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This paper outlines the prospect of obtaining water from atmospheric air by cooling it to the dew point temperature using refrigeration machines in order to partially reduce water scarcity in the arid regions of our planet. To minimize energy costs in the systems for obtaining water from atmospheric air, it is proposed to utilize solar energy with absorption refrigeration units (ARUs) acting as a source of artificial cold. The characteristic thermodynamic processes have been analyzed in a modernized ARU, capable of working at a lower thermal energy source's temperature than its analogs. The possibility has been studied to reduce the temperature of the heat source by including a solution vaporizer in the ARU scheme. The analysis involved an authentic method based on the balance of specific streams of ARU working body components and actual boundary conditions at characteristic points of the cycle. A limit was shown for the level of a minimum boiling temperature in the ARU generator (from 90 °C) when the systems for obtaining water from atmospheric air are operated under current climatic conditions. The simulation of heat-and-mass exchange processes during contact interaction between a steam-gas mixture and ammonia water solution was carried out. Based on variant calculations, it has been shown that the proposed ARU structure with an adiabatic solution vaporizer could work as part of systems to obtain water from atmospheric air at a hot spring temperature above 100 °C and constructively enough fits into the element base of standard models. It has been proposed to use two types of solar thermal energy sources to operate ARU. In a tropical climate, with vacuum solar collectors or solar energy hubs; in a temperate climate zone, with solar collectors with water as a heat carrier

We have investigated the process of constructing the charts of electrical load, as well as electricity consumption, of many-storied apartment houses in a city's neighborhood, taking into consideration the fractal structure and the existence of a long-term dependence, inherent to self-affine stochastic processes. The results from studying daily, weekly, monthly, yearly charts have shown the presence of fractal properties and the existence of short-term and long-term memory. This makes it possible, in order to efficiently predict and control power consumption, to apply a fractal analysis, which establishes the dependence of future values on retrospective information. Feature of the current study is determining a critical value for the Hurst exponent, approaching which leads to that the system loses stability and enters an unstable state under which the parameters are changing rapidly. The Hurst exponent can be transformed into fractal dimensionality, which is a measure for the complexity of a load chart. In the theory of fractal sets and fractal geometry, of significant importance are the self-similar and fractal sets. By using the specified properties of the fractal, this study has proven the existence of a fractal principle in the formation of the dynamics of electrical load on civilian targets using the example of power consumption by many-storied apartment houses within a city's neighborhood. The calculation of the Hurst exponent has made it possible to determine that the series is persistent and suitable for adequate prediction and efficient energy consumption management. The relevance of the current research is predetermined by the application of a fractal analysis to electricity consumption pattern particularly by civilian objects, since the scientific literature analyzes and predicts the processes that form electric load structure on energy systems, at industrial enterprises

Energy consumption, environmental issues, product quality are actual problems related to grain drying processes. It is necessary to pay attention to designing new structures of energy-efficient grain dryers. A structure of an energy-efficient grain dryer based on thermosiphons has been designed; its energy consumption is 3.5...6.8 MJ/kg depending on surface temperature and air flow rate. The dryer includes a layer heater, a drying chamber, a heat generator, a heater, a noria for loading the product, and fans. The structural features of the dryer allow the drying process to be carried out without direct contact between the combustion gases and the product. The efficiency of the designed structure was evaluated for such indicators as heat transfer coefficients to the grain flow, specific energy costs, moisture content, the relative humidity of the air leaving the dryer. The values of coefficients of the heat transfer to the grain flow vary within 36...58 W/m2K at speeds 2.5...8 mm/s. An increase in the flow rate by 3.2 times leads to an increase in the heat transfer coefficient by 1.6 times. The moisture content of the air at the outlet of the dryer reaches 60 g/kg, while the relative humidity is 90 %, which is several times higher than the parameters for convective mine grain dryers. Energy consumption for drying at the surface temperature of thermosiphons Ts=142.9 °C for various grain flow rates is close to a minimum. The energy consumption is lower than in existing convective dryers. 21 % is spent on heating grain in the dryer; 54 % ‒ on moisture evaporation; and 23.6 % are losses. If we consider the energy spent on moisture evaporation usable, the efficiency of convective dryers is only 40 % while that of dryers based on thermosiphons is 54.1 %. It is expected that the designed structure could be a solution for small farmers in the post-harvest drying process

