natural Science Foundation of China,under grant numbers 51876177,51276150,and 51576165。
文摘This study numerically simulated and investigated the flow field characteristics of a typical dual-pulse solid rocket motor with a soft pulse separation device through thermal insulation ablation under high-temperature dual-pulse erosion.The ablation rate of ethylene-propylene-diene monomer(EPDM)insulator was measured after the experiment.Experimental results were analyzed through scanning electron microscopy and microcomputed tomography.The ablation mechanism of the EPDM insulator under the operation conditions of a dual-pulse solid rocket motor was evaluated by analyzing the results.The results reveal that the internal flow field of the motor with a soft pulse separation device is uniform.The original charred layer existing on the EPDM insulator surface in the first pulse combustor is the decisive factor affecting the final ablation rate of the dual-pulse motor during the second pulse operation,and the ablation characteristic region is easily formed with the exfoliation of the charred layer.The ablation rate difference of the insulator increases with gas velocity.
基金Supported by National Science and Technology Major Project of the Ministry of Science and Technology of China(2016ZX05026-002,2016ZX05028-001,2016ZX05024-005)
文摘As the classical transient flow model cannot simulate the water hammer effect of gas well, a transient flow mathematical model of multiphase flow gas well is established based on the mechanism of water hammer effect and the theory of multiphase flow. With this model, the transient flow of gas well can be simulated by segmenting the curved part of tubing and calculating numerical solution with the method of characteristic curve. The results show that the higher the opening coefficient of the valve when closed, the larger the peak value of the wellhead pressure, the more gentle the pressure fluctuation, and the less obvious the pressure mutation area will be. On the premise of not exceeding the maximum shut-in pressure of the tubing, adopting large opening coefficient can reduce the impact of the pressure wave. The higher the cross-section liquid holdup, the greater the pressure wave speed, and the shorter the propagation period will be. The larger the liquid holdup, the larger the variation range of pressure, and the greater the pressure will be. In actual production, the production parameters can be adjusted to get the appropriate liquid holdup, control the magnitude and range of fluctuation pressure, and reduce the impact of water hammer effect. When the valve closing time increases, the maximum fluctuating pressure value of the wellhead decreases, the time of pressure peak delays, and the pressure mutation area gradually disappears. The shorter the valve closing time, the faster the pressure wave propagates. Case simulation proves that the transient flow model of gas well can optimize the reasonable valve opening coefficient and valve closing time, reduce the harm of water hammer impact on the wellhead device and tubing, and ensure the integrity of the wellbore.
基金The project supported by the National Natural Science Foundation of China (19889209)Russian Foundation for Basic Research (97-02-16943)
文摘Heat and mass transfer of a porous permeable wall in a high temperature gas dynamical flow is considered. Numerical simulation is conducted on the ground of the conjugate mathematical model which includes filtration and heat transfer equations in a porous body and boundary layer equations on its surface. Such an approach enables one to take into account complex interaction between heat and mass transfer in the gasdynamical flow and in the structure subjected to this flow. The main attention is given to the impact of the intraporous heat transfer intensity on the transpiration cooling efficiency.
文摘Aiming at acute characteristics of flammability,explosibility,causticity and leakiness of high sour natural gas,giving full consideration to local natural conditions in Sichuan Province and starting with purification process,the paper analyzed process configurations,energy utilization and conservation,safety and environment protection measures. The integrated technology and engineering scheme for high sour natural gas purification was established and successfully used in industrial application.
基金financial support from the National Key Science and Technology Project of China (2011ZX05017-005)the Fundamental Research Funds for the Central Universities (No.22A201514010)
文摘The desulfurization performance of the UDS solvents was investigated at an industrial side-stream plant and was compared with that of MDEA solvent.A mass transfer performance model was employed for explaining the COS absorption into different solvents.Meanwhile,the regeneration performance of the UDS solvents was evaluated in side-stream tests.Results indicate that under the conditions covering an absorption temperature of 40℃,a pressure of 8.0 MPa,and a gas to liquid volume ratio(V/L)of around 230,the H2S content in purified gas can be reduced to 4.2 mg/m3 and 0 by using solvents UDS-II and UDS-III,respectively.Moreover,the total sulfur content in both purified gases is less than 80 mg/m3.As a result,the UDS-III solvent shows by 30 percentage points higher in COS removal efficiency than MDEA.In addition,the total volume mass transfer coefficient of UDS solvent is found to be twice higher than that of MDEA.Furthermore,the UDS solvents exhibit satisfactory thermal stability and regeneration performance.
文摘High energy gas fracturing provides a new way for economic and high efficient development of the low permeability reservoir.By the end of 1993,it is tested and used in more:than 50 oil production and water injection wells in Changqing Oilfield with treatment success rate of more than 92%,and treatment effective rate of 86%,with average increase of oil production 3.4 times and somewhat increase.of water iniectivity in the water wells,cumulative increment of oil produc-tion and water injection had reached 11660 tons and 39220 cubic meters respectively.The test was undertaken by 0il Drilling&Production Tech-nology Research Institute in collaboration with Oil Production Plant,both are subordinated to Changqing Petroleum Exploration Bureau.
