Evaluation of the Air Leakage Flowrate in Sintering Processes

Iron ore sintering is a pre-treatment technology by which orefines are converted into porous and permeable sin-ters,which are the used in blast furnaces.This process can be adversely affected by air leakage phenomena of various types.As experimental measurements are relatively difficult and often scarcely reliable,here a theoretical model based on typicalfluid-dynamic concepts and relationships is elaborated.Through the analysis of two extreme cases,namely,those in which leakage is due to a small hole or a full rupture,a generalized hole-bed mod-el is introduced,which for thefirst time also includes a complete bed permeability equation and can deal with different leakage position conditions.The results show that the model can evaluate the influence of leakage on the system at one time and be used to calculate theflowrate and pressure drop.Notably,the obtained results are within a 15%deviation with respect to available experiment values,used for comparison.

Flowrate behavior and clustering of self-driven robots in a channel

In this paper, the collective motion of self-driven robots is studied experimentally and theoretically. In the channel, the flowrate of robots increases with the density linearly, even if the density of the robots tends to 1.0. There is no abrupt drop in the flowrate, similar to the collective motion of ants. We find that the robots will adjust their velocities by a serial of tiny collisions. The speed-adjustment will affect both robots involved in the collision, and will help to maintain a nearly uniform velocity for the robots. As a result, the flowrate drop will disappear. In the motion, the robots neither gather together nor scatter completely. Instead, they form some clusters to move together. These clusters are not stable during the moving process, but their sizes follow a power-law-alike distribution. We propose a theoretical model to simulate this collective motion process, which can reproduce these behaviors well. Analytic results about the flowrate behavior are also consistent with experiments.

The Measurement of Oil,Gas and Water Flowrates in Three-Phase Slug Flow

Three-sphase flow invo1ving oil-water two immiscible liquids and gas which is often foundin the fields of petroleum production has been studied in this paper.A new method with thecombination of a horizontal tube,a downward flow vertica1 tube and an orifice to measure theflowrates is presented.In this method the frictional pressure drop in the downward vertical tube isreplaced by that in the horizontal tube,the void fraction is derived from the gravitational pressuredrop,then the volume fraction of the individual phase can also be obtained.The individual flowratescan be calculated when the water fraction is known.This method is applicable for many kinds ofoil-wells to measure the flowrates of crude oil,natural gas and water.Compared with other methods,the presented method involves fewer measuring parameters.The experimental results proved quitegood accuracy of the method,with measurement deviation within 10%,and reliable results wereobtained under high Dressure conditions.

An experimental study on flowrate and stability for 600MW supercritical steam-turbine control valve

An experimental study on flowrate and stability of a type of control valve of 600MW supercritical steam-turbine was presented by measuring instruments of static, dynamic pressure and vibration in self-designed test rig. The investigation shows that flow coefficient is 30% up more than that of the control valve of GX-1 type used widely in domestic power plants now, as small-medium lifts. If the relative lift (h/D) is less than 20%, the valve can always work steadily in all the pressure ratios. When the h/D is between 20% to 24%, big vibration of valve stem occurs if the pressure ratio is between 0.7 to 0.8. When h/D is more than 25%, relatively great vibration happens in a wide range of pressure ratios of 0.4 to 0.85.

INFLUENCE OF CAPILLARITY ON NANO-LITER FLOWRATE MEASUREMET WITH DISPLACEMET METHOD

Nanoqiter flowrate measurements in micro-tubes with displacement method were performed and the effect of capillarity force on the accuracy was investigated through lab experiments and theoretical analysis in this article. The experiments were conducted under the pressure drops ranging from 1 kPa to 10 kPa in a circular pipe with a diameter of 50 pm, to give the pressure-flowrate （P-Q） relation and verify the applicability of the classical Hagen-Poiseuille （HP） formula. The experimental results showed that there existed a discrepancy between the experimental data and the theoretical values predicted by the HP formula if the capillary effect was not considered, which exceeded obviously the limit of the system error. And hence a modified formula for the relation, taking the capillary effect into account, was presented through theoretical deduction, and after the HP formula had been modified the error was proved to be less than 3%, which was permitted in comparison with the system error. It was also concluded that only by eliminating the effect of the capillary force in experiments could the original HP formula be employed to predict the pressure-flowrate relation in the Hagen-Poiseuille flow in the micro-tube.

