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Powder spreadability, and thus flowability, is widely considered a critical parameter for metal additive manufacturing (AM) outcome, that is for a stable, repeatable, and viable process. The flowability of metal powders for additive manufacturing can be measured by a variety of methods, with funnels being the simplest ones, thus widely accepted in the AM industry and supported by international standards (ISO and ASTM). What is lacking is a good understanding of what is an acceptable flowability value for a given alloy. It is thus important to understand the theoretical limits (range) on the funnel measurement outcome as prescribed by a standard method for a given metal alloy powder. Herein, we studied different metal alloy powders, including titanium, nickel and aluminum alloys, and their flowability in a funnel as a function of their density. We fitted the experimental data with Beverloo and Johanson models for upper and lower flowability limits, hinting at possible ranges for a funnel flow measurement.

The effects of water depth, flow rate and preheating using heat exchanger were investigated experimentally on solar still. The best performance indicated for shallowest depth and lowest inlet flow ...

This study aims to develop a low-drift air induction (AI) nozzle that meets the requirements of agricultural control unmanned aerial vehicles (UAVs). An AI nozzle was designed and manufactured to satisfy the design goals. The performance of the developed AI nozzle was quantitatively evaluated in terms of injection flow rate, air-to-liquid ratio (ALR), spray angle, and droplet size. The average value of the injection flow rate and the variation over time were measured using a gear-type positive displacement precision flow meter. The spray structure and spray angle were obtained at very high temporal resolution using the single image acquisition function of a two-dimensional particle image velocimetry (PIV) system. The droplet size of the spray was measured using a laser diffraction technique. The injection flow rate of the AI nozzle changes with the pressure recovery characteristics inside the nozzle mixing chamber and affects the dynamic stability of the AI nozzle. The spray angle of the AI nozzle with a flat-fan nozzle tip increases linearly with the injection pressure, and if there is additional consideration for the two-phase flow effect, the prediction equation for the single-phase flow can be applied to estimate the spray angle. The generation of air bubble-containing droplets in AI nozzles is formed by large-diameter ligament disintegration caused by a rolled-up liquid sheet and is larger than that of single-phase flow nozzles. The droplet size (Dv0.5) of the developed AI nozzle was 384 μm, which was smaller than that of a similar commercial AI nozzle. AI nozzle design, manufacturing and performance evaluation technology that satisfies the requirements of agricultural control UAVs, was established through this study.

Radial jet drilling (RJD) technology has been applied to enhance the recovery of difficult-to-produce reserves by multiple horizontal micro-holes. The micro-hole length drilled by high-pressure water jets is of vital importance for the oil and gas recovery effect and is usually tens of meters long for applications in maturing oil fields in China. The water jets are generated by multiple orifices nozzle generally. Many studies focused on improving the self-propelled force generated by water jets to increase the micro-hole length. However, there are few researches on improving the micro-hole extension capacity in terms of optimizing the flexible hose that acts as the drill pipe in conventional drilling technology. This paper firstly studied the relationship between the flexible hose length and the micro-hole extension limit according to the analytical model to calculate the micro-hole extension limit. Then, the method to optimize the flexible hose length and the flow rate was developed aiming to obtain maximum micro-hole extension limit. The results show that the micro-hole extension limit decreases logarithmically with the increase in the flexible hose length under the condition that the takes the maximum value. The optimization model is applied by a field case and is proved to be effective to increase the micro-hole extension limit. This study is significant to improve the micro-hole extension capacity. Moreover, it provides a reference for the design of the hydraulics and selection of flexible hose for the RJD.

Dissolved carbon dioxide (dCO(2)) stripping from a model solution containing sake flavor by feeding gaseous nitrogen (N(2)) using a microbubble (MB) generator was investigated. The effect of dCO(2) stripping by N(2)MB increased significantly with increasing flow rate of gaseous N(2) from 100 to 200 mL/min. dCO(2) stripping from 3,000 mL of the model solution was achieved by feeding N(2)MB at a flow rate of 200 mL/min for 4 min. Volatile components from model solution containing sake flavor were hardly reduced even after feeding N(2)MB at a flow rate of 200 mL/min for 15 min by cooling to below 10 °C. On the other hand, non-microbubbled gaseous N(2) at a flow rate of 200 mL/min was not very effective in stripping dCO(2). Therefore, the use of N(2)MB with cooling to below 10 °C was effective in stripping dCO(2) while maintaining the volatile components in model solution containing sake flavor.

Drilling highly fractured formations, typically fractured carbonates, often experiences kick problems and severe losses of circulation, resulting in a high nonproductive time (NPT). Pressurized mud cap drilling (PMCD) is the most appropriate methodology for such scenarios, being performed by injecting a sacrificial fluid into the annulus, without fluid return to the surface. When a gas kick is detected, the bullheading operation is executed in order to force gas and cuttings back into the formation, also reducing annulus pressure and sealing fractures. However, for a successful operation, the flow rate must be properly selected in order to push gas back into the formation, without causing well damage. The present work aims to solve a nonlinear constrained optimization problem using SQP (Sequential Quadratic Programming) during bullheading operation, ensuring the successful use of the PMCD technique. Simulation studies were carried out and validation tests were performed by employing an experimental facility, which depicts the main characteristics of the oil well drilling process. As a result, the methodology developed is able to provide proper bullheading flow in order to assure safe operation and effective minimization of annulus gas content for carbonate reservoirs, the majority of world oil reserves, characterized as a drilling challenge due to its complexity and heterogeneity nature and where implementing PMCD is the only safe mode of operation.

A concise and accurate prediction method is required for membrane permeability in chemical engineering and biological fields. As a preliminary study on this topic, we propose the concentration polarization model (CPM) of the permeate flux and flow rate under dominant effects of viscosity and solute diffusion. In this model, concentration polarization is incorporated for the solution flow through a semi-permeable membrane (i.e., permeable for solvent but not for solute) in a circular pipe. The effect of the concentration polarization on the flow field in a circular pipe under a viscous-dominant condition (i.e., at a low Reynolds number) is discussed by comparing the CPM with the numerical simulation results and infinitesimal Péclet number model (IPM) for the membrane permeability, strength of the osmotic pressure, and Péclet number. The CPM and IPM are confirmed to be a reasonable extension of the model for a pure fluid, which was proposed previously. The application range of the IPM is narrow because the advection of the solute concentration is not considered, whereas the CPM demonstrates superior applicability in a wide range of parameters, including the permeability coefficient, strength of the osmotic pressure, and Péclet number. This suggests the necessity for considering concentration polarization. Although the mathematical expression of the CPM is more complex than that of the IPM, the CPM exhibits a potential to accurately predict the permeability parameters for a condition in which a large permeate flux and osmotic pressure occur.

