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Air pollution control is a worldwide problem of common concern to all mankind. Electrostatic precipitator (ESP) plays an important role in the purification of flue gas and dust. At present, in a multi-electrode ESP, the middle discharge electrode is often inhibited by the outer discharge electrode, commonly known as electrostatic shielding, which seriously affects the electric field distribution and dust removal effect of ESP. In order to explore this characteristic, this research established a mathematical model of ESP and simulated the electrostatic shielding phenomenon of wire-plate ESP, which quantified the influence of various factors on the degree of electrostatic shielding and analyzed the potential impact of electrostatic shielding on particle charging and dust removal efficiency. The results of the study show that the wire-to-plate distance has the greatest impact on electrostatic shielding, followed by the discharge electrode radius, voltage, and the wire-to-wire distance. When the degree of electrostatic shielding increases, the dust removal efficiency of ESP decreases. In addition, increasing the number of discharge electrodes to increase the dust removal efficiency of ESP is only feasible within a certain range. When the number of discharge electrodes exceeds a certain threshold, the dust removal efficiency of ESP decreases due to the effect of electrostatic shielding. The results of the research provide guidance for the determination of the geometric parameters of ESP and can make theoretical predictions for the occurrence of electrostatic shielding, thereby effectively avoiding the occurrence of electrostatic shielding.

Despite the excellent specific energy of lithium-air batteries, their unclear discharge mechanism and product morphology remain great challenges for successfully replacing commercial lithium-ion ba...

Electrostatic precipitators (ESPs), which remove particles from a flue gas by corona discharge, are widely used in industry. In this work, numerical investigations were carried out to explore the multi-physical characteristics of a wire-plate ESP with different collecting electrodes. By employing the COMSOL Multiphysics simulation tool, the multi-physical fields of ESPs were properly coupled. The effects of different types of collecting electrodes on electric filed, ionic wind, particle transport, and collection efficiency were investigated. The results show the ionic wind induced by corona discharge has a great influence on flow behaviors in ESP. In addition, simulation results indicate the existence of uneven collecting plates could have an impact of suppression on the flow near the plates, which would be beneficial for reducing the re-entrainment dust particles. Compared with C-type plate, the collection efficiency with triangle plate is found 6.87% higher for 5 μm particles, and 10.37% for 10 μm particles.

The knowledge of adsorption behaviors and mechanism of CO2/CH4 in organic matter is of great importance for CO2 geological sequestration with enhanced gas recovery in shale reservoirs. In this stud...

The influence of surfactants is of great importance to the interfacial properties, which is related by the characteristics of molecular arrays at the interface of multicomponent and multiphase systems. Comparing with single type of surfactant, the mixtures of surfactants usually provide superior performances in improving interfacial properties of the oil-water interface in the application of enhanced oil recovery. In this study, molecular dynamics simulations were employed to explore the mechanisms and interfacial behaviors at the microscopic level of pure and binary mixture of anionic-nonionic surfactant alcohol ether sulfates (AES) and cationic surfactant dodecyltrimethylammonium chloride (DTAC) at oil-water interface. The results show that the sulfate groups of AES molecules could attract DTAC molecules in the mixed surfactants, thereby reducing the repulsion between the molecules. DTAC molecules present excellent molecular interfacial behaviors, which could improve the arrangement of AES molecules through the interactions between head groups. In addition, it is found that the number of ethylene oxide (EO) group of AES molecules has a great influence on the behaviors of interface. An increase of EO group number could cause AES molecules to exhibit varying degrees of bending. By controlling the proper number of EO group, the aggregation of surfactants could be avoided and satisfactory interfacial properties will be achieved. Moreover, it is observed that the positive charge of DTAC molecule shows a strong repulsion to salt ions, for example Ca2+ ions, thus enhancing the overall salt resistance of mixed surfactants. The molecular-level insights gained in this work could provide useful guidance for designing the surfactant formulations for tertiary/enhanced oil recovery in low-permeability unconventional reservoirs.

