A novel intermediate fluid vaporization (IFV) technology for LNG re-gasification process with spiral-wound heat exchanging tubes is proposed. The new IFV project combines the advantage of running the shell and tube he...A novel intermediate fluid vaporization (IFV) technology for LNG re-gasification process with spiral-wound heat exchanging tubes is proposed. The new IFV project combines the advantage of running the shell and tube heat exchangers at high pressure with the advantage of compact space of heat exchangers. Thermal analysis on the two processes of forced convection and vaporization type heat transfer in the spiral wound tubes and vapor condensation /re-boiling type of heat transfer via intermediate fluid in shell side shows the feasibility of this promising technology.展开更多
Shell-and-tube vaporizers are the most commonly used and dominated types of vaporizers in liquefied natural gas （LNG） realm. Due to efficient performance, shell-side flow in this type of vaporizers has received cons...Shell-and-tube vaporizers are the most commonly used and dominated types of vaporizers in liquefied natural gas （LNG） realm. Due to efficient performance, shell-side flow in this type of vaporizers has received considerable attention and has been investigated extensively. However, the detailed flow structure in the shell needs to be determined for reliable and effective design. Therefore, the objective of this study was to clarify the flow structure in shell by particle image velocimetry （PIV）. Experiments were conducted using two types of model; 15% baffle cut having inlet and outlet positions !n the direction of 90° to the cut and 30% baffle cut having inlet and outlet positions in the direction of 180° to the cut. Each test section is 169 mm in inner diameter and 344.6 mm in length. The flow features were characterized in different baffle cuts with regards to the velocity vector field and velocity distribution. The results show that the flow characteristics of 15% baffle cut type vaporizer are comparable to those of 30% baffle cut type vaporizer.展开更多
In order to optimize the design of the submerged combustion vaporizer(SCV), an experimental apparatus was set up to investigate the heat transfer character outside the tube bundle in SCV. Several experiments were cond...In order to optimize the design of the submerged combustion vaporizer(SCV), an experimental apparatus was set up to investigate the heat transfer character outside the tube bundle in SCV. Several experiments were conducted using water and CO_2 as the heat transfer media in the tubes, respectively. The results indicated that hot air flux, the initial liquid level height and the tube pitch ratio had great influence on the heat transfer coefficient outside the tube bundle(ho). Finally, the air flux associated factor β and height associated factor γ were introduced to propose a new hocorrelation. After verified by experiments using cold water, high pressure CO_2 and liquid N_2 as heat transfer media, respectively, it was found that the biggest deviation between the predicted and the experimental values was less than 25%.展开更多
Thermal conductivity of frost is not only related to density, but also affected by its microstructure and environmental conditions, and it will continuously change with the formation and growth of frost. Images of fro...Thermal conductivity of frost is not only related to density, but also affected by its microstructure and environmental conditions, and it will continuously change with the formation and growth of frost. Images of frost formation and growth on the cryogenic surface in various shapes at different stages were obtained by experimental measurements, and a numerical simulation of frost formation and growth was carried out based on Diffusion Limited Aggregation (DLA) model of fractal theory in this paper. Based on the frost structure obtained by experiment, the fractal dimension of pore area distribution and porosity of frost layer on the cryogenic finned-tube?vaporizer were calculated by using fractal method, and combined with heat conduction model of frost layer obtained by thermal resistance method, the thermal conductivity of frost on the cryogenic surface was calculated. The result shows that the thermal conductivity calculated by the fractal model coincides with the range of the experimental data. Additionally, comparison with other heat conduction models indicated that it is feasible to introduce the fractal dimension of pore area distribution into heat conduction model to deduce the thermal conductivity of frost.展开更多
The intermediate fluid vaporizer(IFV)is a typical vaporizer of liquefied natural gas(LNG),which in general consists of three shell-and-tube heat exchangers(an evaporator,a condenser,and a thermolator).LNG is heated by...The intermediate fluid vaporizer(IFV)is a typical vaporizer of liquefied natural gas(LNG),which in general consists of three shell-and-tube heat exchangers(an evaporator,a condenser,and a thermolator).LNG is heated by seawater and the intermediate fluid in these heat exchangers.A one-dimensional heat transfer model for IFV is established in this paper in order to investigate the influences of structure and operation parameters on the heat transfer performance.In the rated condition,it is suggested to reduce tube diameters appropriately to get a large total heat transfer coefficient and increase the tube number to ensure the sufficient heat transfer area.According to simulation results,although the IFV capacity is much larger than the simplified-IFV(SIFV)capacity,the mode of SIFV could be recommended in some low-load cases as well.In some cases at high loads exceeding the capacity of a single IFV,it is better to add an AAV or an SCV operating to the IFV than just to increase the mass flow rate of seawater in the IFV in LNG receiving terminals.展开更多
High-purity graphite is extensively utilized in the semiconductor industry.Enhancing its corrosion resistance is crucial for reducing the manufacturing costs of the third-generation semiconductors.In this study,a cont...High-purity graphite is extensively utilized in the semiconductor industry.Enhancing its corrosion resistance is crucial for reducing the manufacturing costs of the third-generation semiconductors.In this study,a continuous and dense TaC coating was fabricated on the surface of graphite using CVD method.The corrosion resistance and mechanism of the coating were investigated in a high-temperature steam environment.This environment involved temperatures exceeding 2200 K and the erosion of the coating by Si-containing mixed steam flows.The results indicated that the corrosion in the affected areas was primarily due to chemical reactions,characterized by the formation of pores and micro-cracks,whereas failure areas were dominated by mechanical delamination,which led to macroscopic defects.Moreover,the mixed high-temperature steam corrosion of the TaC coating showed preferential selectivity,resulting in a stepped corrosion morphology at the crystalline level.The surface roughness of the samples significantly increased after corrosion,from 0.36 to 5.28μm,although the surface composition remained largely unchanged.The TaC coating provides a certain level of protection to the graphite substrate,enhancing the service life of graphite components and demonstrating promising application potential.展开更多
