Numerical simulation of nitrogen oxide formation in dust furnaces

Even though natural sources of air pollution account for over 50 % of sulphur compounds, 93 % of nitrogen oxide which are the most dangerous artificial anthropogenic sources of air pollution and primarily associated with the combustion of fossil fuel. Coal-fired thermal power plants and industrial fuel-burning plants that emit large quantities of nitrogen oxides (NО and NО2), solids (ash, dust, soot), as well as carbon oxides, aldehydes, organic acids into the atmosphere pollute the environment in majority. In the present work, a mathematical model and a scheme for calculating the formation of nitrogen oxide has been developed. Also, the dependence of the rate of release of fuel nitrogen from coal particles at the initial stage of gasification and content of volatiles has been obtained. The main regularities of the formation of NOx at the initial section of the flame in the ignition zone of the swirl burner flame during the combustion of Ekibastuz coal have been revealed. Modern environmental requirements for the modernization of existing and the creation of new heat and power facilities determine the exceptional relevance of the development of effective methods and constructions to reduce emissions of nitrogen oxides, sulfur oxides and ash to 200, 300, and 100 mg/nm3 at a=1.4. The dust consumption in all experiments was kept constant and amounted to 0.042 g/s, as well as with the results of calculating the thermal decomposition of the Ekibastuz coal dust, the recombination of atomic nitrogen into nitrogen molecules, and the kinetics of the formation of fuel nitric oxide. It was found that despite the presence of oxygen in Ekibastuz coal for gases Odaf=11.8 % in an inert atmosphere, nitrogen oxides are not forme

Design of LED Lamp with special spectral characteristics

The goal of this work is the design of LED lamp with adjustable spectral characteristics. The spectral power distribution (SPD) of the lamp can be adjusted to imitate the SPD of the daylight at noon and at evening. Noon light is “bluish” and stimulates cognitive abilities, work productivity and attention; sunlight at evening doesn’t inhibit melatonin production leading to improved sleep during the night and better health. Special combinations of LEDs with different spectral and power characteristics and proper control of the LEDs’ operation are used to achieve the required spectral characteristics of the lamp. Thermal management investigations are made at various ambient temperatures ranging from 20ºC to 45ºC and different current values through LEDs – up to their maximum values. They allow determining safety operating conditions for LEDs depending on the ambient conditions

Теоретическое определение силы счесывания ботвы сахарной свёклы с головки корнеплода

Beet tops harvesting is a complex task of the sugar beet growing industry which forms the qualitative indicators of root crops during their further digging out from the soil and determines the loss of tops and sugar-bearing mass. In the development of theoretical foundations of the optimal tops cutting from heads of sugar beet root by different types of topping working bodies should take into account forces which act at the same time and the rational cutting height. Theoretical researches having been carried out hitherto concerned only the detailed analytical description of the functioning of the new designs of topping working bodies and practically did not concern the general provisions of the separation tops from the head of root crop. The aim of this study is the theoretical determination of the forces that occur at the contact point of cutting working body of topper machines with root crops head of sugar beet root crop. When carrying out theoretical studies are used the methods of mathematics, theoretical mechanics, strength of materials, methods of programming and numerical calculations on PC. As a result, of the theoretical research new analytical dependencies of force describing the processes of crumpling and subsequently cutting of sugar beet heads by topping working body, depending on the size and shape of root crops heads and design parameters of topper have been obtained. As a result, of numerical calculations on PC critical level value of penetration of the cutting element of topping working body into root crops head of sugar beet and maximum value of cutting force at which ejection of root vegetables from the soil doesn’t take place, was defined. The obtained theoretical dependencies and values of normal reaction and cutting forces are the basis for the further working out of a mathematical model of dynamic interaction system of cutting working bodies with the heads of sugar bee

Theoretical study to determine the standard size range of agricultural tractors

Since the tractor is the main energy source in agriculture, the state with highly developed agrarian production, tractor and agricultural machine building should have a fairly clear and consistent policy in the field of organizing the production and supply to agricultural producers of a wide range of tractors for various purposes. Such a policy is based on the type of mobile energy resources, i.e. tractors, based on a deep analysis and study of the volume of agricultural production, the needs for mechanized technologies, the theory of the operation of agricultural machines, the overall assessment of the development of high-tech agriculture. The purpose of this study is to develop theoretical bases for calculating the type of agricultural tractors based on an optimization of technical and economic analysis, taking into account the need for a qualitative and timely implementation of the entire closed set of works in agricultural production. During the research methods of machine use in agriculture, higher mathematics, economics, compilation of programs and numerical calculations on PC were used. The results of the study showed that the classification of tractors should be carried out not according to traction power (as is done in most countries of the world), but by the nominal traction force developed by them. It has been established that this gives a more accurate representation of the operational properties of an energy tool, which in turn allows for the very accurate and correct selection of complexes of appropriate agricultural machinery and implements for its effective operation. The presented theoretical approaches allow to determine with a high degree of accuracy the type of agricultural tractors for any country

