Enhancement of the air ejector performance: primary nozzle and mixing chamber investigation

In the paper, the hydrodynamics of the liquid-gas mixture in the mixing chamber of the ejectors at different spatial positions was analyzed and the comparative study of such ejectors was carried out. It was found that a more ordered mode of movement of the mixture in the mixing chamber is created as a result of the coincidence of the velocity vector of liquid drops and the direction of gravity in the vertical position of the ejectors. This leads to increasing the volume entrainment ratio almost twice. The analysis of the liquid-gas mixture flow in the mixing chamber, evaluation calculations and research allowed to develop and to patent a jet apparatus with a conical-cylindrical (combined) mixing chamber. It was also found that for such ejectors, the volume entrainment ratio is 15–55% higher than for a jet apparatus with a cylindrical mixing chamber due to the reduction of the resistance of the passive flow into the mixing chamber and prevention of the formation of reverse-circulating flows. A study has been conducted on liquid-gas ejectors in the range of the main geometric parameter m (ratio of the mixing chamber area to the nozzle area) 9.4–126.5, which allowed to establish its rational values at which the maximum volume entrainment ratio is achieved (m = 25–40).

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Air to Air Ejector with Various Divergent Mixing Chambers

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.493.50 ◽

2014 ◽

Vol 493 ◽

pp. 50-55

Author(s):

Václav Dvořák

Keyword(s):

Experimental Investigation ◽

Static Pressure ◽

Pressure Fluctuations ◽

Mixing Process ◽

Mixing Processes ◽

Process Characteristics ◽

Pressure Distributions ◽

Mixing Chamber ◽

Air Ejector ◽

Mixing Chambers

The article deals with experimental investigation of subsonic air to air ejector with various configurations of the mixing chamber and the diffuser. A constant mixing chamber, 2° and 4° divergent mixing chambers and 6° diffuser were applied to find differences in the mixing process. Characteristics of the ejector, static pressure distributions and pressure fluctuations were measured to find how the different shape of the mixing chamber affect the efficiency of mixing processes. Pressure fluctuation increased rapidly while the ejection ratio was higher than 1.25 and the highest efficiency of the ejector was obtained when using configuration 4-4-6.

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Preliminary study of the primary nozzle position of a supersonic air ejector with a constant-area mixing chamber

EPJ Web of Conferences ◽

10.1051/epjconf/201714302056 ◽

2017 ◽

Vol 143 ◽

pp. 02056 ◽

Cited By ~ 7

Author(s):

Jan Kracik ◽

Vaclav Dvorak

Keyword(s):

Constant Area ◽

Mixing Chamber ◽

Nozzle Position ◽

Preliminary Study ◽

Air Ejector

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An experience of elaboration and implementation of systems of slag-forming mixtures mechanized feeding into CCM moulds

Ferrous Metallurgy Bulletin of Scientific Technical and Economic Information ◽

10.32339/0135-5910-2020-10-994-1003 ◽

2020 ◽

Vol 76 (10) ◽

pp. 994-1003

Author(s):

S. P. Eron’ko ◽

M. Yu. Tkachev ◽

E. V. Oshovskaya ◽

B. I. Starodubtsev ◽

S. V. Mechik

Keyword(s):