Combining the phase-field method and the moving boundary method,a three-dimensional phase-field simulation was conducted for the growth and grain evolution of Ti films deposited by physical vapor deposition under diff...Combining the phase-field method and the moving boundary method,a three-dimensional phase-field simulation was conducted for the growth and grain evolution of Ti films deposited by physical vapor deposition under different deposition rates and grain orientations.The evolution of grain morphology and grain orientation was also taken into consideration.Simulation results show that at lower deposition rates,the surface of the formed Ti film exhibits a distinct oriented texture structure.The surface roughness of the Ti film is positively correlated with the grain misorientation.Moreover,the surface roughness obtained from the simulation is in good agreement with the experiment results.展开更多
The intermediate fluid vaporizer (IFV), different from other liquefied natural gas (LNG) vaporizers, has many advantages and has shown a great potential for future applications. In this present paper, studies of IFV a...The intermediate fluid vaporizer (IFV), different from other liquefied natural gas (LNG) vaporizers, has many advantages and has shown a great potential for future applications. In this present paper, studies of IFV and its heat transfer characteristics in the LNG vaporization unit E2 are systematically reviewed. The research methods involved include theoretical analysis, experimental investigation, numerical simulation, and process simulation. First, relevant studies on the overall calculation and system design of IFV are summarized, including the structural innovation design, the thermal calculation model, and the selection of different intermediate fluids. Moreover, studies on the fluid flow and heat transfer behaviors of the supercritical LNG inside the tubes and the condensation heat transfer of the intermediate fluid outside the tubes are summarized. In the thermal calculations of the IFV, the selections of the existing heat transfer correlations about the intermediate fluids are inconsistent in different studies, and there lacks the accuracy evaluation of those correlations or comparison with experimental data. Furthermore, corresponding experiments or numerical simulations on the cryogenic condensation heat transfer outside the tubes in the IFV need to be further improved, compared to those in the refrigeration and air-conditioning temperature range. Therefore, suggestions for further studies of IFV are provided as well.展开更多
The Zeeman effect,a fundamental quantum phenomenon,demonstrates the interaction between magnetic fields and atomic systems.While precise spectroscopic measurements of this effect have advanced significantly,there rema...The Zeeman effect,a fundamental quantum phenomenon,demonstrates the interaction between magnetic fields and atomic systems.While precise spectroscopic measurements of this effect have advanced significantly,there remains a lack of simple,visually accessible demonstration for educational purposes.Here,we present a low-cost experiment that allows for direct visual observation of the Zeeman effect.Our setup involves a flame containing sodium(from table salt)placed in front of a sodium vapor lamp.When a magnetic field is applied to the flame,the shadow cast by the flame noticeably lightens,providing a clear,naked-eye demonstration of the Zeeman effect.Furthermore,we conduct two quantitative experiments using this setup,examining the effects of varying magnetic field strength and sodium concentration.This innovative approach not only enriches the experimental demonstration for teaching atomic physics at undergraduate and high school levels but also provides an open platform for students to explore the Zeeman effect through hands-on experience.展开更多
The liquid-only transfer dividing wall column(LDWC)offers a promising path for industrializing dividing wall columns by simplifying vapor split control.However,their energy efficiency is insufficient due to the additi...The liquid-only transfer dividing wall column(LDWC)offers a promising path for industrializing dividing wall columns by simplifying vapor split control.However,their energy efficiency is insufficient due to the addition of heat at the bottom and its removal at the top.Therefore,developing an effective strategy to enhance the energy efficiency of the entire LDWC system is crucial.This work investigates the intensification of LDWC based on the column grand composite curve(CGCC)and thermodynamic analysis,proposing a novel intensification strategy to improve energy efficiency effectively.An optimization model with four blocks is developed to minimize the total annual cost(TAC)of the intensified LDWC.Energy,exergy,economic,and environmental analyses are used to evaluate its performance.Ternary mixtures with different easy separation indexes(ESI)are selected as illustrative examples.For mixtures with ESI≤1,the optimal configuration involves partial feed preheating,compressors and intermediate reboilers on both side sections,along with optimized operating pressure.This setup leads to significant reductions in total energy consumption,TAC,and gas emissions by 43.80%,28.08%,and 42.85%for ESI=1,and by 46.17%,29.06%,and 45.35%for ESI<1,respectively,when compared to conventional distillation sequences(CDS).For mixtures with ESI>1,the best performance is achieved by implementing partial feed preheating and modifications only to the right section.This results in reductions of 21.64%in energy consumption,16.26%in TAC,and 21.51%in gas emissions when compared to CDS.In all cases,the optimal configurations show the lowest lost work and minimum work,indicating an improved thermodynamic performance.展开更多
The January 2022 eruption of Hunga injected unprecedented volumes of water vapor(150 Tg)and modest sulfur dioxide(SO_(2))into the stratosphere,producing accelerated sulfate aerosol formation in the early plume.As the ...The January 2022 eruption of Hunga injected unprecedented volumes of water vapor(150 Tg)and modest sulfur dioxide(SO_(2))into the stratosphere,producing accelerated sulfate aerosol formation in the early plume.As the aerosols gradually spread into the global stratosphere,the role of water vapor,among other factors in the spread and residence time of the sulfate aerosols,remained unclear.We used multisatellite observations to better understand the role of water vapor in the spread and lifetime of Hunga volcanic aerosols.Stratospheric circulation transported the plumes to~26 km within the polar vortices-the Antarctic by August 2022 and the Arctic by January 2023-with the arrival of aerosols lagging behind that of water vapor by months.Even though high injection altitudes(58 km)and strong Brewer-Dobson circulation contributed to prolonging the residence time of aerosols,the water vapor enhanced particle growth and thus accelerated gravitational settling,with the half lifetime of aerosols being 14 months.Our analysis revealed a critical trade-off:after the eruption of the Hunga volcano,an extremely high injection height and strong upward motion slowed the removal of aerosols,but extreme water vapor loading still had a certain impact on the half lifetime of the aerosols.These findings highlight the role of water vapor in the persistence of aerosols from submarine eruptions.展开更多
