Gas Flow Rate Conditions Research Articles

Optimization using central composite design for continuous absorption of CO2 gas with green sodium silicate in a packed bed column

If absolutely nothing is taken to reduce carbon dioxide (CO2) emissions, atmospheric concentrations of carbon dioxide will rise to 550 parts per million by 2050, which will have disastrous effects on the world's climate and food production. An apparatus has been designed and setup to convert CO2 into a useful and vital product which was silica. The effect of different experimental factors on the compositions by weight percent of SiO2 and Na2CO3 were studied including the CO2 gas flow rate (1.037, 1.648 and 2.26 L/min), initial concentration of sodium silicate (Na2SiO3) solution (5, 7.5 and 10 %wt) and the packing size (15.95, 20.175, and 24.4 mm). An optimization process was performed using the Design Expert software program to achieve the optimum experimental conditions at which the maximum weight percent of SiO2 (main product), the minimum weight percent of (Na2CO3) (side product) and the minimum reaction time were determined. From the optimization process, the maximum weight percent of SiO2 (25.63 %), the minimum weight percent of (Na2CO3) (9.62 %) and the minimum reaction time (7.59 min) were achieved at the following optimum experimental conditions of CO2 gas flow rate = 1.648 L/min, packing size = 24.4 mm and initial concentration of sodium silicate solution = 10 %wt.

Generation of low-energy abundant electron energy probability functions using a magnetized plasma source

The generation of low-energy electrons is essential for the plasma source of the charge neutralizer system within the ion implanter process of semiconductors and displays, owing to their exceptional capability of being effectively transported along their ion beams. In this study, we propose a method to produce non-Maxwellian electron energy probability functions (eepfs) characterized by low-energy-abundant electrons, specifically below 5 eV, across an electron extraction system. In the electron transport region with an axial magnetic field under conditions of high discharge voltage and gas flow rate, we observed a significant increase in low-energy electrons in eepfs. The simple global model proposed to analyze these results demonstrated that the wall loss of electrons can be reduced by an elevated plasma potential, which is influenced by the ionization rate in the transport region. These results are consistent with the experimentally measured plasma potential and electron density. Additionally, the reduction in wall losses and increased ionization rate within the transport region resulted in the relaxation of the plasma potential gradient. This phenomenon effectively inhibited the cutting of low-energy electrons within the eepfs, thereby facilitating their consequential transport to the target. This study emphasizes the significance of increasing the ionization rate and minimizing the potential gradient for the dual purposes of generating low-energy electrons and directing them towards the target.

Design and Experiment of a Slotted Antenna Surface Wave Plasma Flood Gun

In a modern ion implanter, plasma flood gun (PFG) is used to neutralize wafer charge during doping process, preventing the breakdown of floating wafers caused by the space charge accumulation. In order to obtain the PFG which can produce ribbon electron beams with the characteristics of high stability, high plasma density, no metal pollution and long life, studies at Peking University (PKU) are focused on surface wave plasma flood gun (SW-PFG) recently. A 2.45 GHz SW-PFG with a quartz plate and a series of metal slotted antenna arrays was designed and tested. Theoretical studies are carried out to optimize the SW-PFG structural parameters. The quartz plate thickness is determined as 15 mm. The size of the plasma chamber is 280 mm×150 mm×40 mm with a 280 mm×2 mm extraction slit. In the experiment, a relatively uniform argon plasma is obtained under the condition of gas flow rate of 2 sccm and input power of 800 W. In this case, the plasma distribution is studied by emission spectrum diagnosis and 73 mA ribbon electron beam is measured.

