Conventional conductivity methods for measuring the void fraction in gas-liquid multiphase systems are typically affected by accuracy problems due to the presence of fluid flow and salinity.This study presents a novel...Conventional conductivity methods for measuring the void fraction in gas-liquid multiphase systems are typically affected by accuracy problems due to the presence of fluid flow and salinity.This study presents a novel approach for determining the void fraction based on a reciprocating dynamic conductivity probe used to measure the liquid film thickness under forced annular-flow conditions.The measurement system comprises a cyclone,a conductivity probe,a probe reciprocating device,and a data acquisition and processing system.This method ensures that the flow pattern is adjusted to a forced annular flow,thereby minimizing the influence of complex and variable gas-liquid flow patterns on the measurement results;Moreover,it determines the liquid film thickness solely according to circuit connectivity rather than specific conductivity values,thereby mitigating the impact of salinity.The reliability of the measurement system is demonstrated through laboratory experiments.The experimental results indicate that,in a range of gas phase superficial velocities 5–20 m/s and liquid phase superficial velocities 0.079–0.48 m/s,the maximum measurement deviation for the void fraction is 4.23%.展开更多
Silicene, a silicon analogue of graphene, has attracted increasing research attention in recent years because of its unique electrical and thermal conductivities. In this study, phonon thermal conductivity and its iso...Silicene, a silicon analogue of graphene, has attracted increasing research attention in recent years because of its unique electrical and thermal conductivities. In this study, phonon thermal conductivity and its isotopic doping effect in silicene nanoribbons（SNRs） are investigated by using molecular dynamics simulations. The calculated thermal conductivities are approximately 32 W/mK and 35 W/mK for armchair-edged SNRs and zigzag-edged SNRs, respectively, which show anisotropic behaviors. Isotope doping induces mass disorder in the lattice, which results in increased phonon scattering, thus reducing the thermal conductivity. The phonon thermal conductivity of isotopic doped SNR is dependent on the concentration and arrangement pattern of dopants. A maximum reduction of about 15% is obtained at 50% randomly isotopic doping with ^（30）Si. In addition, ordered doping（i.e., isotope superlattice） leads to a much larger reduction in thermal conductivity than random doping for the same doping concentration. Particularly, the periodicity of the doping superlattice structure has a significant influence on the thermal conductivity of SNR. Phonon spectrum analysis is also used to qualitatively explain the mechanism of thermal conductivity change induced by isotopic doping. This study highlights the importance of isotopic doping in tuning the thermal properties of silicene, thus guiding defect engineering of the thermal properties of two-dimensional silicon materials.展开更多
Nanofluidics in hydrophilic nanopores is a common issue in many natural and industrial processes. Among all,the mass transport of nanofluidics is most concerned. Besides that, the heat transfer of a fluid flow in nano...Nanofluidics in hydrophilic nanopores is a common issue in many natural and industrial processes. Among all,the mass transport of nanofluidics is most concerned. Besides that, the heat transfer of a fluid flow in nano or micro channels is always considered with adding nanoparticles into the flow, so as to enhance the heat transfer by convection between the fluid and the surface. However, for some applications with around 1 nm channels such as nano filtration or erosion of rocks, there should be no nanoparticles included. Hence, it is necessary to figure out the heat transfer mechanism in the single phase nanofluidics. Via non-equilibrium molecular dynamics simulations, we revealed the heat transfer inside nanofluidics and the one between fluid and walls by setting simulation into extremely harsh condition. It was found that the heat was conducted by molecular motion without temperature gradient in the area of low viscous heat, while it was transferred to the walls by increasing the temperature of fluids. If the condition back to normal, it was found that the viscous heat of nanofluidics could be easily removed by the fluid-wall temperature drop of less than 1 K.展开更多
We study the size dependency of heat conduction in one-dimensional diatomic FPU-β lattices and establish that for low dimensional material,contribution from optical phonons is found more effective to the thermal cond...We study the size dependency of heat conduction in one-dimensional diatomic FPU-β lattices and establish that for low dimensional material,contribution from optical phonons is found more effective to the thermal conductivity and enhance heat transport in the thermodynamic limit N →∞.For the finite size,thermal conductivity of 1D diatomic lattice is found to be lower than 1D monoatomic chain of the same size made up of the constituent particle of the diatomic chain.For the present 1D diatomic chain,obtained value of power divergent exponent of thermal conductivity0.428±0.001 and diffusion exponent 1.2723 lead to the conclusions that increase in the system size,increases the thermal conductivity and existence of anomalous energy diffusion.Existing numerical data supports our findings.展开更多