Economic Effect ◽

Three Dimensional ◽

Movable Part ◽

High Quality ◽

Working Zone ◽

Fine Material ◽

Mixing Chamber ◽

Field Samples ◽

Technical Solutions ◽

Feeding Systems

Effective application of slag-forming mixtures (SFM), being fed into continuous castingg machine (CCM) moulds, depends on their even distribution on the melt surface. Manual feeding of the SFM which is widely usedd does not provide this condition, resulting in the necessity to actualize the work to elaborate systems of SFM mechanized feedingg into moulds of various types CCM. A concept of the designing of a system of SFM feeding into CCM moulds presented with the ratte strictly correspondent to the casting speed and providing formation of an even layer of fine material of given thickness on the whoole surface of liquid steel. The proposed methods of designing of the SFM mechanized feeding systems based on three-dimensional computer simulation with the subsequent verification of the correctness of the adopted technical solutions on field samples. Informattion is presented on the design features of the adjusted facilities intended for continuous supply of finely granulated and powder mixtuures on metal mirror in moulds at the production of high-quality billets, blooms and slabs. Variants of mechanical and pneumo-mechaanical SFM supply elaborated. At the mechanical supply the fine material from the feeding hopper is moved at a adjusted distance bby a rigid horizontally located screw. At the pneumo-mechanical supply the metered doze of the granular mixture is delivered by a sshort vertical screw, the lower part of which is located in the mixing chamber attached from below to the hopper and equipped with ann ejector serving for pneumatic supply of the SFM in a stream of transporting gas. It was proposed to use flexible spiral screws in the ffuture facilities of mechanical SFM feeding. It will enable to eliminate the restrictions stipulated by the lack of free surface for locatiion of the facility in the working zone of the tundish, as well as to decrease significantly the mass of its movable part and to decreaase the necessary power of the carriage moving mechanism driver. The novelty of the proposed technical solutions is protected by thhree patents. The reduction of 10–15% in the consumption of slag-forming mixtures during the transition from manual to mechanizeed feeding confirmed. The resulting economic effect from the implementation of technical development enables to recoup the costs inncurred within 8–10 months.

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A Comparison of Physiological Demand between Self-Propelled and Motorized Treadmill Exercise

International Journal of Physical Education Fitness and Sports ◽

10.26524/ijpefs1842 ◽

2018 ◽

Vol 7 (4) ◽

pp. 13-21

Author(s):

Todd Backes ◽

Charlene Takacs

Keyword(s):

Respiratory Exchange Ratio ◽

Treadmill Exercise ◽

Cardiopulmonary Exercise Testing ◽

Mean Value ◽

The Self ◽

Mixing Chamber ◽

Wide Range ◽

The Subject ◽

The Mean ◽

Computer Controlled

There are a wide range of options for individuals to choose from in order to engage in aerobic exercise; from outdoor running to computer controlled and self-propelled treadmills. Recently, self-propelled treadmills have increased in popularity and provide an alternative to a motorized treadmill. Twenty subjects (10 men, 10 women) ranging in age from 19-23 with a mean of 20.4 ± 0.8 SD were participants in this study. The subjects visited the laboratory on three occasions. The purpose of the first visit was to familiarize the subject with the self-propelled treadmill (Woodway Curve 3.0). The second visit, subjects were instructed to run on the self-propelled treadmill for 3km at a self-determined pace. Speed data were collected directly from the self-propelled treadmill. The third visit used speed data collected during the self-propelled treadmill run to create an identically paced 3km run for the subjects to perform on a motorized treadmill (COSMED T150). During both the second and third visit, oxygen consumption (VO2) and respiratory exchange ratio (R) data were collected with COSMED’s Quark cardiopulmonary exercise testing (CPET) metabolic mixing chamber system. The VO2 mean value for the self-propelled treadmill (44.90 ± 1.65 SE ml/kg/min) was significantly greater than the motorized treadmill (34.38 ± 1.39 SE ml/kg/min). The mean R value for the self-propelled treadmill (0.91 ± 0.01 SE) was significantly greater than the motorized treadmill (0.86 ± 0.01 SE). Our study demonstrated that a 3km run on a self-propelled treadmill does elicit a greater physiological response than a 3km run at on a standard motorized treadmill. Self-propelled treadmills provide a mode of exercise that offers increased training loads and should be considered as an alternative to motorized treadmills.

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Theoretical Studies of the Interaction between Screw Surface and Material in the Mixer

Materials ◽

10.3390/ma14040962 ◽

2021 ◽

Vol 14 (4) ◽

pp. 962

Author(s):

Andrzej Marczuk ◽

Vasily Sysuev ◽

Alexey Aleshkin ◽

Petr Savinykh ◽

Nikolay Turubanov ◽

...

