Mixture Flow Rate Research Articles

Performance of a two-stage ejector with varying liquid fraction at its inlet

Liquid volume fraction (LVF) in a two-phase flow has a certain effect on the flow performance. In this paper, a two-stage ejector applied to a multi-evaporator refrigeration system was proposed by the authors, in which, the refrigerant of R134a is used and then the effects of different LVF in the two-stage ejector inlet on the two-stage performance were studied by using CFD simulation, which is the novelty of this study. One of the main contributions is that the reason for the changed performance of each stage was explained by analyzing the volume flow rates, density and mass flow rates of the two-phase mixture when the LVF of one, two or three inlets varied. The results show that: (1) when the LVF of one inlet increases, the two-phase mass flow rate can be increased evidently due to the significant increase of the density of the mixture; (2) if one inlet fluid is in two-phase, the improvement of the LVF in the first-stage secondary flow, the performance of the first-stage as well as the second-stage can be improved; (3) if two inlet flows are in two-phase, the increase of the LVF of the two inlet flows of the first-stage with the same proportion can offer the best performance to both stages; and (4) when the LVF of three inlet flows increase from 0.04 to 0.12 with the same proportion, the ER of both stages can be increased evidently.

In situ diagnostics of the Si etching structures profile in ICP SF6/C4F8 plasma: Macrostructures

In this work, we studied the influence of technological parameters of plasma chemical etching of silicon on silicon etching rate, photoresist etching rate, etching selectivity of silicon in relation to a photoresist, and sidewall angle of etched structures. It was found that the silicon etching rate increases with raising percentage of SF6 in the gas mixture (25%–50%), pressure (1–2.5 Pa), high-frequency (HF) power (1000–2000 W), and bias voltage module (15–75 V) and decreases with a raising total flow rate of the gas mixture (5–35 SCCM) due to the increasing passivation efficiency of the sample surface. The etching selectivity increases with a raising percentage of SF6 and pressure and decreases with the raising total gas flow rate, HF power, and bias voltage module due to different influences of technological parameters on the photoresist etching rate. In addition, based on the obtained results, a common regularity between the sidewall angle and the optical emission spectra was revealed. The method of in situ diagnostics was proposed, namely, controlling the sidewall angle by a ratio of emission intensities of a carbon line (517.1 nm) to a fluorine line (685.8 and 703.9 nm) designated as parameter X. It was found that the sidewall angle of etched structures takes certain values depending on the value of the X parameter. The ranges of X values at which the sidewall angle is acute, right, and obtuse were estimated. So, at values of X from ≈0.15 to ≈0.35, an acute angle (from 81° ± 0.5° to 89° ± 0.5°) is obtained; at X from ≈0.35 to ≈0.42, a right angle is obtained (90° ± 0.5°); and at X from ≈0.42 to ≈0.75, the values of the sidewall angle are in the range from 91° ± 0.5° to 94° ± 0.5°, no matter which technological parameters were set. Experiments were conducted for etching windows with linear dimensions from 0.5 × 20 to 2 × 20 mm.

Simulating the Influence of a Flow-Through Device for Milk Quality Analysis on The Flow Rate in the Milking Machine

The development of dairy farming proves to require technologies for rapid and non-destructive analysis of milk quality. It is noted that optical methods do not negatively affect dairy products. It is noted that farms may get the desired technology by upgrading milking machines with a flow-through device for milk quality express analysis. (Research purpose) To study the effect of upgrading the milking machine with a flow-through device for milk quality express analysis on the flow of the milk-air mixture in the milk hose. (Materials and methods) For this purpose the SolidWorks simulation modeling was used. Both the developed device and the simulation model are made in cylindrical geometry to ensure their compatibility with the milk hoses of 14 millimeters in diameter. The measurement took into account the angular distribution of light scattered by milk flowing inside an optically transparent cylindrical glass tube. The flow of the milk-air mixture was affected only by a change in the inner diameter of the milk tubes. (Results and discussion) It is noted that the simulation model demonstrates an increase in the flow rate of the milk-air mixture in the areas of flow transition between the milk hose and the fitting (to a smaller internal diameter), as well as between the fitting and the measuring chamber of the device (to a larger internal diameter). The mirror result is recorded at the flow outlet from the measuring chamber to the nozzle and the transition from the nozzle to the milk hose. (Conclusions) It is found that the use of the device results in a 14 percent increase in the average flow rate of 0.3-0.7 meters per second. It is determined that due to the incomplete filling of the milk hose during milking, the difference in the flow rates of the milk-air mixture before and when applying the device does not have any adverse impact on the milking machine operation. The feasibility of upgrading the milking machine with a flow-through device for milk quality express analysis is proved.