The lattice thermal conductivity of boron nitride nanoribbon（BNNR） is calculated by using equilibrium molecular dynamics（EMD） simulation method. The Green–Kubo relation derived from linear response theory is used...The lattice thermal conductivity of boron nitride nanoribbon（BNNR） is calculated by using equilibrium molecular dynamics（EMD） simulation method. The Green–Kubo relation derived from linear response theory is used to acquire the thermal conductivity from heat current auto-correlation function（HCACF）. HCACF of the selected BNNR system shows a tendency of a very fast decay and then be followed by a very slow decay process,finally,approaching zero approximately within 3 ps. The convergence of lattice thermal conductivity demonstrates that the thermal conductivity of BNNR can be simulated by EMD simulation using several thousands of atoms with periodic boundary conditions. The results show that BNNR exhibit lower thermal conductivity than that of boron nitride（BN） monolayer,which indicates that phonons boundary scatting significantly suppresses the phonons transport in BNNR. Vacancies in BNNR greatly affect the lattice thermal conductivity,in detail,only 1% concentration of vacancies in BNNR induce a 60% reduction of the lattice thermal conductivity at room temperature.展开更多
Ionogels have enabled flexible electronic devices for wide-ranging innovative applications in wearable electronics,soft robotics,and intelligent systems.Ionogels for flexible electronics need to essentially tolerate s...Ionogels have enabled flexible electronic devices for wide-ranging innovative applications in wearable electronics,soft robotics,and intelligent systems.Ionogels for flexible electronics need to essentially tolerate stress,temperature,humidity,and solvents that may cause their electrical conductivity,structural stability,processing compatibility and sensibility failure.Herein,we developed a novel in-situ photopolymerization protocol to fabricate intrinsically conductive,self-gated ionogels via ion-restriction dual effects.Highly sensitive and intelligent safety sensors with tunable stretchability,robust chemical stability,favorable printability,and complete recyclability,are programmed from defined microneedle arrays printed by the intrinsically conductive ionogel.Ultrahigh elasticity(~794%elongation),high compression tolerance(~90%deformation),improved mechanical strength(tensile and compressive strength of~2.0 MPa and~16.3 MPa,respectively)and remark-able transparency(>91.1%transmittance),as well as high-temperature sensitivity(-2.07%℃^(-1))and a wide working range(-40 to200℃)can be achieved.In particular,the intrinsic sensing mechanisms of ion-restriction dual effects are unlocked based on DFT calculations and MD simulations,and operando temperature-dependent FTIR,and Raman technolo-gies.Moreover,the real-time intelligent monitoring systems toward physical signals and precise temperature based on the microneedle array-structures sensors are also presented and demonstrate great potential applications for extreme environ-ments,e.g.,fire,deep-sea or aerospace.展开更多
An oriented cluster perforating technology,which integrates both advantages of cluster and oriented perforating,will help solve a series of technical complexities in horizontal well drilling.For realizing its better a...An oriented cluster perforating technology,which integrates both advantages of cluster and oriented perforating,will help solve a series of technical complexities in horizontal well drilling.For realizing its better application in oil and gas development,a series of technologies were developed including perforator self-weight eccentricity,matching of the electronic selective module codes with the surface program control,axial centralized contact signal transmission,and post-perforation intercluster sealing insulation.In this way,the following functions could be realized,such as cable-transmission horizontal well perforator self-weight orientation,dynamic signal transmission,reliable addressing&selective perforation and post-perforation intercluster sealing.The combined perforation and bridge plug or the multi-cluster perforation can be fulfilled in one trip of perforation string.As a result,the horizontal-well oriented cluster perforating technology based on cable conveying was developed.This technology was successfully applied in unconventional gas reservoir exploitation,such as shale gas and coalbed methane,with accurate orientation,reliable selective perforation and satisfactory inter-cluster sealing.The horizontal-well oriented cluster perforating technology benefits the orientation of horizontal well drilling with a definite target and direction,which provides a powerful support for the subsequent reservoir stimulation.It also promotes the fracturing fluid to sweep the principal pay zones to the maximum extent.Moreover,it is conductive to the formation of complex fracture networks in the reservoirs,making quality and efficient development of unconventional gas reservoirs possible.展开更多
基金the National Natural Science Foundation of China(No.62173049)the Open Fund of the Hubei Key Laboratory of Oil and Gas Drilling and Production Engineering(Yangtze University),YQZC202309.