The rheology of suspensions showing discontinuous shear thickening (DST) is well documented in conventional rheometer with rotating tools, but their study in capillary flow is still lacking. We present results obtained in a homemade capillary rheometer working in an imposed pressure regime. We show that the shape of the experimental curve giving the volume flow rate versus the wall stress in a capillary can be qualitatively reproduced from the curve obtained in rotational geometry at imposed stress but instead of a sharp decrease of the volume flow rate observed at a critical stress, this transposition predicts a progressive decrease in flow rate. The Wyart-Cates theory is used to reproduce the stress-shear rate curve obtained in rotational geometry and then applied to predict the volume flow rate at imposed pressure. The theoretical curve predicts a total stop of the flow at high stress, whereas experimentally it remains constant. We propose a modification of the theory which, by taking into account the relaxation of the frictional contacts in the absence of shear rate, well predicts the high stress behavior. We also hypothesized that the DST transition propagates immediately inside the capillary, once the wall shear stress has reached its critical value: $\tau_R=\tau_c$, even if the internal shear stress $\tau(r, Comment: Rheologica Acta, Springer Verlag, 2021

The effects of the ladle bottom stirring flow rate and the number of argon plugs on the circulation flow rate and mixing time in an RH degasser were studied using a physical simulation method. The flow field in the RH ladle was studied using particle image velocimetry (PIV). The results show that applying the ladle bottom stirring process has a great influence on the flow field in the RH ladle. When only stirring under the upleg, the circulation of the RH ladle was enhanced. The velocity of molten steel circulation was accelerated, the RH circulation flow rate was increased, and the mixing time was decreased. When the lifting gas flow rate is 133.3 m3 h−1 and the ladle bottom stirring rate is 166.7 L min−1, the circulation flow rate increases by approximately 25 pct, and the mixing time decreases between 36 and 40 pct compared with that without ladle bottom stirring. Stirring in the argon plug below the downleg is not conducive to improving the circulation flow rate but is beneficial to reducing the molten steel mixing time. Double-ladle argon plug stirring can improve molten steel activity on both sides of the snorkel at the upper part of the RH ladle, but this can negatively affect the original vessel circulation. To ensure that the circulation flow is not reduced during double-ladle bottom argon plug stirring, the snorkel upleg lifting gas flow rate must be greater than 133.3 m3 h−1 for the system studied in this work.

The effect of the water-saturated supercritical carbon dioxide (scCO2) flow rate on the corrosion behavior of API 5L X80 steel at a temperature of 35°C and pressure of 80 bar was investigated. Tests were performed with the samples attached to a rotating shaft inside an autoclave. Results indicate that increasing the scCO2 flow rate had no significant influence on the general/localized corrosion rate under the various dynamic conditions considered. The average general corrosion rate was 0.064 mm/y, while the average measured pitting penetration rates were one order of magnitude higher. The size of the corrosion features on the surface of the samples, which were believed to provide an indication as to the size of the condensed water droplets, was much smaller than the calculated critical droplet size needed to be displaced by the flow, supporting the theory as to why flow rate had little effect on the corrosion response.

In the current study, the biogas production was carried out by using a semi-continuous stirring tank reactor (CSTR). Consequently, the producer biogas was scrubbed/enriched by the combination of three steps of scrubbing (H2S scrubber, packed column water scrubber (PCWS), and activated charcoal scrubber (CS)). In PCWS, the static water scrubbing (SWS) and flowing water scrubbing (FWS) techniques were employed. In SWS, the biogas was scrubbed at a defined water level for a defined time while in FWS, the biogas was scrubbed at different water/gas (w/g) flow rates. In case of SWS, removal of was up to 95% H2S removal, removal of was up to 89% CO2 removal and 97% methane refinement was achieved. While for FWS, 97% removal of H2S, 90% removal of CO2 and 97% methane refinement was achieved. Both processes proved remarkable impacts on methane refinement but FWS was found more practical because CO2 was found more soluble in flowing water as compared with static water scrubbing.

Fouling reduces the heat transfer and increases the heat loss of the process units such as heat exchangers. Due to fouling, the costs of operation and maintenance are increasing significantly. In addition, heat transfer equipment is often overworked because of the expected fouling. Therefore, fouling is a major element in design and operation of heat exchangers. Through the grey correlation analysis, the relationship among microbial fouling thermal resistance, flow rate and water quality parameters are investigated. The fouling experiments are finished in a laboratory scale set-up of a tubular type heat exchangers. The fouling thermal resistance under different flow rates and different water quality parameters are obtained. And the changes of water quality parameters under different flow rates are also obtained. The results are analyzed. The analysis shows that the fouling resistance decreases with the increase of flow velocity under the same conditions of temperature and concentration, and it has different influences on thermal resistance when water quality parameters change in different periods. With the change of water quality parameters, the fouling resistance of slime forming bacteria gradually stabilized after 62 h. The correlation analysis of the three shows that the change of flow rate will affect the water quality parameters, and then affect the fouling resistance. The OD, pH and the conductivity are found to be related to changes of velocity. The strongest correlation is 0.6273 between conductivity and flow rate. The strongest correlation is 0.8755 between OD and fouling resistance. When the velocity increases, pH change rate increase 20%, but the changes rate in fouling resistance is slower than other two factors. It is necessary to analyze and study fouling from the perspective of heat and mass transfer.

A proppant transport simulator coupled with multi-planar 3D (multi-PL3D) fracture propagation has been developed to examine the proppant distribution among multiple hydraulic fractures during multi-cluster fracturing in a horizontal well. The multi-PL3D fracture model considers wellbore friction, multi-fracture stress interaction, fluid leak-off, and multi-scale propagation regimes. The proppant transport is described by the two-phase (slurry/proppant) flow equations that consider proppant settling, jamming and flow regime transition. A high-resolution weighted essentially non-oscillatory (WENO) finite difference (FD) scheme is adopted to solve the nonlinear proppant transport equations. An efficient time-stepping scheme is developed to solve the solid/fluid coupling equations and moving boundaries for the multi-PL3D model. The proppant transport model and multi-PL3D model are both validated against previously published results. Using the model, we examine the proppant distributions under different injection schedules, proppant sizes, proppant density, and fluid viscosity. Results show that proppant distribution among multiple fractures is different as the flow rate and fracture width distribution vary due to multi-fracture stress interaction. The proppant in the middle cluster settles remarkably as the flow rate is lowest among the multiple clusters. The proppant is usually jammed at the pinch point, where the fracture width reduces sharply. Proppant adding schedule has a significant effect on the proppant distribution. A constant-concentration results in a proppant stack at the fracture front. In contrast, an increasing concentration favors the prop of the near-wellbore fracture. The proppant distribution area ratio (defined as the proppant distribution area divided by the fracture area) is only 20% for 20/40 mesh proppant, while the ratio is 45% for 100 mesh proppant. Slick water can increase the fracture area but not favor promoting the proppant distribution area ratio. The results can be helpful for proppant design for multi-cluster fracturing in a horizontal well.