There are various types of compounds studied and applied for plant disease management, and some of them are environment friendly and suitable in organic production. An example is indole-3-carboxaldehyde (A1) and indole-3-carboxylic acid (A2) derived from Purpureocillium lilacinum H1463, which have shown a strong activity in the control of tobacco mosaic virus (TMV). In this study, the effects of these compounds were studied on suppressing TMV and corresponding mechanism. Both A1 and A2 exhibited strong anti-TMV activities in vitro and in vivo. They fractured TMV virions and forced the fractured particles agglomerated. A1 and A2 also induced immune responses or resistance of tobacco to TMV infection, including expressing hypersensitive reaction (HR), increasing defense-related enzymes and overexpressing pathogenesis-related (PR) proteins. The upregulation of salicylic acid (SA) biosynthesis genes PAL, ICS, and PBS3 confirmed that SA served as a defense-related signal molecule. Therefore, indole derivatives have a potential for activating defense of tobacco against TMV and other pathogens and can be used for disease control.

This study proposes a multiscale model combining molecular simulation and the lattice Boltzmann method (LBM) to explore gas flow behaviors with multiple transport mechanisms in nanoporous media of shale matrix. The gas adsorption characteristics in shale nanopores are first investigated by molecular simulations, which are then integrated and upscaled into the LBM model through a local adsorption density parameter. In order to adapt to high Knudsen number and nanoporous shale matrix, a multiple-relaxation-time pore-scale LBM model with a regularization procedure is developed. The combination of bounce-back and full diffusive boundary condition is adopted to take account of gas slippage and surface diffusion induced by gas adsorption. Molecular simulation results at the atomic scale show that gas adsorption behaviors are greatly affected by the pressure and pore size of the shale organic nanopore. At the pore scale, the gas transport behaviors with multiple transport mechanisms in nanoporous shale matrix are explored by the developed multiscale model. Simulation results indicate that pressure exhibits more significant influences on the transport behaviors of shale gas than temperature does. Compared with porosity, the average pore size of nanoporous shale matrix plays a more significant role in determining the apparent permeability of gas transport. The roles of the gas adsorption layer and surface diffusion in shale gas transport are discussed. It is observed that under low pressure, the gas adsorption layer has a positive influence on gas transport in shale matrix due to the strong surface diffusion effect. The nanoporous structure with the anisotropy characteristic parallel to the flow direction can enhance gas transport in shale matrix. The obtained results may provide underlying and comprehensive understanding of gas flow behaviors considering multiple transport mechanisms in shale matrix. Also, the proposed multiscale model can be considered as a powerful tool to invesigate the multiscale and multiphysical flow behaviors in porous media.

The multiphase fluid system in the presence of surfactant is frequently encountered in numerous scientific and engineering applications. Developing a model for accurately simulating such a complex system is of great significance. In this work, we propose a multi-relaxation-time phase-field lattice Boltzmann model for simulating droplet dynamics with soluble surfactants. The accuracy and validity of the model are verified by benchmark cases including static droplet and Rayleigh–Taylor instability tests. The effects of surfactant, capillary number, and density ratio on single-droplet deformation and two-droplet interaction under shear flow are investigated. Simulation results indicate that the Marangoni stress generated by the inhomogeneous distribution of surfactant at the interface plays the role of promoting droplet deformation and hindering droplet coalescence. Within the studied range, it tends to be much easier for droplets to deform with the decrease in density ratio. The increase in the capillary number and surfactant concentration is conducive to promoting the deformation and breakup of droplets. In addition, a higher surfactant concentration is found to result in greater liquid film thickness between droplets, which would hinder the coalescence of the droplets.

Aims To extract and identify the metabolites of strain A217 as well as its antifungal spectrum and control effect on various plant pathogens. Methods and results Strain A217 was identified as a Streptomyces sp. which was most similar to Streptomyces lienomycini. An antimicrobial spectrum test indicated that strain A217 inhibited several plant pathogenic fungi and strong antibacterial effect such as Phytophthora capsici, Botrytis cinerea, Sclerotinia sclerotiorum, Fusarium oxysporum, Pseudomonas syringae and Xanthomonas campestris. An in vivo tissue test demonstrated that the fermentation broth of strain A217 exerted therapeutic and protective effects of 49·47 and 61·60% respectively, on S. sclerotiorum. Additionally, the fermentation broth of A217 exerted control effects on walnut black spot disease in walnut leaves and branches amounting to 79·33 and 81·52% respectively. In a pot experiment, the fermentation broth exhibited a stronger protective and control effect (68·29%), as well as better bacteriostatic and disease control effects on Phytophthora blight of pepper, compared with Metalaxyl. Compounds possessing antifungal and antibacterial activities were obtained from the fermentation broth of strain A217, using column chromatography and HPLC. Chemical and structural analyses conducted using MS and nuclear magnetic resonance confirmed that these compounds were 1H-pyrrole-2-carboxylic acid and 1H-pyrrole-2-carboxamide. The EC50 values of compound 1H-pyrrole-2-carboxylic acid1 for S. sclerotiorum and P. capsici were 20·13 and 50·36 μg ml-1 respectively. Compound 1H-pyrrole-2-carboxamide2 showed significant antibacterial activity against different plant pathogenic bacteria. The MIC values of P. syringae, X. campestris and X. campestris pv. jugiandis were 7·5, 30 and 15·0 μg ml-1 respectively. Conclusions Actinomyces A217 fermentation products have a broad spectrum of bacteriostasis, and have good bacteriostasis activity to many plant pathogenic fungi and bacteria. Significance and impact of the study The present study revealed a new antimicrobial producing strain of Streptomyces and its potential application as a biological control agent for plant diseases.

