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As the processing of cereals technology improves, grains are separated, cleaned and sorted by modern machines: centrifugal separators, pneumatic tables, aerodynamic separators. Sorting quality may vary depending on machine operating parameters and grain aerodynamic properties. The aim of the study was experimentally determine the influence of widening, narrowing and constant cross-section of the sorting chambers shape, as well as the air flow rate and the supplied grain flow on a grain sorting quality. In order to implement this research, following tasks were done. Primarily a grain sorting stand was made (Figure 1). The widening sorting chamber is highlighted in black. Also the aerodynamic properties and humidity of the grain were predetermined. An analysis of grain dispersion by varying the sorting chamber, air flow rate, tilting angle of the sorting chamber, and supplied grain flow were presented. The influence of the shape of the grain sorting chamber and the distribution of air flow on the quality of grain sorting was evaluated. Recommendations for improving the quality of grain sorting were provided. This article presents the research results of the "Skagen" wheat with an average humidity of 14 % conducted in 2020. The distribution of air flow velocity was measured in these chambers, as well as wheat grain sorting studies were performed by varying the air flow velocity, the supplied wheat flow, and the chambers tilt angle. Studies have shown that the narrowing chamber is adapted to lower grain flows compared to the constant cross-section and widening chambers, when the air flow rate is the same in all cases. When using a narrowing chamber, it is recommended to select a higher air flow rate and reduce the supplied grain flow, this will give more space for the grains movement and they will be more pulled out, which will affect their better fluidity and dispersion. It can also be argued that the widening chamber requires a lower air flow rate and increased grain flow to achieve the same performance and quality compared to other chambers. This shape of the chamber allows the grains move more easily in the longitudinal direction of the chamber, which improves their dispersion. Recommended parameters to achieve the best grain distribution using an expanding chamber: grain flow q = 8-10 kg⋅min-1 and air flow rate v = 10 m⋅s-1. With a straight chamber, maximum performance can be achieved without compromising on quality with a grain flow v = 12 m⋅s-1 and an air flow rate v = 12 m⋅s-1. The recommended parameters for narrowing chamber are: grain flow q = 4 kg⋅min-1 and air flow rate v = 11 m⋅s-1 or when grain flow q = 8-10 kg⋅min-1, and the air flow rate v = 12 m⋅s-1. [ABSTRACT FROM AUTHOR]

All companies aim to produce the best quality product and receive the highest profit. Also ensuring a healthy environment for employees is of high importance. Choosing the right type of spray booth will assure the latter in any company that is involved in painting. The article reviews and evaluates different airflow type spray booths. Using analysis of options the optimal decision is determined taking into account the price, simplicity of construction, paint finish quality, general spray booth size and energy consumption.

The study deals with ten strongest air pollution episodes in Vilnius and their relationship with meteorological conditions. The main task of the study was an assessment of air flow impact on daily concentration of particulate matter (PM10). PM10 data are available at the Lithuanian Environment Protection Agency. Airflow was assessed using 30-hour backward trajectory of air particle (horizontal and vertical) to Vilnius based on data of three different reanalysis: ERA-Interim, NCEP/NCAR, and NCEP/DOE. The impact of meteorological conditions on pollution was assessed analysing the changes in the atmospheric stability criteria: boundary layer depth, the strength of surface temperature inversions, and the intensity of vertical mixing. These characteristics are available at NOAA Air Resources Laboratory Archived Meteorology website. These 10 selected episodes were detected in the period from 2005 to 2016. The selected height of the endpoint of the backward trajectory was within the boundary layer - 1000 and 925 hPa. All trajectories were classified into three appropriate ranges of distances: local (<300 km), regional (300-500 km), and remote (>500 km). In 4 of the 10 episodes the backward trajectories based on all three reanalyzes, ERA-INTERIM, NCEP/NCAR, NCEP/DOE, showed a homogeneous airflow. Five out of 6 remaining cases revealed a weak connection between ERA-INTERIM and NCEP/NCAR and NCEP/DOE trajectories (differences reached 12.5%), and one case had the longest backward trajectory extending more than 800 km per 30 h. The most typical directory of the backward trajectory was from north, south and southwest. The shallow highpressure gradient field was the typical influencing surface pressure pattern for 5 episodes, high-pressure area (centre) for 4 episodes, and the warm sector of cyclone for one episode. [ABSTRACT FROM AUTHOR]