A novel low pressure-difference fluctuation electro-hydraulic large flowrate control valve for fuel flowrate control of aeroengine afterburner system

To address the control accuracy of large fuel flowrate during pressure fluctuation,a novel electro-hydraulic fuel metering unit(FMU)is constructed for afterburner fuel system of military aeroengine.Different from the previous FMU,the proposed FMU can achieve the higher precision opening control by a new metering valve with double control chambers(MVDCC),and realize the lower pressure difference fluctuation regulating by a novel two-stage constant pressure difference compensated valve(CPDCV)with dynamic damping orifice and damping piston.The experimental and AMESim simulation results verify the validity and superiority of the novel FMU.Since the temperature-induced variation in fuel properties and device capabilities may degrade or even impair the properties of novel FMU,the discharge flowrate is analyzed by global sensitivity analysis to research the effect proportion of each factor,the temperature effect is explored to ensure the working reliability in long-span temperature variation.Finally,the optimization of structure parameters for novel CPDCV can further reduce pressure difference fluctuation during pressure regulation,and the overshoot,adjust time and the integral of time multiplied by absolute value of error(ITAE)can be reduced by 24%,30%and 26%,respectively.This paper provides a reference for improving the stability of large flowrate during pressure fluctuation.

Electrochemical drilling of small holes by regulating in real-time the electrolyte flowrate in multiple channels

Electrochemical drilling(ECD)provides an alternative technique for drilling multiple small holes in difficult-to-machine materials in numerous industrial applications such as for aeroengines.The value and fluctuation of electrolyte flowrate can seriously affect the machining stability and hole quality in ECD.In particular,when drilling multiple holes,the distribution and fluctuations of the electrolyte flowrate in each channel could influence the uniformity of the electrolyte flowrate among multiple tube electrodes,thereby affecting the machining stability and the maximum feed rate.Thus,an eight-channel flow control system was developed to measure and regulate in real time the electrolyte flowrate supplied into each individual tube electrode.This paper proposes ECD of small holes with real-time flowrate control to improve the uniformity of electrolyte flowrate in each tube electrode and reduce the fluctuations in the electrolyte flowrate.In single-hole drilling,when the electrolyte flowrate was regulated in real time,the hole quality and machining stability were considerably better than without regulation.This is because the electrolyte flowrate remains basically constant,which stabilizes the flow field.Moreover,by considering the hole profile,it was found that an electrolyte flowrate of 200.0 m L/min can be acceptable for ECD of small holes.When the eight-channel flow control system was used in multiple-hole drilling,the uniformity of the electrolyte flowrate in each tube electrode was obviously improved,which led to a more stable process.Additionally,the maximum feed rate can attain 2.40 mm/min in multiple-hole drilling.Based on these findings,a matrix(5×32)of multiple small holes was successfully fabricated with a satisfactory diameter consistency,as the machining stability and machining efficiency had been enhanced.

Non-intrusive flowrate measurement and monitoring system of plant-protection unmanned aircraft systems based on pump voice analysis