MODELING OF THE PROCESS OF MEASURING CONVERSION OF THE FLOW OF LIQUID AND GASEOUS MEDIA BY THE METHOD OF VARIABLE PRESSURE DROP

On the basis of material and heat balances, taking into account the initial and boundary conditions, a mathematical model of the process of measuring the transformation of liquid and gaseous technological media by the method of variable pressure drop is constructed. The analysis of the results of studying the influence of non-stationary flows of a controlled medium on the uncertainty of the results of measuring the flow rate of liquids and gaseous mixtures with a changing hydrodynamic structure of the flow of a controlled medium is performed. A comparative analysis of the calculated and experimental transient processes in the measuring channel of the primary converter was performed, which showed good agreement between the compared data.

Coherent Anti-Stokes Raman Scattering Measurements of Time and Length Scales of Temperature Fluctuations in a Turbulent Flame.

The ability to derive temporal and spatial scales of "instantaneous" local temperature variations in a turbulent flame by means of coherent anti-Stokes Raman scattering (CARS) spectroscopy is demonstrated, for the first time to our knowledge. The measurements employed two CARS spectrometers with synchronized nanosecond pulse-repetitive lasers. The system was enabling to record, with a high temporal resolution of about 10 ns, series of single laser shot CARS spectra of N2 molecules from two spatially overlapped or displaced probe volumes as small as 0.03 × 0.03 × 2 mm3. The spectra were being recorded at a variable delay between two sequential shots, following each other in pairs at a repetition rate of 10 Hz. The series of 500 coupled measurements, at the delays in the range 1 μs-10 ms and the displacements up to 2.5 mm, have been performed in a few points of an open premixed methane-air flame of a laboratory burner with the time-averaged temperatures in the range 1200-1800 K. From the spectra, "instantaneous" temperatures, at the given delay and probe volume distance, have been derived. This allowed the auto-correlation coefficients of temperature fluctuations versus the delay and the displacement to be calculated. These dependences enabled to evaluate temperature correlation times and lengths under various mixture flow rates and equivalence ratios.

Dry Reforming of Methane Using a Swirl-Induced Plasma Discharge Reactor

This study reports the dry reforming of methane (DRM) using non-thermal plasma in a swirl-induced point-plane electrode discharge reactor to produce syngas. This reactor geometry facilitates better mixing of the reactant gases in the plasma region, thus increasing the residence time and conversion of the reactants. The effect of varying flow rates and compositions of CO2/CH4 (v%/v%) on conversion was studied. A high-voltage AC power input of 50 W and 70 W at a frequency of 19 kHz was provided. The voltage–current characteristics with respect to time were studied. The results show that with an increase in the flow rate of the gas mixture from 0.5 to 2 LPM the conversion of both CO2 and CH4 decreases, while an increase in the concentration of CO2 or CH4 (from 25 to 75%) increases the conversion of the respective reactant. The products, viz. syngas (CO and H2), C2 hydrocarbons, and solid carbon, were characterized and quantified. The maximum total conversion of 44% was obtained for a CO2:CH4 ratio of 25:75 (v%/v%) at a flow rate of 0.5 LPM. The solid carbon collected from the reactor walls was analyzed, and it was found to be 89.9% pure with traces of oxygen functionality. The increase in flow rate decreased the specific energy input, which eventually resulted in lowering the energy cost.