Airflow movement and thermal parameters of indoor microclimate are discussed in this paper reviewing satisfaction of hygiene standards required for residential and working places in real conditions. Accuracy and influencing factors for measurement devices (thermal anemometers) for the range of low velocities are revealed. Article in Lithuanian. Gyvenamųjų ir darbo patalpų aplinkos oro sąlygų vertinimo kokybiškumo ir tikslumo tyrimas naudojant plačiai metrologijoje taikomus termoanemometrus Anotacija. Oras, esantis gyvenamosiose ir biuro patalpose, naudojamas veikiant įvairiems faktoriams, priklausomai nuo patalpų paskirties. Negrynas oras tampa kenksmingas ar net pavojingas gyventojams, pastatų konstrukcijai ir įrangai. Todėl reikia užtikrinti nuolatinį oro cirkuliavimą. Šio darbo tikslas – parodyti, kad oro srauto savybių tyrimams reikia ne tik tinkamų matavimo priemonių, norint įvertinti srauto tėkmės parametrus, bet ir ypatingą dėmesį skirti detaliam mikroaplinkos (oro judėjimo ir jo pasiskirstymo, pulsacijų, temperatūros ir drėgmės kitimo) tyrimui, prietaisų tiksluminėms charakteristikoms ir jų naudojimo sąlygų nustatytų reikalavimų atitikčiai. Reikšminiai žodžiai: mikroklimatas, oro srautas, greitis, temperatūra, drėgmė.

In order to properly analyse the operation of a two-level multichannel cyclone. a study on how air flow moves inside the cyclone is necessary. The two-level multichannel cyclone is designed to separate solid particles from the air stream and has been built in the Environmental Protection Laboratory at Vilnius Gediminas Technical University. Researches on finding how the air flow distributes within two levels and channels of the six-channel cyclone were made. Air velocity was measured using multimeter Testo-400 and dynamic Pito tube. Air velocity measurements in ducts before and after the device were done using an anemometer. The results showed that the air volume at both cyclone levels were equal, and air velocity in the channels that were the same at both levels was also distributed equally. The highest air speed was measured at the end of the last IV channel and reached 13 m/s. Minimum air velocity can be observed when the rings are arranged in such way that 75% of the air flow returns to the previous channel, and the maximum speed is when the previous channel returns 25% of the air flow. [ABSTRACT FROM AUTHOR]

The rotation of combine harvester threshing cylinder creates an air flow within threshing crescent, part of which is directed through the openings in the concave. The present article gives the air flow velocity trials within threshing crescent. Experimental studies were carried out with a stationary tangential threshing cylinder stand which consisted of 0.6 m diameter and 1.2 m wide eight rasp bars tangential threshing cylinder which is surrounded by concave with 146º. Air velocity was measured at 56 locations, distributed dependent on construction of concave. The air velocity was measured using a hot wire anemometer unit. The output data was recorded on PC using 10 bit ADC converter. Nine levels of cylinder peripheral speed (from 11.0 m·s-1 to 23.6 m·s-1) at cylinder-concave clearances of: 36 mm at front, 32 mm in middle, and 20 mm at rear part of concave were used in this experiment. The results of the experiment show that there were significant differences of air velocity among cylinder peripheral speeds and locations. The air velocity increased with increased cylinder peripheral speed and towards the rear of the concave. Air flow velocity within threshing crescent dependence on technological and constructional parameters of the threshing cylinder is presented. [ABSTRACT FROM AUTHOR]