Application of Unmanned Aircraft Systems(UAS)for plant protection is becoming a common tool in agricultural field management.To avoid shortcomings of intrusive flowrate sensors including poor measurement accuracy and poor anti-vibration ability,a non-intrusive flowrate measurement and monitoring system of plant-protection UAS was developed based on pump voice signal analysis.It is mainly composed of STM32 processor,microphone and signal-conditioning circuit.By collecting and analyzing the voice signal of the pump in the UAS,the monitoring system will output the real-time values of spraying flowrate and amount.An extraction model was developed to determine operation status and primary frequency of the pump based on voice signal analysis.Real-time spray flowrate can be determined from the real-time extracted primary frequency and the fitted correlation formulas of spraying flowrate under outlet area and pump primary frequency.The flowrate correlation equation of one certain pump from 4-rotor UAS 3WQFTX-1011S was obtained,the max deviation rate of fitted spray flowrate was only 2.8%.In primary frequency extraction test,the error rate of primary frequency extraction was less than 1%.In the 4-rotor UAS flight tests:the max deviation of operating starting/end point was only 0.7 s and the max deviation of extracted total operating time was only 0.8 s;the deviation of extracted spray flowrate was less than 2%,and the max deviation rate of total spray amount was 3.2%.This research could be used as a guidance for plant-protection UAS non-intrusive flowrate measurement and monitoring.

Flowrate Measurement in Turbulent Liquid Metal Channel Flow Using Time-of-Flight Lorentz Force Velocimetry:Experimental Investigations and Numerical Modeling

Lorentz force velocimetry(LFV)is a suitable non-contact technique to measure flow velocity and flowrates in electrically conducting high-temperature melts.LFV is based on the principles of magnetohydrodynamics:when an electrically conducting fluid passes the field lines produced by a magnet system,eddy currents are induced within the fluid.The interactions of the eddy currents with the magnetic field generate Lorentz forces.Using LFV the counterforce acting on the magnet system is measured.Such a flowmeter consists of a permanent magnet system and an attached digital force sensor.The force recorded by the flowmeter is proportional to the flowrate Q and depends on both the electrical conductivity σ of the fluid and the spatial distribution of the applied magnet field B.However,in metallurgical applications,σ is often unknown or fluctuates in time as it strongly depends on both temperature and composition of the melt.In the present paper we investigate a technique called Time-of-Flight Lorentz force velocimetry ToF LFV.In this technique,the flowrate can be determined by just cross-correlating the two force signals recorded by two flowmeters which are arranged one behind the other separated by a certain distance D.Sensing the passage of the triggered vortices, this ToF LFV measures the transit time τ of these vortices.Then we recalculate the velocity V according to the relation V = D/τ.We experimentally and numerically study turbulent liquid metal flow in the test facility EFCO(electromagnetic flow control channel)using the eutectic alloy GainSn as a test fluid.Our experiments show that this electromagnetic ToF LFV is well suited to determine the flow velocity and flowrate.The experiments are accompanied by numerical simulations using the commercial program package FLUENT.

Laminar flow of micropolar fluid in rectangular microchannels

Compared with the classic flow on macroscale, flows in microchannels have some new phenomena such as the friction increase and the flow rate reduction. Papautsky and co-workers explained these phenomena by using a micropolar fluid model where the effects of micro-rotation of fluid molecules were taken into account. But both the curl of velocity vector and the curl of micro-rotation gyration vector were given incorrectly in the Cartesian coordinates and then the micro-rotation gyration vector had only one component in the z-direction. Besides, the gradient term of the divergence of micro-rotation gyration vector was missed improperly in the angular moment equation. In this paper, the governing equations for laminar flows of micropolar fluid in rectangular microchannels are reconstructed. The numerical results of velocity profiles and micro-rotation gyrations are obtained by a procedure based on the Chebyshev collocation method. The micropolar effects on velocity and micro-rotation gyration are discussed in detail.

Effect of stress sensitivity on displacement efficiency in CO_2 flooding for fractured low permeability reservoirs

Carbon dioxide flooding is an effective means of enhanced oil recovery for low permeability reservoirs. If fractures are present in the reservoir, CO2 may flow along the fractures, resulting in low gas displacement efficiency. Reservoir pore pressure will fluctuate to some extent during a CO2 flood, causing a change in effective confining pressure. The result is rock deformation and a reduction in permeability with the reduction in fracture permeability, causing increased flow resistance in the fracture space. Simultaneously, gas cross flowing along the fractures is partially restrained. In this work, the effect of stress changes on permeability was studied through a series of flow experiments. The change in the flowrate distribution in a matrix block and contained fracture with an increase in effective pressure were analyzed. The results lead to an implicit comparison which shows that permeability of fractured core decreases sharply with an increase in effective confining pressure. The fracture flowrate ratio declines and the matrix flowrate ratio increases. Fracture flow will partially divert to the matrix block with the increase in effective confining pressure, improving gas displacement efficiency.