Northeast China(NEC),a critical agricultural and ecological zone,has experienced intensified hydrological variability under global warming,with cascading impacts on food security and ecosystem resilience.This study ut...Northeast China(NEC),a critical agricultural and ecological zone,has experienced intensified hydrological variability under global warming,with cascading impacts on food security and ecosystem resilience.This study utilized observational data and two new generation reanalysis products(i.e.,the fifth major global reanalysis produced by ECMWF(ERA5)and the Japanese Reanalysis for Three Quarters of a Century(JRA-3Q))to investigate the shift changes in precipitation in NEC around 2000 and associated water vapor transport.The analysis identified a pivotal interdecadal shift in 1998/99,transitioning from moderate increases(17.5 mm/10 yr during 1980-1998)to accelerated but more variable precipitation growth(85.4 mm/10 yr post-1999).While the mean precipitation during the post-shift period decreased,enhanced anticyclonic circulation amplified moisture divergence over continental NEC,redirecting vapor flux toward coastal regions.Crucially,trajectory analysis demonstrated regime-dependent moisture sourcing:midlatitude westerlies dominated during wet extremes(44% of trajectories in 1998),whereas East Asian monsoon flows prevailed in drought years(36% of trajectories in 2007).The post-1998 period exhibited increased reliance on localized recycling(45%of mid-tropospheric trajectories),reflecting weakened monsoonal inflow.These findings highlight NEC’s growing vulnerability to competing moisture pathways and atmospheric blocking-a dual mechanism that explains rising extremes despite declining mean precipitation.By reconciling dataset discrepancies(ERA5 vs.JRA-3Q trends)and elucidating circulation-precipitation linkages,this work provides actionable insights for climate-resilient agriculture in NEC’s water-stressed ecosystems.展开更多
An advanced AlCrSiN/AlCrN/CrN/Cr multilayer coating was developed via hybrid multiarc ion plating and high-power impulse magnetron sputtering.The multilayer design enhanced the substrate-coating compatibility,achievin...An advanced AlCrSiN/AlCrN/CrN/Cr multilayer coating was developed via hybrid multiarc ion plating and high-power impulse magnetron sputtering.The multilayer design enhanced the substrate-coating compatibility,achieving a critical load of 87.8 N.Silicon doping induced nanocrystallization and amorphization,increasing the hardness to 26 GPa.At high temperatures,a nanoscale Cr-rich(Cr,Al)_(2)O_(3) layer was formed,effectively inhibiting oxygen diffusion.The coating underwent unique phase transformations,during which Cr_(2)N and amorphous Si3N4 were converted into dispersed SiCr_(3) nanoparticles,which stabilized Cr atoms and suppressed their outward diffusion.Ab initio molecular dynamics simulations revealed that Cr atoms exhibited higher chemical activity and oxygen-capture capability than Al atoms and Si atoms served as diffusion barriers by pinning onto the oxidized surface,considerably improving the oxidation resistance of the coating.展开更多
In Global Navigation Satellite System(GNSS)meteo rology,the atmospheric weighted mean temperatu re(T_(m))is a critical intermediate parameter for converting zenith wet delay(ZWD)to precipitable water vapor(PWV),essent...In Global Navigation Satellite System(GNSS)meteo rology,the atmospheric weighted mean temperatu re(T_(m))is a critical intermediate parameter for converting zenith wet delay(ZWD)to precipitable water vapor(PWV),essential for accurate atmospheric water content estimation.However,global models often overlook regional climatic variability,leading to reduced accuracy in localized applications.This study introduces an improved T_(m)model developed using radiosonde observations across Iran and GNSS radio occultation(RO)profiles from CHAMP,GRACE,MetOp-A/B/C,COSMIC,TerraSAR-X,and TanDEM-X missions collected between 2007 and 2022.A novel integral formulation was proposed to estimate T_(m)more accurately by incorporating vertical water vapor distribution and temperature linearity.Based on this formulation,three regional T_(m)models were constructed using annual,semiannual,and diurnal periodicities,along with surface temperature(T_(s)),each varying in structure and complexity.Validation against independent radiosonde observations from 2022 showed that Models Two and Three outperformed the Bevis model,reducing RMSE by 30.7%.When evaluated against GNSS RO profiles,Model One—excluding T_(s)due to its inaccessibility in RO data—yielded the highest accuracy,with a 42.6%improvement in RMSE over the Bevis model.To evaluate the practical effectiveness of the proposed T_(m)model,PWV was derived from GNSS data at the tehn and tabz stations during the second half of 2022and compared with PWV values obtained from co-located radiosonde observations in Tehran and Tabriz.Using T_(m)from Model One improved PWV estimation compared to the Bevis model,reducing RMSE and MAE by up to 54%and 53.8%in Tabriz and 50.6%and 52.9%in Tehran,respectively.These results demonstrate that regionalized T_(m)modeling,particularly approaches that avoid dependence on T_(s),can significantly enhance GNSS-based PWV estimation in areas with limited surface data.展开更多
The absence of large-size gallium nitride(GaN) substrates with low dislocation density remains a primary bottleneck for advancing GaN-based devices. Here, we demonstrate the achievement of 8-inch freestanding GaN subs...The absence of large-size gallium nitride(GaN) substrates with low dislocation density remains a primary bottleneck for advancing GaN-based devices. Here, we demonstrate the achievement of 8-inch freestanding GaN substrates grown by hydride vapor phase epitaxy. Critical to this achievement is the improvement in gas-flow uniformity, which ensures exceptional thickness homogeneity and enables the crack-free growth of GaN. After laser lift-off(LLO) separation, the freestanding GaN substrate exhibits superior crystal quality, evidenced by full width at half maximum values of 68 and 54 arcsec for X-ray diffraction rocking curves of(002) and(102) planes, alongside a low dislocation density of 1.6 × 10^(6) cm^(-2). This approach establishes a robust pathway for the production of large-size GaN substrates, which are essential for advancing next-generation power electronics and high-efficiency photonics.展开更多