Solar energy is a most promising resource of non-conventional energy to utilize for heating. Based on the application there are two kinds of utilization one is water heating and the second one is air heating. This is generally done by flat plate solar collector but due to its limitations to use in higher temperature ranges (i.e., 70–95 °C) and poor performance led to introduce the application of evacuated tube and parabolic trough collector. To fabricate the solar air heater, one ended evacuated tube is used as a receiver of the parabolic trough and U-tube copper pipe is inserted within the evacuated tube. The air heating process is done at various mass flow rates and it was found that the average outlet temperature was more at the minimum mass flow rate, but the average efficiency was less. At maximum mass flow rate, the average outlet temperature was minimum, and the average thermal efficiency was maximum. The maximum thermal efficiency obtained was 24.1% at the 0.0082 kg/s mass flow rate and the maximum temperature that was obtained was 151 °C at 0.0062 kg/s mass flow rate. Hot air being used for different application in space heating, food processing, fruits and vegetable drying and in regeneration of desiccant.

Sebagian besar limbah domestik yang berada pada aliran sungai mengandung logam berat yang memberikan dampak negatif untuk ekosistem dan makhluk hidup yang menggunakannya. Ion Exchange merupakan salah satu metode yang efektif untuk mengatasi masalah pencemaran akibat logam berat tersebut. Penelitian ini bertujuan untuk menurunkan kadar ion logam berat pada sistem perairan atau pada air sungai dengan resin kation. Jenis resin yang digunakan adalah resin kation lewatit. Resin kation sebagai media penukar ion antara ion logam pada air sungai dengan ion yang terdapat di dalam resin. Proses pelaksanaan penelitian ini dengan mengontakkan air sungai dengan resin kation pada alat penukar ion dengan proses continue dengan laju alir dan waktu pengontakkan sesuai variabel. Pengujian kadar logam berat dianalisa menggunakan AAS (Atomic Absorption Spectroscopy). Kondisi pertukaran ion terbaik terjadi pada variabel berat resin 250 gram dan laju alir 60 ml/menit, dimana pada variabel tersebut diperoleh kadar ion Fe sebesar 0.129 mg/L, kadar ion Pb sebesar 0.037 mg/L, kadar ion Ag sebesar 0.091 mg/L, dan kadar ion Mg sebesar 46.66 mg/L.

Control system is a major component in the industrial operations control process. In some industries that make use of chemicals, an error variables or parameters settings can cause some damage. For the environment or the industry itself. So, utilization and development in this field is an awful lot to do. This control system is designed to measure and control the flow rate of the fluid in the pipes. This tool is composed by using a pressure sensor MPX5100dp as the primary sensor and also the servo motor that became the controlling actuator faucets. The results showed that this system can control the fluid's flow rate according to what expected. For monitoring, the system can can determine the rate changes that occur in the pipe. This tool can measure the pressure of 100kPa and rotate the actuator up to faucets with a range of more or less 5 degree.

A thermal desalination system with a flash drum, a spray-nozzle system, and a condenser under vacuum is designed. Theoretical yield of water vapor in the vacuum flash drum has been evaluated based on conservation equations of mass and energy in the range from 0.35 % to 8.37% at temperature of saline feed water from 40 °C to 60 °C, salinity from 0.035 to 0.04 kg/kg, feed flow rate of 40000 kg/day, and supersaturation from 2 °C to 50 °C. A thermal-fluid model has been adopted to simulate the dynamics of saline water droplets for flash evaporation under vacuum. At a moderate droplet velocity, the model predicts time scales for evaporation from 0.5 s to 1 s with yield of flashing vapor from 69.24 % to 84.59 % at droplet radius from 100 μm to 150 μm. The yield increases with the increase in supersaturation and feed temperature, whereas it increases appreciably with the decrease in droplet size. The design is based on the evaporation time scale and the theoretical yield. Both droplet dynamics for flash evaporation and theoretical yield have been validated with results from the literature.

Pseudo-emulsion based hollow fiber strip dispersion (PEHFSD) is a promising alternative technique due to its stability, simplicity and cost of operation. This is an efficient process due to its high surface area for extraction as well as stripping, and low energy consumption for creating the pseudo-emulsion and for the separation of phases. This technique takes the combine advantages of emulsion liquid membrane and overcomes the sufferings of membrane stability in the supported liquid membrane systems. Present work includes extraction of neodymium (III) (Nd) by using TODGA and HNO3 as the extractant cum strippant in PEHFSD technique. A model is developed to study the transport of Nd under different hydrodynamic and chemical conditions that includes organic ratio (A/O) in dispersion, effect of speed of impeller on drop size formation, effect of feed acidity, effect of carrier concentration, effect of feed flow rate. A code is written to solve the model equations numerically to predict the concentration of the feed reservoir with time. Experiments are conducted to obtain the best optimum extraction conditions. Results obtained from the numerical simulations are validated with the experimental data and found a good agreement between them.

The slag-metal-gas multiphase system in converters is crucial for smelting effectiveness and process stability during steelmaking. However, as a key course of the multiphase interaction, slag foaming was not the focus in previous studies due to its complexity. Therefore, we designed a modeling method of slag foaming. Using this method, this article investigated the effects of top blowing impingement and bottom blowing agitation on slag foaming in a combined top and bottom blowing converter. The experimental results indicated that foamed slag, primarily caused by the slag-metal reaction releasing gas, is a significant part of the multiphase system. The maximum height of foamed slag was reduced with increasing bottom blowing gas flowrate as the result of the acceleration of gas escaping. The top blowing gas presented a suppression effect on the foamed slag, which was strengthened by a decrease in top blowing lance height and increase in top blowing gas flowrate.