Synthesis of the fluid machinery network in a circulating water system

Energy consumption of the fluid machinery network in a circulating water system takes up a large part of energy consumption in the process industry, so optimization on the network will enhance the economic and environmental performance of the industry. In this paper, a synthesis approach is proposed to obtain the optimal network structure. The effective height curves are used as tools to perform energy analysis, so that the potential placement of water turbines and auxiliary pumps can be determined with energy benefit. Then economic optimization is carried out, by the mathematical model with the total cost as the objective function, to identify the branches for water turbines and auxiliary pumps with economic benefit. In this way, the optimal fluid machinery network structure can be obtained. The results of case study indicate that the proposed synthesis approach to optimize the fluid machinery network will obtain more remarkable benefits on economy, compared to optimizing only the water turbine network or pump network. The results under different flowrates of circulating water reveal that using a water turbine to recover power or adding an auxiliary pump to save energy in branches are only suitable to the flowrate in a certain range.

Rarefaction and Temperature Gradient Effect on the Performance of the Knudsen Pump

The prediction of the multiscale flow in the Knudsen pump is important for understanding its pumping mechanism.However,there is little research on such interesting multiscale phenomenon in the Knudsen pumps.In this paper,a novel numerical analysis method combining the direct simulation Monte Carlo（DSMC） method with the smoothed particle hydrodynamics（SPH） method is presented for simulating the multiscale flow,which is often encountered in the application of the Knudsen pumps.Validity and accuracy of the new method are given by comparing its results with that of the previous research.Using the coupled multiscale approach,the rarefaction and the temperature drive are studied,which are two main factors on the performance of the Knudsen pumps.To investigate the effect of rarefaction on the performance of the Knudsen pump,various pump operation pressures are compared.The flow characteristics and pumping ability at different rarefaction are analyzed,and the phenomenon of the multiscale flow is also discussed.Several cases with different linear or nonlinear temperature gradients are set to investigate the effect of temperature gradient on the performance of the Knudsen pump.The flow characteristics of the Knudsen pump such as the velocity,pressure increase,and the mass flowrate are presented.A unique phenomenon,the reverse transpiration effect caused by the nonlinear temperature gradient is studied,and the reason of the significant pressure increase in the pump channel is also analyzed.Since the multiscale gas flow is widely encountered in the microflow systems,the above method and its results can also be greatly beneficial and provide significant insights for the design of the MEMS devices.

Systematic exploration of the applicability of the idiomatic vapor balance rule to distillation column consolidation

For N-component distillation(N≥3),consolidation between different column sections is an inevitable manipulation when synthesizing complex distillation configurations.In the consolidation,the idiomatic vapor balance(IVB)rule,in which the larger vapor flowrate in the two columns before consolidation will be chosen as the balanced vapor flowrate at the consolidation point,has been widely used.However,the applicability of the IVB rule has not been verified,which is of essential importance to the accuracy of the distillation configuration synthesis.In the present study,the applicability of the IVB rule to distillation column consolidation was systematically explored by rigorous method for the first time.First,the separation of ideal and non-ideal three-component mixtures with variable compositions was studied,and the optimized configurations before and after consolidation were determined by a rigorous method.The results indicated that for the separation of an ideal mixture,the IVB rule was applicable for the whole composition range,while for the separation of a non-ideal mixture,the IVB rule was only applicable for very limited composition range.Finally,two cases of synthesizing distillation configurations for the separation of non-ideal mixtures were studied to verify the remarkable deviations the IVB rule may cause.The results indicated that the applicability of the shortcut method using the IVB rule to the distillation configuration synthesis depended on the composition of the non-ideal mixture,and a remarkable error might result and the truly optimal configuration might be missed if the IVB rule is applied to a non-ideal mixture.