The hydrogen evolution reaction(HER)is crucial for hydrogen production and sustainable energy storage.Molybdenum disulfide(MoS_(2)),a representative transition metal dichalcogenides(TMDs),shows potential as an HER cat...The hydrogen evolution reaction(HER)is crucial for hydrogen production and sustainable energy storage.Molybdenum disulfide(MoS_(2)),a representative transition metal dichalcogenides(TMDs),shows potential as an HER catalyst but suffers from limited performance due to poor charge transfer and interfacial effects.Here,we report a salt-assisted chemical vapor deposition(CVD)method for synthesizing high-quality tungsten ditelluride(WTe_(2))with tunable morphologies using alkali halides(NaCl,KCl and LiCl).The prepared WTe_(2) nanoribbons and hexagonal nanosheets exhibit morphology-dependent electrical conductivity,with nanosheets showing superior performance.To evaluate WTe_(2) as a contact electrode,WTe_(2)−MoS_(2) heterostructures were fabricated and compared with graphene-MoS_(2) counterparts.The WTe_(2)−MoS_(2) heterostructure exhibits a superior Tafel slope of 111.57 mV/dec and an overpotential of 298 mV at-10 mA/cm^(2),significantly outperforming graphene-based electrodes.This improvement is attributed to the excellent conductivity of WTe_(2) and reduced interfacial Schottky barriers.Moreover,we systematically investigate the influence of WTe_(2) thickness on HER performance and assess the electrochemical durability and structural stability of the heterostructure,further confirming the effectiveness of WTe_(2) as a contact electrode for enhancing the HER activity of MoS_(2).This study offers a novel approach for enhancing the HER performance of MoS_(2) through controlled WTe_(2) growth and application as a contact electrode.Our findings provide valuable insights into the synthesis of high-quality WTe_(2) and broaden the potential applications of two-dimensional materials in energy catalysis.展开更多
Silicon(Si)-based anodes have emerged as promising candidates for the next-generation lithium-ion batteries(LIBs)due to their high theoretical capacity(4200 mAh g^(-1)).However,their further application is hindered by...Silicon(Si)-based anodes have emerged as promising candidates for the next-generation lithium-ion batteries(LIBs)due to their high theoretical capacity(4200 mAh g^(-1)).However,their further application is hindered by critical challenges,including severe volume expansion(~300%),formation of unstable solid electrolyte interphase(SEI),and inherently low conductivity.While extensive research has sought to alleviate the substantial internal stress caused by volume expansion through the rational design of Si-based anode structures,the underlying mechanisms that govern these improvements remain insufficiently understood,leaving significant gaps in mechanical and interface electrical failure.To build a comprehensive understanding relationship between structural design and performance enhancement of Si-based anodes,this review first analyzes the characteristics of various Sibased anode structures and their associated internal stresses.Subsequently,it summarizes effective strategies to optimize the performance of Si-based anodes,including doping design,novel electrolyte design,and fu nctional binder design.Additionally,we assess emerging technologies with high commercial potential for structural design and interfacial modification,such as porous carbon carriers,chemical vapor deposition(CVD),spray granulation,and pre-lithiation.Finally,this work provides perspectives on the structural design of Si-based anodes.Overall,this review systematically summarizes modification strategies for Si-based anodes through structural regulation and interface engineering,thereby providing a foundation for advanced structural and interfacial design.展开更多
The performance degradation of micro light-emitting diodes(micro-LEDs)is closely associated with the deterioration of sidewall passivation layers under prolonged electrical bias.We investigate reliability improvements...The performance degradation of micro light-emitting diodes(micro-LEDs)is closely associated with the deterioration of sidewall passivation layers under prolonged electrical bias.We investigate reliability improvements in 20μm×20μm InGaN/GaN blue micro-LEDs by suppressing the formation of an unstable interfacial layer during sidewall passivation.SiO_(2)is deposited on the etched mesa sidewalls using either Sputtering or plasma-enhanced chemical vapor deposition(PECVD).Comparative analysis reveals that PECVD-passivated devices experience more severe performance degradation,primarily due to the increased leakage current.After 100 h of accelerated aging,external quantum efficiency decreases by 44%in PECVD-passivated samples,whereas Sputter-passivated devices exhibit only an11%reduction.This discrepancy is attributed to the formation of a thicker and chemically unstable gallium oxynitride(Ga-O_(X)-N_(1-X))interfacial layer at the SiO_(2)∕GaN-based interface,which facilitates the generation of sidewall defects.Suppressing the formation of this interlayer enhances the crystallinity and structural stability of the passivation layer,thereby mitigating the activation of point defects.Notably,Sputter deposition is more effective in minimizing the formation of Ga-O-N interlayer.These findings emphasize the critical role of achieving low-defect-density sidewall passivation to improve the reliability of micro-LEDs for next-generation high-resolution display applications.展开更多
In this study,we use observations from the Sounding of the Atmosphere using Broadband Emission Radiometry(SABER)instrument onboard the Thermosphere–Ionosphere–Mesosphere Energetics and Dynamics(TIMED)satellite to de...In this study,we use observations from the Sounding of the Atmosphere using Broadband Emission Radiometry(SABER)instrument onboard the Thermosphere–Ionosphere–Mesosphere Energetics and Dynamics(TIMED)satellite to develop and apply a new local-time binning method to investigate the long-term evolution of mesospheric water vapor at high latitudes.The proposed method accounts for the gradual local-time drift of the SABER orbit by aligning seasonal observation windows and selecting samples observed at similar local times.This approach minimizes tidal aliasing and ensures more consistent sampling,yielding more reliable estimates of long-term water vapor trends at high latitudes.The results show that drying signals primarily appear in the polar regions.However,in the southern hemisphere,a drying trend is observed only in autumn,whereas winter and summer mainly show moistening trends.In contrast,the northern hemisphere exhibits drying signals in the polar regions during all seasons,showing a clear seasonal asymmetry.Additionally,the water vapor trend in the northern hemisphere is particularly pronounced in February(late winter),with moistening reaching up to+2.0 ppmv.The winter in the southern hemisphere(July–August)also shows moistening,but the trend is still weaker than in the northern hemisphere.These differences highlight the strong moistening trend in the northern hemisphere during winter and underscore the significant asymmetry in seasonal water vapor changes between the two hemispheres.These findings emphasize the limitations of water vapor trend estimates across different seasons and latitudes.Moreover,they provide new insights into the spatiotemporal variability associated with tidal structures,underscoring the importance of optimizing local-time sampling strategies for reliable long-term trend detection.展开更多
基金supported by grants from the Fundamental Research Funds for the Central Universities(DUT12JN01)the National Natural Science Foundation of China(51106017)
文摘A novel intermediate fluid vaporization (IFV) technology for LNG re-gasification process with spiral-wound heat exchanging tubes is proposed. The new IFV project combines the advantage of running the shell and tube heat exchangers at high pressure with the advantage of compact space of heat exchangers. Thermal analysis on the two processes of forced convection and vaporization type heat transfer in the spiral wound tubes and vapor condensation /re-boiling type of heat transfer via intermediate fluid in shell side shows the feasibility of this promising technology.