Recent theoretical and experimental studies have shown that the formation of Li2O2, the main discharge product of nonaqueous Li-O2 batteries, is a complex multistep reaction process. The formation, nucleation, and adsorption of LixOy (x and y = 0, 1, and 2) and (Li2O2)n clusters with n = 1-4 on the surface of carbon nanotubes (CNTs) were investigated by periodic density functional theory calculation. The results showed that both Li2O2 and Li2O on CNT electrodes are preferentially generated by lithiation reaction rather than disproportionation reaction. The free energy profiles demonstrate that the discharge potentials of 2.54 and 1.29 V are the threshold values of spontaneous nucleation of (Li2O2)2 and (Li2O)2 on a CNT surface, respectively. The electronic structure indicates that Li2O2 is a p-type semiconductor, while Li2O exhibits the properties of an insulator. Interestingly, once Li2O2 molecules condense into large clusters, they will be repelled away from the CNT surface and continue to grow into large-sized Li2O2. Our results provide insights into the full understanding of the electrochemical reaction mechanism and product formation processes of lithium oxides in the cathodes of Li-O2 batteries.

Understanding the adsorption mechanism of CO2/CH4 in kaolinite clay is essential for the carbon dioxide geological sequestration and enhanced gas recovery in shale reservoirs. In the present work, grand canonical Monte Carlo simulations were employed to investigate the mechanism of competitive adsorption of CO2/CH4 in kaolinite clay. The effects of pore size (1–6 nm), pressure (0.1–30 MPa), temperature (298–378 K), and moisture content (0–0.122 g/cm3) on the adsorption behaviors of pure CH4 and CO2/CH4 mixture were explored in-depth. Specifically, two adsorption layers, i.e., strong and weak adsorption layers, in kaolinite slitlike micropore under high pressure condition have been observed. It was found that pore size and pressure have great effects on the gas adsorption mechanism in kaolinite. The two adsorption mechanisms including monolayer adsorption and micropore filling under high pressure or small pore size conditions were discussed. In addition, simulation results showed that CO2 has much stronger...

Carbon dioxide enhanced coalbed methane recovery (CO2-ECBM) has been proposed as a promising technology for the natural gas recovery enhancement as well as mitigation of CO2 emissions into the atmosphere. Adsorption and diffusion of CO2/CH4 mixture play key roles in predicting the performance of CO2-ECBM project, i.e., the production of coalbed methane as well as the geological sequestration potential of carbon dioxide. In the present work, the mechanism of competitive adsorption and diffusion of CO2/CH4/H2O mixture in brown coal were investigated by employing grand canonical Monte Carlo and molecular dynamics simulation. The effects of temperature and pressure on competitive adsorption and diffusion behaviours were explored. It is found that CO2 has much stronger adsorption ability on brown coal than CH4. The adsorption amounts of CO2/CH4 increase with pressure but have a decreasing trend with temperature. High adsorption selectivity of CO2/CH4 is observed with pressure lower than 0.1 MPa. In addition, the effects of moisture content in brown coal on the adsorption characteristics have been examined. Simulation results show that the adsorption capacities of CO2/CH4 are significantly suppressed in moist brown coal. The competitive adsorption of CO2/CH4/H2O follows the trend of H2O ≫ CO2 > CH4. Moreover, the results reveal that moisture content has great effects on the self-coefficients of CO2/CH4. Compared with dry coal, the self-diffusion coefficients of CO2 and CH4 reduce by 78.7% and 75.4% in brown coal with moisture content of 7.59 wt%, respectively. The microscopic insights provided in this study will be helpful to understand the competitive adsorption and diffusion mechanism of CO2/CH4/H2O in brown coal and offer some fundamental data for CO2-ECBM project.