The present work embodies the effect of abrasive waterjet milling process parameters on surface roughness in alumina ceramic material that is modelled with a machine learning approach. Experiments are carried out on the basis of response surface methodology (RSM) involving the Box–Behnken approach. The individual and interactive effects of the abrasive waterjet milling process parameters on surface roughness are studied through analysis of variance, and a quadratic regression model is developed. The combinations of abrasive waterjet milling input process parameters such as the pressure of 200 MPa, the step over of 0.2 mm, the abrasive flow rate of 0.42 kg/min and the traverse rate of 1000 mm/min have resulted in minimum surface roughness. In addition, the $$\varepsilon$$ -support vector regression model of machine learning is developed to predict the surface roughness. To enhance the support vector regression model, its hyperparameters are tuned using grid search with fivefold cross-validation. The tuned hyperparameters are found to have the cost function $$(C)$$ of 5, $$\varepsilon$$ -insensitive loss function of 0.0001, width of the radial basis function $$(\gamma )$$ of scale and radial basis kernel function. The support vector regression model (92.4%) has outperformed the quadratic regression model (70%) in the prediction of surface roughness.

One of the most widespread problems afflicting people throughout the world is adequate access to clean water. Problems with water are expected to grow worse in the coming decades, with water scarcity occurring globally, even in regions currently considered water-rich. Research on the effects of temperature, transmembrane pressure (TMP), and aeration rate on the quality of effluent is of great significance in the case of membrane bioreactor. By means of the box-Behnken design (BBD) response surface methodology experiments; for the experimental investigation, the three factors are selected for optimization like the temperature is optimized in the range of 27.6–37.4 °C, transmembrane pressure is 35–63 mm Hg, and aeration rate is optimized in the range of 75–90 L/min and regression models are established. The optimal control parameters of temperature, TMP, and aeration rate are found utilizing the BBD optimizer. The removal mechanism of pollutants is discussed, and GC–MS analysis of effluent of the MBR system is also reported. The results show that the aeration flow rate affected effluent quality more significantly compared to temperature and TMP. When the aeration flow rate is 90 L/min, the temperature is 37.4 °C, and TMP is 35 mm Hg, the obtained COD, BOD, TKN, and TP values achieve the standard quality governed by the Central Pollution Control Board (CPCB) of India.

Closed-loop geothermal energy recovery technology has advantages of being independent of reservoir fluid and permeability, experiencing less parasitic load from pumps, and being technologically ready and widely used for heat exchange in shallow geothermal systems. Commercial application of closed-loop geothermal technology to deep high-enthalpy systems is now feasible given advances in drilling technology. However, the technology it uses has been questioned due to differences in heat transport capacities of convective flow within the wellbores and conductive flux in the surrounding rock. Here we demonstrate that closed-loop geothermal systems can provide reasonable temperature and heat duty for over 30 years using multiple laterals when installed in a suitable geological setting. Through use of two analytical methods, our results indicate that the closed-loop geothermal system is sensitive to reservoir thermal conductivity that controls the level of outlet temperature and interference between wells over time. The residence time of the fluid in the horizontal section, calculated as a ratio of the lateral length to flow rate, dictates heat transport efficiency. A long vertical production section could cause large drops in fluid temperature in a single lateral production system, but such heat loss can be reduced significantly in a closed-loop system with multiple laterals.

A Mixed-mode Forced Convection Solar Cabinet Dryer (MFCSCD) is designed for the maximum harnessing of solar radiation. It utilizes the direct heat from solar radiation through glass cover as well as preheated air from two solar air heaters (SAHs) fixed in series having a double pass. The experimental research works were performed in the metrological conditions of Guwahati, India. The drying performance of MFCSCD was analyzed under different air mass flow rates in terms of specific moisture extraction rate (SMER), pickup efficiency, and dryer efficiency for the drying of cluster fig. Further, a thin layer drying kinetics analysis was carried out to find the best suited mathematical model for representing the drying behavior of cluster fig in MFCSCD and open sun drying. Cluster fig dried from moisture content (MC) of 5.67 to 0.08 kg/kg on a dry basis in 7.0, 8.0, 8.5, and 9.5 h at airflow rates of 3.72, 2.76, 1.8, and 1.08 kg/min, respectively, whereas it took 14 h to attain the same moisture level under open sun drying. The experimental results showed higher dryer and pickup efficiencies and SMER at 3.72 kg/min air flow rate. The quality analyses of solar and sun-dried were carried out to estimate the total phenolic content, antioxidant activity, and rehydration ratio.

The flowability of metal powders is critical to many additive manufacturing (AM) processes, particularly for laser or electron-beam powder bed fusion. Many poewder features may simultaneously influence its powder flow behavior, yet how particle size distribution (PSD) individually affects its flowability has not been comprehensively evaluated. The plasma atomization technique allows the production of high-quality spherical metal powders with various PSDs. The recent development of powder characterization techniques offers an opportunity to accurately measure a variety of powder flow properties, including Hausner ratio, Hall flow rate, rheology properties. In this study, we measured the flow properties for six Ti-6Al-4V powders with distinct PSDs. Our results show that the PSD plays a significant role in powder flowability: (1) Either a larger mean particle size or a narrower PSD enhances the powder flowability; The multimodal distribution of PSD is beneficial for the powder bulk flow properties. (2) Either a larger particle mean size or a narrower PSD enhances the powder rheology. (3) Powder dynamic flowing behavior is only influenced by the powder mean size, but not affected by PSD. Powder dynamic flowability improves with increasing particle size. Furthermore, we propose a general formula that can be used to qualitatively estimate the average score of the flowability for metal powders based on the three types of indicators. This study could provide a general guide to predict metal powder flowability based on PSD.

Background Many techniques are used to improve the thermal efficiency of flat plate solar collectors. The previous studies showed the high potentials of nanofluids for thermal efficiency improvement of flat plate solar collectors. Methods In this study, a numerical simulation is carried out to investigate the thermal efficiency of the flat plate thermosyphon solar water heater with different nanofluids. The water-aluminum oxide, water-copper oxide, water-copper, and water-titanium oxide nanofluids are used. The effects of different parameters, such as the volume fraction of nanoparticles, volumetric flow rate, solar radiation intensity, ambient temperature, and inlet temperature of water on the efficiency, useful energy, and mean temperature of absorber of the solar collector are investigated. Findings The results indicated that among the various nanoparticles, the addition of copper nanoparticles, followed by copper oxide, results in the greatest improvement in the efficiency and useful energy. The efficiency and useful energy increase with increasing the volumetric flow rate and volume fraction of nanoparticles. As the volume fraction of nanoparticles increases, the mean temperature of absorber decreases. As the ambient temperature increases from 20 °C to 40 °C, the efficiency increases by 5.5%. As the inlet temperature of water increases from 30 °C to 55 °C, the efficiency decreases by 15%. The efficiency decreases with increasing the solar radiation intensity.