This work is focused on the numerical simulations of gas-solid flow in an industrial cyclone-calciner furnace. «ANSYS Fluent 15» software was used for numerical simulation. The computer model allows us to investigate modes of work with different fractional composition of material. For different boundary conditions of inlet gas flow, the trajectory of the particles and residence time in the apparatus, as well as hydrodynamic flow structure were determines. In addition the influence of additional revolving flow in the furnace on a distribution of particles was investigated too. The simulation results show good agreement between predicted and experimental data. This means that the behaviour of complex furnace system can be predicted using the CFD. The obtained results will be used in the future to optimize the design of the furnace and determination of optimal modes of operation.

We have experimentally investigated the patterns in the influence of opening angle of the scraper unit, inclination angle of scrapers, and motion speed of the scraper unit, on specific energy consumption by the improved scraper unit. We have experimentally substantiated the hourly schedule of manure accumulation and a schedule for turning the scraper unit on; it is proposed to remove manure 5 times during 24 hours: at 7, 9, 14, 18, 22, which would significantly reduce resource consumption and energy costs associated with the launch of a conveyor. Experimental study enabled determining the structural (opening angle of the scraper unit and inclination angle of the working surfaces of scratchers) and technological (motion speed of the scraper unit) parameters, at which the improved scraper unit would demonstrate minimum specific energy consumption. The optimal parameters for a scraper unit, at which the improved scraper unit would have minimum specific energy consumption, are the scraper unit opening angle in the range of 105 to 115°; inclination angle of the working surface of scrapers is 60°, motion speed of the scraper unit is 0.13 m/s. Based on these indicators, we assembled the developed scraper unit for manure removal. We have conducted comparative experimental study into operation of the developed scraper unit for manure removal and the prototype, commercially available scraper unit USG-3. This study demonstrated the advantage of the developed scraper unit compared to USG-3; specific energy consumption reduces by the amount of 44 to 48 % to 0.34‒0.36 kW h/t. The established rational parameters and operating modes of the scraper unit reduce energy consumption of the scraper unit required, while maintaining the required quality for cleaning a manure channel, which confirms the feasibility of its industrial production. The research results reported here could be applied when designing the bulldozers and other melioration equipment.

The key directions of the development and improvement of the fuel supply system for internal combustion engines with ignition from compression of the fuel/air mixture were pointed out. The need for the comprehensive implementation of electromechanical principles of fuel injection control in accordance with the various conditions of diesel engines operation was proved. The relevance of further development and modernization of the hydromechanical fuel systems on the background of ever-increasing interest in their electro-controllable analogues was highlighted. The unused potential possibilities of hydromechanical fuel equipment to improve the conditions of the fuel supply process were listed. To intensify fuel injection, it was proposed to use the electromechanical device that is mounted in the fuel discharge pipeline and modifies the phase-amplitude characteristic of the wave process of propagation of a single supplying pulse between the high-pressure fuel pump and the hydromechanical nozzle. We highlighted the important aspects of the procedure for constructing the calculation model of the switchgear-type fuel system of direct action with a new device for fuel supply intensification. It was proposed to consider the fuel injection process at some stages, taking into consideration the characteristics of functioning of a particular hydraulic node of the fuel system, including the proposed technical means of intensification. The systems of differential and analytical equations that make it possible to perform mathematical modeling of the process of propagation and mutual influence of the pressure waves in the pressure-pumping tract were presented. The resulting systems make it possible to obtain characteristics of a change in hydraulic pressure in different fuel volumes, the kinematics of motion of shut-off elements in a high-pressure pump and nozzle, etc. In the course of a comparative study, carried out on the basis of the presented calculation model, the fuel injection process for the standard and improved fuel system for a turbo-diesel, a significant improvement of the injection quality by a large number of indicators was revealed. According to the results of calculations, the existence of high-rate character of increasing and decreasing of injection pressure at the initial and final phase of the process of fuel supplyi to the cylinders of a diesel engine is observed. It was noted that the rate of pressure change can reach 170 MPa/deg, maximum, and average injection pressure increases up to 75 MPa and 30...40 MPa, respectively. Calculation studies were carried out with the employment of the numerical method of integration – the Adams interpolation method, the choice of which is caused by the necessity of obtaining consistent solutions when solving the described systems of differential equations, which belong to the category of the rigid