基金supported by the National Research Foundation of Korea Grant funded by the Korean Government (NRF-2010-013-D00007)2010 Research Professor Fund of Gyeongsang National University,Korea
文摘Shell-and-tube vaporizers are the most commonly used and dominated types of vaporizers in liquefied natural gas （LNG） realm. Due to efficient performance, shell-side flow in this type of vaporizers has received considerable attention and has been investigated extensively. However, the detailed flow structure in the shell needs to be determined for reliable and effective design. Therefore, the objective of this study was to clarify the flow structure in shell by particle image velocimetry （PIV）. Experiments were conducted using two types of model; 15% baffle cut having inlet and outlet positions !n the direction of 90° to the cut and 30% baffle cut having inlet and outlet positions in the direction of 180° to the cut. Each test section is 169 mm in inner diameter and 344.6 mm in length. The flow features were characterized in different baffle cuts with regards to the velocity vector field and velocity distribution. The results show that the flow characteristics of 15% baffle cut type vaporizer are comparable to those of 30% baffle cut type vaporizer.
文摘In order to optimize the design of the submerged combustion vaporizer(SCV), an experimental apparatus was set up to investigate the heat transfer character outside the tube bundle in SCV. Several experiments were conducted using water and CO_2 as the heat transfer media in the tubes, respectively. The results indicated that hot air flux, the initial liquid level height and the tube pitch ratio had great influence on the heat transfer coefficient outside the tube bundle(ho). Finally, the air flux associated factor β and height associated factor γ were introduced to propose a new hocorrelation. After verified by experiments using cold water, high pressure CO_2 and liquid N_2 as heat transfer media, respectively, it was found that the biggest deviation between the predicted and the experimental values was less than 25%.
文摘Thermal conductivity of frost is not only related to density, but also affected by its microstructure and environmental conditions, and it will continuously change with the formation and growth of frost. Images of frost formation and growth on the cryogenic surface in various shapes at different stages were obtained by experimental measurements, and a numerical simulation of frost formation and growth was carried out based on Diffusion Limited Aggregation (DLA) model of fractal theory in this paper. Based on the frost structure obtained by experiment, the fractal dimension of pore area distribution and porosity of frost layer on the cryogenic finned-tube?vaporizer were calculated by using fractal method, and combined with heat conduction model of frost layer obtained by thermal resistance method, the thermal conductivity of frost on the cryogenic surface was calculated. The result shows that the thermal conductivity calculated by the fractal model coincides with the range of the experimental data. Additionally, comparison with other heat conduction models indicated that it is feasible to introduce the fractal dimension of pore area distribution into heat conduction model to deduce the thermal conductivity of frost.
文摘The intermediate fluid vaporizer(IFV)is a typical vaporizer of liquefied natural gas(LNG),which in general consists of three shell-and-tube heat exchangers(an evaporator,a condenser,and a thermolator).LNG is heated by seawater and the intermediate fluid in these heat exchangers.A one-dimensional heat transfer model for IFV is established in this paper in order to investigate the influences of structure and operation parameters on the heat transfer performance.In the rated condition,it is suggested to reduce tube diameters appropriately to get a large total heat transfer coefficient and increase the tube number to ensure the sufficient heat transfer area.According to simulation results,although the IFV capacity is much larger than the simplified-IFV(SIFV)capacity,the mode of SIFV could be recommended in some low-load cases as well.In some cases at high loads exceeding the capacity of a single IFV,it is better to add an AAV or an SCV operating to the IFV than just to increase the mass flow rate of seawater in the IFV in LNG receiving terminals.
文摘High-purity graphite is extensively utilized in the semiconductor industry.Enhancing its corrosion resistance is crucial for reducing the manufacturing costs of the third-generation semiconductors.In this study,a continuous and dense TaC coating was fabricated on the surface of graphite using CVD method.The corrosion resistance and mechanism of the coating were investigated in a high-temperature steam environment.This environment involved temperatures exceeding 2200 K and the erosion of the coating by Si-containing mixed steam flows.The results indicated that the corrosion in the affected areas was primarily due to chemical reactions,characterized by the formation of pores and micro-cracks,whereas failure areas were dominated by mechanical delamination,which led to macroscopic defects.Moreover,the mixed high-temperature steam corrosion of the TaC coating showed preferential selectivity,resulting in a stepped corrosion morphology at the crystalline level.The surface roughness of the samples significantly increased after corrosion,from 0.36 to 5.28μm,although the surface composition remained largely unchanged.The TaC coating provides a certain level of protection to the graphite substrate,enhancing the service life of graphite components and demonstrating promising application potential.