Measurement of individual hypoxic sensitivity by means of mouth occlusion pressure

mouth occlusion pressure (P0.1) rather than inspiratory ventilation （V1）and mean inspiratory airflow （（?）） was used for expounding the mechanism of indi-vidual hypoxic sensitivity.Eighteen young healthy male subjects participated inthe experiment of progressive isocapnic hypoxia produced by rebreathing method.The results showed that there were significantly linear relationship （P【0.01） be-tween V1 and P0.1,as well as （?） and P0.1 during the hypoxic loading of twoend-tidal carbon dioxide pressure (PETCO2 levels,4.3 and 5.9kPa.Ventilation in-creased with progressive hypoxia.Therefore,they all represent the useful indexesof inspiratory drive.P0.1 is more sensitive than V1 and （?） because it isindependent of pulmonary mechanics.

Experimental investigation of hydrate formation in water-dominated pipeline and its influential factors

Blockage in water-dominated flow pipelines due to hydrate reformation has been suggested as a potential safety issue during the hydrate production.In this work,flow velocity-dependent hydrate formation features are investigated in a fluid circulation system with a total length of 39 m.A 9-m section pipe is transparent consisted of two complete rectangular loops.By means of pressurization with gas-saturated water,the system can gradually reach the equilibrium conditions.The result shows that the hydrates are delayed to appear as floccules or thin films covering the methane bubbles.When the circulation velocity is below 750 rpm,hydrate is finally deposited as a“hydrate bed”at upmost of inner wall,narrowing the flow channel of the pipeline.Nevertheless,no plugging is observed during all the experimental runs.The five stages of hydrate deposition are proposed based on the experimental results.It is also revealed that a higher driving pressure is needed at a lower flow rate.The driving force of hydrate formation from gas and water obtained by melting hydrate is higher than that from fresh water with no previous hydrate history.The authors hope that this work will be beneficial for the flow assurance of the following oceanic field hydrate recovery trials.

The Principle of Calibration Using the Ionic Current——A New Calibration Method for Electro-Magnetic Flowmeters

An equivalent relationship between electro magnetic flowmeters (EMFs) and the Hall effect is discussed in principle and three equivalent conclusions about their measuring equations are derived. Thereby,the calibration using the ionic current (CUIC) is introduced to the calibration of EMFs in a special Hall effect system. A basic system with these equations is specially given and discussed for realizing the method. Two key points about CUIC are proved by a simple experiment.

Oldoinyo Lengai Volcanic Ash for Removal of Hydrogen Sulfide and Ammonia from Biogas

Oldoinyo Lengai mountain located in Northern Tanzania is the only active natrocarbonatite volcano with unusually alkali-rich natrocarbonatites which are not found elsewhere in the world. Volcanic ash formed earlier during eruptions was collected from different sites along the mountain, and its potency to adsorb hydrogen sulfide (H2S) and ammonia (NH3) from biogas was investigated. The samples were calcinated at different temperatures (550℃ - 850℃) and were characterized by X-ray florescent, scanning electron microscopy and X-ray diffraction techniques. The on-site adsorption experiments were conducted at the biogas digester at ambient conditions. The calcinated ash was packed into the reactor bed, biogas allowed to pass through the adsorbent, and the inlet and outlet concentrations of H2S and NH3 were measured. The height of the site where the adsorbent was taken from, calcination temperature, biogas flowrate and mass of the adsorbent were variable parameters and found to influence greatly on the efficiency of H2S and NH3 removal. The efficiency is increased with calcination temperature raise and mass of adsorbent and decreased with flowrate increase. The samples collected from the top site of the mountain and calcinated at 850℃ exhibited the best sorption performance.

