The design of a flat-chamber type of electrobaromembrane device for cleaning technological solutions of chemical, machine-building and agroprocessing industries is updated. The design of such a device is analyzed and the operation of the device is described. The developed design of the device makes it possible to increase the solution separation area, reduce the hydraulic resistance in the overflow channels for circulation of the separated solution, increase the productivity and efficiency of solution separation, and reduce stagnation in the cathodic and anodic permeate removal path.
In this work, the fine structure and mechanical properties of the surface white layer of 60S2A steel subjected to combined strengthening by electromechanical treatment with finishing surface plastic deformation are studied. The electron microscopy results of the fine structure of the surface white layer are analyzed. Moreover, comparative assessment of the transformation of the structure, corrosion, and temperature strength of the surface-hardened layer after exposure to aggressive environments (exposure to NaCl and heating to a temperature of 400 °C) associated with the specific operating conditions of the parts is provided.
С использованием модуля для вычислительной гидродинамики проведены расчёты режимных параметров работы запатентованного пластинчатого теплообменника с пластинами с каплевидным рельефом и с типовыми гофрированными пластинами. Установлено, что в запатентованном теплообменнике обеспечиваются меньшие энергетические затраты на перекачивание теплоносителей при равенстве количества передаваемой теплоты. Calculations of operating parameters of a patented plate heat exchanger with plates with drop-shaped relief and with typical corrugated plates have been carried out using a module for computational fluid dynamics. It is established that the patented heat exchanger provides less energy costs for pumping heat carriers at the same amount of transferred heat.
Herein, we discuss designs of single- and multidisc grinding tools for formation of sealing surfaces (SSs) of valves of pipe fittings. We study on the effect of microcutting on the parameters of “undulation” and “roughness,” following which the surface quality of the SS is evaluated. While processing the measurement results, the programs Microsoft Excel and Statistica 6.1.478 are used to reduce the time of research and determine optimal processing modes.
The paper presents a method for calculating the thermodynamic parameters of refrigerant vapors during their compression in a scroll compressor. The method takes the properties of a refrigerant as a real gas into account, as well as the process of mixing two vapor portions inside the scroll unit when the full geometric degree of compression is reached.
The paper presents a new method for ice slurry generation, based on a periodic heating of the ice formation surface by an alternating electromagnetic field from an inductor. In comparison with conventional approaches to ice slurry generation, this method is characterized by a decrease in the temperature head between the coolant boiling and solution crystallization, increased reliability, economic efficiency due to the use of thin-walled heat-exchanging materials, and lower energy consumption. The ice generating capacity, energy consumption, and operating modes of the ice slurry generator prototype with induction heating are provided. The obtained results were compared with the indicators of scraper ice slurry generators.
Ensuring safe and long-term storage of liquefied natural gas (LNG) is essential for improving the environmental and cost effectiveness of LNG-based power plants. A method for calculating heat fluxes from the environment to the working fluid in a cryogenic tank is proposed, taking into account the heat inputs through thermal bridges, including pipelines and supports of the internal vessel. In accordance with the calculations, performed for a tank with a volume of 6.8 m3, the average time of the LNG drainless storage in various modes of operation and refueling equals 6–8 days at an average heat flux of 396 W.
One of the promising directions of energy efficiency enhancement and operating cost reduction when small-scale natural gas liquefaction plants where mixed refrigeration machines are employed is the use of mixed refrigerant composition regulating systems which do away with the refrigeration circuit recharging procedure. A method for regulating refrigeration machine operation is described. Numerical modeling of the operation of a mixed refrigeration machine under regulated conditions was carried out. The energy efficiency of the natural gas liquefaction plant with a mixed refrigerant composition regulating system under ambient temperature variation conditions was studied. The feasibility of introduction of the regulation method into small-scale natural gas liquefaction plants was analyzed.
Analysis of the results of experimental studies of bulk materials mixing process in a developed laboratory centrifuge having an adapter with alternating radial channels, nozzles and blades showed that the operating parameter of the device (rotation speed) has a significant effect on the pattern of distribution of the number of particles of each bulk component (in case of formation of rarefied component flows) along the height of the vertical trap. Particularly, with increase of the rotor speed by 1.67 times the maximum mass fraction of all particles of the descending rarefied flow shifts by one cell of the vertical trap. It was observed that for two types of mixtures (with 0.67 and 0.62 ratios of true densities of the substances of the key and transporting components) the conditions of their quality mixing are met. The obtained results may be useful for verification of stochastic models of formation of rarefied flows of particles of components being mixed using a rotating adapter with radial channels, nozzles and blades.
In this paper, we investigate the effect of adding silver (Ag) nanoparticle coated with polyvinylpyrrolidone (PVP) at an Ag concentration of 0.3 wt
This study discusses an option for combating the harmful space of reciprocating compressors by installing an elastomeric disk made of HNBR-70 type rubber at the piston end. The required disk thickness was calculated to exclude a completely dead volume and the presence of allowable stresses in the elastomeric element. We conducted a comparative analysis of the supply coefficients, following which we can say that installing an elastomeric disk enhances the performance of reciprocating compressors.