We have proposed an adjustable structure of the converter of energy of electric drive in the electrotechnical complex of a mine electric locomotive from power sources with different voltage levels ‒ from a contact network and a battery of traction accumulators. A characteristic feature of the converter is the presence of inverter units that can be connected either sequentially or in parallel. When powered by a low­voltage source, inverter units are connected in parallel over the entire range of change in the output voltage. When powered by a high voltage source, inverter units are connected sequentially in the range of low output voltages and in parallel in the range of high output voltages. Such an approach makes it possible to align the power voltage levels of traction asynchronous motors of a mine electric locomotive at a lower level. The expected alignment of voltage levels is carried out at a lower level compared to a standard circuit of the three­phase bridge autonomous inverter and is achieved by controlling the paired bridges in the power circuit of traction induction motors. Given this, the frequency of voltages of width­pulse modulation does not change, which is important for the process of reducing dynamic losses of power in the drive’s elements. It has been confirmed that an increase in the output voltage distortion coefficient in the IGB­transistors of the inverter with the minimal level of energy losses in the electric drive’s elements is achieved by modulating the voltage at a constant switching frequency at different voltage levels. We have proven the fact that the best indicators for the harmonic coefficient were obtained at frequencies about 30 Hz, which are the working ones, so the converter operating mode is most effective at these frequencies. The result of analysis of the classical scheme of the inverter has revealed that increasing the frequency of pulse­width modulation by three times significantly increases electrical losses in the windings of traction electric motor. In the proposed circuit of the voltage inverter of engine’s power, at leveling the voltage at low level, there is no need to increase the frequency of pulse­width modulation, which does not lead to a growth in the electrical losses in a traction motor

This paper considers the processes of incineration, gasification, and slow pyrolysis. The common approach implies the use of individual models for the description of separate processes. When parameters acquire the values close to the boundary processes, the accuracy of description of the studied phenomena decreases. The specified processes do not have distinct boundaries between themselves and can smoothly transfer from one to another at changing external influences. While the physical and chemical processes are similar, the composition of the products of reactions, which are determined on the boundaries with the use of adjacent models, is different. In the most general form, the problems associated with incineration, gasification and slow pyrolysis are solved based on a unified model. The solution is complicated by the possibility of an unpredictable change in the composition of original substances. In addition, they can be located in various phase states: gaseous, liquid and solid. The previously developed system of equations that describes the process of combustion of organic fuel of unknown composition was taken as a basis for the unified model. The partial pressures of the products of reaction are the parameters of the model. In this approach, their condition is considered to be gaseous. The feature of the proposed unified model is the possibility of taking into account the condensed phase (coaly residue) of reaction products that is characteristic of slow pyrolysis. For a unified model, which describes the processes of incineration, gasification and pyrolysis, the calculation processes have differences. When studying the gasification and incineration processes, the temperature of the products of reaction is determined based on the equality of their enthalpy and the enthalpy of resulting substances. When studying the process of pyrolysis, the temperature of reactions and, respectively, of its products, is assigned. The found composition of the products and the assigned temperature allows calculating their enthalpy. The necessary amount of energy in the form of warmth to ensure the reaction of pyrolysis can be calculated based on the difference between the found enthalpy and the enthalpy of resulting substances. To prove the adequacy of the model, the calculations of cases of incineration and gasification of gaseous (methane), liquid (ethyl alcohol) and solid (pine wood) substances were conducted. The calculation of slow pyrolysis was performed for pine wood. Coincidence of the results with the data available in literature proved the relative errors admissible for engineering calculations. Based on the joint use of the model and previously developed method for determining the composition of gases mixture in the process of its incineration, the method of identification of the composition of hydrocarbon compounds of combustible substances in different aggregate states in real time mode was proposed.

