REDUCING SEED DAMAGE IN THE RAW COTTON SEPARATOR

The article discusses the design features of the CX cotton separator. As a result of the analysis, the main reasons are established that lead to increased mechanical damage to seeds, and, as a consequence, to a decrease in the quality of products of the cotton ginning industry. The modernisation of the existing design of the separator is proposed by installing a visor at the outlet of the air flow into the separating chamber. On the basis of experimental studies, a regression mathematical model was obtained, which made it possible to assess the influence of the main design and technological parameters on the mechanical damage of seeds. It was found that this parameter, in addition to the position of the visor, is significantly influenced by the air flow rate at the entrance to the separation chamber and the separator performance. Recommendations on the choice of the position of the visor are obtained.

Comparative performance analysis of innovative separation chamber configurations: Numerical and experimental investigations

Aim of study: Novel configurations of separation chamber are proposed to resolve the critical issue of separation in agro-industrial equipment.Area of study: Dept. of Mechanical and Biosystems Engineering, Urmia, IranMaterial and methods: Precise and instrumented experimentation has been conducted to calibrate the computational fluid dynamics (CFD) methodology in the modeling and simulating chickpea pod separation. Mechanisms were selected based on optimizing separation efficiency, relative purification and required airflow as a criterion for energy consumption.Main results: Applying a guiding blade and suction fans may potentially increase the separation efficiency while reducing the relative purification and required airflow. The highest separation efficiency (95%), the lowest required airflow (545 m³/h) and the lowest pressure drop (16.3 Pa), were obtained by such configuration. Furthermore, the highest relative purification of 90% was achieved when the mechanism was free of blade and fans.Research highlights: To integrate the advantages of the above-mentioned configurations, a series-type assembling them is proposed to preserve the separation efficiency and relative purification at the highest level, meanwhile reducing the required airflow. Also, 15% enhancement in the separation efficiency and 302.8 m³/h reductions in the airflow were found as a crucial finding. The high correlation of experimental and theoretical CFD results is the key point to motivate the researchers for extension of similar case projects.

EFFECT OF TURBULENT PULSATIONS ON THE FRACTIONAL SEPARATION OF FINE POWDERS OF METAL NITRIDES

This paper presents a numerical study of a two-phase swirling turbulent flow in a separation element of a vortex chamber. The paper considers a process of fractional separation in the separation chamber with three particular features in its design. The main feature is the separation mobile element located at the outlet of the separation area. Changes in the position of this element can affect the boundary size and the sharpness of the separation. The second feature of the considered separation chamber is the presence of a rotating element along the vertical axis. This element helps to align the field of the circumferential velocity component. The third feature of this chamber is the presence of a branch pipe for the auxiliary gas flow supply intended to push the particles away from the chamber wall and to blow the separated particles in order to prevent them from agglomeration. In this work, the trajectories of the motion of fine nitride particles are calculated taking into account the turbulent diffusion effect. A possibility to control the boundary size of the particles, when moving the separation element located at the outlet of the vortex chamber, is demonstrated. Numerical study results show that the turbulent pulsations cause significant changes in the separation process and affect the boundary size and the sharpness of the separation.

Calculation method for determining the capacity of intermediate storage tanks in storm sewer networks (for discussion)