The present study numerically investigates the implication of air throttling on the combustion performance of ethylene fueled cavity-strut-based scramjet combustor using three-dimensional Large Eddy Simulation. With the augmentation of combustion performance by throttling being established, the effects of the mass flow rate of throttling and its location on the combustion performance are discussed. Our results indicate a strong interplay of flow rate and location of throttling on the combustion performance. Further, it is observed that with the introduction of air throttling there is enhancement in combustion efficiency due to the generation of pre-combustion shock train. The optimum mass flow rate of throttling enhances the mixing of fuel and air due to the shock-shear interactions increasing recirculation inside the cavity. Furthermore, the location of throttling essentially dictates the extent and intensity of the recirculation zone pinpointing a fixed zone and air throttling further upstream or downstream deteriorates the combustion performance. Optimum combustion efficiency is attained when air throttling is about 20% of the inlet mass flow rate at 83.6 mm from the cavity aft.

Owing to the storage and transportation problems of hydrogen fuel, exploring new methods of the real-time hydrogen production from ammonia becomes attractive. In this paper, non-thermal arc plasma (NTAP) combining with NiO/Al2O3 catalyst is developed to produce hydrogen from ammonia with high efficiency and large scale. The effects of ammonia gas flow rate and discharge power on the gas temperature, electron density, the hydrogen production rate, and energy efficiency were investigated. Experimental results show that the optical emission spectrum of NTAP working with pure ammonia medium was dominated by the atom spectrum of H α , H β , and molecular spectrum of NH component. Under the optimum experimental condition of plasma discharge, the highest energy efficiency of hydrogen production reached 783.4 L/kW ⋅ h at NH3 gas flow rate of 30 SLM. When the catalyst was added, and heated by the NTAP simultaneously, the energy efficiency further increased to 1080.0 L/kW ⋅ h.

The solid particle flow characteristics inside the cone valve were experimentally and numerically studied. The experiments were conducted at different valve sizes, valve opening positions, pressure drops, and fluidization velocities. Numerical simulation using the computational particle fluid dynamic method was also carried out over broader conditions. It is found that the solid particle flow inside the cone valve demonstrated the three-stage phenomena as the solid particle flew passing through two in-series connected orifice systems. The explanation of the three-stage phenomena of the solid particle flow rate to the valve opening was given according to the double-orifice flow model. Based on the physical nature of the solid particle flow characteristics, a semi-empirical model of the solid particle flow rate inside the cone valve was proposed. The model parameters, such as the saturated solid flow rate, the saturated valve opening, were determined using the experimental data and the existing knowledge of orifice systems. The model was then verified using the experimental data and presented acceptable prediction accuracy.

Two-phase closed thermosyphon heat exchangers (TPCTs) have considerable potential for use in ground source heat pump systems. This paper proposes a new metal-polyethylene TPCT that uses water as the working fluid and is composed of a galvanized steel pipe and a polyethylene pipe. The heat transfer rate characteristics of the metal-polyethylene TPCT were studied using a constant-temperature water bath test bench. The experimental results show that the metal-polyethylene TPCT has the best heat transfer rate when the vacuum degree and filling ratio are 1.00 kPa and 12.5%, respectively. The average heat transfer rate increased as the temperature of the heat source and the flow rate of the cooling water increased. Finally, a sandbox test bench was built, which provided seepage and non-seepage experimental conditions for the metal-polyethylene TPCT. In the sandbox experiment, the heat transfer rate capacity of the metal-polyethylene TPCT was initially studied and compared with that of a single U-tube heat exchanger, and the heat transfer rates were similar. When the evaporation section length was 0.5 m, the heat transfer rates were 34.89 W/m and 111.75 W/m under non-seepage and seepage conditions, respectively. The experimental results show that the metal-polyethylene TPCT is feasible as a new type of ground heat exchanger.

An effective air staging strategy is of great importance for achieving low emissions and sensible heat losses through flue gas extraction. In cases where a commercially available system needs to be optimised, often the only viable measure is the modification of process parameters. In this work, the aim is to (1) Discover a combination of the most suitable process parameters based on a multi-criteria decision-making method and (2) To unveil relevant correlations between the two process parameters under study (PA/SA ratio and excess air), emissions and combustion temperatures. A modified commercial small-scale hot water wood pellet boiler was installed into a laboratory heating system. Nine different cases have been addressed within a parametric study, differing in the PA/SA ratio and overall excess air. Emissions, temperatures inside the combustion chamber and the flow rate of air entering the combustion chamber were measured. A low PA/SA ratio of 0.53 (54.7% reduction from factory settings), combined with a low O2 concentration in the flue gases of 5.26% (39.8% reduction from factory settings), and the elimination of infiltration air resulted in a simultaneous reduction of NOx and CO emissions by 14.4% and 93.9% respectively and a flue gas sensible heat loss reduction of 31.6%.

The simultaneous dry scrubbing of gaseous HCl and SO2 by hydrated lime in the entrained mixing reactor has been studied at condition of simulating waste incineration flue gas. The entrained mixing reactor combining a numerical optimized entrained mixing up flow reactor with a rectifier for homogeneous flue gas mixing flow distribution were developed as reaction chambers for the dry scrubbing of gaseous HCl and SO2 with hydrated lime powders. The dry scrubbing performance of this technology was experimented at the pilot scale entrained mixing reactor with 0.3 m in diameter of lower part chamber, 1.29 m in diameter of upper part chamber and 6.0 m in total height. Three kind of hydrated lime powders with different surface area and pore volume were injected with carrier compressed air into the reaction chamber for absorption of acid gaseous. The experimental conditions were the following: reaction temperature 180 °C, gas flow rate 1800Nm3/h and HCl and SO2 concentration in inlet gas 250 ppm, respectively, giving different values for the ratio the amount of fresh hydrated lime and acid gaseous concentration at the inlet of reaction chamber and that corresponding to the stoichiometric molar ratio (SR). The gaseous HCl and SO2 removal efficiencies ranged from 89 to 99% and 87 to 99% respectively. The best performance of dry scrubbing was obtained for high surface area and pore volume of the hydrated lime. Increased the surface area and pore volume of hydrated lime improved the removal performance of the gaseous HCl and SO2 as well as the solid reactant conversion. The concentration of HCl and SO2 at the downstream of bag filter was measured to predict the absorption of gaseous HCl and SO2 on the surface of bag filter.