In biological wastewater treatment plants, the right selection of an aerator is one of the most important elements. The choice of the aerator must take in account its performance -- dissolved oxygen content per unit of energy consumed, oxidative capacity and supply of the required amount of air so that the required concentration of oxygen is saturated properly. The experiments have been conducted carefully examining the efficiency of the selected deep-cavitation aerator operating without the aerator tip or with attached two and three-blade tips. The performed investigation included air dispersion methods of opposite ejecting for determining air flow, flow pressure and dependence of vibration on different placement of the aerator under varying positions of comers. It has been established that compared to air ejecting flow, changes in pressure and vibration are most significantly influenced by a deep-cavitation aerator having a three-blade tip. [ABSTRACT FROM AUTHOR]

The conducted investigation is aimed at providing information on air flow parameters in the cylindrical and spiral shell (de-vices are designed for separating solid particles from air flow having tangent flow inlet). Experimental research has employed multi-cyclones created by the Department of Environmental Protection at Vilnius Gediminas Technical University. The study is focused on investigating and comparing the distribution of the dynamic pressure of the airflow in six-channel cyclones inside the structures of devices. The paper establishes and estimates the efficiency of air cleaning changing air phase parameters using different particulate matters. The efficiency of the cyclone has been defined applying the weighted method based on LAND 28-98/M-08 methodology. The article presents the results of experimental research on the air cleaning efficiency of cylindrical and spiral shells using 20 µm glass and clay particulate matter under the initial concentration that may vary from 500 mg/m³ to 15 g/m³ using semi-rings with windows at different positions. The obtained results has shown that the maximum efficiency of the cylindrical shell increases up to 87,3 % while the initial concentration of glass makes 15 g/m³. [ABSTRACT FROM AUTHOR]

A four -- section trickle biofilter was constructed for experimental research. The filter was filled with the packing material of artificial origin. The material consists of plastic balls having a large surface area. The dependence of biofilter aerodynamic resistance on supply air flow rate and the number of filter sections was determined. The aerodynamic resistance of the biofilter was measured in two cases. In the first case, the packing material of the filter was dry, whereas in the second case it was wet. The experimental research determined that an increase in the air flow rate from 0.043 m/s to 0.076 m/s causes an increase in biofilter aerodynamic resistance from 30.5 to 62.5 Pa after measuring four layers of dry packing material. In case of wet packing material, biofilter aerodynamic resistance after measuring four layers of plastic balls increases from 42.1 to 90.4 Pa. [ABSTRACT FROM AUTHOR]

Experimental results, their analysis and generalization are presented for local heat transfer from the convex and concave surfaces of rectangular helical channels in the initial part of thermal stabilization in air flow over a wide range of operating (Re = 10³-4 ⋅ 105) and geometrical (D/h = 5-90, b/h = 2-20) parameters at one-side heating. It was established that, depending on the length of the helical channels, heat transfer from a convex surface decreases and from a concave surface increases approaching the stabilized values which in a channel of highest curvature (D/h = 5.5) reaches up to -50% for a convex surface and up to +60% for a concave surface versus those in a straight flat channel. With a decrease of channel curvature (an increase of parameter D/h), heat transfer intensity from both surfaces decreases in comparison with a straight flat channel. Also, heat transfer stabilization on a convex surface occurs later than on a concave surface or in a straight flat channel. Correlations were obtained for changes of heat transfer from convex and concave surfaces of helical channels in the initial part of thermal stabilization in comparison with stabilized heat transfer. [ABSTRACT FROM AUTHOR]

Copyright of Agricultural Sciences / Zemès ukio Mokslai is the property of Lithuanian Academy of Sciences Publishers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Experimental and RELAP5 modelling results of the two-phase air-water flow in a horizontal rectangular (1200 x 100 x 50) are presented. The aim of the work was to determine the channel inclination angle needed to maintain a uniform water depth in the channel when the air velocity varies from 4 to 10 m/s. Experimental results show that the measured inclination angle fairly meets the theoretical calculations and other authors' results. To achieve a better agreement between experimental and RELAP5 modelling results, additional adaptation of the software and / or the model is needed according to the shape of a rectangular channel and the specifics of the process. [ABSTRACT FROM AUTHOR]

