Methane, as an alternative to traditional motor fuels, is the most perspective for the incoming decades of the current century. The most widely spread method of the modification of diesel engines for operating with methane is a conversion of a basic model by changing both the way of ignition - compulsory spark ignition instead of self-ignition by compression, and the method of power control - quantitative, with the help of a throttle in case of a gas version, instead of qualitative in a diesel version. The main task of such conversion is to achieve the best possible energy and economic performance of the engine. Moreover, the peculiarity of the operation procedure of the gas engine, the necessity to avoid detonation combustion, should be taken into account. Consequently, in the process of converting a diesel engine into a gas one manufacturers have to decrease both the compression ratio and boost pressure, which leads to decline in engine efficiency. The authors found out, that there is a potential possibility to achieve much better eco-nomic and power characteristics of gas engines by applying Miller cycle to the operation procedure. In this case it becomes possible having very high geometric compression ratio and corresponding high val-ues of gas expansion to obtain relatively low values of actual compression ratio. This is the value that can lead to detonation combustion. The program of calculating the characteristics of operation procedure of Miller-cycle gas engines was worked out. The authors suggested a system of calculation, according to which detonation behavior is estimated on the basis of actual data of a particular model of the engine. Due to such analyses of the particular model of the engine we found out actual maximum values of compression pressure and compression temperature, which do not lead to the onset of detonation. So it may be stated that the parameter value that significantly increases the overall efficiency of the Miller-cycle gas engine, created on the base of Kamaz engines, is found.
The problem of searching for alternative ways of power supply for the transport and technological complex of the agroindustrial complex is discussed. The ecological and economic expediency of the transfer of agricultural machinery (mainly diesel) to supply by fuel produced from biomass is substantiated. It is noted that the large-scale use of biological energy as the main motor fuel for diesel engines is hampered by a significant difference in their physicochemical properties from the properties of traditional hydrocarbon fuels. One of the alternative solutions to the problem is the use of energy biological products as an additive to the base hydrocarbon fuel. At the same time, the most acceptable physicochemical properties of a two-component fuel, meeting the requirements of efficient organization of the working process of a diesel engine are provided by appropriate choice of the value of this additive. The paper suggests a technique for optimizing the component composition of binary fuel, which provides the utmost possible improvement of the economic and environmental performance of an engine running on this fuel. A method for improving the combustion performance of biohydrocarbon fuels based on the use of chemical activation agents is methodologically substantiated. Results of experimental approbation of a set of proposed measures for improving binary fuel parameters in conditions of full-scale tests on the engine are presented. Based on the results of the conducted study, it is concluded that the proposed concept of the method aimed at improving the indicators of binary biohydrocarbon fuels can be attributed to one of the promising directions in the field of actively developing bioener-gy. The use of such fuels makes it possible to convert almost any serial engine into a competitive power plant with higher environmental and economic performance compared to engines running on traditional petroleum fuels. In its key basis, the method is aimed at an efficient and cost-effective solution of urgent problems of energy conservation and raising the level of environmental and fuel and energy security in the environment of agricultural production.
Results of comparative analysis of technologies for converting some kinds of alternative energy sources into fuel for motor-and-tractor engines are given. Choosing of the most acceptable raw material for production of efficient motor fuel is substantiated.
An integrated perfection method of ecological and fuel-economic indicators of tractor diesel on the basis of two-component biodiesel fuel and chemical activation means application was suggested.
The purpose of this paper is to search for the optimal configuration of the variable parameters of the reinforcing layer of a compressor wheel made of a composite material. The composite material considered in this paper is a carbon matrix filled with carbon fiber. Variable parameters were the fiber fraction in the composite, the total thickness of the reinforcing layer, and the fiber fraction in the composite oriented in the circumferential direction of the disk. The objective function in this study is the safety factor of the wheel. The parameters were optimized by the Gauss-Seidel method. At each optimization step, the problem of the theory of thermoelasticity of anisotropic media was solved by the finite element method. In the course of the study it was found that the maximum safety factor of the wheel 1,15 is achieved with the maximum fiber fraction in the composite, the thickness of the reinforcing layer 1,4 mm and the fiber fraction 0,581 oriented in the circumferential direction. The deformations of the wheel with the above parameters remain at an acceptable level. According to the results of calculations it is established that it is possible to increase the level of manufacturability of the impeller production due to the transition to the reinforcement of the disk only in the circumferential direction. At the same time, the reduction of the general safety factor will be less than 6 %. Proceeding from the results obtained during the optimization process, it follows that in the future the optimization problem for the component base considered in the work can be carried out only with respect to the fiber fraction oriented in the circumferential direction. In the final part of the work, an analysis of the mass-inertial characteristics of a composite wheel with a wheel produced using traditional technology was made. The mass and moment of inertia of the rotor in the case of a wheel from composite material will be reduced by 11 % and 18 %, respectively.
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