Целью работы является дополнение и уточнение методик, приведенных в действующей нормативно-методической базе, для инженерного расчета схем регулирования расходов в сетях дождевого водоотведения. Методом математического моделирования с применением системы компьютерной алгебры проанализированы три схемы регулирования, включающие емкости, насосы и разделительные камеры. Предложена универсальная расчетная формула определения объема регулирующего резервуара в схеме регулирования с опорожнением емкости насосами для всех типов разделительных камер. Установлены зависимости и приведены графики, показывающие влияние на величину объема резервуара коэффициента, который учитывает непостоянство расхода, отводимого разделительной камерой в коллектор. Для схемы регулирования без насоса и разделительной камеры подобрана степенная аппроксимирующая функция, позволяющая проводить расчет величины объема с приемлемой точностью, без численного интегрирования. Для двух схем регулирования с опорожнением самотеком предложены новые формулы определения объема регулирующего резервуара в широких диапазонах коэффициентов регулирования и параметров дождей. Приведены уточненные таблицы, упрощающие инженерные расчеты регулирующих резервуаров. Предложенные в работе формулы и таблицы позволяют рассчитывать емкость резервуаров для всех рекомендуемых схем регулирования расходов. The work aims at supplementing and clarifying the methods given in the current regulatory and methodological framework for the engineering calculation of flow control schemes in storm sewer networks. By the method of mathematical modeling using a computerized algebra system, three control schemes are analyzed, including tanks, pumps and separation chambers. A universal calculation formula for determining the capacity of an intermediate storage tank in a control scheme with emptying the tanks by pumps is proposed for all types of separation chambers. Dependencies are established and graphs are presented that show the effect on the tank capacity of a coefficient that takes into account the variations of the flow discharged by the separation chamber into the sewer. For the control scheme without a pump and a separation chamber, an exponential approximating function has been selected that allows calculating the capacity value with acceptable accuracy, without numerical integration. For two control schemes with gravity emptying, new formulas are proposed for determining the capacity of an intermediate storage tank in wide ranges of control coefficients and rain parameters. Amended tables are given that simplify the engineering calculations of intermediate storage tanks. The formulas and tables proposed in the paper allow calculating the capacity of tanks for all the recommended flow control schemes.

Visualization of Streams of Small Organic Molecules in Continuous-Flow Electrophoresis

Continuous-flow electrophoresis (CFE) separates a stream of a multi-component mixture into multiple streams of individual components inside a thin rectangular chamber. CFE will be able to benefit flow chemistry when it is capable of generically detecting streams of small organic molecules. Here we propose a general approach for molecular stream visualization via analyte-caused obstruction of excitation of a fluorescent layer underneath the separation chamber – fluorescent sublayer-based visualization (FSV). We designed and fabricated a CFE device with one side made of quartz and another side made of UV-absorbing visibly-fluorescent, chemically-inert, machinable plastic. This device was demonstrated to support non-aqueous CFE of small organic molecules and quantitative detection of their streams in real-time with a limit of detection below 100 µM. Thus, CFE may satisfy conditions required for its seamless integration with continuous flow organic synthesis in flow chemistry.<br>

Visualization of Streams of Small Organic Molecules in Continuous-Flow Electrophoresis

Continuous-flow electrophoresis (CFE) separates a stream of a multi-component mixture into multiple streams of individual components inside a thin rectangular chamber. CFE will be able to benefit flow chemistry when it is capable of generically detecting streams of small organic molecules. Here we propose a general approach for molecular stream visualization via analyte-caused obstruction of excitation of a fluorescent layer underneath the separation chamber – fluorescent sublayer-based visualization (FSV). We designed and fabricated a CFE device with one side made of quartz and another side made of UV-absorbing visibly-fluorescent, chemically-inert, machinable plastic. This device was demonstrated to support non-aqueous CFE of small organic molecules and quantitative detection of their streams in real-time with a limit of detection below 100 µM. Thus, CFE may satisfy conditions required for its seamless integration with continuous flow organic synthesis in flow chemistry.<br>

Influence of Particle Charge and Size Distribution on Triboelectric Separation—New Evidence Revealed by In Situ Particle Size Measurements

Triboelectric charging is a potentially suitable tool for separating fine dry powders, but the charging process is not yet completely understood. Although physical descriptions of triboelectric charging have been proposed, these proposals generally assume the standard conditions of particles and surfaces without considering dispersity. To better understand the influence of particle charge on particle size distribution, we determined the in situ particle size in a protein–starch mixture injected into a separation chamber. The particle size distribution of the mixture was determined near the electrodes at different distances from the separation chamber inlet. The particle size decreased along both electrodes, indicating a higher protein than starch content near the electrodes. Moreover, the height distribution of the powder deposition and protein content along the electrodes were determined in further experiments, and the minimum charge of a particle that ensures its separation in a given region of the separation chamber was determined in a computational fluid dynamics simulation. According to the results, the charge on the particles is distributed and apparently independent of particle size.