We present results of an experimental investigation of local opposing mixed convection heat transfer in a vertical flat channel with symmetrical heating in the laminar-turbulent transition region. The experiments were performed in an airflow (p = 0.1, 0.15, 0.2 and 0.4 MPa) in the range Re from 2 ⋅ 103 to 5 ⋅ 104 and Grq up to 1.5 ⋅ 1010 at the limiting condition qw1 = qw2 = const. Numerical two-dimensional simulations were performed also for the same channel and for the same conditions as in experiments using the FLUENT 6.1 code. Experimental investigations show a sharp increase in heat transfer for the air pressure of 0.15 MPa up to Re &symph; 3 ⋅ 103, 0.2 MPa up to Re &symph; 4 ⋅ 103 and 0.4 MPa up to Re &symph; 8 ⋅ 103 in comparison to forced convection heat transfer. The numerical investigations revealed this intensification of heat transfer to be caused by the formation of vortices under the effect of buoyancy. Analysis of local heat transfer also shows that for some regimes there are regions with a vortex flow at the beginning of the heating, but due to the turbulization effect the non-vortical flow is prevailing along the channel. However, under a strong effect of buoyancy such vortices are dominating along the whole length of the channel. [ABSTRACT FROM AUTHOR]

Test results of flow velocity profiles in a horizontal rectangular channel (h/a = 1.16) are presented. The air velocity profiles were measured in stratified air-water flow and air flow without water in the channel when the average velocity of the air flow varied within 4-8 m/s (Re = 14710-29410). Measurements without water in the channel were taken with a rough and with a smooth bottom wall of the experimental channel. Analysis of the test results shows that air velocity profiles become non-symmetric when air flows above a wavy water surface. It causes an increase of roughness on the interphase surface when waves and secondary flows appear. [ABSTRACT FROM AUTHOR]

Copyright of Agricultural Sciences / Zemès ukio Mokslai is the property of Lithuanian Academy of Sciences Publishers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Results of the numerical modelling of mixed convection in a vertical flat channel in case of a transitional region for aiding flows are presented. Unsteady numerical two-dimentional simulations were performed using the FLUENT 6.1 code. Investigations were performed in airflow of 0.2 MPa absolute pressure for Reynolds number 2016 and Grashof number 3.9x108 (in quasisteady state). Numerical results revealed three characteristic zones of the flow along the channel. In the first zone, the parabolic velocity profile was transformed into an M-shaped profile. This was a stable zone. For the flow parameter indicated above it existed up to x/de = 8. The region of x/de = 8 -- 10 was a region of the reversal flow in the core of the channel (zone with recirculation). Next to that zone we had a zone with an unstable vortex flow. In this zone, a typical wall temperature and Nusseldt number pulsations were noted. The results of heat transfer modeling were compared with the experimental data and showed a good agreement (difference between numerical and experimental data was no more than 4%) in the region of the stable laminar flow and a sufficient agreement (with the difference no more than 12%) in the recirculation zone. [ABSTRACT FROM AUTHOR]

A free from droplet size limitations, combined analytical-numerical solution methodology for unsteady heat and mass transfer in dispersed evaporating liquid is presented. Temperature and pressure jumps in the Knudsen layer were taken into account in a numerical investigation scheme where evaporating droplet surface temperature was calculated by the fastest descent method minimizing the energy flow balance. Heating and evaporation of water droplets in air flow were numerically investigated. The importance of a parameter expressed by the droplet surface temperature ratio to the temperature of equilibrium evaporation during conductive heating, for evaluation of a dispersed liquid thermal state change was highlighted. [ABSTRACT FROM AUTHOR]