In this study, mixed convection heat transfer of Al2O3/water nanofluid in a double lid-driven cubic cavity with different heat sources was numerically investigated. The lattice Boltzmann method (LBM) was developed to solve the governing equations. The effects of nanoparticle volume fraction, Reynolds number and Richardson number on heat transfer characteristics were examined. The results show that they have great effects on both velocity profiles and heat transfer performance. Additionally, the effects of different lid directions and heat sources on heat transfer were explored. It is found that the case of cold wall moving down and hot wall moving up double lid-driven cavity has the best heat transfer performance. Numerical results also indicate that different heat sources have significant impacts on both the local Nusselt number distribution on the hot wall and temperature field in the cavity. In order to improve the computation efficiency, the Open Multi-Processing (OpenMP) was employed for the parallelization of the proposed 3D LBM model. The phenomenon of super linear speedup was noted and discussed.

In the present study, competitive adsorption behaviour of supercritical carbon dioxide and methane binary mixture in shale organic nanopores was investigated by using grand canonical Monte Carlo (GCMC) simulations. The model was firstly validated by comparing with experimental data and a satisfactory agreement was obtained. Then the effects of temperature (298–388 K), pressure (up to 60 MPa), pore size (1–4 nm) and moisture content (0–2.4 wt%) on competitive adsorption behaviour of the binary mixture were examined and discussed in depth. It is found that the adsorption capacity of carbon dioxide in shale organic nanopores is much higher than that of methane under various conditions. The mechanism of competitive adsorption was discussed in detail. In addition, the results show that a lower temperature is favorable to both the adsorption amount and selectivity of CO2/CH4 binary mixture in shale organic nanopores. However, an appropriate CO2 injection pressure should be considered to take into account the CO2 sequestration amount and the exploitation efficiency of shale gas. As for moisture content, different influences on CO2/CH4 adsorption selectivity have been observed at low and high moisture conditions. Therefore, different simulation technologies for shale gas production and CO2 sequestration should be applied depending on the actual moisture conditions of the shale reservoirs. It is expected that the findings in this work could be helpful to estimate and enhance shale gas resource recovery and also evaluate CO2 sequestration efficiency in shale reservoirs.

TiC has attracted tremendous recent attention in lithium-oxygen batteries as a means of reducing the irreversible accumulation of by-products (i.e., Li2CO3) on the air cathode. However, TiC is intrinsically reactive to oxygen under ambient conditions, and its stability is completely determined by the surface overlayer. Herein, the catalytic effects of oxide overlayer (TiO) on adsorption mechanism, reaction path, and growth morphology of lithium oxides were comprehensively elucidated using periodic density functional theory calculations. The results indicate that the TiO overlayer on the surface of TiC(100)-TiO enhances the adsorption of lithium oxides. As compared to the disproportionation reaction, the lithiation reaction is the primary contributor to the formation of Li2O2 and Li2O on TiC(100) surface. Interestingly, the oxidized TiC(100)-TiO performs better in inhibiting the generation of undesirable Li2O. Analysis demonstrates that the discharge performance is not only related to the widely known morphology and size of product but also to the adsorption of (Li2O2)n clusters on the TiC(100) surface. The electronic structures of (Li2O2)n clusters on TiC(100)-TiC and TiC(100)-TiO surfaces have been examined to study the influence of TiO overlayer on the conductivity of accumulated products, which helps explain the innovative discovery of the experiment that TiC has excellent performance in improving the cycle ability of lithium-oxygen batteries. Our results promote the understanding of the ORR mechanism on TiC surface and provide theoretical guidance for the design of efficient and stable air cathodes for lithium-oxygen batteries.