Experimental studies of the heat stress of the parts of the cylinder–piston group, the flow rate of the coolant, and the feed rate of a piston-type hybrid power machine with two suction valves were performed with a change in the crankshaft rotational speed and the discharge pressure of compressible gas. The analysis established the general patterns of change in these response functions depending on the crankshaft rotational speed. The highest coolant flow rate, and therefore, the best cooling of gas and parts of the cylinder–piston group of the compressor, is achieved at a crankshaft rotational speed of 1,200 min –1 . The nature of the dependence of the feed rate on the rotational speed is affected by the discharge pressure. At a discharge pressure ( p ) of 0.4 MPa, the maximum value of the feed rate ranges from 1,100 min –1 to 1,300 min –1 .
This study presents the experimental results of a piston-type hybrid-power machine with two suction valves using various coolants (water, antifreeze, and automatic transmission fluid (ATF) oil). When analyzing the working processes of a piston-type hybrid-energy positive-displacement machine (PHEPDM), the requirements for its coolant were determined, which were high density, high specific heat, high thermal conductivity, and low dynamic viscosity. Experimental studies estimated the maximum flow rate of the coolant, the best cooling of the cylinder–piston group parts and the intake gas, and the highest feed rate when using water. Herein, the water consumption exceeds the oil consumption by up to 50
Investigations of a prototype positive-displacement piston hybrid power machine having two suction valves showed that the cooling-fluid flow rate is maximum at a compressed gas discharge pressure of 0.5 MPa. Elevation of discharge pressure leads to a decline in machine performance on both suction and discharge and a decrease in delivery coefficient. The components of the delivery coefficient and the physical mechanisms of their change were disclosed. Analysis of the effect of discharge pressure on the temperature of the cylinder-piston group parts revealed that there is a significant nonuniformity of temperature distribution along the cylinder generatrix, which reaches 26 K. This nonuniformity increases with increase of crankshaft speed. The maximum value of the indicator isothermal efficiency of the studied machine is observed at 0.5 MPa discharge pressure.
An analysis of industrial operation of EGAV 1-19-15-6-2 electrostatic precipitators designed for purifying non-aggressive non-explosive process gases and aspiration air from dust was carried out. The nonuniformity of flow distribution at the inlet to the working volume of electrostatic precipitators was revealed. This non-uniformity can lead to efficiency deterioration, increased energy consumption, and frequent cleaning of precipitation electrodes. The authors proposed constructive improvements of electrostatic precipitators supported with calculations.
The results of an experimental study into the hydraulic resistance of heat exchange modules, which are part of a heat and mass-exchange device, are presented. Literature data on the study of hydraulic resistance in plate heat exchangers, which are similar in design, is analyzed. The description of an experimental unit, control devices, and experimental methods are given. The dependencies of the hydraulic resistance coefficient on the Reynolds number for modules of different types are obtained as a result of experimental data processing. Dependencies for calculating the hydraulic resistance coefficient are determined. It is established that an increase in the Reynolds number leads to a decrease in the hydraulic resistance coefficient. An increase in the module thickness leads to an increase in the resistance coefficient. The exponent of the Reynolds number is close to the values given in the literature for plate heat exchangers.
This article presents a study of cold accumulators using binary ice in air conditioning systems. The main advantages and disadvantages of conventional methods for producing binary ice are considered. An installation for obtaining binary ice by vacuum-evaporative crystallization is analyzed. Operation modes of a binary ice generator and a vapor-compression chiller (in comparison) at their parallel connection are given. The optimal operation mode of a binary ice generator when used in the air conditioning system for the premises of the E4 department of Bauman Moscow State Technical University is proposed.
This paper presents the developed mathematical model that describes the influence of pressure and velocity factors on changes in the product of the external friction and lateral pressure coefficients during the pressing of powdered materials in a closed die. As the pressing velocities in a closed die are rather low, this model considers the influence of only the velocity of slipping motion on the deformation component in shear strength calculations. Processing of experimental data was performed according to the least squares method using a third-order linear regression model. The results of the correlation analysis indicate a strong interaction between the product of the external friction and lateral pressure coefficients with pressing modes (pressure and velocity), as well as the independence of the velocity and pressure factors.
The impact of dead space volume on the working processes of a positive-displacement piston hybrid power machine (PDPHPM) with two suction valves is investigated. Due to the fact that the process of back expansion in this machine proceeds with variable gas mass, an expression for determining the volume coefficient at variable mass of expanding gas is obtained. The numerical experiment carried out using the previously developed mathematical model established the effect of the dead space volume on the instantaneous integral characteristics of the machine. It is shown that an increase in the dead space volume leads to increase in the duration of the expansion process (despite a decrease in the mass of the expanding gas), a decrease in the coolant consumption, a significant decrease in the flow coefficient, and a slight decrease in the indicator isothermal efficiency.