Natural circulation systems (NCSs) are extensively applied in nuclear power plants because of their simplicity and inherent safety features. For some passive natural circulation systems in floating nuclear power plants (FNPPs), the ocean is commonly used as the heat sink. Condensation induced water hammer (CIWH) events may appear as the steam directly contacts the subcooled seawater, which seriously threatens the safe operation and integrity of the NCSs. Nevertheless, the research on the formation mechanisms of CIWH is insufficient, especially in NCSs. In this paper, the characteristics of flow rate and fluid temperature are emphatically analyzed. Then the formation types of CIWH are identified by visualization method. The experimental results reveal that due to the different size and formation periods of steam slugs, the flow rate presents continuous and irregular oscillation. The fluid in the horizontal hot pipe section near the water tank is always subcooled due to the reverse flow phenomenon. Moreover, the transition from stratified flow to slug flow can cause CIWH and enhance flow instability. Three types of formation mechanisms of CIWH, including the Kelvin-Helmholtz instability, the interaction of solitary wave and interface wave, and the pressure wave induced by CIWH, are obtained by identifying 67 CIWH events.

Coal mine methane (CMM) emissions from underground coal mines is becoming a global problem since it produces greenhouse gas contributing to global warming. It is critical to reduce low-concentration CMM(LCM) and ventilation air methane (VAM) emissions, which has become the focus to be solved urgently. One of the methods is utilizing this VAM as a fuel by mixing of CMM with the help of the porous burning system. In order to optimize the performance of a porous burning system composed of alumina particles, a series of complex porous media burners composed of two layers of alumina particles were proposed, after which a laboratory experimental system based on these burners was built. The lean-burn limits, lean-burn stabilization temperature and lean-burn fluctuation patterns of the burners built in this study were tested and reported in this paper. Results show that cylindrical burner with equal segment length of 3 mm diameter alumina particles at the upstream and 6 mm diameter alumina particles at the downstream is suitable for lean-burn with low flow rate, and cone burner with equal segment length of 3 mm diameter alumina particles at the upstream and 6 mm diameter alumina particles at the downstream is more suitable for lean-burn with high flow rate and low methane concentration, and the lean-burn limits for cone burner with volume methane concentration of 1.5% is obtained, which is the lowest lean-burn limit have reported at present.

Foams would play a substantial role in mobility control and are considered an efficient chemical agent to improve the oil recovery factor. Co-injection of foam and carbon dioxide (CO2) would be one of the optimum injectivity scenarios in fractured tight core samples. This paper aimed to experimentally investigate the surfactant alternating gas injection and CO2-foam injection and how to determine the optimum parameters like foam quality, flow rate, and the number of cycles. It is observed that 0.65 is the optimum foam quality for the fractured tight core samples, and by the increase of foam quality, the pressure drop has been decreased. By increasing foam quality, pressure drop increases up to a specific value ( f g = 0 .65), and after this point, pressure drop has been decreased. Moreover, by the increase of injectivity cycles, pressure drop has increased subsequently. It is observed that five cycles are the optimum number of cycles, and after that, there is no pressure drop decrease in the system. Due to the surfactant property to control the mobility ratio, CO2 breakthrough has occurred at 1.2 PV. Its oil recovery factor at breakthrough is about 48%, and the total oil recovery factor is about 65%. CO2-foam were injected into the system, and due to the presence of a foaming agent in CO2, a CO2 breakthrough occurred at 1.8 PV. The total oil recovery factor is about 83% that indicated the efficiency of this scenario.

A comprehensive entrainment performance evaluation system of the ejector was built including four indexes. An ejector's Computational Fluid Dynamics (CFD) model was established, and the sensitivity analysis of the entrainment performance to four key geometry parameters of the ejector, namely, the nozzle diameter (Dn), the primary nozzle exit position (NXP), the mixing tube diameter (Dm), and the secondary flow inlet diameter (Ds) was performed. Based on the quantified boundary conditions obtained by the Simulink simulation, the ejector structure was optimized with a new method. It is found that the total recirculation ratio increases but the hydrogen recirculation ratio decreases with the increase of the relative humidity of the secondary flow. The hydrogen recirculation ratio shows a unidirectional increase tendency with the increase of Ds and the decrease of Dn and NXP. The hydrogen recirculation ratio increases firstly and then decreases with the increase of Dm. High hydrogen recirculation ratio with low primary hydrogen flow rate, corresponding to low current operation point of fuel cell system and low sensitiveness to the changing relative humidity are usually incompatible. The hydrogen recirculation ratio with low primary flow rate degrades significantly when Dn increases and Dm is larger than a certain value. The ejector with smaller Ds shows lower sensitiveness to the changes of relative humidity, while the hydrogen recirculation ratio with low primary hydrogen flow rate is not affected badly. When matching with a specific system, it is necessary to balance the ejection performance at low current density operating points and the sensitiveness to the changes of relative humidity in combination with the anodic gas state at each operating point, so as to find the optimal structural parameters. The optimization sequence of structural parameters should follow: Dn is selected firstly, then NXP and Ds are optimized, and finally Dm is chosen.

Improving efficiency and yield of a parabolic trough collector (PTC) field is of paramount technological importance. Here, an attempt toward this goal is made through combined optical and thermal simulation. Two major factors that affect the performance of an individual trough are mass flow rate and aperture width, which scales with rim angle. Performance of PTC-field is observed to have a non-linear scale-up rule as opposed to the same for an individual trough. Wider aperture leads to higher heat collection for individual trough; however, the same results in higher inter-trough shading limiting the number of troughs in a field and the effective unshaded hours. It also depends on insolation and latitude. Therefore, there lies a possibility of trade-off where flow rate, rim angle and design hours of operation require careful tuning to maximize annual energy yield. Here, a step by step procedure is demonstrated for Kanpur, India where optimal values of flow rate, rim angle and hours of operation are obtained to be 1.1 kg/s (for Syltherm 800 as the heat transfer fluid), 70° and 4 h around solar noon on winter solstice day, respectively. The methodology is illustrated to be generally applicable to any location or working fluid.

Based on the cooling characteristics of dry ice on high heat flux chip, a variety of radiator models with different dry ice inlet and outlet positions are proposed in the present study. The influence of these radiator models on temperature field, velocity field, dry ice distribution and chip cooling time are analyzed. The results demonstrate that when the diameter of inlet and outlet is 12 mm and the chip power P0 = 95W, the average temperature of all models' chip bottom has reached below 50 °C when t = 70 s. The inlet of Model g is located in the center of the upper surface of the radiator and the outlet is located in the center of the side surface, the chip overall temperature of Model g is the most uniform distribution with 90% of the area temperature at 25 °C. Model g combines the advantages of the phase change heat transfer and the jet impingement heat transfer, which can realize the optimal coupling of the flow rate and the heat transfer, ensuring the safety and reliability of the chip more effectively. Moreover, the results of simulation and optimization are in good agreement with the relevant experiments, laying a foundation for further optimization of the structural scale of the radiator and better coupling of the heat flow field of the dry ice cooling system.