We have developed an energy approach to estimating the dynamics and fuel economy of cars that makes it possible to determine interrelation between consumption of energy and the kinetic energy of a car. We determined coefficients of the specified interrelation for basic and additional (unproductive) consumption of energy. Based on the obtained coefficients, it is possible to rank energy losses, as well as identify the ways to reduce them. As indicators of energy evaluation of the car’s dynamics, we proposed indicators of its dynamics ‒ the level of kinetic energy possessed by a vehicle at full weight and maximal motion speed; energy indicator of the car’s dynamics that can be applied as the unit for measuring energy consumption of engine, employed to move the car. The equations were derived that determine the following: a number of units of energy losses caused by the elastic and dynamic losses of car and transmission (per one meter of the distance); additional consumption of engine energy at fluctuations of the car guide wheels in the horizontal plane are caused by their imbalance. We present dependences that allowed us to do the following: determine maximal total consumption of engine energy while driving; assess a reduction in the additional costs for the motion of hybrid cars under the established mode at an increase in the share of torque generated by electric motors. The interrelations were determined between energy indicators of the dynamics and fuel economy of cars. We found that the smaller the number of units of energy consumption by engine, required to move the car, the higher energy efficiency of the vehicle. Calculation of all types of energy consumption in the units of kinetic energy of the car enables their comparison, analysis of their causes, and the identification of possible ways for their reduction. The proposed dependences could be used to determine engine energy consumption, required for the car motion, taking into account various factors. The equations derived make it possible to assess energy efficiency of the car at the stages of its design and modernization. We have shown the way to improve dynamics and fuel efficiency of a car by reducing additional losses in the vehicle transmission through the use of a combined electromechanical drive of the driving wheels. Applying energy approach allowed us, using hybrid cars as an example, to determine energy saving at their steady motion. This saving for a car with a number of cylinders of 6‒8 can reach 25‒30 %

The generators of classical design ‒ with a cylindrical stator and rotor ‒ are of interest. This is predetermined by that a given structure is the most common, simple, and technological. The result of the development of such electric machines is a possibility to build a combined series of induction motors and magnetoelectric synchronous machines. In these machines, replacing a short-circuited rotor by a rotor with permanent magnets and controlled working magnetic flux turns the induction machine into a magnetoelectric synchronous one. All existing generators with permanent magnets have a major drawback: there is almost no possibility to control output voltage and, in some cases, power. This is especially true for autonomous power systems. Known methods of output voltage control lead to higher cost, compromised reliability, deterioration of mass-size indicators. This paper reports the construction of a three-dimensional field mathematical model of a magnetoelectric synchronous generator with permanent magnets. The model has been implemented using a finite element method in the software package COMSOL Multiphysics. We show the distribution of the electromagnetic field in the active volume of the generator under control and without it. The impact of a control current in the magnetized winding on the external characteristics of the generator at a different coefficient of load power has been calculated. Applying the devised model has enabled the synthesis of a current control law in the magnetizing winding at a change in the load over a wide range. The results obtained demonstrate that it is possible to control output voltage of the generator with permanent magnets by using an additional magnetizing winding. The winding acts as an electromagnetic bridge for the main magnetic flux, which is created by permanent magnets. Our analysis of results has shown that it is possible to regulate the output voltage of the generator with constant magnets within –35 %, +15 %.