Vol 85, No 2 (2018)

The subject of the investigation was the waste heat recovery system of a small-scale heat electropower station that can be used as stationary and primary, reserve or additional source of electrical and thermal energy. The object of the investigation was the waste heat recovery system of the diesel engine D 180 and the small-scale heat electropower station on the basis of the diesel generator plant DGU-100C produced by JSC «ChTZ». The aim of the investigation was an experimental estimation of the efficient use of the diesel engine’s waste heat recovery system. The recovery system was consisted of an original heat exchanger for the recovery of the waste heat of the diesel engine’s cooling system, the waste heat of the lubricating system, the centers of which is made in a common housing, and the heat exchanger for the recovery of the exhaust gases waste heat from the diesel engine (pre-heater boiler PZD-600). The article presents the small-scale heat electropower station’s arrangement with the waste heat recovery system, the original heat exchanger arrangement and a scheme of the small-scale heat electropower station with the waste heat recovery system. The principle of operation of the proposed system is described. In comparison with the known constructions, in the proposed cogeneration power plant there is no need to separately regulate the temperature of the cooling liquid and the lubricating oil at the inlet to the piston internal combustion engine and the necessity to use an additional liquid-oil heat exchanger or oil cooler in the operation of the cogeneration plant without thermal load. Collectively, it was ensured a reduction of the complexity, material consumption and overall dimensions of the recovery system and the cogeneration power plant in general. The absolute economic effect from the using of the waste heat recovery system is 240…300 thousand rubles for the engine life, specific - 22…28 rubles/h. The payback period of the waste heat recovery system is less than a year. The obtained results convincingly indicate the economic feasibility of implementing the proposed system of waste heat recovery of the diesel engine D 180 of a small-scale heat electropower station based on the DGU-100S.

Currently, for the surface application of fertilizers, both in Europe as well as in Russia, spreader devices of various designs and arrangements are used. The metering devices in them, as a rule, are centrifugal type disk mechanisms with a vertical axis of rotation. Overview and analysis of their work shows that they do not completely meet the agrotechnical requirements, namely, distribute fertilizers on the soil surface with significant deviations from the permissible unevenness. Therefore, the development of a working body for increasing the uniformity of the distribution of mineral fertilizers over the field surface is an urgent challenge. The uniformity of the distribution of mineral fertilizers by a centrifugal working body is based on the difference in the speeds of fertilizer’s granules at the moment of their descent from the working body. The magnitude of the velocity affects the range of flight of particles (the coverage) and depends on the structural and kinematic parameters of the working body. At the department of agricultural machines of the Mordovia State University a centrifugal working body has been developed, at any point of which the descent of mineral fertilizer’s granules proceeding at different speeds. That had been achieved through the the fact that the working body contains a conical surface, along the generatrix of which, blades of different lengths are rigidly fastened. When working, the fertilizers are fed to the conical part and are distributed in a uniform layer and continue directed movement along the conical surface. The circumferential velocity of the working surface towards the base increases, and consequently the velocity of particle descent from different points of the working surface increases. The rest of the fertilizers flows continuously to the spherical disk and is directed to the soil surface by the blades. From blades of different lengths, fertilizers come off at different heights, at different angles of inclination to the horizon and at different speeds, which will affect the uniformity of their application. The results of the investigations are showed that the use of the experimental working body allows to increase the working width from 10 to 14 m and to reduce the uneven distribution of mineral fertilizers over the total width by 14,2 %.

The possibilities of a prediction of the heads of cylinder durability of the automotive diesel engines at the design stage and their completion to specified parameters, especially for reliability are considered. Since diesel engines operate in the unsteady modes, the main load is not only mechanical, but also thermal. At that, it occurs when the operating modes of the diesel engine change. The most loaded sections in the cylinder head are the bridges between the inlet and exhaust valves, as well as the bridges between the nozzle holes and inlet and exhaust valves. Under the influence of the thermal load, the distortions of the crystal lattice appear in the sections of the cylinder head at first, which leads to the appearance in some direction in which the greatest tangential stresses act, tears, gradually change under the influence of alternating stresses in the crack. When the total accumulated damage reaches a certain critical value, and the crack substantially weakens the cross section, fatigue failure occurs. To ensure the reliability of the diesel engine in operation, it is necessary to choose such methods of calculation and testing that would ensure a specified durability of the cylinder head. Since the reliability check in operation takes considerable time, that accelerated testing is used to reduce the test time. The place occupied by the accelerated tests in the design of diesel engines, as well as the sequence of the formation of their program are considered. It is shown that in practice it is possible to achieve only a certain degree of change in the technical condition of the cylinder head due to the degree of completeness of the accounting of the interacting operational loads and their distortion during reproduced on the test equipment. Possible modes of testing the cylinder heads on a non-motorized thermal bench are proposed with the aim of a determination their durability. They correspond to the modes of accelerated tests for the reliability of the automobile diesel engines. The problem of convergence of the results at accelerated tests and the data under operating conditions is considered.