文摘Conventional conductivity methods for measuring the void fraction in gas-liquid multiphase systems are typically affected by accuracy problems due to the presence of fluid flow and salinity.This study presents a novel approach for determining the void fraction based on a reciprocating dynamic conductivity probe used to measure the liquid film thickness under forced annular-flow conditions.The measurement system comprises a cyclone,a conductivity probe,a probe reciprocating device,and a data acquisition and processing system.This method ensures that the flow pattern is adjusted to a forced annular flow,thereby minimizing the influence of complex and variable gas-liquid flow patterns on the measurement results;Moreover,it determines the liquid film thickness solely according to circuit connectivity rather than specific conductivity values,thereby mitigating the impact of salinity.The reliability of the measurement system is demonstrated through laboratory experiments.The experimental results indicate that,in a range of gas phase superficial velocities 5–20 m/s and liquid phase superficial velocities 0.079–0.48 m/s,the maximum measurement deviation for the void fraction is 4.23%.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11504418 and 11447033)the Natural Science Fund for Colleges and Universities in Jiangsu Province,China(Grant No.16KJB460022)the Fundamental Research Funds for the Central Universities of CUMT,China(Grant No.2015XKMS075)
文摘Silicene, a silicon analogue of graphene, has attracted increasing research attention in recent years because of its unique electrical and thermal conductivities. In this study, phonon thermal conductivity and its isotopic doping effect in silicene nanoribbons（SNRs） are investigated by using molecular dynamics simulations. The calculated thermal conductivities are approximately 32 W/mK and 35 W/mK for armchair-edged SNRs and zigzag-edged SNRs, respectively, which show anisotropic behaviors. Isotope doping induces mass disorder in the lattice, which results in increased phonon scattering, thus reducing the thermal conductivity. The phonon thermal conductivity of isotopic doped SNR is dependent on the concentration and arrangement pattern of dopants. A maximum reduction of about 15% is obtained at 50% randomly isotopic doping with ^（30）Si. In addition, ordered doping（i.e., isotope superlattice） leads to a much larger reduction in thermal conductivity than random doping for the same doping concentration. Particularly, the periodicity of the doping superlattice structure has a significant influence on the thermal conductivity of SNR. Phonon spectrum analysis is also used to qualitatively explain the mechanism of thermal conductivity change induced by isotopic doping. This study highlights the importance of isotopic doping in tuning the thermal properties of silicene, thus guiding defect engineering of the thermal properties of two-dimensional silicon materials.
基金Supported by the National Basic Research Program of China(2015CB655301)the National Natural Science Foundation of China(21506091)+2 种基金the Jiangsu Natural Science Foundations(BK20150944)the Special Program for Applied Research on Super Computation of the NSFC-Guangdong Joint Fund(the second phase)the Project of Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘Nanofluidics in hydrophilic nanopores is a common issue in many natural and industrial processes. Among all,the mass transport of nanofluidics is most concerned. Besides that, the heat transfer of a fluid flow in nano or micro channels is always considered with adding nanoparticles into the flow, so as to enhance the heat transfer by convection between the fluid and the surface. However, for some applications with around 1 nm channels such as nano filtration or erosion of rocks, there should be no nanoparticles included. Hence, it is necessary to figure out the heat transfer mechanism in the single phase nanofluidics. Via non-equilibrium molecular dynamics simulations, we revealed the heat transfer inside nanofluidics and the one between fluid and walls by setting simulation into extremely harsh condition. It was found that the heat was conducted by molecular motion without temperature gradient in the area of low viscous heat, while it was transferred to the walls by increasing the temperature of fluids. If the condition back to normal, it was found that the viscous heat of nanofluidics could be easily removed by the fluid-wall temperature drop of less than 1 K.
基金Computer facility developed under DST-FIST Level–I programme,Department of Science and Technology,Government of India,New Delhi and financial assistance under DRS-SAP-I from University Grants Commission,New Delhi
文摘We study the size dependency of heat conduction in one-dimensional diatomic FPU-β lattices and establish that for low dimensional material,contribution from optical phonons is found more effective to the thermal conductivity and enhance heat transport in the thermodynamic limit N →∞.For the finite size,thermal conductivity of 1D diatomic lattice is found to be lower than 1D monoatomic chain of the same size made up of the constituent particle of the diatomic chain.For the present 1D diatomic chain,obtained value of power divergent exponent of thermal conductivity0.428±0.001 and diffusion exponent 1.2723 lead to the conclusions that increase in the system size,increases the thermal conductivity and existence of anomalous energy diffusion.Existing numerical data supports our findings.