A Turbidity Module to Measure Spray Mixture Concentration for Premixing In-Line Injection System

Highlights A turbidity sensor module was investigated to monitor concentrations of pesticide mixtures in real time. A flow-through measurement platform was built to calibrate the turbidity sensor and determine its accuracy. Optimal location of the turbidity sensor was determined for monitoring in-line mixture concentrations. Spray mixture uniformity reached acceptable level for the premixing in-line injection system. Abstract. Monitoring mixture concentrations for precision pesticide spray systems in real time can assure the desired amount of chemicals distributed uniformly to target areas. An in-line turbidity sensor module was investigated to monitor concentrations of spray mixtures produced with a premixing in-line injection system developed for precision variable-rate orchard sprayers. The turbidity sensor was calibrated with simulated pesticides at concentrations ranging from 0% to 30.0%. A cubic polynomial regression model was established for the relationship between sensor output voltages and mixture concentrations. Sensors were mounted at three in-line locations to detect the mixture uniformity differences in the premixing in-line injection system. The module was found to have adequate precision and accuracy to measure concentrations of spray mixtures with simulated pesticides. Relative errors of the sensor were less than 4.70% and the sensor accuracy did not vary with mixture flow rates. Mounting the turbidity sensor downstream of the buffer tank in the premixing in-line injection system would be the optimal location to monitor spray mixture uniformity for variable-rate spray applications. At this location, the relative errors of measured mixture concentrations were between 0.12% and 3.70% which agreed with previous manual measurements. Therefore, there would be a great potential to integrate the in-line turbidity sensor into the variable-rate and even conventional constant-rate sprayers to achieve uniform spray applications in the target field. Keywords: Agitation, Mixture uniformity, Pesticide concentration, Sensor calibration, Variable-rate sprayer.

COMPUTER MODELING AND EVALUATION OF THE POSSIBILITY OF CONTROLLING THE CATALYTIC PROCESS IN THE POLYTROPIC MODE OF OPERATION OF A TUBULAR REACTOR

The results of the development of a mathematical model for quantifying the current profile of the conversions of the key component of a chemically active reaction gas mixture in the course of its movement in a polytropic tubular reactor of the "pipe in a pipe" type are presented. The volume of the inner tube of the reactor is filled with catalyst granules and is an exothermic chemical reaction zone. To develop models of concentration and temperature fields in the reaction zone, the corresponding balance differential equations were used. Such a mathematical model allows for an operational analysis of the technological regime of the reactor when preparing initial data for the design and development of an automatic control system. For computer simulation, the mathematical description of the reactor is represented by a system of differential equations in the form of a Cauchy. The model was tested on the example of evaluating the process of catalytic contact oxidation of sulfur dioxide in a reactor with a direct-flow circuit of heat carriers and the return of a heated initial gas mixture to the inlet of pipes with a catalyst. The obtained dependence of the conversion on the temperature during the course of the reactor has a characteristic form that coincides with that described in the literature sources. A structural model of the automatic control system of a polytropic tubular reactor is proposed, which is oriented to the use of computer simulation. The model of the automatic control system was tested on a specific example of stabilization of the conversion of sulfur dioxide at the reactor outlet with an unstable flow rate of the initial gas mixture at the inlet. To assess the capability and quality of the developed control system, the SimInTech dynamic modeling environment of technical systems was used. It is assumed that the mathematical model developed in the article can be used to create adaptive or self-adjusting process control systems that use tubular reactors. For citation: Andreev A.S., Aksenchik K.V. Computer modeling and evaluation of the possibility of controlling the catalytic process in the polytropic mode of operation of a tubular reactor. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 2. P. 120-127. DOI: 10.6060/ivkkt.20236602.6727.