基金National MCF Energy R&D Program of China(2018YFE0306100)Natural Science Foundation of Hunan Province for Distinguished Young Scholars(2021JJ10062)+1 种基金National Natural Science Foundation of China(52101028)China Postdoctoral Science Foundation(2021M703628)。
文摘Combining the phase-field method and the moving boundary method,a three-dimensional phase-field simulation was conducted for the growth and grain evolution of Ti films deposited by physical vapor deposition under different deposition rates and grain orientations.The evolution of grain morphology and grain orientation was also taken into consideration.Simulation results show that at lower deposition rates,the surface of the formed Ti film exhibits a distinct oriented texture structure.The surface roughness of the Ti film is positively correlated with the grain misorientation.Moreover,the surface roughness obtained from the simulation is in good agreement with the experiment results.
文摘The intermediate fluid vaporizer (IFV), different from other liquefied natural gas (LNG) vaporizers, has many advantages and has shown a great potential for future applications. In this present paper, studies of IFV and its heat transfer characteristics in the LNG vaporization unit E2 are systematically reviewed. The research methods involved include theoretical analysis, experimental investigation, numerical simulation, and process simulation. First, relevant studies on the overall calculation and system design of IFV are summarized, including the structural innovation design, the thermal calculation model, and the selection of different intermediate fluids. Moreover, studies on the fluid flow and heat transfer behaviors of the supercritical LNG inside the tubes and the condensation heat transfer of the intermediate fluid outside the tubes are summarized. In the thermal calculations of the IFV, the selections of the existing heat transfer correlations about the intermediate fluids are inconsistent in different studies, and there lacks the accuracy evaluation of those correlations or comparison with experimental data. Furthermore, corresponding experiments or numerical simulations on the cryogenic condensation heat transfer outside the tubes in the IFV need to be further improved, compared to those in the refrigeration and air-conditioning temperature range. Therefore, suggestions for further studies of IFV are provided as well.
基金the National Natural Science Foundation of China for support under grant No.12305037the Fundamental Research Funds for the Central Universities under grant No.2023NTST017。
文摘The Zeeman effect,a fundamental quantum phenomenon,demonstrates the interaction between magnetic fields and atomic systems.While precise spectroscopic measurements of this effect have advanced significantly,there remains a lack of simple,visually accessible demonstration for educational purposes.Here,we present a low-cost experiment that allows for direct visual observation of the Zeeman effect.Our setup involves a flame containing sodium(from table salt)placed in front of a sodium vapor lamp.When a magnetic field is applied to the flame,the shadow cast by the flame noticeably lightens,providing a clear,naked-eye demonstration of the Zeeman effect.Furthermore,we conduct two quantitative experiments using this setup,examining the effects of varying magnetic field strength and sodium concentration.This innovative approach not only enriches the experimental demonstration for teaching atomic physics at undergraduate and high school levels but also provides an open platform for students to explore the Zeeman effect through hands-on experience.
基金support provided by the National Natural Science Foundation of China(U24B6016)the Higher Education Institution Academic Discipline Innovation and Talent Introduction Plan(“111 Plan”)(No.B23025)are gratefully acknowledged.
文摘The liquid-only transfer dividing wall column(LDWC)offers a promising path for industrializing dividing wall columns by simplifying vapor split control.However,their energy efficiency is insufficient due to the addition of heat at the bottom and its removal at the top.Therefore,developing an effective strategy to enhance the energy efficiency of the entire LDWC system is crucial.This work investigates the intensification of LDWC based on the column grand composite curve(CGCC)and thermodynamic analysis,proposing a novel intensification strategy to improve energy efficiency effectively.An optimization model with four blocks is developed to minimize the total annual cost(TAC)of the intensified LDWC.Energy,exergy,economic,and environmental analyses are used to evaluate its performance.Ternary mixtures with different easy separation indexes(ESI)are selected as illustrative examples.For mixtures with ESI≤1,the optimal configuration involves partial feed preheating,compressors and intermediate reboilers on both side sections,along with optimized operating pressure.This setup leads to significant reductions in total energy consumption,TAC,and gas emissions by 43.80%,28.08%,and 42.85%for ESI=1,and by 46.17%,29.06%,and 45.35%for ESI<1,respectively,when compared to conventional distillation sequences(CDS).For mixtures with ESI>1,the best performance is achieved by implementing partial feed preheating and modifications only to the right section.This results in reductions of 21.64%in energy consumption,16.26%in TAC,and 21.51%in gas emissions when compared to CDS.In all cases,the optimal configurations show the lowest lost work and minimum work,indicating an improved thermodynamic performance.
基金funding from the National Natural Science Foundation of China(Grant Nos.U2442210 and 42275059)supported by funding from Chengdu University of Information Technology(Grant No.X202310621039).
文摘The January 2022 eruption of Hunga injected unprecedented volumes of water vapor(150 Tg)and modest sulfur dioxide(SO_(2))into the stratosphere,producing accelerated sulfate aerosol formation in the early plume.As the aerosols gradually spread into the global stratosphere,the role of water vapor,among other factors in the spread and residence time of the sulfate aerosols,remained unclear.We used multisatellite observations to better understand the role of water vapor in the spread and lifetime of Hunga volcanic aerosols.Stratospheric circulation transported the plumes to~26 km within the polar vortices-the Antarctic by August 2022 and the Arctic by January 2023-with the arrival of aerosols lagging behind that of water vapor by months.Even though high injection altitudes(58 km)and strong Brewer-Dobson circulation contributed to prolonging the residence time of aerosols,the water vapor enhanced particle growth and thus accelerated gravitational settling,with the half lifetime of aerosols being 14 months.Our analysis revealed a critical trade-off:after the eruption of the Hunga volcano,an extremely high injection height and strong upward motion slowed the removal of aerosols,but extreme water vapor loading still had a certain impact on the half lifetime of the aerosols.These findings highlight the role of water vapor in the persistence of aerosols from submarine eruptions.