基金Supported by the Natural Science Foundation of Hubei Province(2014CFB610)the Excellent Young Innovation Team Project of Hubei Province(T201429)
文摘The lattice thermal conductivity of boron nitride nanoribbon（BNNR） is calculated by using equilibrium molecular dynamics（EMD） simulation method. The Green–Kubo relation derived from linear response theory is used to acquire the thermal conductivity from heat current auto-correlation function（HCACF）. HCACF of the selected BNNR system shows a tendency of a very fast decay and then be followed by a very slow decay process,finally,approaching zero approximately within 3 ps. The convergence of lattice thermal conductivity demonstrates that the thermal conductivity of BNNR can be simulated by EMD simulation using several thousands of atoms with periodic boundary conditions. The results show that BNNR exhibit lower thermal conductivity than that of boron nitride（BN） monolayer,which indicates that phonons boundary scatting significantly suppresses the phonons transport in BNNR. Vacancies in BNNR greatly affect the lattice thermal conductivity,in detail,only 1% concentration of vacancies in BNNR induce a 60% reduction of the lattice thermal conductivity at room temperature.
基金supported by the National Key R&D Program of China(2020YFA0709900)the National Natural Science Foundation of China(22175167)the National Key R&D Program of the MOST of China(Grant No.2022YFA1602601).
文摘Ionogels have enabled flexible electronic devices for wide-ranging innovative applications in wearable electronics,soft robotics,and intelligent systems.Ionogels for flexible electronics need to essentially tolerate stress,temperature,humidity,and solvents that may cause their electrical conductivity,structural stability,processing compatibility and sensibility failure.Herein,we developed a novel in-situ photopolymerization protocol to fabricate intrinsically conductive,self-gated ionogels via ion-restriction dual effects.Highly sensitive and intelligent safety sensors with tunable stretchability,robust chemical stability,favorable printability,and complete recyclability,are programmed from defined microneedle arrays printed by the intrinsically conductive ionogel.Ultrahigh elasticity(~794%elongation),high compression tolerance(~90%deformation),improved mechanical strength(tensile and compressive strength of~2.0 MPa and~16.3 MPa,respectively)and remark-able transparency(>91.1%transmittance),as well as high-temperature sensitivity(-2.07%℃^(-1))and a wide working range(-40 to200℃)can be achieved.In particular,the intrinsic sensing mechanisms of ion-restriction dual effects are unlocked based on DFT calculations and MD simulations,and operando temperature-dependent FTIR,and Raman technolo-gies.Moreover,the real-time intelligent monitoring systems toward physical signals and precise temperature based on the microneedle array-structures sensors are also presented and demonstrate great potential applications for extreme environ-ments,e.g.,fire,deep-sea or aerospace.
基金Project supported by the National Major S&T Project“Shale gas reservoir stimulation technology”(No.:2012ZX05018-004).
文摘An oriented cluster perforating technology,which integrates both advantages of cluster and oriented perforating,will help solve a series of technical complexities in horizontal well drilling.For realizing its better application in oil and gas development,a series of technologies were developed including perforator self-weight eccentricity,matching of the electronic selective module codes with the surface program control,axial centralized contact signal transmission,and post-perforation intercluster sealing insulation.In this way,the following functions could be realized,such as cable-transmission horizontal well perforator self-weight orientation,dynamic signal transmission,reliable addressing&selective perforation and post-perforation intercluster sealing.The combined perforation and bridge plug or the multi-cluster perforation can be fulfilled in one trip of perforation string.As a result,the horizontal-well oriented cluster perforating technology based on cable conveying was developed.This technology was successfully applied in unconventional gas reservoir exploitation,such as shale gas and coalbed methane,with accurate orientation,reliable selective perforation and satisfactory inter-cluster sealing.The horizontal-well oriented cluster perforating technology benefits the orientation of horizontal well drilling with a definite target and direction,which provides a powerful support for the subsequent reservoir stimulation.It also promotes the fracturing fluid to sweep the principal pay zones to the maximum extent.Moreover,it is conductive to the formation of complex fracture networks in the reservoirs,making quality and efficient development of unconventional gas reservoirs possible.