Numerical study of pressure profiles in an annular combustor and a manifold during continuous spin detonation of nonstoichiometric hydrogen-air mixtures

A closed mathematical model of continuous spin detonation of nonstoichiometric hydrogen-air mixtures in a quasi-three-dimensional unsteady gas-dynamic formulation taking into account the reverse effect of the oscillation processes in the combustor on the mixture injection system is utilized in pressure profiles in the combustion chamber and in the manifold investigation. Numerical simulations are performed for the flow-type annular combustor 503 mm in diameter with an annular gap of width 18 mm and other geometric dimensions corresponding to experiments. Three-wave mode of continuous spin detonation is calculated and the flow structure is analyzed for the equivalence ratio of 0.6 and the specific hydrogen-air mixture flow rate of 390.6 kg/(s·m2). The static, the mean static and the mean total pressure distributions in the combustor are calculated. The results are validated against experimental data.

Modeling Isothermal Reduction of Iron Ore Pellet Using Finite Element Analysis Method: Experiments & Validation

Iron ore pellet reduction experiments were performed with pure hydrogen (H2) and mixtures with carbon monoxide (CO) at different ratios. For direct reduction processes that switch dynamically between reformed natural gas and hydrogen as the reductant, it is important to understand the effects of the transition on the oxide reduction kinetics to optimize the residence time of iron ore pellets in a shaft reactor. Hence, the reduction rates were studied by varying experimental parameters such as the temperature (800, 850 & 900 °C), reactant gas flow rate (100, 150 & 200 cm3/min), pellet size and composition of the reactant gas mixture. The rate of reduction was observed to increase with an increase in temperature and reactant gas flow rate, but it decreased with an increase in pellet size. SEM greyscale analysis was performed to analyze the porosity and phase composition of partially reduced pellets. The porosity of the pellets was observed to increase from 0.3 for unreacted pellet to 0.42 for a completely reduced pellet. Energy-dispersive X-ray spectroscopy (EDAX) analysis was performed to identify the phases observed in the SEM images. The fraction of iron phase was observed to increase from the shell region of the pellet to the core region with an increase in the degree of reduction. A 2D-axisymmetric numerical model was developed on COMSOL Multiphysics, and it was validated using the conversion (X) vs. time curves obtained from each experiment. The model was able to accurately predict the total time needed for the complete conversion of a single iron ore pellet for multiple experiments. Effects of changes in the porosity and tortuosity of the pellet on the model were also studied and the rate of reduction was observed to be sensitive to changes in both porosity and tortuosity. The SEM analysis and the model results show that tortuosity is higher for pellets reduced with H2 than for pellets reduced with H2-CO gas mixtures.

Effect of non-condensable gas on submerged steam jet condensation in a narrow pipe

A visualization study was performed to investigate the effect of non-condensable gas on stable submerged steam jet condensation in water flow in a narrow pipe. The direct contact condensation (DCC) characteristics including jet plume shapes, dimensionless penetration length and average heat transfer coefficient were analyzed in a wide range of water flow subcooling, Reynolds number of water flow and steam–air mixture flow rates. As four different steam plume shapes for pure steam jet in subcooled water flow in a pipe were reported in the previous research, the effect of non-condensable gas on the four steam plume shapes was investigated by introducing a certain amount of air into steam. In the current study, the submerged steam–air mixture jet behavior was investigated through direct visualization techniques. The effect of non-condensable gas on jet plume shapes was recorded by using a high speed camera. The gas–liquid interface and the dimensionless penetration length was obtained by digital image processing method implemented by a MATLAB subroutine. Then the average heat transfer coefficient was calculated based on thermal equilibrium of gas–liquid interface. In the experiment, the gas mass flux at nozzle exit was within 320–780 kg/m2/s, with no more than 1 % non-condensable gas. The results indicated that the non-condensable gas plays an important role on the gas–liquid interface, jet penetration length and heat transfer coefficient. It was found that when 1 % non-condensable gas was mixed with steam jet, the dimensionless penetration length was extended by 16–70 %, and the average heat transfer coefficient decreased by 12–50 %. Based on the force-balance of jet plume, a new quantitative correlation for the steam–air mixture jet penetration length was proposed. The predicted jet penetration length agrees well with the experimental measured values.

The Investigation of Gas Distribution Asymmetry Effect on Coriolis Flowmeter Accuracy at Multiphase Metering.