T-junction is a classical structure for the two-phase separation. The analysis of gas-liquid flow and the interface movement at the T-junction is very important to the mechanism understanding especially for T-micro-junctions with unequal diameter joint. A simulation of the passive draining process and the corresponding flow pattern modulation of slug flow in a tube with three T-micro-junctions are presented in this paper. Using the volume of fluid (VOF) method and the dynamic grid adaption method the interface movement was tracked precisely especially at the region of drainage junctions. As results, with the separation of liquid no apparent change of gas slugs’ length but shortened water plugs. The gas fraction in main tube is increased more than 10%. During the separation process, the interface movement at unequal diameter junctions mainly consisted of three stages: the generation of penetrating bubbles, a stable sliding stage and the retraction to mother bubble. These constitute one piston movement of penetrating bubbles, which is the vital mechanism of phase separation. The cooperation of interface pressure difference, surface tension, interphase shear force and characteristic sizes of micro-channel drainages brings into a separation. A preliminary model to optimize characteristic sizes of porous materials is proposed in order to getting a successful liquid separation from a slug flow, which could improve the condensation heat transfer performance.

Energy structure adjustment is a significant way to resolve constrained resources and environment, improve the security of energy supply, and achieve sustainable development, which is a complicated itself but further challenged by existence of uncertainties. In this study, an inexact multistage stochastic cost-risk balanced programming model is developed for energy system management under considering the policies of coal-consumption control and pollutants emission reduction. The method is an integration of inexact multistage stochastic programming and a risk management tools from modern financial theory, and could tackle uncertainties described as interval values and probability distributions. The method could reflect energy system dynamic characteristic in a multi-period problem, and provide an effective linkage between conflicting economic cost and the system stability. The proposed method is applied to a real case of planning electric power structure adjustment in Shandong province, China, where the energy system is faced with lots of difficulties complexities in electric power structure adjustment. The impact of coal-consumption control level and pollutants emission reduction scenarios on energy system structure adjustment, and resources and environmental effect were compared and analyzed. The results are valuable for supporting the adjustment or justification of the existing power generation schemes of the complicated regional energy system.

Recent theoretical and experimental studies have shown that the formation of Li

In this work, an improved comprehensive model was developed for large coal particles to predict temperature variation and volatile component yields. The kinetics model of volatile component yields, where the volatile matters were assumed to comprise nine species, was combined with heat transfer model. The interaction between volatile yield and heat transfer during pyrolysis of large Maltby coal particles was investigated. An apparent temperature difference has been observed between the surface and core of particles at the initial heating stage. The non-uniform temperature distribution inside coal particles causes non-simultaneous volatile yields release from the surface and core area. The volatile release occurs after the coal temperature rises higher than 350 &deg, C, and its yield steeply increases within the temperature range of 450&ndash, 520 &deg, C. The peak of volatile release rate corresponds to about 485 &deg, C due to the rapid release of tar and H2O. The tar is almost completely released at around 550 &deg, C. With the increasing particle size, the difference in temperature and volatile yield between the surface and core increases at the end of heating. The results are expected to provide insights into the interaction between heat transfer and volatile yields during pyrolysis of large coal particles.

As calcium carbide (CaC2) production is an energy-intensive industry, a novel low rank coal to CaC2 (LRCtCC) process has been developed. This study is aimed to evaluate the techno-economic performance of the LRCtCC process. A model integrating particle swarm optimization and nonlinear programming (PSO-NLP) is developed to predict the behavior of coal pyrolysis. The techno-economic assessment of the LRCtCC process is analyzed. Results show that the power consumption of electric arc furnace is expected to drop to 2845 from 3169 kW·h/t with the hot material (HM) temperature increasing from 25 to 850 °C. The effect of increasing HM temperature is greater than that of adjusting the composition of fuel on system efficiency, cost of CaC2, and internal rate of return. In addition, the effects of typical economic factors on net present value (NPV) of the LRCtCC process are compared. Results show that variations of CaC2 price and power consumption pose a remarkable impact on NPV. The findings of this study suggest that the LRCtCC process would be an attractive method for the improvement of CaC2 production.

In the present study, a three dimensional thermal lattice Boltzmann model was developed to investigate the flow dynamics and mixed convection heat transfer of Al2O3/water nanofluid in a cubic cavity in the presence of magnetic field. The model was first validated with previous numerical and experimental results. Satisfactory agreement was obtained. Then the effects of Rayleigh number, nanoparticle volume fraction, Hartmann number and Richardson number on nanofluid flow dynamics and heat transfer were examined. Numerical results indicate that adding nanoparticles to pure water leads to heat transfer enhancement for low Rayleigh numbers. However, this enhancement might be weakened and even reversed for high Rayleigh numbers. In addition, the results show the external applied magnetic field has an effect of suppressing the convective heat transfer in the cavity. Moreover, the results demonstrate that the Richardson number in mixed convection has significant influences on both streamlines and temperature field.