Effect of Argon Flow Rate on Tribological Properties of Rare Earth Ce Doped MoS2 Based Composite Coatings by Magnetron Sputtering

Exploring the doping components of the coating is of great significance for improving the tribological properties of the MoS2-based coating. The optimization of magnetron sputtering process parameters can also improve the coating quality. In this paper, the effects of working gas flow rate on the microstructure in a vacuum chamber, nano-hardness, and tribological properties of Ce-Ti/MoS2 coatings were studied using DC and RF unbalanced co-sputtering technology. It is found that the coating structure was coarse and porous when the Ar flow rate was excessive (70 sccm), significantly affecting the mechanical properties; there are pit defects on the surface of the coating when the flow rate is just minor (30 sccm), and the coating easily falls off during the friction process. When the flow rate is 40~60 sccm, the coating grows uniformly, the hardness reaches 7.85 GPa at 50 sccm, and the wear rate is only 4.42 × 10−7 mm3 N−1 m−1 at 60 sccm. The coating doped with Ce and Ti is an approximate amorphous structure. Under appropriate gas flow rate conditions, the friction induces a transfer film with a layered structure, and the MoS2 (002) crystal plane orientation is arranged in parallel at the edge of the wear debris, effectively reducing the shear force during sliding and reducing wear. Based on rare earth doping, this study improves the tribological properties by optimizing the working gas parameters, which plays a reference role in preparing high-quality MoS2-based coatings.

Geometrical optimization of city gate station’s water bath indirect heater to minimization of fuel consumption

Gas industry as one of the greatest sectors of energy, has a major role in environmental issues. A category of energy intensive parts in gas industry is heaters in City Gate Stations which consume colossal volumes of the purified gases. Different optimization strategies to improve the efficiency of these heaters entailing preheating, waste heat recovery of exhausts, insulating pipelines and mounting economizers or recuperators or even using renewable energy sources have been already introduced. Besides, finding the optimized geometry is very essential in improving the efficiency. In this study, a far efficient model for heaters was introduced using the thermal modeling of the process. Based on the properties of the inlet gas, the volume of the gas passing from the CGS and ambient conditions, the consumption of the fuel as well as heater efficiency have been computed as a function of inlet gas properties, CGS’s gas flow rate and ambient condition. Then, results were verified by real data taken from Arak CGS station in Iran. The comparison proves the great correlation between the theoretical and experimental results. Findings show that with an increase in the heater length, a reduction in thermal re-sistance coincides with a higher thermal hysteresis. This causes higher fuel consumption and lower efficiency. Moreover, the higher the length of the fire tube, the more heat is transferred to the pure water and the higher is the efficiency. Considering the optimized heater configu-ration the efficiency improves two folds; changing from 32% to 71%.

Production of diesel-range oil through pyrolysis of polyolefins recovered from municipal solid waste.

Pyrolysis is an effective method to valorize plastic waste and obtain value-added fuels. This study adopted the ANN-GA (artificial neural network-genetic algorithm) coupled with a central composition factorial design to optimize the oil production from the pyrolysis of waste polyolefins (WP). The interactive effects of PE mass fraction (20-80 wt%), residence time (20-60 min), and carrier gas flow rate (0-100 mL/min) on the yields of WP pyrolysis products were investigated extensively by ANN. Moreover, the highest WP pyrolysis oil production of 78.87 wt%, optimized by GA, was obtained under 80 wt% PE, 60 min, and 0 mL/min. It was found that the different conditions of PE mass fraction, residence time, and carrier gas flow rate did not change the types of oil's main functional groups (-CH2-, -C=C-, -C=CH2, -CH3, and =C-H). The conditions affected the WP pyrolysis oil fractions significantly. The highest diesel selectivity of 91.42% was obtained under 20 wt% PE, 20 min, and 0 mL/min. Additionally, according to the interactive effects of different conditions on the productions of WP pyrolysis products, the pyrolysis pathways were proposed to understand the pyrolysis mechanism of WP better.

Two-dimensional modeling and experimental investigation of an inverse molten carbonate fuel cell

Molten carbonate electrolyzers (MCECs) represent an innovative method for the conversion of electrical energy into chemical energy, coupling the advantages of both low- and high-temperature electrolysis processes. In the present work, a planar MCEC was experimentally tested under different temperature, gas flow rate and composition conditions. A 2D model was developed for the first time and validated against experimental data. The model was found to accurately describe the behavior of the cell, both in terms of the relationship between applied voltage and flowing current and of product gas composition. The model was then used to predict thermal effects in case of adiabatic operation of the cell, showing that, in the absence of temperature control, the cell temperature could increase significantly and that the presence of thermochemical reactions alongside the electrochemical processes could significantly affect the behavior of the cell.