Theoretical research into directional stability of trailed tandem- type disk harrow

Received: August 27th, 2021 ; Accepted: October 6th, 2021 ; Published: October 7th, 2021 ; Correspondence: [email protected] is one of the methods of soil cultivation, provides its effective crumbling, loosening, partial mixing and soil inversion. This ensures that crop residues on the soil surface are shredded and intermixing with loosened soil particles. Since, in addition to crop stubble, weeds are also counted as crop residues, soil disking, along with the use of herbicides, is often regarded as the most effective method of controlling the weediness of the agricultural background. Despite the fact that numerous studies on the disk harrow working process are available, insufficient attention has been paid to the study of the stability of harrow machine-tractor units, especially trailed ones. The purpose of this study is to establish the theoretical patterns that would provide for selecting the trailed disk harrow parameters that ensure the desired directional stability of the implement, which, in its turn, helps to achieve the desired qualitative performance of the disk harrowing machine-tractor unit. The principles of the theory agricultural machine, analytical mechanics, higher mathematics, as well as methods of PC-assisted numerical calculations have been used. According to the results of the study, it has been established that sufficient directional stability of the trailed disk harrow can be ensured if its working width B, the distance from the hitch point to the centre of resistance (parameter d) and the operating speed are properly selected. Determining the above-mentioned parameters of the disk harrow with the use of the obtained new analytical relations ensures achieving just their optimal combination, which provides for the maximum field productivity of the harrow machine-tractor unit with the satisfactory stability of disk harrow movement in the horizontal plane

Numerical modelling of the operation of a two-phase thermosyphon

In the recent years, the interest towards the application of two-phase thermosyphons as an element of heat recovery systems has significantly increased. The application of thermosyphons is steadily gaining popularity in a wide range of industries and energy solutions. In the present study, a 2-D numerical modelling of a two-phase gas/liquid flow and the simultaneously ongoing processes of evaporation and condensation in a thermosyphon is presented. The technique volume of fluid was used for the modelling of the interaction between the liquid and gas phases. The operation of a finned tubes thermosyphon was studied at several typical operating modes. A parametric study over a non-ribbed and finned tubes thermosyphon was carried out. The commercial software ANSYS FLUENT 14.0 was used for the numerical analysis. It was proven that the numerical modelling procedure adequately recreates the ongoing flow, heat and mass transfer processes in the thermosyphon. The numerical result from the phase interaction in the thermosyphon was visualized. Otherwise, such visualization is difficult to achieve when only using empirical models or laboratory experiments. In conclusion, it is shown that numerical modelling is a useful tool for studying and better understanding of the phase changes and heat and mass transfer in a thermosyphon operation

Specifics in the operating modes of thermosyphon air heater of steam generators №1 and №2 in TPP "Republika" at fuel switch from coal to natural gas

A fuel switch is motivated both by the necessity of increasing energy efficiency and the compliance with the ever-stricter regulations regarding the release of harmful emissions in the environment. In this paper a thorough financial and energy analysis on the fuel switch from coal to natural gas is carried out, in particular with respect to waste heat recovery systems (two phase thermosyphons). As a result of the calculation of the heat transfer coefficients for both fuels, it is established that the system running on natural gas has a lower value, due to the lower air velocity, caused in turn by the lower requirement for excess air. The heat transfer coefficients of the evaporation and condensation zones respectively are established hfgas=104.9 И hair=84.9 (W/m2.K) for coal and hfgas И hair =84.7 (W/m2.K) respectively for gas. A numerical study is also carried out and a methodology for the analysis of the efficiency of two phase thermosyphons with complex geometry is presented

INTELLIGENT SYSTEM FOR IMPROVED SAFETY OF PEDESTRIAN TRAFFIC LIGHTS

The high concentration of vehicles and pedestrians at traffic lights makes them a common place for road accidents to occur. The main reason for them is the behavior of vehicle drivers and pedestrians, who often violate the traffic law because of incorrect judgments. This study investigates a special type of traffic lights, which are located on places without roads intersection. In the present study, a concept for improving the safety of such traffic lights is suggested. The method suggests a novel algorithm for the detection of pedestrians, based on image processing and a background pattern. The concept of the detection system makes it applicable in different climatic conditions, such as rain, snow, dust, etc., and offers many advantages over the current situation in Bulgaria. The intelligent system only detects pedestrians in the waiting zones, in order to optimize the traffic problems, such as traffic delays, use by disabled people, protection against troublesome users, etc