The article is devoted to the solution of an important scientific and practical problem - optimization of the tire shell design parameters of the leading wheels of combine harvesters of high productivity, operating in conditions with low bearing capacity. Optimization of the parameters of the pneumatic tire, as a link in the oscillatory system and the main element of the wheel propulsion, is one of the directions for improving the functioning of combine harvesters. One of the factors affecting the performance indicators of combine harvesters is the perfection of wheeled propellers. Their agrotechnical properties can be improved due to a rational choice of tire parameters depending on the type of rolling surface, which will also help to reduce fuel consumption. On the basis of the abovementioned, the aim of this paper is to investigate the effect on the performance of combine harvesters of the characteristics of the tires used on the driving wheels and to improve their agrotechnical properties by optimizing the parameters of the pneumatic tires. The description, methods and results of experimental studies using specially designed and providing reliable results of devices for determining deformations of the inner and outer shells of the tire relative to the rim in the circumferential and radial directions, as well as contact pressures and stresses in the soil are described. On the basis of theoretical and experimental studies of the work of combine harvesters of high productivity, the influence of the parameters of the pneumatic tires of the driving wheels on the performance of them has been established. The optimum combination of design parameters of the experimental pneumatic tire of a radial design for grain harvesters is determined. The results of the research will make it possible to develop recommendations for the selection of optimal parameters for pneumatic tires that contribute to improving the performance of grain harvesters used under various operating conditions by bundling their driving wheels with radial-type tires.

Investigation of the effect of internal pressure on the distribution of hardness in the fuel pipe wall was conducted. In the high pressure circuits of Common Rail systems, the fuel pressure is much higher than the pressure level in conventional fuel systems. Thas is why it is of practical interest to change the mechanical properties of the component materials during operation. In the present work, an attempt was made to evaluate the influence of the multi-cycle loading of the fuel pipe with a high internal pressure on the hardness of the material from which the fuel line was made. The loading was carried out under the conditions of a non-motorized test bench with a pressure of diesel fuel of 160 MPa. The test duration was 500 hours. With the selected pump shaft speed and the response frequency of the electrohydraulic control valves this was equivalent to approximately 96x106 cycles. Before and after the tests, hardness measurements were made in the cross section of the fuel lines. The distributions of hardness values are obtained, which testify the existence, under the given loading conditions of a self-hardening process of the material. In the initial state, fuel lines are characterized by a certain anisotropy of hardness and, accordingly, strength characteristics. In this case, the inhomogeneity of the field of values of hardness decreases with decreasing radius of location of the material layer. Dispersion of hardness values takes place both along the axis of the fuel pipe and in the circumferential direction. Loading of fuel pipes of the Common Rail type with pulsating hydraulic pressure leads to a redistribution of the hardness values in the fuel pipe wall. It is found that in the layers of material located closer to the central channel of the fuel pipe, the hardness equalization occurs to a greater extent as it is used, than in layers located far from the central channel. In general, the hardness is increased, which can be interpreted as the hardening of the fuel line during operation.

When harvesting grain crops with combine with combining fairing, the process of contact of plants with its fairing includes the impact of the head of the plant on the surface of the fairing, and movement along its surface. The greatest probability of loss of those head grains that contact through the scales covering them with the fairing of the header was analyzed. The type of impact of these grains depends on the shape of the fairing and the angle of inclination of the plant. At the direct impact of the speed before and after impact are proportional to the recovery factor and can be sent in the forward or reverse direction. If the impact is oblique and the deviation of the velocity vector is within the angle of friction the velocity after impact is determined on the basis of Newton's dry friction hypothesis. In grain crops, a stalk is of low stiffness, and, according to our data, compensates for the damping properties of the grain covering the scales. When the head strikes, the grains acquire the kinetic energy expended on the deformation of the contacting surfaces (the lost energy) and the energy of recovery. The loss of grain will occur if the energy of grain recovery is greater than the energy required for its separation. The purpose of the research, the determination of the energy released during the restoration of the head grains, contacting through the scales covering them with the header fairing. The method was tested by comparing the renewal energy of the grain of winter wheat, which is insensitive to the contact of the head with the surface of the fairing made of steel and high-strength polymers. It is established that on the eighth day of harvesting, with a breadmaking humidity of 9-11 %, the work required to separate one grain from the head is reduced to 0,0015 J. Under these conditions, the harvesting unit equipped with a combing header with a fairing made of steel can work without loss of grain in the first phase of interaction with it at speeds up to 2,3 m/s, and with a header, the fairing of which is made of ultra-high molecular weight polyethylene, at speeds up to 3,5 m/s.

The main indicator of the physical state of soils is the density of structure. When comparing the values of the equilibrium and optimal soil density for agricultural crops, the need of one or another mechanical treatment is determined. This suggests that at present the soil treatment system can not be uniform, universal, equally suitable and effective at different points in the field. It must be differentiated, adapted to soil and climatic conditions. Proceeding from the above, there appeared the idea of the need to create a combined cultivator for differentiated soil cultivation, which provided the desired predictable process of work under accomplished conditions. The purpose of the study is to reduce energy costs, improve the quality of surface preparation of the soil through the application of differentiated tillage without reducing yields. Field studies on determining density and hardness of the soil were carried out at a temperature of + 20 ± 2 °C at different depths (0 ... 10, 10 ... 20, 20 ... 30 and 30 ... 40 cm) and repeated 4 times for each depth to determine the average values of the amplitudes. The moisture content of the soil during the treatment varied from 20 % to 26 %. The limiting relative error in the measurement was 5 %. When examining the hardness and density of the soil, one point (as one dimension) was laid on 4 ... 5 hectare. The results of the studies showed that the hardness and density of the soil in different points of the field are different. Over time their values increase. The minimum values of hardness and density were observed at a depth of 0 ... 10 cm and amounted to 8 kg/cm2 and 0,94 g/cm3, maximum at a depth of 30 ... 40 cm - 34,3 kg/cm2 and 1,41 g/cm3. In this direction, we proposed the creation of an experimental combined machine for differentiated soil cultivation, which automatically changes the depth of processing, depending on the density and hardness of the soil.