The existence of confining walls limits the prediction accuracy of nanoconfined fluids using macroscopic equations of state(EOSs);moreover,appropriate EOSs for multicomponent mixture fluids in nanoconfined spaces are ...
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The existence of confining walls limits the prediction accuracy of nanoconfined fluids using macroscopic equations of state(EOSs);moreover,appropriate EOSs for multicomponent mixture fluids in nanoconfined spaces are ***,we derive the EOS of multicomponent mixture fluids confined in nanospaces at high temperatures and pressures,mainly considering the nanoconfinement effect and the competitive adsorption effect between different ***,the EOSs are validated through comparison with the molecular dynamics-simulated Pv T data of CO_(2)/H_(2)O mixtures in graphite *** consider the above effects,we derive two EOSs via two modeling methods:EOS I is obtained through modification of the actual component occupation volume in the Peng-Robinson equation of state(PR EOS)by fitting the binary component interaction coefficient and the number of adsorbed molecules according to a selectivity coefficient,while EOS II is obtained by considering the decreased pressure of the fluids in PR EOS by adding an attractive term between components and *** the simulation results as a benchmark,the two EOSs exhibited good prediction accuracies under low CO_(2) concentrations,and generally,EOS II was more accurate than EOS *** study fills the gap in the EOSs of nanoconfined mixture fluids,and the obtained equations can help to further describe the thermodynamic properties of confined mixture fluids.
In this paper,a numerical model was built by ANSYS FLUENT to investigate the heat transfer performances of supercritical water in a circumferential non-uniformly heated vertical *** Shear Stress Transport(SST)k-ωmode...
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In this paper,a numerical model was built by ANSYS FLUENT to investigate the heat transfer performances of supercritical water in a circumferential non-uniformly heated vertical *** Shear Stress Transport(SST)k-ωmodel was adopted for describing *** operating parameters are chosen according to a 660 MW ultra-supercritical CFB *** heat transfer performances under different operating parameters,such as boiler load,flow direction and heat flux distribution are *** temperature and heat flux on inner wall varies along the circumference and show symmetric *** overall heat transfer performances at each cross section are better than the local heat transfer performance of midpoint of heating *** direction has a great influence on heat transfer performance;it changes the radial distribution of axial velocity and then affects the turbulence ***,upward flow condition shows a better heat transfer *** heat flux improves both the overall and local heat transfer *** the heat flux area is not conducive to the overall heat transfer,but does not affect the local heat transfer at the midpoint of heating ***,a new correlation is fitted based on the simulated results of supercritical water heat transfer with circumferential non-uniform heat flux distributions.
Bunsen burner is a typical geometry for investigating the turbulence-flame *** most experimental studies,only turbulence intensity u′and integral scale l0 are used to characterize the turbulent flow field,regardless ...
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Bunsen burner is a typical geometry for investigating the turbulence-flame *** most experimental studies,only turbulence intensity u′and integral scale l0 are used to characterize the turbulent flow field,regardless of the perforation geometry of perforated ***,since the geometry influences the developing process and vortex broken,the plate geometry has to be considered when discussing the flame-turbulence *** order to investigate conditions at the same l0 and u′using different geometries,large eddy simulation of CH_(4)/air flames with dynamic TF combustion model was *** model validation shows good agreement between Large Eddy Simulation(LES)and experimental *** the non-reacting flows,the Vortex Stretching of circular-perforated plate condition is always larger than that of slot-perforated plate condition,which comes from the stresses in the flow fields to stretch the vorticity *** reacting flows,at the root of the flame,the Vortex Stretching plays a major role,and the total vorticity here of circular-perforated plate condition is still larger(53.8%and 300%larger than that of the slot-perforated plate at x/D=0 and x/D=2.5,respectively).More small-scale vortex in circular-perforated plate condition can affect and wrinkle the flame front to increase the Probability Density Function(PDF)at large *** 3D curvature distributions of both cases bias to negative *** negative trend of curvatures at the instant flame front results from the Dilatation ***,the value of the Vortex Stretching and the Dilatation at the flame front of circular-perforated plate condition is obviously larger.
Combining water electrolysis and rechargeable battery technologies into a single system holds great promise for the co-production of hydrogen (H_(2)) and ***,the design and development of such systems is still in its ...