Beneficiation of White Kaolinitic Sandstone to Produce Kaolin Concentrate from Wadi Siq-Rakyia Area in Wadi Araba, Jordan

Kaolinitic sandstone samples of Lower Cretaceous from Wadi Siq-Rakyia area in Wadi Araba/south of Jordan were studied and assessed as a source of Kaolin. Three channel samples and a composite bulk sample were studied for their mineralogical, geochemical, and grain size distribution analysis. The aim of this research work was to achieve kaolin concentration by examining the best-suited and cost-effective processing method(s) with appropriate product recovery. Following the initial sample characterisation at “bench scale”, a pilot study was performed on the bulk sandstone sample. Kaolin was accumulated in the fine size fraction (−125 μm) after agitating and wet screening of the sample. The −125 μm size fraction sample was used to produce kaolin concentrate. Hydrocyclone classification was applied in the pilot study for this purpose. The mass flowrate of the feeds and the products in the hydrocyclones was calculated for the bulk sample as well as the amount of water required operating the process. A kaolin-enriched product was produced following the use of hydrocyclones. A kaolin concentrate at a grade of 71% and a recovery of 78% was produced which could be used in the ceramic industry for tableware and sanitaryware.

Low impact development technologies for mitigating climate change:Summary and prospects

Many cities are adopting low impact development(LID)technologies(a type of nature-based solution)to sustainably manage urban stormwater in future climates.LIDs,such as bioretention cells,green roofs,and permeable pavements,are developed and applied at small-scales in urban and peri-urban settings.There is an interest in the large-scale implementation of these technologies,and therefore assessing their performance in future climates,or conversely,their potential for mitigating the impacts of climate change,can be valuable evidence in support of stormwater management planning.This paper provides a literature review of the studies conducted that examine LID function in future climates.The review found that most studies focus on LID performance at over 5 km2scales,which is quite a bit larger than traditional LID sizes.Most paper used statistical downscaling methods to simulate precipitation at the scale of the modelled LID.The computer model used to model LIDs was predominantly SWMM or some hybrid version of SWMM.The literature contains examples of both vegetated and unvegetated LIDs being assessed and numerous studies show mitigation of peak flows and total volumes to high levels in even the most extreme climates(characterized by increasing rainfall intensity,higher temperatures,and greater number of dry days in the inter-event period).However,all the studies recognized the uncertainty in the projections with greatest uncertainty in the LID’s ability to mitigate storm water quality.Interestingly,many of the studies did not recognize the impact of applying a model intended for small-scale processes at a much larger scale for which it is not intended.To explore the ramifications of scale when modelling LIDs in future climates,this paper provides a simple case study of a large catchment on Vancouver Island in British Columbia,Canada,using the Shannon Diversity Index.PCSWMM is used in conjunction with providing regional climates for impacts studies(PRECIS)regional climate model data to determine the relationship between catchment hydrology(with and without LIDs)and the information loss due to PCSWMM’s representation of spatial heterogeneity.The model is applied to five nested catchments ranging from 3 to 51 km2and with an RCP4.5 future climate to generate peak flows and total volumes in 2022,and for the period of 2020–2029.The case study demonstrates that the science behind the LID model within PC stormwater management model(PCSWMM)is too simple to capture appropriate levels of heterogeneity needed at larger-scale implementations.The model actually manufactures artificial levels of diversity due to its landuse representation,which is constant for every scale.The modelling exercise demonstrated that a simple linear expression for projected precipitation vs.catchment area would provide comparable estimates to PCSWMM.The study found that due to the spatial representation in PCSWMM for landuse,soil data and slope,slope(an important factor in determining peak flowrates)had the highest level of information loss followed by soil type and then landuse.As the research scale increased,the normalized information loss index(NILI)value for landuse exhibited the greatest information loss as the catchments scaled up.The NILI values before and after LID implementation in the model showed an inverse trend with the predicted LID mitigating performance.