Graphite-assisted laser ablation dielectric barrier discharge optical emission spectrometry for rapid detection of cadmium and zinc in cigarettes

A study of the capability of graphite-assisted laser ablation dielectric barrier discharge optical emission spectrometry (GALA-DBD-OES) for direct analysis of cadmium and zinc in cigarettes was undertaken. GALA-DBD-OES allowed direct sampling of cigarette samples in the condensed phase with the irradiation of a continuous wave infrared laser for subsequent atomization/excitation by a DBD plasma. The graphite in the sample matrix functioned as a laser energy converter and a thermal transmitter to improve the desorption efficiency of analytes. Under optimal conditions of the plasma gas flow rate, the discharge current and the proportion of graphite in the matrix, Cd and Zn were detected with limits of detection of 0.09 μg/g and 0.20 μg/g, respectively. Inter-day relative standard deviations of 4.5% for Cd at 45 μg/g and 2.6% for Zn at 30 μg/g indicate a good method repeatability. The accuracy of the present technique was verified by analyzing a certified reference material of cigarette. Quantitative results of Cd and Zn in commercial cigarettes allowed direct comparisons of cigarettes of different prices and geographical locations. All these features suggest the promising role of GALA-DBD-OES as a routine tool for real-time and on-site analysis of heavy metals in cigarettes.

Degradation of mixed typical odour gases via non-thermal plasma catalysis

The simultaneous treatment of H2S and NH3 typical odours by plasma was investigated and the co-treatment of both was found to have a facilitating effect the conversion. The degradation efficiency and by-product emissions of single plasma technology and plasma co-catalytic two-stage technology were compared and the degradation mechanism was further analyzed. The results show that in the single plasma technology conversion experiment, the conversion rate of the treated odours mixture is higher than that of the treated single odours, and the by-product emissions of SO2 and NOx are also reduced due to the reaction of intermediate products and by-products during the reaction process. The absolute removal of the odours mixture is optimal when treating at a gas flow rate of 6 L/min, a voltage of 16 kV and a frequency of 200 Hz. The M(Ce,Cu)-Mn/13X loaded catalyst was synthesized by co-precipitation method. Under the conditions of gas flow rate of 3–7 L/min, the efficiency of H2S and NH3 removal and the reduction of by-product emission were ranked as: uncatalyzed > Cu-Mn/13X > Ce-Mn/13X, which proved that Ce-Mn/13X showed better catalytic activity and application value.

Hydrogen reduction behaviors and mechanisms of vanadium titanomagnetite ore under fluidized bed conditions

Vanadium titanomagnetite ore has prominent latent applications in the recovery of iron, vanadium and titanium. In this study, the reduction effect and product characteristics of vanadium titanomagnetite ore using hydrogen as reductant under fluidized bed conditions were investigated by X-ray diffraction, scanning electron microscopy and energy dispersive spectrometer. Under the optimal condition of gas flow rate of 1000 mL·min−1, reduction temperature of 850 °C, reduction time of 30 min and H2 concentration of 80%, the reduced product with a metallization degree of 90.22% was obtained. The titanium-bearing maghemite in raw ore was reduced to titanomagnetite, the massive generated rutile and minor hardly reducible Fe3-xMxO4(M = Mg/Al/Si/) hindered the further aggregation of metallic iron grains, and there was no FeO detected during the whole reduction process. Thus,the phase transformation process of vanadium titanomagnetite is suggested as follows: γ-(Fe,Ti)2O3 → Fe3-xTixO4 → FeTi5O8 → Fe2TiO5 → Fe2TiO4 → Fe + FeTiO3 → Fe + TiO2.