Multiphase flows are encountered in various industries, and the Coriolis flowmeter (CFM) is considered a high potential flowmeter for the metering of these flows. However, the decoupling effect and asymmetrical gas distribution in a CFM might decrease the accuracy of its multiphase flow metering The asymmetry of gas distribution in a CFM and its influence on the metering accuracy have only been qualitatively investigated in a few studies. The present paper quantitatively describes the gas distribution asymmetry in several CFMs under different flow conditions by numerical simulation. The simulation methodology is developed and validated by a results comparison with a conducted experiment and published data for bubbly, stratified and transitional flow regimes. U-shaped and triangle-shaped CFMs of different diameters are investigated at different gas volume fractions and flow rates. It is shown that the increase in the gas volume fraction and the reduction in the mixture flow rate lead to the increase in the gas distribution asymmetry. The strong correlation between the gas distribution asymmetry and the experimentally observed CFM error is demonstrated. The correction of the CFM error is proposed based on this correlation allowing the metering error to be decreased from 34% to 10% for the investigated conditions.

Numerical study on the extinction dynamics of partially premixed meso-scale methane-air jet flames with hydrogen addition

In this paper, a model of partially premixed jet flames that sustained above a meso-scale short tube was established for an individual flame port of domestic gas stoves. The effects of hydrogen addition (volume ratio β = 0%, 10%, 20%, 30%) on the extinction dynamics of CH4-air jet flames were numerically investigated. It is found that flame oscillation occurs once (β = 10% and 20%) or twice (β = 30%) in the extinction process. Moreover, the larger of β, the longer the extinction process can sustain. Analysis was performed in terms of both chemical effect and thermal effect. As to the chemical effect, in the first place, the reaction rate decreases as the inlet velocity is reduced. As a result, the consumption rate of O2 will be less than the supply rate from the incoming mixture, which makes the O2 concentration in the flame center increase. On the other hand, the amount of H radicals increases with the increase of β, and when the O2 content at the flame center reaches a “critical point”, the key elementary reaction “H + O2 ↔ O + OH” will be enhanced and consequently the total reaction rate will also be intensified. After that, the consumption rate of O2 will be larger than the supply rate due to the reduced flow rate of incoming mixture. The total heat release rate will decrease sharply and extinction occurs. As regards the thermal effect, it is revealed that heat recirculation effect (indirect preheating effect) lags behind the variation of the reaction zone (i.e., flame), thus, it has a negligible impact on flame oscillation. In contrast, the preheating temperature in the vicinity of flame front (named as “direct preheating effect”) exhibits a similar variation tendency with the total heat release rate of the flame. And the larger of β, the more remarkable of the direct preheating effect can be. In summary, due to the chemical effect and thermal effect caused by hydrogen addition, the flame can survive for a longer time with fluctuation during the extinction process.

Design of Experiments as a Tool to Optimize the Process of Coating Minitablets with Commercial Gastro-Resistant Coating Mixtures.

According to the Quality by Design (QbD) concept, Design of Experiment (DoE) was used to indicate critical process parameters and optimize the fluid bed coating of minitablets in a laboratory size batch. Full factorial design was employed to increase knowledge of the process for three kinds of minitablet (MT) cores using two commercial gastro-resistant coating mixtures. The statistical analysis showed that different critical process parameters were indicated for the tested minitablets: X3: the coating mixture flow rate for MTs with pantoprazole sodium and Eudragit L; X2: the product temperature; X3 and X4: the spraying pressure for MTs with pantoprazole sodium and Acryl Eze II; and X1 and X2: MTs with diclofenac sodium. Such differences were the result of features, such as the sub-coat, size, and mass of the cores and the core and coating mixture composition. No optimal parameters were found for any of the tested MT types. Therefore, DoE should be considered as a statistical tool to individually optimize the process for the product, equipment, and tested parameters. However, optimization of the fluid bed coating allowed us to predict the values of the process parameters necessary to obtain good-quality products. Therefore, fluid bed coating may be successfully used to obtain modified-release MTs of high quality after applying the statistical tool DoE.