Electrostatic precipitator (ESP) is the mainstream technology for controlling emissions of coal-fired thermal power units in China. The barbed electrode (RS or BS) is paired with the electrostatic precipitators. However, such electrodes have serious internal suppression effects and easily cause the current density in some areas to be zero, affecting the electric field distribution. To explore this characteristic, the current density distribution on the surface of the collecting plate was tested on the electrostatic precipitator experimental device, and the suppression effect of the BS barbed electrode and the existence of the “current blind zone” were obtained. The mathematical model of corona discharge was then established to numerically solve the V-I characteristics of the BS barbed electrode's inner and outer discharge tips and quantify the suppression effect between the discharge tips. Finally, to improve the suppression effect and the current density distribution, the BS barbed electrode's structural parameters optimization schemes and supporting circular tubes in the single electrode-plate ESP model were proposed. The results show that the spurs' optimized structure can effectively improve the corona discharge capacity and weaken the suppression effect. At the same time, it was found that when the supporting component is a round tube or flat plate, the shielding effect will be produced. The addition of auxiliary needles on the supporting round tube cannot improve the current density distribution. Additional needles on the supporting plate can eliminate the phenomenon that the current density is zero. The shielding effect of the supporting tube is further explained. The research results provide a theoretical and experimental basis for the optimal design of barbed electrode and ESP's electrode configuration.

Gas flow behaviors in shale are significantly complicated because of the inherent complexity and heterogeneity of shale formations. Revealing the gas transport characteristic is critical for achieving high efficiency of shale gas exploitation. In this work, a multiscale approach combined molecular simulation and lattice Boltzmann method has been proposed for investigating gas transport in shale organic nanopores. Firstly, the characteristic of adsorbed gas in shale nanopore was obtained by molecular simulation. Then, the adsorption properties were integrated to develop a lattice Boltzmann model, which can capture slippage and surface diffusion effects in shale nanopores. By employing this proposed multiscale model, the effects of pressure, temperature and pore size on shale gas adsorption and transport characteristics in organic nanopore were studied. Numerical results show pore size and pressure have great influences on gas adsorption behaviors. The gas apparent permeability tends to increase with the increment of temperature and decrease of pressure. Moreover, the influences of pore size and pressure on surface diffusion permeability were examined. Numerical results indicate the contribution of surface diffusion to overall apparent permeability tends to be enhanced in small pore and low pressure. However, this influence will be greatly weakened with the increasing pore size.

The use of carbon nanotubes (CNTs) as the cathodes of Li–O2 batteries is highly desirable but challenging. The growth of Li2O2 is likely to originate from condensed nanoclusters, which will slowly accumulate into microscopic or macroscopic deposits. In this work, we investigate (Li2O2)n clusters adsorption on CNTs by applying periodic density functional theory. The theoretical results indicate that Li2O2 clusters rely on hole conduction, similar to Li2O2 films and Li2O2 crystals. A comparison of all sites on the CNTs reveals that monomer Li2O2 has the strongest adsorption when it is placed horizontally on C atoms. The adsorption stability of Li2O2 on the adsorption sites of CNTs follows the order of T > Bz > Ho > Ba. Another noteworthy finding is that the adsorption energy of Li2O2 is closely related to CNT type and tube diameter. Notably, small clusters can stably adsorb on the external surface of CNTs, whereas large clusters are distant from the surface due to repulsion between C and O atoms. Finally, the conductivity of the system is enhanced with the increment in (Li2O2)n volume because of the metallicity of the clusters. Film-like Li2O2 is mainly composed of small clusters with low conductivity, whereas toroidal Li2O2 is primarily composed of large clusters with high conductivity. The results of this work can improve the understanding of the microscopic chemical reaction mechanism of Li–O2 batteries and guide the design of novel high-performance electrodes.