Pilot scale test of wet dust removal by high gravity intensification technology in fertilizer plant

Industrial dust can cause serious harm to the environment and human body. High gravity wet dust removal is a new type of high-efficiency dust removal technology, with the advantages of high dust removal efficiency, low economic cost, convenient operation and maintenance. In this work, a cross-flow rotating packed bed was used as the wet dust removal equipment, and a pilot scale dust removal experiment platform was built at the production site of the enterprise. The dust removal effect of high gravity wet dust removal technology on granulation waste gas in actual production was also studied. The second compound fertilizer plant of TianJi Group emitted dust-containing exhaust gas with a dust content of about 2500 mg/m3 during the production process. Different key parameters including high gravity factor, liquid flow rate and liquid circulation time were investigated on dust removal efficiency and fractional efficiency, and the mechanism of high gravity wet dust removal was analyzed. The obtained results suggested that under the conditions of gas flow rate of 400 m3/h, liquid flow rate of 0.5 m3/h and high gravity factor of 205.61, the dust removal rate was as high as 99.88% with an outlet concentration of less than 10 mg/Nm3. Under three hours of clean water absorption cycle, the dust concentration after purification could still be reduced to less than 10 mg/Nm3, and the dust removal efficiency could reach more than 99%. The relationship between the fractional efficiency of the cross-flow rotating packed bed and the dust particle size was nonlinearly fitted, which showed a good fit. High gravity wet dust removal technology increased the inertial force of particles in the gas through rotation, while atomizing the liquid into a micro liquid. The scales of the two were matched, and the inertial collision was effectively enhanced to improve the dust capture effect. Therefore, high gravity wet dust removal technology can effectively control industrial dust emissions and has a strong potential for industrial applications.

Experimental Research on Distribution Characteristics of NO x Conversion Efficiency of a Diesel Engine SCR Catalyst.

An experimental investigation of the distribution characteristics of NOx conversion efficiency inside a selective catalytic reduction system is presented in this paper. Wash-coated and extruded vanadium-based selective catalytic reduction catalysts were investigated under an ANR (ammonia nitrogen ratio) of 1.0 and various exhaust gas temperature and flow rate conditions. A moveable sampling probe was located at various measuring points on the exit cross section of the selective catalytic reduction catalyst shell, and the final distribution maps of NOx conversion efficiency were obtained by the interpolation of measured data. The experimental result showed that the distribution of NOx conversion efficiency of the wash-coated selective catalytic reduction catalyst at the exit cross section was extremely nonuniform and the efficiency of the extruded SCR catalyst was uniform with a higher distribution at the center. A comparison experiment with 180° rotation of the selective catalytic reduction catalysts was implemented, and the efficiency distribution map of the wash-coated selective catalytic reduction catalyst also rotated 180° but that of the extruded selective catalytic reduction catalyst remained unchanged. The uniformity coefficient of the extruded selective catalytic reduction catalyst was higher than that of the wash-coated selective catalytic reduction catalyst used in this study.

Microbioreactor (micro-Matrix) potential in aerobic and anaerobic conditions with different industrially relevant microbial strains.

Microscale fermentation systems are important high throughput tools in clone selection, and bioprocess set up and optimization, since they provide several parallel experiments in controlled conditions of pH, temperature, agitation, and gas flow rate. In this work we evaluated the performance of biotechnologically relevant strains with different respiratory requirements in the micro‐Matrix microbioreactor. In particular Escherichia coli K4 requires well aerated fermentation conditions to improve its native production of chondroitin‐like capsular polysaccharide, a biomedically attractive polymer. Results from batch and fed‐batch experiments demonstrated high reproducibility with those obtained on 2 L reactors, although highlighting a pronounced volume loss for longer‐term experiments. Basfia succiniciproducens and Actinobacillus succinogenes need CO2 addition for the production of succinic acid, a building block with several industrial applications. Different CO2 supply modes were tested for the two strains in 24 h batch experiments and results well compared with those obtained on lab‐scale bioreactors. Overall, it was demonstrated that the micro‐Matrix is a useful scale‐down tool that is suitable for growing metabolically different strains in simple batch process, however, a series of issues should still be addressed in order to fully exploit its potential.