Thermal performance of water‐based brines as a heat carrier for ground heat exchanger under severely cold environments

AbstractThe aim of the present study is to investigate the performance of water‐based brine solutions in the ground heat exchanger (GHX) for space heating applications under severely cold climate conditions. The conventional ethylene glycol (EG) and propylene glycol (PG)‐based water solutions have been considered for investigation. For the closed‐loop vertical U‐tube GHX, a mathematically built model is developed for ambient temperature below 0°C. The thermal performance analysis of GHX is carried out for the variation in fluid flow rate and brine solutions for different mixture percentages of water in EG and PG. The percentage of the mixture and fluid flow rate varied from 25% to 60% and 0.2 to 0.6 LPS, respectively. GHX performance parameters, namely convective coefficient, pressure drop, borehole resistance, and GHX effectiveness are determined for both EG and PG brines. Better performance of GHX is noticed with EG brines as compared to PG brines for similar operating conditions. The drop in convective coefficient from 22% to 44% in the case of PG brines as compared to EG brines with the increase in mixture percentage from 25% to 60%, for the same operating conditions. The pressure drops decreased from 15% to 74% for EG mixture as compared to PG mixture at considered flow rate and mixture percentage. The effectiveness and overall borehole resistance were higher for EG as compared to the PG solution.

Optimization of the gas-air path system parameters for trapping automotive fuel vapors

Introduction (statement of the problem and parameters relevance). The composition of the mixture of air and gasoline vapors differs in air and vapors ratio when purging the absorber at different time of the car operation. Therefore, the air-fuel mixture entering the engine for afterburning can create uncertainties in lambda control.The purposeof the research was to determine the main features of lambda regulation in an unstable fuel-air mixture.Methodology and research methods. An analysis of the mixed air and fuel vapor flows entering the engine during absorber purge was made. The composition and quantity effect of this mixture on the excess air coefficient was determined. The main parameters of air and gasoline vapor mixture in the fuel tank vapor space were established.Scientific novelty and results. An equation obtained testifies that the excess air coefficients in the flows of the fuel-air mixture relate to the mixture flow rate during absorber purge. The requirements for the composition of the fuel-air mixture leaving the absorber have been formulated. In order not to exceed these values the threshold values of short-term fuel supply were corrected and the relative mass flow value rate of gasoline vapors from the tank in relation to the air flow rate purge was determined.Practical significance. The factors limiting the flow sections of the absorber gas-air paths and the optimal ratios of the flow sections were determined on the example of a two-chamber absorber to exclude excessive enrichment of the fuel-air mixture entering the engine during purge.

Performance and emission characteristics of a diesel engine with on-board produced hydrogen-oxygen injection

In this research, experimental study is conducted on a generator connected to a diesel engine to enhance the performance and reduce the emissions using on-board produced H2/O2 gas mixture. The H2/O2 gas mixture is generated and supplied by a HYDI unit, which uses electrolysis of water to produce the required H2/O2 mixture. It is found that through the addition of the H2/O2 mixture via the inlet air there is significant reductions in the exhaust emissions of PM concentrations. The average reductions in PM concentrations are 10.34%, 24.77% and 41.05% across the load range at H2/O2 mixture flow rates of 0.42 LPM, 0.84 LPM and 1.25 LPM, which are equivalent to 0.022%, 0.045% and 0.067% hydrogen energy substitution (HES), respectively. The maximum reduction in exhaust emission of PM concentrations is 56% at 115.4% of the rated load with H2/O2 mixture flow rate of 0.067% HES. It is also found that there are slight reductions in the exhaust emission of CO. The average reductions in CO emissions are 5.50%, 3.40% and 2.32% across the load range at H2/O2 mixture flow rates of 0.022% HES, 0.045% HES and 0.067% HES, respectively. Since the maximum flow rate of H2/O2 gas mixture is only 0.067% HES, there is little or no change of fuel mass flowrate, thermal efficiency and bsfc. The power needed to produce H2/O2 gas mixture is provided by the battery/alternator. It only uses a little amount power of 360 W and there is no issue to start the generator after overnight shutdown. The storage and consumption of water do not possess any issue as it only consumes 0.974 L of water for 24-hours operation.