Carbon dioxide enhanced coalbed methane recovery (CO

In the present study, competitive adsorption behaviour of supercritical carbon dioxide and methane binary mixture in shale organic nanopores was investigated by using grand canonical Monte Carlo (GCMC) simulations. The model was firstly validated by comparing with experimental data and a satisfactory agreement was obtained. Then the effects of temperature (298-388 K), pressure (up to 60 MPa), pore size (1-4 nm) and moisture content (0-2.4 wt%) on competitive adsorption behaviour of the binary mixture were examined and discussed in depth. It is found that the adsorption capacity of carbon dioxide in shale organic nanopores is much higher than that of methane under various conditions. The mechanism of competitive adsorption was discussed in detail. In addition, the results show that a lower temperature is favorable to both the adsorption amount and selectivity of CO

In this study, the effects of a magnetic field on natural convection heat transfer in an enclosure filled with nanofluid are numerically investigated by using lattice Boltzmann method. The calculations were performed for a wide range of governing parameters. The results show that increase of Rayleigh number and nanoparticle volume fraction improves heat transfer in the enclosure, but an opposite trend is found when Hartmann number increases. The results also indicate that there are critical values for Raleigh number and the magnetic field orientation at which the impacts on flow and heat transfer are the most pronounced.

Thermal condition is crucial to the safety and performance of battery and battery pack. In this work, a two–dimensional, axisymmetric, electrochemical–thermal coupled model of 18,650 lithium–iron–phosphate battery is established and validated by our own experimental results. The model is used to investigate the effect of ambient temperature on battery performance and heat generation. The results show that the temperature rise in the battery increases with decreasing ambient temperature, which is mainly due to the increase in heat generated from Ohmic loss and polarization with decreased ambient temperature. While considering the welded structure, in which the cylindrical batteries are assembled into a battery pack, the effect of spot–welded nickel strip on battery performance under different discharge rates is experimentally studied at the ambient temperature of 298.15 K. It is found that the battery with the spot-welded nickel strip has a lower discharge plateau and a higher heat generation rate. The nickel strip has a greater impact on battery performance and temperature if the discharge C-rate increases.

Due to its distinctive characteristics nanofluid has drawn much attention from academic communities since the last decade. Compared with conventional fluids, nanofluid has higher thermal conductivity and surface to volume ratio, which enables it to be an effective working fluid in terms of heat transfer enhancement. Recent experimental works have shown that with low nanoparticle concentrations (1–5 vol.%), the effective thermal conductivity of the suspensions can increase by more than 20% for various mixtures. Although many outstanding experimental works have been carried out, the fundamental understanding of nanofluid characteristics and performance is still not sufficient. Much more theoretical and numerical studies are required. Over the past two decades, the lattice Boltzmann method (LBM) has experienced a rapid development and well accepted as a useful method to simulate various fluid behaviours. In the present study, the LBM is employed to investigate the characteristics of nanofluid flow and heat transfer. By coupling the density and temperature distribution functions, the hydrodynamics and thermal features of nanofluids are properly simulated. The effects of the parameters including Rayleigh number and volume fraction of nanoparticles on hydrodynamic and thermal performances are investigated. The results show that both Rayleigh number and solid volume fraction of nanoparticles have influences on heat transfer enhancement of nanofluids; and there is a critical value of Rayleigh number on the performance of heat transfer enhancement.

In this paper, the electro-osmotic flow (EOF) in micro-porous media is investigated regarding to the flow rate caused by the combined effect of electro-osmosis force and the gravitational force. It is noticeable that the actual electro-osmosis pumping force can be achieved at flow rate of 10 μL/min in our designed system. With a constant external DC electric field supplied, in which the external electric field exerts the same effect of voltage density on the whole particle interface, the flow resistance inside the pores deceases when water entering into the electro-osmosis pumping section. Moreover, the mass flow rate by the effect of electro-osmosis pumping can be achieved at 1.49 × 10−4 g/s under 5 V DC supply. To simplify the practical flow pattern in the micro-porous media, a specific micro-channel is assumed with a compact spherical stacking-up model. To simulate this geometrical model, a modified lattice Boltzmann method is set up in order to form the electro-osmotic flow of a practical problem from our experiment. The numerical results are obtained and analysed for fitting the present model with the micro-porous media. Both the experimental and numerical results have provided some useful instructions of electro-osmosis performance for designing micro-porous channels in such as filtering the compounds of drug delivery, particle purification and liquid separation applications etc.