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Combining water electrolysis and rechargeable battery technologies into a single system holds great promise for the co-production of hydrogen (H_(2)) and ***,the design and development of such systems is still in its ***,an integrated hydrogen-oxygen (O_(2))-electricity co-production system featuring a bipolar membrane-assisted decoupled electrolyzer and a Na-Zn ion battery was established with sodium nickelhexacyanoferrate (NaNiHCF) and Zn^(2+)/Zn as dual redox *** decoupled electrolyzer enables to produce H_(2)and O_(2)in different time and space with almost 100%Faradaic efficiency at 100 mA cm^(-2).Then,the charged NaNiHCF and Zn electrodes after the electrolysis processes formed a Na-Zn ion battery,which can generate electricity with an average cell voltage of 1.75 V at 10 m A cm^(-2).By connecting Si photovoltaics with the modular electrochemical device,a well-matched solar driven system was built to convert the intermittent solar energy into hydrogen and electric energy with a solar to hydrogen-electricity efficiency of 16.7%,demonstrating the flexible storage and conversion of renewables.
NiFe(oxy)hydroxide(NiFeOOH)is recognized as a highly active non-precious metal catalyst in alkaline water electrolysis due to its exceptional catalytic *** this work,high valence molybdenum(Mo)is introduced to improve...
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NiFe(oxy)hydroxide(NiFeOOH)is recognized as a highly active non-precious metal catalyst in alkaline water electrolysis due to its exceptional catalytic *** this work,high valence molybdenum(Mo)is introduced to improve the electronic structure and enhance the electrical conductivity of NiFeOOH for oxygen evolution reaction(OER).The introduction of Mo results in a Mo-doped NiFeOOH catalyst with a significantly reduced overpotential of 205 mV at 10 mA/cm^(2)and a Tafel slope of 31.7 mV/dec,enabling stable operation for up to 170 *** empirical experiment and theory simulations are employed to gain insight into the 3d-electron interactions between molybdenum and nickel(Ni),iron(Fe)in Mo-doped *** results indicate that Mo-doping enhances the valence states of Ni and Fe,leading to a shift in the d-band center of the bimetallic active *** modification affects the transformation of Mo-doped NiFeOOH into theγ-NiFeOOH active *** potent combination lends credence to its potential suitability and utility in OER applications.
Large vertical pipes are key structures connecting subsea wells to offshore ***,existing studies mainly focus on small vertical *** a vertical acrylic pipe with 80 mm inner diameter and 11 m height,a high-speed camera...
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Large vertical pipes are key structures connecting subsea wells to offshore ***,existing studies mainly focus on small vertical *** a vertical acrylic pipe with 80 mm inner diameter and 11 m height,a high-speed camera was used to visually research the influences of pipe diameters,liquid properties and inlet effect on air-water co-flow *** flow regime maps of vertical pipes(diameters are in the range of 50e189 mm)were compared and the critical gas velocity of the transition boundary from bubble to slug flow tended to increase with the increase of diameters at D≥80 ***-flux models were established in different flow regimes and liquid properties have a significant effect on drift coefficients of bubble flow and slug flow(void fraction a≤0.4).The influence of inlet turbulent effect on the gas-liquid interface distribution gradually weakened and disappeared from the pipe base to 85D,where the flow was fully *** frequency has a trend of increase first and then decrease with the gas Weber numbers increasing at low liquid superficial velocities(J_(L)≤0.31 m/s).And on the basis of this law,a new slug frequency correlation was *** was found that there was an exponential relationship between the ratio of lengths of Taylor bubble to slug and the void fraction.
As a benign energy vector,hydrogen has been discussed for a long *** water gasification was one of good ways to produce ***,supercritical water gasification system with H_(2)O transporting was energy consuming in the ...
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As a benign energy vector,hydrogen has been discussed for a long *** water gasification was one of good ways to produce ***,supercritical water gasification system with H_(2)O transporting was energy consuming in the process of heating due to the high specific heat of H_(2)O.A new supercritical water gasification system was established in this paper with supercritical CO_(2)as medium *** plastics were used as the sample transported by CO_(2).Production yields,energy flow and exergy flow of the system were collected and the influence of temperature,pressure,gasification concentration and transporting concentration was *** flow of H_(2)O input into the reactor was 1000 kg/*** typical condition was as follow:temperature 923.15 K,pressure 23 MPa,and the mass ratio of water,sample and transporting medium was 100:9:*** of H_(2),CH4,CO and CO_(2)at this condition was 8.1 kg/h,39.6 kg/h,6.6 kg/h and 137.5 kg/h,*** system with H_(2)O transporting was used to compare with the supercritical CO_(2)transporting system and proved that system with CO_(2)transporting could reduce the loss of both energy and exergy while the reduce of each gas production yield was less than 0.1 mol/mol.
