• Energy Research

The object of research is the process of ensuring uniform distribution of fuel over the combustion surface of the combustion chamber of a solid fuel boiler operating on biomass. The uniform distribution of fuel over the combustion surface is one of the important levers for eliminating the phenomena of its chemical and mechanical under-conditioning, which increases the efficiency of boiler equipment. One of the problems of studying this issue is the lack of a sufficient theoretical base and practical experience in the process of chemical-thermal conversion of plant biomass to other types of energy.An approach is proposed based on the hypothesis that it is possible to increase the efficiency of boiler equipment on plant biomass by establishing an intensive and high-quality combustion process, ensuring an even distribution of fuel on the combustion surface. And also to identify patterns and indicate methods for optimizing the structure of boiler equipment designs by adapting it to plant materials. The implementation of this approach is carried out by conducting a multivariate experiment. During the experiment, the dependence of the coefficient of uneven distribution of fuel along the combustion plane on the height of the loader nozzle, the angle of inclination of the loader control plate to the surface of the combustion mirror and mass fuel supply is determined.As a result of the study, practical results are obtained, mathematical dependences of the coefficient of uneven distribution of fuel over the combustion surface on the indicated variable factors in the form of a second-order polynomial are presented.The obtained research results will improve the efficiency of the process of heat production from low-grade solid fuels of vegetable origin in boiler plants, facilitate their wider use, and increase the environmental component of the process.The research results are interesting both for manufacturers of boiler equipment based on vegetable raw materials and for its users who want to burn the biomass available on the farm to meet energy needs.

Drum mixers ensure a high level of uniformity when mixing the components of feed additives. However, the issues on theoretical and experimental substantiation of the structural and kinematic parameters of drum mixers have not been scientifically explored in detail. The aim of this study is to improve the efficiency of producing feed mixtures by ensuring the optimal angular rotation velocity of a drum mixer.To determine the radial speed of a particle's motion along a drum blade, we solved a homogeneous differential equation. The numerical value for angular velocity was determined by a computer simulation method. We experimentally studied the uniformity of redistribution of feed components in a mixture of fodder using the designed experimental drum mixer. The mixer included a chamber, a rectangular frame, a supporting frame, and a drive. The mixing chamber included a loading/unloading window with a closed lid. Radial blades were installed inside the chamber along its entire length and evenly along the perimeter.Experiments were conducted using a drum mixer with a drum radius of 0.17 m, which included radial blades with a width of 25 mm, with a chamber's fill factor of 0.5. It was established that the drum mixer ensures the maximum scattering of a material's particles on the surface of the working segment at the drum's angular rotation velocity of 9.69 rad/s.The results of experimental research have established that at rotation frequency of the laboratory plant's drum of 9.42 rad/s the uniformity of mixture is 92.5‒93 %, which meets acting zootechnical requirements for all types of mixed fodder. In this case, a maximum deviation of the theoretical and experimental data was about 9 %. The results obtained suggest the possibility of determining a numerical value for the angular velocity of drum mixers by using the proposed method of computer simulation.

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.

One of the issues related to the fermentation of substrates made from biological raw materials in drum-type reactors is the difficulty of ensuring uniform mixing of their components, which adversely affects the quality of the compost produced. Uniform mixing is achieved if the components of the material are fully dispersed at the free surface of the substrate segment. It was established that in order to fully disperse the particles of the substrate by a descending flow, it is necessary that the particles, which last fall from the blade, should reach the contact point of the drum’s shell and the free surface of the substrate. To describe the established conditions, a mathematical model has been built, which links the equation of the boundary of the blockage of substrate particles in the drum and their fall along a parabolic trajectory. The equations are given to determine the kinematic parameters of the mixing process, provided that the substrate particles are dispersed in the transverse and longitude cross-sections of the drum. The result of solving the differential equations is the equation of the linear speed of particle movement on the curved surface of the drum blade at which their full dispersal at the free surface of the substrate segment is achieved. In order to conduct this research, an experimental drum reactor was designed and manufactured. It was experimentally determined at which humidity values of the substrate and the angular velocity of the reactor drum the uniformity of the distribution of components in the substrate reaches maximum values while the resulting compost meets the acting requirements in terms of microbiological indicators. The adequacy of the mathematical model to the experimental data has been confirmed. The reported results are important because knowing the physicochemical properties of the substrate makes it possible to set such parameters of the process and equipment at which the high uniformity of mixing of substrate components is ensured, which affects the compost quality

The object of this study is the structural and technological parameters of the gas blower unit in the gasification chamber of a gas generator. The task to enable uniform distribution of air masses in the gas generator has been solved using the ANSYS Fluent software. The study is based on a simulation of the movement of air flows in the characteristic cross-sections of the gas generator, in particular the cross-section of the gasification chamber at the border of the oxidation and reduction zones. Seven structures of the gas blower unit were analyzed, the effectiveness of which was determined by the coefficient of variation. The most effective was the design whose value of the coefficient of variation is the smallest and equal to 93 %. At the same time, the total area of zones with no movement of air masses, that is, the absence of a gasification process, does not exceed 12 % of the total cross-sectional area of the gas generator. The speed of air masses at the boundary of the oxidation and reduction zones is aligned in the entire cross-section of the chamber and is V»4.5 m/s. The average value of the vertical component of the speed of air masses in the cross-section at the inlet to the recovery zone of the gasification chamber is V»0.6 m/s. Under such conditions, the production of synthesis gas of high calorific value with the absence of resins, acids, heavy hydrocarbons, and mechanical impurities is ensured. The correspondence of the simulation results with experimental data is confirmed by the coefficient of determination, which amounted to 0.87. The results reported here could be the basis of a modernized methodology for the study of aerodynamic, heat and mass exchange processes that occur during biomass gasification. This would make it possible to define the rational structural and technological parameters of gas generators and improve the efficiency of the gasification process as a whole.