The Characterization of hydrocarbon compounds in bio-oil produced by pyrolysis of biomass from the essential oil distilled residue using ZSM-5 and YSZ catalysts

The main hydrocarbon containing in petroleum and natural gas are important feedstocks for various kinds of fuel and petrochemical products, but these non-renewable resources will diminish their supply over time and that is why the development of environmentally friendly hydrocarbon resources whose more secure should be driven. One of the origins could become the residue of the distillation process of essential oils using catalytic pyrolysis that would produce the hydrocarbon distribution products. The use of acid catalysts such as ZSM-5 can improve the hydrocarbon in bio-oil. However, the use of zeolites can mainly accelerate the cracking of long molecules to make hydrocarbon molecules simpler by forming carbonium ions from the carbon-carbon chain. Thus, requiring a modification of the catalyst with adds YSZ catalyst, which can cut off oxygen from the hydrocarbon group is needed to improve the results of catalytic pyrolysis. The results of this study showed that the maximum temperature at 550 °C was able to increase the yield of steam products and the production of non-oxygenated hydrocarbon compounds. Similarly, the optimization condition of the argon gas flow rate is 100 mL/min. In that condition, the fluidization of biomass material occurs maximally, and the occurrence of the heat transfer process is very fast. While the optimum ratio of YSZ/ZSM-5 catalyst was achieved by a 3:2 ratio. YSZ is very effective at 550 °C in assisting ZSM-5 to form non-oxygenated hydrocarbon compounds. It can be proofed by GC-MS results that non-oxygenated compounds produced such a group of non-oxygenated hydrocarbon cyclic, paraffin, and aromatic compounds are dominant.

High-rate Deposition of Polycrystalline Diamond Film Using Time-series Exposure of Modulated/Non-modulated Induction Thermal Plasmas at Different Flow Rates of Carbon Source Gas

In this paper $$\hbox {CH}_4$$ / $$\hbox {H}_2$$ gas flow rate effect on polycrystalline diamond deposition was studied using a time-series exposure technique of modulated induction thermal plasma (M-ITP) and non-modulated induction thermal plasma (NM-ITP). The M-ITP was used to make nucleation of diamond particles in the first stage, and then non-modulated ITP was used to grow diamond particles in the next stage. The diamond films fabricated after exposure by M-ITP and then by NM-ITP were studied in terms of morphology and constituents. Experimental results showed that higher $$\hbox {CH}_4$$ / $$\hbox {H}_2$$ gas flow rate condition to 0.1/10 slpm provided a higher deposition rate of polycrystalline diamond film. This result implied that higher $$\hbox {CH}_4$$ / $$\hbox {H}_2$$ gas flow rate would give a higher neutral hydrocarbon fluxes onto the substrate, which was also supported from the numerical simulation model.

Carbon Dioxide Capture by Chemical Solvents Based on Amino Acids: Absorption and Regeneration

AbstractThe use of sodium salts of aqueous solutions of different amino acids (glycinate and prolinate) for carbon dioxide (CO2) separation by chemical absorption is analyzed in a bubble‐column reactor under different experimental conditions of solvent concentration and gas flow rate. The differences in absorption rate and reaction mechanism caused by the presence of carboxylic groups in comparison to the case without (monoethanolamine and pirrolidine) are evaluated. Glycinate solvent reaches a similar behavior than monoethanolamine aqueous solutions but with a higher destabilization of carbamate that allows to increase CO2 loading. Prolinate exhibits a similar behavior than pirrolidine at low CO2 loadings. Both solvents show a significant reduction in absorption capacity when stripping regeneration is carried out.