基金supported by the National Natural Science Foundation of China[grant numbers 42275185 and 42205032]the Fundamental Research Funds for the Central Universities[grant number B250201118]。
文摘Northeast China(NEC),a critical agricultural and ecological zone,has experienced intensified hydrological variability under global warming,with cascading impacts on food security and ecosystem resilience.This study utilized observational data and two new generation reanalysis products(i.e.,the fifth major global reanalysis produced by ECMWF(ERA5)and the Japanese Reanalysis for Three Quarters of a Century(JRA-3Q))to investigate the shift changes in precipitation in NEC around 2000 and associated water vapor transport.The analysis identified a pivotal interdecadal shift in 1998/99,transitioning from moderate increases(17.5 mm/10 yr during 1980-1998)to accelerated but more variable precipitation growth(85.4 mm/10 yr post-1999).While the mean precipitation during the post-shift period decreased,enhanced anticyclonic circulation amplified moisture divergence over continental NEC,redirecting vapor flux toward coastal regions.Crucially,trajectory analysis demonstrated regime-dependent moisture sourcing:midlatitude westerlies dominated during wet extremes(44% of trajectories in 1998),whereas East Asian monsoon flows prevailed in drought years(36% of trajectories in 2007).The post-1998 period exhibited increased reliance on localized recycling(45%of mid-tropospheric trajectories),reflecting weakened monsoonal inflow.These findings highlight NEC’s growing vulnerability to competing moisture pathways and atmospheric blocking-a dual mechanism that explains rising extremes despite declining mean precipitation.By reconciling dataset discrepancies(ERA5 vs.JRA-3Q trends)and elucidating circulation-precipitation linkages,this work provides actionable insights for climate-resilient agriculture in NEC’s water-stressed ecosystems.
基金financially supported by the National Science and Technology Major Project(No.2024ZD1404705)。
文摘An advanced AlCrSiN/AlCrN/CrN/Cr multilayer coating was developed via hybrid multiarc ion plating and high-power impulse magnetron sputtering.The multilayer design enhanced the substrate-coating compatibility,achieving a critical load of 87.8 N.Silicon doping induced nanocrystallization and amorphization,increasing the hardness to 26 GPa.At high temperatures,a nanoscale Cr-rich(Cr,Al)_(2)O_(3) layer was formed,effectively inhibiting oxygen diffusion.The coating underwent unique phase transformations,during which Cr_(2)N and amorphous Si3N4 were converted into dispersed SiCr_(3) nanoparticles,which stabilized Cr atoms and suppressed their outward diffusion.Ab initio molecular dynamics simulations revealed that Cr atoms exhibited higher chemical activity and oxygen-capture capability than Al atoms and Si atoms served as diffusion barriers by pinning onto the oxidized surface,considerably improving the oxidation resistance of the coating.
文摘In Global Navigation Satellite System(GNSS)meteo rology,the atmospheric weighted mean temperatu re(T_(m))is a critical intermediate parameter for converting zenith wet delay(ZWD)to precipitable water vapor(PWV),essential for accurate atmospheric water content estimation.However,global models often overlook regional climatic variability,leading to reduced accuracy in localized applications.This study introduces an improved T_(m)model developed using radiosonde observations across Iran and GNSS radio occultation(RO)profiles from CHAMP,GRACE,MetOp-A/B/C,COSMIC,TerraSAR-X,and TanDEM-X missions collected between 2007 and 2022.A novel integral formulation was proposed to estimate T_(m)more accurately by incorporating vertical water vapor distribution and temperature linearity.Based on this formulation,three regional T_(m)models were constructed using annual,semiannual,and diurnal periodicities,along with surface temperature(T_(s)),each varying in structure and complexity.Validation against independent radiosonde observations from 2022 showed that Models Two and Three outperformed the Bevis model,reducing RMSE by 30.7%.When evaluated against GNSS RO profiles,Model One—excluding T_(s)due to its inaccessibility in RO data—yielded the highest accuracy,with a 42.6%improvement in RMSE over the Bevis model.To evaluate the practical effectiveness of the proposed T_(m)model,PWV was derived from GNSS data at the tehn and tabz stations during the second half of 2022and compared with PWV values obtained from co-located radiosonde observations in Tehran and Tabriz.Using T_(m)from Model One improved PWV estimation compared to the Bevis model,reducing RMSE and MAE by up to 54%and 53.8%in Tabriz and 50.6%and 52.9%in Tehran,respectively.These results demonstrate that regionalized T_(m)modeling,particularly approaches that avoid dependence on T_(s),can significantly enhance GNSS-based PWV estimation in areas with limited surface data.
基金supported by the National Key Research and Development Program of China (Nos. 2022YFB3605203 and 2022YFB3608100)the National Natural Science Foundation of China (Nos. 62321004, 62227817, and 62374001)。
文摘The absence of large-size gallium nitride(GaN) substrates with low dislocation density remains a primary bottleneck for advancing GaN-based devices. Here, we demonstrate the achievement of 8-inch freestanding GaN substrates grown by hydride vapor phase epitaxy. Critical to this achievement is the improvement in gas-flow uniformity, which ensures exceptional thickness homogeneity and enables the crack-free growth of GaN. After laser lift-off(LLO) separation, the freestanding GaN substrate exhibits superior crystal quality, evidenced by full width at half maximum values of 68 and 54 arcsec for X-ray diffraction rocking curves of(002) and(102) planes, alongside a low dislocation density of 1.6 × 10^(6) cm^(-2). This approach establishes a robust pathway for the production of large-size GaN substrates, which are essential for advancing next-generation power electronics and high-efficiency photonics.
基金support from the National Natural Science Foundation of China(No.22175060).