Formic acid(FA)is a potential biomass resource of syngas with contents of carbon monoxide(CO,60 wt.%)and hydrogen(H_(2),4.4 wt.%).Among the technologies for FA conversion,the photoreforming of FA has received widespre...
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Formic acid(FA)is a potential biomass resource of syngas with contents of carbon monoxide(CO,60 wt.%)and hydrogen(H_(2),4.4 wt.%).Among the technologies for FA conversion,the photoreforming of FA has received widespread attention due to its use of green solar energy conversion technology and mild reaction ***,a V-W bimetallic solid solution,V_(x)W_(1-x)N_(1.5) with efficient co-catalytic properties was first and facilely *** CdS was used as a photocatalyst,the activity performance of the V_(0.1)W_(0.9)N_(1.5) system was over 60%higher than that of the W_(2)N_(3) *** computational simulations and experiments showed the V_(0.1)W_(0.9)N_(1.5) had great metallic features and large work functions,contributing a faster photo-generated carrier transfer and less recombination,finally facilitating a great performance in cocatalyst for syngas production in photoreforming *** work provides an approach to synthesizing novel transition metal nitrides for photocatalysis.
Although electrocatalytic water splitting holds significant promise for hydrogen production,unfavorable reaction energy barriers and kinetic properties lead to unsatisfactory conversion ***,we provide an innovative st...
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Although electrocatalytic water splitting holds significant promise for hydrogen production,unfavorable reaction energy barriers and kinetic properties lead to unsatisfactory conversion ***,we provide an innovative strategy to optimize the electrochemical activity of the Fe/Ni_(2)P catalyst through near-infrared(NIR)-induced photothermal *** Fe/Ni_(2)P-NIR yields a current density of 10 mA cm^(-2)at ultralow overpotentials of 16 mV for the hydrogen evolution reaction(HER)and 167 mV for the oxygen evolution reaction(OER),with Tafel slopes of 38.7 and 46.2 mV dec^(-1),*** bifunctional catalyst also delivers 10 mA cm^(-2)at a low voltage of 1.40 V for overall water *** NIR photoinduced local thermal effect activates abundant catalytic sites,accelerates charge and mass transfer,and improves intrinsic reaction *** by density functional theory(DFT)calculations,the photothermal effect reduces the energy barriers of the rate-determining steps(RDS)for^(*)H desorption on Fe/Ni_(2)P during HER and^(*)O formation on its reconstructed active phase NiFeOOH during *** realized photothermal-electrochemical integration with Fe/Ni_(2)P-NIR in an anion exchange membrane(AEM)electrolyzer,attaining 500 mA cm^(-2)at 1.76 V,with excellent stability over 50 *** strategy may significantly advance energy conversion technology towards economic hydrogen production through water electrolysis.
Solar-driven photothermal catalytic CO_(2) conversion into fuels offers a promising approach to reducing fossil fuel *** enhance the efficiency of photothermal CO_(2) reduction,photothermal catalyst design must not on...
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Solar-driven photothermal catalytic CO_(2) conversion into fuels offers a promising approach to reducing fossil fuel *** enhance the efficiency of photothermal CO_(2) reduction,photothermal catalyst design must not only sustain the high temperatures required for the reaction but also effectively utilize the entire solar *** this study,we present a novel photothermal catalyst architecture BiVO_(4)/Bi/BiOCl that surpasses traditional designs by integrating plasmonic metal Bi as the“hot spot”and BiOCl as the thermal insulation layer on the outermost *** structure realizes thermal management,contributing to maintaining the high temperatures required for the *** BiVO_(4)/Bi/BiOCl multi-component system synergistically absorbs the full solar light spectrum and achieves band-division utilization:short-and mid-wavelengths drive reduction and oxidation reactions,respectively,while long-wavelengths induce the photothermal *** BiVO4/Bi/BiOCl catalyst demonstrates high-efficiency CO_(2) conversion performance in an outdoor concentrating system,achieving a CO production rate of 9.5μmol/*** work presents a design strategy for functional photothermal catalysts,making them viable candidates for industrial-scale CO_(2) conversion processes.
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