The Effect of Ultra Fine Bubbles Water on the Human Skin

1. Introduction Skin barrier function refers to a role of preventing evaporation of moisture from the body and a role of protecting the body from invasion and irritation of foreign matter from the outside. In order to maintain this function, a certain amount of water must be retained in the stratum corneum of the skin, so it is necessary to supply water to the stratum corneum of the skin and prevent evaporation. Lotions and moisturizers are commonly used as countermeasures. However, the preservatives and surfactants contained therein have an adverse effect on children with weak skin, elderly people, patients with atopic predisposition, etc., such as inducing skin dryness and inflammation. Therefore, methods for improving the skin barrier function that have little effect on the human body are being studied. Ultra-fine bubbles (UFB) refers to bubbles having a diameter of 1㎛ or less, has a lower floating speed in water than ordinary bubbles, and has a property of target gas in water for a long time. It is also said that bubbling at the time of UFB water production subdivide water clusters and lowers surface tension1). Since ordinary water has a large cluster, it is difficult to penetrate into the stratum corneum of the skin. Therefore, we thought that the use of UFB water with a small water cluster would facilitate penetration into the stratum corneum of the skin and help to improve the skin barrier function that is kind of the body. In this paper, we evaluated the effects of UFB water on the human skin.2. Experimental2.1 Generation of oxygen UFB water UFB water was prepared by gas-liquid mixed shear method with compact generator (Sunstar Inc.). In this equipment, UFB water was produced under the conditions of gas flow rate of 0.45 L/min, number of revolutions 4000 rpm, operating time 10 min, and amount of pure water 1 L. The kinds of gas selected were oxygen, air, nitrogen and argon. The dissolved oxygen (DO) concentration in the water was measured by DO meter of Thermo Fisher Scientific Co. The meter can measure the DO concentration 0 to 50mg/L. Size distribution of oxygen UFB was measured by laser scattering Nano-Sight LM10-HFV (Malvarn Panalytical).2.2 Evaluation of the effect of UFB water on skin model The skin model used was Human three-dimensional cultured epidermis LabCyte EPI-MODEL24 (Japan Tissue Engineering Co., Ltd.). Pure water and UFB water containing each gas were dropped on the skin model, and the water content and transepidermal water loss (TEWL) before and after dropping were compared respectively.2.3 Evaluation of contact angle of UFB to the human skin Tape stripping was performed on the inside of the subject’s forearm. Then, the skin collected by tape stripping was used as a substrate, and pure water and UFB water containing each gas were dropped respectively thereon to generate droplets. Thereafter, the affinity of each solution to the skin was compared by measuring the contact angle of droplet using a contact angle meter DM300 (Kyowa Interface Science Co., Ltd.).3. Results and Discussion The results of water content value for the skin model with each water showed the highest water content in the case of oxygen UFB water. And also, we found the lowest TEWL with oxygen UFB water. These results suggested that oxygen UFB water has an effect of improving the skin barrier function. From the contact angle measurement, we could find the smallest value with oxygen UFB water on the skin. In addition, the contact angle with air UFB water produced by supplying air instead of oxygen was not different from that of pure water. These results show that the affinity with the skin is not increased by the subdivision of the water cluster by bubbling, but that the higher the concentration of oxygen UFB, the higher the affinity with the skin. Zeta potential of oxygen UFB showed negative charge. In addition, it has been reported that anionic substances easily penetrate the skin2). Therefore, it was suggested that oxygen UFB water has a high affinity for the skin and has an effect of improving the skin barrier function.References1) Shozo Himuro, A New Washing Method Using Microbubbles, Progress in multiphase flow research, 2, 39-45 (2001).2) Onseok Lee, Influence of surface charge of gold nanorods on skin penetration, Skin research and technology, 19 (2012).

A Three-Dimensional Conjugate Heat Transfer Model of a Turbocharger Turbine Housing

The turbine housing is subjected to thermal load which is essential to be taken into account in the design process. In this paper, a three-dimensional conjugate heat transfer simulation of a wastegated turbine housing has been performed. The model has been validated with data from thermocouple measurements and thermography pictures. Moreover, the effect of ventilation speed on temperature distribution of turbine housing is investigated. As the air velocity increases from 8 to 20 m/s, the turbine housing temperature decreases about 114 K. The wastegate valve could be gradually opened by stepping-up the speed of the engine. The ratio of wastegate flow to the turbine housing gas flow is near 30% for the high rotational speeds and loads. Therefore, the exhaust gas passes through the wastegate channel and the velocity reaches 538 m/s for 2° opening of the wastegate valve. Simulation results show that 1.5 mm decreasing the wall thickness of the volute wall causes 30 Kelvin higher temperature in the turbine housing wall. According to the results of the simulation, the impeller specific work of high gas flow condition was observed to be up to 2.5 times of low mass flow rate operation. Furthermore, the specific amount of gas heat transfer at a closed wastegate condition is significantly higher in comparison to the high gas flow rate and open wastegate condition. In addition, the results show that at low speed and closed wastegate condition, 15 percent of the specific heat transfer occurs before the turbine wheel.