Keyword(s):

Friction Coefficient ◽

High Efficiency ◽

Animal Feed ◽

Structural Features ◽

Power Demand ◽

Friction Coefficients ◽

Length Unit ◽

Mixing Chamber ◽

Size Of Particles ◽

The Impact

Mixing is one of the most commonly used processes in food, animal feed, chemical, cosmetic, etc., industries. It is supposed to provide high-quality homogenous, nutritious mixtures. To provide appropriate mixing of materials while maintaining the process high efficiency and low energy consumption it is crucial to explore and describe the material flow caused by the movement of mixing elements and the contact between particles. The process of mixing is also affected by structural features of the machine components and the mixing chamber, speed of mixing, and properties of the mixed materials, such as the size of particles, moisture, friction coefficients. Thus, modeling of the phenomena that accompany the process of mixing using the above-listed parameters is indispensable for appropriate implementation of the process. The paper provides theoretical power calculations that take into account the material speed change, the impact of the material friction coefficient on the screw steel surface and the impact of the friction coefficient on the material, taking into account the loading height of the mixing chamber and the chamber loading value. Dependencies between the mixer power and the product degree of fineness, rotational speed of screw friction coefficients, the number of windings per length unit, and width of the screw tape have been presented on the basis of a developed model. It has been found that power increases along with an increase in the value of these parameters. Verification of the theoretical model indicated consistence of the predicted power demand with the power demand determined in tests performed on a real object for values of the assumed, effective loading, which was 65–75%.

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A New Device Hypothesis for Water Extraction from Air and Basic Air Condition System in Developing Countries

Energies ◽

10.3390/en14154507 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4507

Author(s):

Paolo Maria Congedo ◽

Cristina Baglivo ◽

Giulia Negro

Keyword(s):

Heat Pumps ◽

Outlet Temperature ◽

Water Recovery ◽

African City ◽

Photovoltaic Panel ◽

Water Storage Tank ◽

New Device ◽

Mixing Chamber ◽

Air Handling Units ◽

Pre Treatment

This work proposes a new device for air treatment with dehumidification and water recovery/storage, with possible mitigation of indoor environmental conditions. The system is based on Peltier cells coupled with a horizontal earth-to-air heat exchanger, it is proposed as an easy-to-implement alternative to the heat pumps and air handling units currently used on the market, in terms of cost, ease of installation, and maintenance. The process provides the water collection from the cooling of warm-humid air through a process that leads to condensation and water vapor separation. The airflow generated by a fan splits into two dual flows that lap the two surfaces of the Peltier cells, one flow laps the cold surfaces undergoing sensible, latent cooling with dehumidification; the other flow laps the hot surfaces and heats up. The airflow undergoes thermal pre-treatment through the underground horizontal geothermal pipe that precedes the Peltier cells. In the water storage tank, which also works as a mixing chamber, the two air streams are mixed to regulate the outlet temperature. The system can be stand-alone if equipped with a photovoltaic panel and a micro wind turbine, able to be used in places where electricity is absent. The system, with different configurations, is modeled in the African city Kigali, in Rwanda.

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Cavitation patterns in high-pressure homogenization nozzles with cylindrical orifices: Influence of mixing stream in Simultaneous Homogenization and Mixing

Experimental and Computational Multiphase Flow ◽

10.1007/s42757-020-0088-9 ◽

2021 ◽

Author(s):

V. Gall ◽

E. Rütten ◽

H. P. Karbstein

Keyword(s):

High Pressure ◽

Process Design ◽

High Speed ◽

State Of The Art ◽

Back Pressure ◽

High Pressure Homogenization ◽

Unit Operation ◽

Mixing Chamber ◽

Cavitation Intensity ◽

Droplet Sizes

AbstractHigh-pressure homogenization is the state of the art to produce high-quality emulsions with droplet sizes in the submicron range. In simultaneous homogenization and mixing (SHM), an additional mixing stream is inserted into a modified homogenization nozzle in order to create synergies between the unit operation homogenization and mixing. In this work, the influence of the mixing stream on cavitation patterns after a cylindrical orifice is investigated. Shadow-graphic images of the cavitation patterns were taken using a high-speed camera and an optically accessible mixing chamber. Results show that adding the mixing stream can contribute to coalescence of cavitation bubbles. Choked cavitation was observed at higher cavitation numbers σ with increasing mixing stream. The influence of the mixing stream became more significant at a higher orifice to outlet ratio, where a hydraulic flip was also observed at higher σ. The decrease of cavitation intensity with increasing back-pressure was found to be identical with conventional high-pressure homogenization. In the future, the results can be taken into account in the SHM process design to improve the efficiency of droplet break-up by preventing cavitation or at least hydraulic flip.

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