Wastewater is an inevitable product in industry. How to remove fine particles and enhance the impurity removal efficiency of the wastewater purification equipment has always remained a hotspot issue. In this study, a novel hydrocylone with bi-symmetrical involue inlet, thick-wall overflow pipes and conical segment structure was designed and compared with other hydrocyclones including different structures of inlets, i.e., The flow field and separation performance of the novel hydrocylone were investigated via numerical analysis, The simulation results show that the inner flow field in the novel hydrocyclone is more stable, accompanied with significant decline in both short-circuit and circulating flow rates; moreover, using the novel hydrocyclone, the tangential velocity, the axial velocity and the pressure increase significantly, which can make the particle obtain great centrifugal driving force and effectively reduce the number of dislocated particles. The recovery ratio of fine particles with the diameter of 1 μm also shows significant enhancement. Conclusively, using the designed novel hydrocyclone can obtain higher product quality. The present study can provide theoretical foundation for the design of a novel hydrocyclone.

Unsteady flow structures unrelated to rotating frequency in the turbine wheel space cavity has been observed and reported in a number of recent rim sealing investigations. These flow structures are relatively large in scale and have a significant influence on the sealing effectiveness prediction. As a result, it is important to capture these flow structures in numerical simulation. Small computation sectors, due to the circumferential symmetry assumption, have been proved to fail to capture these flow structures. This paper aims to find a minimum computation sector size that can capture these flow structures, at the same time save computation resources and shorten the convergence process for a simple axial rim seal. Four different sector model (10, 20, 30, 180-degree) are set into simulation using RANS and URANS method. The steady and unsteady simulation results are compared. By comparison, the 20-degree sector model is considered appropriate to conduct successive investigations. Then the 20-degree model is set into unsteady simulation under four different sealing flow rates c w = 0 (non-sealing flow case), c w = 2500 , c w = 5000 , c w = 10000 ). It was found that due to the large-scale flow structure, a staggering pressure distribution is found in the cavity. Increasing the sealing flow rate diminishes these structures and stabilizes the flow in the wheel space cavity. The staggering pressure distribution causes the sealing effectiveness to show an abnormal variation trend. Unsteady pressure oscillation waves at two different circumferential positions are subjected to cross-correlation analysis, by which the rotating speed and number of the flow structure could be calculated.

The present work focuses on investigating the effect of process variables (power, travel speed, powder flow rate) on microstructure and mechanical properties of Laser Metal Deposited (LMD) γ-TiAl thin walls. To this end, LMD technique was used to deposit γ-TiAl thin walls at different processing conditions. Microstructures of as-deposited samples were investigated using both optical and scanning electron microscopy. X-ray diffraction (XRD) technique was used to determine the phases present. Microhardness measurements were carried out along both longitudinal and build directions. Microstructural analysis of as-deposited samples revealed a fine lamellar structure comprising of γ and α2 phases. Colony size of 30-60 μm and lamellar spacing between 0.1 to 0.7 μm were observed. XRD analysis confirmed the presence of γ and α2 phases. Comparison of elemental analysis results on both powder and as-deposited samples revealed a negligible loss of Al and no oxygen pick up in the deposited thin walls. Hardness values were found to decrease with an increase in wall height, and hardness values increased marginally (5%) with an increase in travel speed. Further, 3D transient thermal analysis was also carried out to complement the LMD of thin walls in terms of melt pools and cooling rates. It was found that the melt pool depth (MPDc = 0.266 mm) is smaller at the centre than the edge (MPDe = 0.513 mm) of the wall. A higher cooling rate of 1.05×105 °C/s near the wall substrate was found for 200-12.

This numerical paper addresses the effects of using a cooling fluid (H2O) with the presence of carbon nanotubes (MWCNTs - SWCNTs) and micro-sprays aimed at reducing the heat peak of the interior of the electrical system, i.e., enhancing the shelf life of components. The studied process was assessed under steady-state conditions and employing the k-omega (k- ω ) turbulence modeling ANSYS-FLUENT software. The simulation is conducted so that the heat flux applied to the electrical system (Diode and IGBT) was on a constant basis. In accordance with the results, it was realized that increasing the volume fraction of nanoparticles (to 5%) causes the thermal diffusivity of the fluid to elevate and ultimately the temperature peak is created in smaller values. Besides, it was deducted that using micro-spray (Case 3) because of its special geometry and dimensions, causes fluid behavior to be created turbulently. This also leads to increasing the generated flow rate; therefore, along the embedded duct, the hydrodynamic effects prevail over the thermal effects and the module temperature is reduced (to 326 K). This transcendental cooling power has caused the performance coefficient (COP) of Case 3 to have the lowest rate relative to Case 1, while the pumping power (Pp) trend is the opposite.

This work uses a recently developed MRI method to measure the solid fraction and velocity in three-dimensional (3D) hoppers quantitatively. We demonstrate that the measurements are quantitative by calculating the mass flow rate within the hopper using MRI and show good agreement with the mass flow rate measured gravimetrically. We study the velocity and solid fraction in hoppers with various angles and outlet sizes. We show that the solid fraction decreases smoothly from the bulk value above the outlet, indicating that the assumption of a “free-fall arch” used in some mass flow correlations is invalid. Furthermore, we show that the solid fraction, velocity and vertical evolution of the acceleration are all self-similar when normalised by the value at the centre of the outlet in a 3D hopper, in agreement with recent studies of 2D hoppers. Thus, these quantitative measurements enable evaluation of phenomenological models describing the flow rate from hoppers.

In recent years, widespread use of advanced ceramics in vast areas of the industries such as medical technology and automotive industries has led to the growth of the advanced ceramics market. Due to the difficult machining processes and the difficulty of forming complex parts, manufacturing of ceramic components has been restricted. Powder injection molding can be used to overcome these restrictions. In this paper, SiC feedstock was injected at various temperatures and flow rates. Numerical and experimental results of injection step and imbalance filling were studied. As well as the separation of powder and binder was simulated and verified by experimental tests. Thermogravimetric analyzer and rotational rheometer were employed to evaluate the separation in the green parts and rheological properties of the prepared feedstocks, respectively.