基金Project(2017YFB0305801)supported by the National Key R&D Program of ChinaProject(U1508213)supported by the Joint-Fund of NSFC-Liaoning,ChinaProject(51771051)supported by the National Natural Science Foundation of China.
文摘Ti-6 Al-4 V alloy powder was processed by electrode induction melting gas atomization(EIGA)at high gas pressure(5.5-7.0 MPa).The effects of atomizing gas pressure on the powder characteristics and the microstructure,along with the mechanical properties of the as-fabricated block by laser melting deposition(LMD),were investigated.The results indicate that the diameters of powders are distributed in a wide range of sizes from 1 to 400μm,and the median powder size(d50)decreases with increasing gas pressure.The powders with a size fraction of 100-150μm obtained at gas pressures of 6.0 and 6.5 MPa have better flowability.The oxygen content is consistent with the change trend of gas pressure within a low range of 0.06%-0.20%.Specimens fabricated by LMD are mainly composed ofα+βgrains with a fine lamellar Widmanstatten structures and have the ultimate tensile strength(UTS)and yield strength of approximately 1100 and 1000 MPa,respectively.Furthermore,the atomized powders have a favorable 3 D printing capability,and the mechanical properties of Ti-6 Al-4 V alloys manufactured by LMD typically exceed those of their cast or wrought counterparts.
基金Supported by the Scientific Research Funds from China University of Petroleum(Beijing)(No.2462014YJRC018)partially supported by the National Natural Science Foundation of China(No.21506253 and No.91534204)
文摘In the last several decades, circulating fluidized bed reactors have been studied in many aspects including hydrodynamics, heat and mass transfer and gas–solid two phase contacting. However, despite the abundance of review papers on hydrodynamics, there is no summary paper on gas–solid contact efficiency to date, especially on high density circulating fluidized beds(CFBs). This paper gives an introduction to, and a review of the measurement of contact efficiency in circulating fluidized bed riser. Firstly, the popular testing method of contact efficiency including the method of heating transfer experiment and hot model reaction are discussed, then previous published papers are reviewed based on the discussed methods. Some key results of the experimental work are described and discussed. Gas–solid contact efficiency is affected by the operating conditions as well as the particle size distribution. The result of the contact efficiency shows that the CFB riser is far away from an ideal plug flow reactor due to the characteristics of hydrodynamics in the riser. Lacunae in the available literature have been delineated and recommendations have been made for further work.
基金the Major State Basic Research Program of China which provided for our financial support (No. 2005CB221501)
文摘For a low permeability single coal seam prone to gas outbursts, pre-drainage of gas is difficult and inefficient, seriously restricting the safety and efficiency of production. Radical measures of increasing gas extraction efficiency are pressure relief and infrared antireflection. We have analyzed the effect of mining conditions and the regularity of mine pressure distribution in front of the working face of a major coal mine of the Jiaozuo Industrial （Group） Co. as our test area, studied the width of the depressurization zone in slice mining and analyzed gas efficiency and fast drainage in the advanced stress relaxation zone. On that basis, we further investigated and practiced the exploitation technology of shallow drilling, fan dril- ling and grid shape drilling at the working face. Practice and our results show that the stress relaxation zone is the ideal region for quick and efficient extraction of gas. By means of an integrated extraction technology, the amount of gas emitted into the zone was greatly reduced, while the risk of dangerous outbursts of coal and gas was lowered markedly. This exploration provides a new way to control for gas in working faces of coal mines with low permeability and risk of gas outbursts of single coal seams in the Jiaozuo mining area.
基金Funded by the Construction of Key Disciplines for Young Teacher Science Foundation of the Southwest Petroleum University(No.P209)the Research Fund for the Doctoral Program of Higher Education(No.20105121120002)the National Natural Science Foundation of China(Nos.51004084 and 51374177)
文摘The effects of plastic deformation and H2 S on fracture toughness of high strength casing steel（C110 steel） were investigated. The studied casing specimens are as follows： original casing, plastic deformation（PD） casing and PD casing after being immersed in NACE A solution saturated with H2S（PD＋H2S）. Instrumented impact method was employed to evaluate the impact behaviors of the specimens, meanwhile, dynamic fracture toughness（JId） was calculated by using Rice model and Schindler model. The experimental results show that dynamic fracture toughness of the casing decreases after plastic deformation. Compared with that of the original casing and PD casing, the dynamic fracture toughness decreases further when the PD casing immersed in H2 S, moreover, there are ridge-shaped feature and many secondary cracks present on the fracture surface of the specimens. Impact fracture mechanism of the casing is proposed as follows： the plastic deformation results in the increase of defect density of materials where the atomic hydrogen can accumulate in reversible or irreversible traps and even recombine to form molecular hydrogen, subsequently, the casing material toughness decreases greatly.