文摘The hydrogen evolution reaction(HER)is crucial for hydrogen production and sustainable energy storage.Molybdenum disulfide(MoS_(2)),a representative transition metal dichalcogenides(TMDs),shows potential as an HER catalyst but suffers from limited performance due to poor charge transfer and interfacial effects.Here,we report a salt-assisted chemical vapor deposition(CVD)method for synthesizing high-quality tungsten ditelluride(WTe_(2))with tunable morphologies using alkali halides(NaCl,KCl and LiCl).The prepared WTe_(2) nanoribbons and hexagonal nanosheets exhibit morphology-dependent electrical conductivity,with nanosheets showing superior performance.To evaluate WTe_(2) as a contact electrode,WTe_(2)−MoS_(2) heterostructures were fabricated and compared with graphene-MoS_(2) counterparts.The WTe_(2)−MoS_(2) heterostructure exhibits a superior Tafel slope of 111.57 mV/dec and an overpotential of 298 mV at-10 mA/cm^(2),significantly outperforming graphene-based electrodes.This improvement is attributed to the excellent conductivity of WTe_(2) and reduced interfacial Schottky barriers.Moreover,we systematically investigate the influence of WTe_(2) thickness on HER performance and assess the electrochemical durability and structural stability of the heterostructure,further confirming the effectiveness of WTe_(2) as a contact electrode for enhancing the HER activity of MoS_(2).This study offers a novel approach for enhancing the HER performance of MoS_(2) through controlled WTe_(2) growth and application as a contact electrode.Our findings provide valuable insights into the synthesis of high-quality WTe_(2) and broaden the potential applications of two-dimensional materials in energy catalysis.
基金supported by the Science and Technology Plan of Fujian Provincial,China(2022G02020 and 2022H6002)the Collaborative Innovation Platform Project for Advanced Electrochemical Energy Storage Technology,Fuxiaquan National Independent Innovation Demonstration Zone,China(3502ZCQXT2022001)+1 种基金the Significant Science and Technology Project of Xiamen(the Future Industrial Area),China(3502Z20231058)the Scientific Research Startup Funding for Special Professor of Minjiang Scholars。
文摘Silicon(Si)-based anodes have emerged as promising candidates for the next-generation lithium-ion batteries(LIBs)due to their high theoretical capacity(4200 mAh g^(-1)).However,their further application is hindered by critical challenges,including severe volume expansion(~300%),formation of unstable solid electrolyte interphase(SEI),and inherently low conductivity.While extensive research has sought to alleviate the substantial internal stress caused by volume expansion through the rational design of Si-based anode structures,the underlying mechanisms that govern these improvements remain insufficiently understood,leaving significant gaps in mechanical and interface electrical failure.To build a comprehensive understanding relationship between structural design and performance enhancement of Si-based anodes,this review first analyzes the characteristics of various Sibased anode structures and their associated internal stresses.Subsequently,it summarizes effective strategies to optimize the performance of Si-based anodes,including doping design,novel electrolyte design,and fu nctional binder design.Additionally,we assess emerging technologies with high commercial potential for structural design and interfacial modification,such as porous carbon carriers,chemical vapor deposition(CVD),spray granulation,and pre-lithiation.Finally,this work provides perspectives on the structural design of Si-based anodes.Overall,this review systematically summarizes modification strategies for Si-based anodes through structural regulation and interface engineering,thereby providing a foundation for advanced structural and interfacial design.
基金supported by the Samsung Research Funding&Incubation Center of Samsung Electronics under Project No.SRFC-MA2402-05supported by the KENTECH Center for Shared Research Facilities。
文摘The performance degradation of micro light-emitting diodes(micro-LEDs)is closely associated with the deterioration of sidewall passivation layers under prolonged electrical bias.We investigate reliability improvements in 20μm×20μm InGaN/GaN blue micro-LEDs by suppressing the formation of an unstable interfacial layer during sidewall passivation.SiO_(2)is deposited on the etched mesa sidewalls using either Sputtering or plasma-enhanced chemical vapor deposition(PECVD).Comparative analysis reveals that PECVD-passivated devices experience more severe performance degradation,primarily due to the increased leakage current.After 100 h of accelerated aging,external quantum efficiency decreases by 44%in PECVD-passivated samples,whereas Sputter-passivated devices exhibit only an11%reduction.This discrepancy is attributed to the formation of a thicker and chemically unstable gallium oxynitride(Ga-O_(X)-N_(1-X))interfacial layer at the SiO_(2)∕GaN-based interface,which facilitates the generation of sidewall defects.Suppressing the formation of this interlayer enhances the crystallinity and structural stability of the passivation layer,thereby mitigating the activation of point defects.Notably,Sputter deposition is more effective in minimizing the formation of Ga-O-N interlayer.These findings emphasize the critical role of achieving low-defect-density sidewall passivation to improve the reliability of micro-LEDs for next-generation high-resolution display applications.
基金supported by the National Key R&D Program of China(Grant No.2022YFF0503703)the National Natural Science Foundation of China(Grant Nos.42130203,42275133,and 42241135).
文摘In this study,we use observations from the Sounding of the Atmosphere using Broadband Emission Radiometry(SABER)instrument onboard the Thermosphere–Ionosphere–Mesosphere Energetics and Dynamics(TIMED)satellite to develop and apply a new local-time binning method to investigate the long-term evolution of mesospheric water vapor at high latitudes.The proposed method accounts for the gradual local-time drift of the SABER orbit by aligning seasonal observation windows and selecting samples observed at similar local times.This approach minimizes tidal aliasing and ensures more consistent sampling,yielding more reliable estimates of long-term water vapor trends at high latitudes.The results show that drying signals primarily appear in the polar regions.However,in the southern hemisphere,a drying trend is observed only in autumn,whereas winter and summer mainly show moistening trends.In contrast,the northern hemisphere exhibits drying signals in the polar regions during all seasons,showing a clear seasonal asymmetry.Additionally,the water vapor trend in the northern hemisphere is particularly pronounced in February(late winter),with moistening reaching up to+2.0 ppmv.The winter in the southern hemisphere(July–August)also shows moistening,but the trend is still weaker than in the northern hemisphere.These differences highlight the strong moistening trend in the northern hemisphere during winter and underscore the significant asymmetry in seasonal water vapor changes between the two hemispheres.These findings emphasize the limitations of water vapor trend estimates across different seasons and latitudes.Moreover,they provide new insights into the spatiotemporal variability associated with tidal structures,underscoring the importance of optimizing local-time sampling strategies for reliable long-term trend detection.