Water management is a key factor affecting the performance and lifetime of proton exchange membrane fuel cells. A transparent single fuel cell with an active area of 100 cm2 was designed in this paper to characterize the water distribution. High-strength transparent borosilicate glass was used as the end plate to ensure uniform clamping forces, and a water-cooling chamber was adopted for the uniform temperature distribution. The effects of temperature, humidity, flow rate and pressure on the cell performance were investigated. It was found that in a certain range, a large cathode flow resulted in a relatively stable power output and a low level of water distribution. However, a better cell performance and higher level of water distribution can be observed with lower temperature, higher operation pressure and higher humidity. The actual voltage was determined by a compensatory calculation through the voltage changes caused by all of the influencing factors, and the compensatory voltages were quite close to each other. The results showed that under 40 °C and 60 °C, 0 Bar and 1.5 Bar, and 50 RH% and 100 RH%, the compensated voltages were 0.873 V and 0.864 V, 0.869 V and 0.855 V, and 0.843 V and 0.844 V, respectively.

Spatial Filter Velocimetry (SFV) is a technique that has been used for agglomeration processes during the past few years as it can monitor, control, and understand granulation and its implications in particle size distribution. This work has considered and aimed to analyze the evolution of the process as time goes on and in real-time and the influence of operating conditions on the process. A Plackett-Burman design was proposed with seven factors and three replicates at the central point condition, using microcrystalline cellulose (CMC) as the raw material and a maltodextrin solution as a liquid binder. Binder concentration, binder flow rate, powder initial moisture content, and fluidizing air temperature were significant at a 90% confidence level. A new approach was proposed for delimiting the stages of the fluidized bed agglomeration process, based on particle size classes that were obtained from the SFV probe data.

Physical heterogeneity in the subsurface creates preferential flowpaths that have the potential to impact mineral dissolution rates. Previous studies using numerical simulations have found that physical heterogeneity can reduce the mineral dissolution rate by an order of magnitude relative to homogeneous simulations. These findings indicate that the long-studied difference between laboratory dissolution rates, and field dissolution rates could be the result of processes caused by heterogeneity in the subsurface, specifically variable fluid flowpaths controlling the approach to fluid saturation. In this study, we investigate the behavior of mineral dissolution rates in heterogeneous fractured rock domains through time. Domains containing albite and non-reactive quartz evolve through 1 million years as rainwater percolates through the system and allows for albite dissolution and secondary mineral precipitation. Fracture density and orientation vary in the domains to determine the importance of fracture topology on mineral dissolution rates. In addition, the volumetric flow rate through each domain is systematically varied to determine the impact of changing flow conditions relative to reaction rates. Temporal analysis of the simulation results indicates that domain-averaged dissolution rates decrease with time, similarly to what has been observed in field systems and long-term laboratory experiments. Spatial analysis of the mineral dissolution rates throughout the simulations, indicates that fractures remain reaction limited through most of the simulation, while the matrix is transport limited. Since most of the domain consists of matrix, the domain is transport limited as a whole. However, speciation of the flux-weighted fluid leaving the domain indicates that the fluid is undersaturated with respect to albite, potentially leading to an interpretation that dissolution within the domain is not transport limited. The direct comparison of the spatial distribution of rates and the integrated flux signal appears contradictory, however, this approach reveals that the transport-limited signal that persists through most of the domain is diluted by the higher volume of water that leaves the system through fast-flowing fracture pathways compared to the mass of solutes diffusing out of disconnected portions of the domain. This parsing of the domain into transport-limited regions and kinetic-limited regions, induced by physical heterogeneity, has the potential to further explain the differences between laboratory dissolution rates and field dissolution rates. It is possible that mineral weathering is dominated by transport-limited conditions in many field systems with disconnected fluid pathways where reaction rates are slow due to a buildup of solutes, despite integrated signals in streams indicating far-from equilibrium conditions for dissolution reactions of primary minerals.

Background Nanofluids are an innovative attractive challenging field suitable for many heat transfer applications. The helical coil is preferred due to compactness and additional curvature flow disturbance. Method Heat transfer and pressure drop characteristics of Ag, ZnO and TiO2 water based nanofluids through helical coil tubes under isothermal boundary conditions are experimentally investigated with 0.25% nanoparticles volume concentration Ag/water, ZnO/water and TiO2/water nanofluids. Five coils are constructed with different coil pitches of 2, 4, 6, 8 and 10 cm. The flow rate of the nanofluid varies between 1 to 3.5 L/min with inlet temperature from 30 °C to 60 °C. Findings The results showed that increasing the coil pitch reduces Nusselt number and pressure drop. The nanofluids have a positive impact on the enhancement of heat transfer but with a pressure drop penalty. Average Nusselt number enhancement up to 11.8 %, 17.8 % and 28.7 % was achieved at Ag/water, ZnO/water and TiO2/water with average pressure drop increasing up to 25.4%, 23.5% and 28.5% respectively. The results showed that an increase in coil pitch decreases hydrothermal performance index (HTPI) and utilizing nanofluids increases HTPI for all types of nanofluids Ag/water, ZnO/water and TiO2/water. Novel correlations were developed to predict Nusselt number and pressure drop.

International audience; Among the various existing technologies for water treatment, the jet clarifier is considered as an effective and compact system as it couples flocculation and clarification in a single unit. In this work, a quasi-two-dimensional apparatus was designed to visualise the interaction between floc size distribution and hydrodynamics in the flocculation zone of a jet clarifier. Measurements of the number of flocs and their size distributions are performed by means of shadowgraphy method and image analysis. Thanks to a coupling between population size distributions and results on local hydrodynamics, the evolution of the number of aggregates along the jet is directly correlated to the recirculation loop present in the flocculation zone. The relative independence of the floc size distributions on the flow rate is discussed in light of the Camp number Gt which remains constant for different flow rates investigated and can thus explain the efficiency of the jet clarifier in terms of flocculation.

A technology was developed for producing in a plasma reactor glass microspheres using the ferruginous quartzite tailings of the Kursk Magnetic Anomaly [KMA]. The predictable effects of the plasma-forming argon-gas flow rate and the plasma reactor power on the fractional composition were determined. It is shown that on increasing the plasma-forming gas flow rate from 1.5 to 2.5 m3/h and the current strength from 400 to 500 A the fraction amount over 630 μm increases due to coagulation processes. It is shown that the glass microspheres are enriched in aluminum and calcium oxides and depleted of silicon, magnesium, sodium, potassium, and iron oxides. It is shown that at high plasma temperatures, of the order of 9000 – 12,000 K, the particles melt completely and spherical glass microspheres ranging in size from 80 to 1250 μm are formed. Operational metrics, such as microhardness, acid resistance, and alkali resistance, of the glass microspheres based on the ferruginous quartzite tailings of KMA were investigated.