The lattice Boltzmann method was employed to simulate electroosmotic driven flow and Debye layer screening in conducting electrolyte around a porous structure with average size of 40 nm. The charge screening around the nanopores was investigated by solving the vector-superpositioned potential equilibrium distribution function and adding electro-kinetic force term to the evolution equation. In this intermediate case of moderate Debye length, the electrophoresis problem becomes complicated. The motion of the particles distorts the screening cloud, which becomes asymmetric, resulting in very complex interactions between the electrolyte, the screening cloud and the particle; but the Electroosmotic Flow (EOF) behaviour was still considered based on the Helmoholtz-Smoluchowski model with adaptation to fit nanoporous flow in the porous structure. In the present approach, the flow in the nanopores is directly modelled; the detailed flow information can be obtained by simplifying the repeated macrostructure. Due to the symmetry of the domain, the size of computational domain can be largely reduced by less repeated spherical nanoparticles. Each pore of the medium contains several lattice nodes on the simplified curved edges and potential gradients are produced by adjusting the zeta potential value. The velocity results for pressure-driven and EOF flows agree well with the analytical solutions and recent experimental results. In particular, the interface between solid particles and fluids, the influences of porosity, solid particle diameter, yield stress and electric parameters in EOF were investigated. The anti-adhesion effect of electroosmotic pumping effect was evaluated, and the pulsed DC was applied in order to enhance the performance of the electroosmotic pumping. The results demonstrate that the present lattice Boltzmann model is capable of modelling flow through nanoporous media at certain restrictions while some results deviate from the predictions based on the macroscopic theories.

Ferrofluid, also known as magnetic fluid, is a new-type fluid whose property and morphology can be controlled by the external magnetic field. It mainly consists of carrier fluid and suspended magnetic particles (diameter usually 10 nanometers or less). Ferrofluids behave as a smart or functional fluid and has been finding more and more applications in a variety of fields such as electronic packing, mechanical engineering, aerospace, bioengineering, and thermal engineering. It has therefore recently attracted many researchers’ interest. Due to the nanosize particles and complex interactions between the nanoparticles and carrier fluid, it is difficult to get insights into ferrofluid by pure experimental or theoretical study. To fully understand the mechanism of ferrofluid, efficient and robust computational methods for the numerical simulation of their dynamical behavior are constantly in high demand. Several numerical models have been proposed for ferrofluid. Over the last decade, lattice Boltzmann method, a new mesoscopic approach, has emerged as a powerful tool for the numerical investigation of a broad class of complex flow, including multicomponent and multiphase flows. Compared with other numerical methods, lattice Boltzmann method, which is based on kinetic theory, has advantages to deal with the interfacial interactions of multiphase flow in micro/nano scale. In the present study, we present a multicomponent lattice Boltzmann model to simulate ferrofluid. In this model, the interactions between internal and external forces of ferrofluid are considered. To validate the coupling of the magnetic field, the velocity field and the evolution of the interface, the steady-state shape of the ferrofluid droplet is analysed. Then the influence of the external magnetic field on the ferrofluid droplet formation and deformation process is numerically investigated. The parameters affecting the interfacial phenomena of ferrofluid, including the magnetic Bond number and the susceptibility, are discussed in this paper. The change in the droplet size and the magnetic strength is simulated. The simulation results show the ferrofluid droplet size increases with increasing magnetic strength. All the results are also compared with previous numerical or experimental studies. The simulation results presented in this paper indicate that lattice Boltzmann method is a capable method to study complex magnetic fluid phenomena. It is also hoped that the simulation results offer helpful information on controlling ferrofluid in our practical applications.

The superhydrophobicity of the microchannels are dependent not only upon the surface energy of the wall but also closely related to the micro- and/or nano-structures on their surfaces. Recent experiments have found that superhrydrophobic surfaces can be achieved by pattering roughness on hydrophobic surfaces. In this paper, the wettability of droplet on microchannel with different wettability and surface micro-structures is numerically studied by using lattice Boltzmann method (LBM). In particular, the effects of different kinds of surface micro-structures on the superhydrophobicity are analyzed. The simulation results show that the surface micro-structures have a significant influence on the wettabiltiy on the solid surfaces. Also, the results have manifested that LBM has a good application prospect in the study of wettability in micro- or nano-channels.Copyright © 2011 by ASME

This paper studies the roughness effect of the two-dimensional micro Poiseuille gas flows in a curved channel by a modified lattice Boltzmann model. A method relating to the Knudsen number (Kn) with the relaxation time is discussed. In addition, to capture the slip velocity on a solid boundary more accurately, a combined boundary scheme (CBC), which combines the no-slip bounce-back and the free-slip specular reflection schemes, is applied to boundary condition treatment. The rough wall of the micro-channel is described by uniformly distributed rectangular or triangular rough elements. The simulation results show that the roughness and the geometries of the channel have great effects not only on velocity distribution but also on pressure distribution.Copyright © 2009 by ASME