基金financially supported by the Natural Science Foundation of Shandong Province (Nos. ZR2021QB136 and ZR2022MH091)the Innovation and Entrepreneurship Training Program for Undergraduates of Shandong Province (No.S202110439100)+2 种基金Tai'an Science and Technology Innovation Development Project (No.2021GX068)the Academic Promotion Program of Shandong First Medical University (No. 2019QL008)the Chinese Academy of Sciences。
文摘High-performance gas sensing materials operated at room temperature(RT) are attractive for a variety of real-time gas monitoring applications,especially with the excellent durability and flexibility of wearable sensor.The constructing heterostructure is one of the significant approaches in design strategies of sensing materials.This heterostructure effectively increases the active site for improving sensing performance and decreasing energy consumption.Herein,the heterostructure of Au nanoparticles modified CeO_(2)@carbon-quantum-dots(Au/CeO_(2)@CQDs) with a three-dimensional(3D) scaffold structure are successfully synthesized by an effective strategy,which can apply for preparing flexible gas sensor.The gas sensing properties of Au/CeO_(2)@CQDs based on flexible substrate are obtained under long-term repeated NO_(2) exposure at RT.Meanwhile,the long-term mechanical stability of this gas sensing device is also detected after different bending cycles.The Au/CeO_(2)@CQDs based on flexible substrate sensor exhibits excellent performance,including higher sensitivity(47.2),faster response(18 s)and recovery time(22 s) as well as longer-term stability than performance of pure materials.The obtained sensor also reveals outstanding mechanical flexibility,which is only a tiny response fluctuation(8.1%) after 500 bending/relaxing cycles.Therefore,our study demonstrates the enormous potential of this sensing materials for hazardous gas monitoring in future portable and wearable sensing platform.
基金funded by the Basic Research Program of the National Natural Science Foundation of China[grant numbers 52206131,U2333217,U2233213,and 51775025]National Key R&D Program of China[grant number 2022YFB2602002 and 2018YFB0104100]+1 种基金Zhejiang Provincial Natural Science Foundation of China[grant number LQ22E060004]Science Center of Gas Turbine Project[grant number P2022-A-I-001-001].
文摘The poppet valves two-stroke(PV2S)aircraft engine fueled with sustainable aviation fuel is a promising option for general aviation and unmanned aerial vehicle propulsion due to its high power-to-weight ratio,uniform torque output,and flexible valve timings.However,its high-altitude gas exchange performance remains unexplored,presenting new opportunities for optimization through artificial intelligence(AI)technology.This study uses validated 1D+3D models to evaluate the high-altitude gas exchange performance of PV2S aircraft engines.The valve timings of the PV2S engine exhibit considerable flexibility,thus the Latin hypercube design of experiments(DoE)methodology is employed to fit a response surface model.A genetic algorithm(GA)is applied to iteratively optimize valve timings for varying altitudes.The optimization process reveals that increasing the intake duration while decreasing the exhaust duration and valve overlap angles can significantly enhance high-altitude gas exchange performance.The optimal valve overlap angle emerged as 93°CA at sea level and 82°CA at 4000 m altitude.The effects of operating parameters,including engine speed,load,and exhaust back pressure,on the gas exchange process at varying altitudes are further investigated.The higher engine speed increases trapping efficiency but decreases the delivery ratio and charging efficiency at various altitudes.This effect is especially pronounced at elevated altitudes.The increase in exhaust back pressure will significantly reduce the delivery ratio and increase the trapping efficiency.This study demonstrates that integrating DoE with AI algorithms can enhance the high-altitude performance of aircraft engines,serving as a valuable reference for further optimization efforts.
文摘Labeled polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs)were extracted by three different methods,i.e.,soxhlet extraction,hot extraction and accelerated solvent extraction(ASE).The PCDD/Fs were detected by high resolution gas chromatography-high resolution mass spectrometry.Comparisons of the three methods were carried out by recovery of PCDD/Fs,solvent consumption and extraction time.The results showed that all of the method could extract labeled PCDD/Fs efficiently.ASE was a time saving procedure with lowest consumption of solvents compared with the other two methods.
文摘A rapid pretreatment method of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in soil and analysis by high resolution gas chromatograph-high resolution mass spectrometry was present.The extraction and alumina clean up of PCDD/Fs in soil was achieved by accelerated solvent extractor.Then the multi-layer silica-gel column was used for further clean up.The whole method has been evaluated on certified reference soil and farm soil.Accuracy and precision of this method was tested with satisfactory results.
基金supported by National Natural Science Foundation of China(No.31000428)National Basic Research Program of China(973Program)(No.2012CB619101)
文摘Stable austenitic structure in medical stainless steels is basically required for surgical implantation. A weak magnetism was found in a high nitrogen nickel-free austenitic stainless steel for cardiovascular stent application. This magnetic behavior in high nitrogen stainless steel was investigated by optical microscopy, X-ray diffraction （XRD）, electron probe microanalysis （EPMA） and superconducting quantum interference device （SQUID）. The results showed that the magnetism came from the composition segregation of ferrite formation elements such as Cr and Mo in the steel and some 6-ferrites were locally formed during the pressurized electroslag remelting process. The magnetism of high nitrogen stainless steel could be eliminated by a proper high temperature gas nitriding （HTGN）.