An investigation of a gas–liquid swirling flow with shear-thinning power-law liquids

A gas–liquid swirling flow with shear-thinning liquid rheology exhibits complex behavior. In order to investigate its flow characteristics, experiments and computational fluid dynamics (CFD) simulations are conducted based on dimensional analysis. A Malvern particle size analyzer and electrical resistance tomography are applied to obtain the bubble size distribution and section void fraction. A Coriolis mass flowmeter is applied to obtain the mixture flow rate and mixture density for an entrance gas volume fraction smaller than 7%. The CFD coupled mixture multiphase model and large eddy simulation model are applied, considering the liquid shear-thinning power-law rheology. The results show that the swirling flow can be divided into developing and decaying sections according to the swirl intensity evolution in the axial direction. A gas–liquid swirl flow with shear-thinning liquid prohibits a core-annulus flow structure. A smaller index n contributes to maintaining the development of the swirl flow field and its core-annulus flow structure so that the swirl flow can form over a shorter distance with a stronger intensity. For a more uniform distribution of the apparent viscosity, the gas column in the pipe center is thinner. On the other hand, a larger consistency k enlarges the stress tensor. The amplitude of the velocity and the pressure of the core-annulus flow structure are reduced. A weaker swirl intensity appears with a wider gas column appearing as a consequence. Furthermore, the swirl number decays with an exponential behavior with parameters sensitive to the consistency k and index n of the decaying section of the swirling flow field. These are beneficial to gas–liquid separator design and optimization when encountering the shear-thinning power-law liquid phase in the petroleum industry.

Model Test of the Water and Sand Mixture Inrush in the Mining-Induced Caving Zone

In western China coal mines, the mining-induced caving zone is regarded as a main pathway for water and sand inrush mixture hazards. The paper experimentally studied the flow behavior and the mechanism of water and sand mixture through mining-induced caving zones. Transport experiments are performed by using a laboratory-scale model, and the caving zone is modelled by using different sizes of glass beads. Four different sand sizes are used for the sand layer. The test results reveal that the mass flow rate of sand and water mixture increases with the increase of the initial water head. And an equation is proposed for the mass flow rate of sand and water mixtures that correctly reproduces the data for all the conditions. In addition, the sudden decreases in water head loss is monitored at the commencement of the water and sand flow, which would result in a large number of sand particles that rapidly start up and make the kinetic energy transfer from water to sand.

1D model for n-butane adsorption and thermal variation for EVAP canister of gasoline-fueled vehicles: Validation with experimental results and DFSS optimization

Gasoline evaporation from vehicle fuel tanks is a major source of VOCs, that represents a serious threat for both human health and environment. To limit these emissions, the most adopted strategy is to use a carbon canister filter to store fuel vapors and then burn them inside the engine along with the fresh charge. However, the canister saturation level is usually unknown, and it can easily reach the full saturation, especially in particular conditions. As hybrid vehicles are becoming more popular in the market, this issue becomes even more important, since canister purging phase has even less time to be performed. In this activity, a 1D transient, non-isothermal, non-adiabatic model has been developed to specifically simulate the carbon canister filter of a common EVAP system and analyze its behavior during fuel vapor adsorption, with particular attention to the mutual influence of carbons adsorption performance and temperature variation. The model presented is based on an adsorption isotherm derived from the potential theory of adsorption, and it has been developed to be usable with only few canister properties. A system of two coupled PDEs has been coded and solved in MATLAB® environment, and results have been compared to experimental data in terms of mass and internal temperature variation on a common European canister, found in a previous study, with a standard loading flow rate of n-butane mixture and standard environmental temperature. The model has then been analyzed by using the Design For Six Sigma (DFSS) method, which has allowed a good optimization on calibration parameters with a relatively low amount of tests. Results show a significant increment in the predictive capabilities of the optimized model (up to 90% of the experimental value), with respect to the first simulations. This model helps to understand and evaluate the influence of environmental temperature on the canister filter performance, and can be used for both canister design and control of the purging strategies performed by an on-road vehicle.