Vol 83, No 7 (2016)

The article is devoted to the modeling of process of nitrogen oxides formation in the cylinder of diesel engine operating on compressed natural gas. The combustion of methane-air mixture, ignited by atomized pilot oil that is injected through multijet nozzle, in the cylinder of gas-diesel engine increases the rate of turbulent fluctuations, which leads to intensification of heat and mass exchange in the plume, and significantly increases the rate of formation and decomposition of nitrogen oxides. The calculation of expected emissions of nitrogen oxides in the cylinder of diesel engine and their content in the exhaust gases is carried out. It is done on the basis of the results of kinetic systems modeling for calculation of the kinetics of nitrogen oxides formation during combustion of natural gas and diesel fuel, taking into account the influence of turbocharging, intermediate cooling of charged air and exhaust gas recirculation. In the mathematical modeling of nitrogen oxide formation in the cylinder of diesel engine, the combustion process is divided into two zones, namely the zone of fresh mixture and the zone of combustion products. First zone is a mixture of fresh air with recycled gases (if there is a process of recycling) and residual gases. Before combustion starts, this zone occupies the whole cylinder. During combustion, the volume of zone of combustion products increases. Theoretical researches are carried out on the basis of developed mathematical model for calculation of nitrogen oxides in the cylinders of 4Ch 11.0/12.5 and 4ChN 11.0/12.5 diesel engines. The high precision of theoretical calculations of volumetric content and mass concentration of nitrogen oxides is confirmed, compared to the results of experimental researches (the difference does not exceed 5%).

With the use of current technologies of preparation of pressed forage, the losses of valued leaf part of grass plants come up to 14%, which is equivalent to significant losses of total weight of harvested hay. From this perspective, the purpose of the research is to develop a resource-saving technology of preparation of high-quality chopped hay, and to design a pick-up chopper for its implementation. To substantiate the offered technology, the method of system analysis is applied; to develop the structural and technological scheme of universal pick-up chopper, the method of design of agricultural machinery is used. As a result of theoretical researches, the analytical expression is obtained for determination of total yield losses, that are equivalent to the losses of leaf part of forage. The expression is proposed as a new optimization criterion for substantiation of different technologies of forage preparation. To improve the quality of forage and to exclude operations leading to the losses of leaf part of grass plants, a technology of preparation of chopped hay is proposed. Hammer and knife working bodies of a pick-up chopper provide high-quality chopping of dry and wet forage. The machine is equipped with new pick-up mechanism without treadmill, rollers, cranks or bearings for reliable hay picking up. The results of experimental researches allow to determine the following optimal parameters of the machine: the air flow speed in deflector 15 m/s; the rotation speed of pick-up reel 60 rpm; the optimal productivity 8-9 t/h; the losses of chopped forage 1.83%. The performance tests of a pick-up chopper equipped with hammer mill and new pick-up mechanism showed that it provides the preparation of high-quality chopped hay with reduction of operating costs by 2 times as compared to the roll technology of forage preparation.

The paper deals with the improvement of starting characteristics of diesel engine with low compression ratio. The processes in inlet manifold and cylinder of diesel engine during pre-start preparation and start-up are submitted as the subject of study. The purpose is to improve the starting characteristics of diesel engine with low compression ratio by using of inlet electrical air heaters instead of electric torch device. The object of study is a modification of tractor constant power engine of 4ChN 15/20.5 type with low compression ratio equal to 12.5. During the experiment one electric torch device and three tubular electric heaters with heat power of 0.8 kW each were sequentially installed in the inlet manifold of diesel engine. A calculation method for heat transfer from the surface of inlet manifold to the ambient air is proposed. Conditions of fuel self-ignition in the combustion chamber of diesel engine with electric torch device are theoretically substantiated, as well as its critical shortcomings, namely: raise of temperature of fuel self-ignition due to the decrease in oxygen concentration of air charge in cylinders, as a result of its consumption in the flame of electric torch device; ability to work only during engine cranking by electric starter with a limited timespan of 20 seconds. It is proved that a valid method providing the cold starting of 4ChN 15/20.5 diesel engine with low compression ratio equal to 12.5 is air preheating by tubular electric heaters placed throughout the length of inlet manifold, with total heat power of 1.6-2.4 kW. Rational design parameters of a cold start aid system with tubular electric heaters and its operation modes are determined. The results of the study were used for modernization of production models of ChTZ-Uraltrac tractor diesel engines and for development of new ones, so they can be recommended for introduction in engine building companies.

The performance of livestock farms and complexes largely depends on the quality of feed preparation for feeding. It is proved that feeding efficiency is increased with the use of feed mixtures in the diet, which allows to increase animal performance, to reduce feeding period and feed consumption per production unit. Despite of the wide use of different types of mixers, their working process is understudied, and therefore the study of influence of design and technological parameters of mixers on the quality characteristics of mixture is the crucial task. The aim of the study is the improvement of technological process of feed mixtures preparation in a horizontal ribbon mixer by improving quality of mixing and reducing energy intensity of working process. Experimental studies of a horizontal ribbon mixer were carried out in the laboratory of mechanization of animal husbandry at the Zonal Research Institute of Agriculture of the North-East. For the studies, the mixture consisting of a basis (80% of barley and 20% of rye) and a control component (pea) was used. The implementation of multifactorial experiment allows to obtain approximate mathematical models of the process, that link together all the factors taken into account. Experimental studies allow to determine the numerical values of coefficients of regression equations, by which it is possible to assess the degree of influence of relevant factors. During the tests, Box-Behnken design matrix was implemented. According to the results, the maximum value of the uniformity coefficient of finished product is 86,1%, which meets the zootechnical requirements for feeding of cattle and poultry, and is achieved in the presence of 620 kg of basis and 146 kg of control component in the mixture. The mixing time is 4 minutes, and the throughput capacity of mixer is 5,75 t/h, when the specific energy consumption is 1,55 kilowatt-hours per ton.

In recent years, some foreign companies pay special attention to development and creation of multipurpose power vehicles supplied with sets of replaceable technology adapters. The North Caucasus Research Institute of Agricultural Engineering and Electrification in cooperation with Gomselmash presented a constructive layout diagram of multipurpose power vehicle. Its principal differences are the replacement of technology adapters by means of mechanism mounted on power vehicle, and the possibility of straight-flow moving of processed material in harvesting modules. The efficiency of multipurpose power vehicle is straightly correlated with its annual utilization, that depends on natural-climatic conditions defining the structure of crop areas, the technologies and the period of operations. The efficiency of multipurpose power vehicle according to state standard is evaluated by application to the conditions of typical farm. The research objective is the technical and economic evaluation of functioning of machine and tractor fleets formed with production machines in basic version, and with production machines and multipurpose power vehicles developed for the subzones of regions of the South of Russia - in new version. Evaluation is made with the use of a developed mathematical model of optimization of technological complexes and machine and tractor fleets in general. The introduction into machine and tractor fleet of multipurpose power vehicles with complexes of replaceable modules meant for subzones of regions of the South of Russia will allow to reduce the operational costs of entire set of works of field crop cultivation by 12.4-20.6% and the cost of machine fleet by 17.5-29%; reduce the relative energy consumption that accounts for 100 hectares by 28.3-38.1% and the relative material consumption by 16.5-33.4%; increase the net present value by 31.8-246%. For reducing the costs of fuel and lubrication materials, the ballasting of chassis during energy-intensive works and use of variable-power engine are proposed.