Spray and mixing characteristics of liquid jet in a tubular gas–liquid atomization mixer

For the design and optimization of a tubular gas–liquid atomization mixer, the atomization and mixing characteristics of liquid jet breakup in the limited tube space is a key problem. In this study, the primary breakup process of liquid jet column was analyzed by high-speed camera, then the droplet size and velocity distribution of atomized droplets were measured by Phase-Doppler anemometry (PDA). The hydrodynamic characteristics of gas flow in tubular gas–liquid atomization mixer were analyzed by computational fluid dynamics (CFD) numerical simulation. The results indicate that the liquid flow rate has little effect on the atomization droplet size and atomization pressure drop, and the gas flow rate is the main influence parameter. Under all experimental gas flow conditions, the liquid jet column undergoes a primary breakup process, forming larger liquid blocks and droplets. When the gas flow rate ( Q g ) is less than 127 m 3 ·h −1 , the secondary breakup of large liquid blocks and droplets does not occur in venturi throat region. The Sauter mean diameter (SMD) of droplets measured at the outlet is more than 140 μm, and the distribution is uneven. When Q g > 127 m 3 ·h −1 , the large liquid blocks and droplets have secondary breakup process at the throat region. The SMD of droplets measured at the outlet is less than 140 μm, and the distribution is uniform. When 127 < Q g < 162 m 3 ·h −1 , the secondary breakup mode of droplets is bag breakup or pouch breakup. When 181 < Q g < 216 m 3 ·h −1 , the secondary breakup mode of droplets is shear breakup or catastrophic breakup. In order to ensure efficient atomization and mixing, the throat gas velocity of the tubular atomization mixer should be designed to be about 51 m·s −1 under the lowest operating flow rate. The pressure drop of the tubular atomization mixer increases linearly with the square of gas velocity, and the resistance coefficient is about 2.55 in single-phase flow condition and 2.73 in gas–liquid atomization condition. The breakup morphologies of liquid jet with different liquid and gas flow rates are photographed by a high-speed camera respectively. The liquid jet column swings and breaks up into large droplets and liquid blocks in the air flow. When flow through the Venturi throat, these large droplets and liquid blocks break up into smaller droplets. The particle size and velocity distribution of atomized droplets were measured by Phase-Doppler anemometry (PDA). Under the same gas flow rate condition, the droplet sizes at different measured points are basically the same, and the droplet size decreases gradually with the increase of gas velocity. With the increase of gas velocity, the droplet size distribution of each measured point is closer to a straight line, and the uniformity of atomized droplet distribution in the tube is better. With the value of the gas velocity 72 m 3 ·h −1 , the average droplet size is about 200 μm, and with the value of the gas velocity 216 m 3 ·h −1 , the average droplet size is about 50 μm. • Experiments were performed on droplet size and velocity in tubular atomizing mixer. • Breakup morphologies of liquid jet under different flow conditions were obtained. • The relationship between gas flow rate and droplet size was obtained. • Gas–liquid atomizing and mixing characteristics in tubular mixer were analyzed.

Effective generation of atmospheric pressure plasma in a sandwich-type honeycomb monolith reactor by humidity control

Large-volume atmospheric-pressure plasma based on corona discharge was successfully generated in a sandwich-type plasma reactor by controlling the humidity of the feed gas. The reactor comprised a 5-cm-high and 9-cm-wide commercial honeycomb monolith and two perforated stainless-steel disk electrodes with 3-mm holes, which covered up both sides of the monolith. The high-voltage applied disk electrode was placed 2 ~ 6 mm away from the monolith, whereas the counter ground electrode typically touched it. The characteristics of air plasma such as power delivery, breakdown voltage, current, and impedance were found to strongly depend on the water vapor content in the feed gas as well as in the monolith, exhibiting an exponential increase of discharge power with increasing the humidity. The discharge characteristics also depended on the gas flow rate and the electrode-monolith distance. Better discharge performance was observed as the electrode was closer to the monolith, and as the air flow rate was higher. Discharge power above 30 W was achieved under the condition of gas flow rate 75 L/min, applied voltage 25 kV, and humidity 2.1%(v/v) when the high-voltage electrode was 2 mm away from the monolith, and the ground electrode kept up against it. The air plasma produced reactive species, being demonstrated by the formation of ozone at several tens of ppm, depending on specific energy input. The plasma source has potential applications in the abatements of odor, organic compounds, and NOx with high throughputs.