In this publication it is a question of alternative types of fuel and prospect of their application on tractor diesel engines.
According to many experts, gaseous fuel, especially natural and passing oil gases, use of spirit fuel generally ethanol and methanol, and also hydrogen and other types of fuel can become perspective fuel for diesel engines in the near future.
ALTERNATIVE FUELS AND PROSPECTS of THEIR APPLICATION ON TRACTOR DIESEL ENGINES
The numerous forecasts predicting gradual and quite close "dying off" of piston internal combustion engines (DVS) as the most mass power power plant, appeared insolvent. Moreover, DVS weren’t forced out from one area of the application, including and aviation engines. This results from the fact that DVS and, first of all, diesel engines, are for today the most economic thermal engines which far haven’t settled the potential possibilities. The DVS park structure constantly changes towards increase in specific weight of diesel engines. In the next 10-15 years it is possible to expect that diesel engines completely will replace DVS with compulsory ignition on cargo transport, city and international buses and partially on automobile transport. Such tendencies are characteristic for all industrially developed states and speak as higher fuel profitability of diesel engines (for 30-35 % better, than at petrol DVS), and mnogotoplivnost integrally inherent in diesel process. These two features are extremely important, as allow to solve a problem of fuel resources both at the expense of their economy, and at the expense of expansion of their source of raw materials.
On the other hand, the wide dizelizatsiya of all branches of a national economy and, first of all, agricultural industry and motor transport, causes of increase in production of diesel fuel. At existing technology of oil refining its exit makes about 20 % (gasoline – about 15 %). Possible ways of satisfaction of constantly increasing requirement for diesel fuel is transition to use by diesel engines of all types of the unified fuel of shirokofraktsionny structure, and also additional involvement to fuel balance of alternative types of fuel both in the form of additives to existing diesel, and in a "pure" look.
The analysis of prospects of use of alternative types of fuel for diesel engines is necessary for carrying out taking into account a source of raw materials for receiving this fuel, proceeding from total of fuel and energy resources. Needs of mankind for energy are provided for today for 95 % at the expense of combustible minerals.
Within the XX century the energy balance structure essentially changed. If at the beginning of the century about 95 % of world requirements for energy were satisfied at the expense of coal, now its share makes about 30 %, and the share of oil and natural gas in an energy balance increased to 65 %.
Now about a third of all extracted oil, and its stocks make about 11 % from fuel and energy resources of combustible minerals, is used for receiving fuel, the exit of diesel fuel at oil refining makes, as it was already noted, about 20 %. The big consumption of oil in the world forces to improve ways of its extraction from an earth subsoil that, in turn, will cause considerable deterioration of operational qualities of oil products received from it as the share increases in total amount of oil extraction heavier, viscous, with the raised content of sulfur and other impurity. The oil products received from such oil, demand more careful cleaning. Their application causes of increased operational reliability of fuel equipment, sleeves, piston rings and other details of engines.
Ukraine can’t provide itself with completely necessary amount of oil, and its power policy in many respects depends on the export countries. Besides, need of transition to oil use as main raw materials for the chemical and microbiological industry forces to think now already of rational reorganization of structure of power, to look for additional raw material resources of diesel fuel besides oil. The major task in this reorganization complete replacement of the light oil products used in DVS, alternative fuels is represented whenever possible.
As production of diesel fuel from oil is connected with receiving fuel oil, and also the average fractions going for production of jet fuel, reorganization of structure of fuel balance shouldn’t lead to violation of balance of these types of fuel.
Extent of use of oil considerably is defined now by depth of its processing and development of production of fuel for engines. The most power-intensive processes are connected with receiving high-octane components of commodity gasolines, and these processes are accompanied by loss of hydrocarbons. A number of scientists and experts the offer on expansion of production of diesel fuel at the expense of reduction in production of gasolines and the reduction of release of engines connected with it with spark ignition, as less economic in comparison with diesel engines expresses.
A certain interest represents also application of the water fuel emulsions increasing profitability of work of a diesel engine. The researches which have been carried out in this area for sredneoborotny diesel engines, showed not only some increase of profitability, but also decrease in an ash-content of final gases.
Recently searches of types of the fuel alternative diesel, received on the basis of oil refining extended. They can or replace completely diesel, or be used in a mix with the last. In the latter case fuel will be called as smesevy.
Use in diesel engines of only alternative fuel often happens impossible, for example, because of low tsetanovy number, and then diesel fuel is used as zapalny for the main fuel which is alternative. Probably also introduction in a power supply system of additional units for creation of stable mixes, for example, emulsifiers.
Besides, work on pure alternative fuel with excellent from diesel properties will demand entering of some changes into a diesel engine design (optimization of extent of compression, improvement of greasing of plunzherny pair of fuel pump of a high pressure, the device for preardent preparation of fuel etc.).
Briefly we will characterize some possible alternative fuels and sources for their receiving. According to many experts, for diesel engines gaseous fuel, especially natural and passing oil the gases which explored reserves many times over exceed oil explored reserves in the near future can become perspective. Difficulties of use natural and passing oil gases are connected with remoteness of their fields that causes additional considerable costs of transportation (additional construction of gas pipelines and gas-distributing stations).
In some cases perspective use of spirit fuel which can be applied both in diesel engines, and in engines with spark ignition is represented. And methanol, it is possible to receive alcohols, generally ethanol from coals, natural gas and a biomass.
Very perspective sources for receiving liquid types of hydrocarbonic fuel are coal (including low-calorie), combustible slates and petroliferous sand. These liquid fuels carry the name synthetic and on the properties are close to the traditional diesel. The main obstacle for their wide use is higher cost in comparison with diesel fuel.
The main problem of application of hydrogen as fuel for DVS is the organization of its storage onboard a vehicle, and also providing a stock of a course, comparable with work on liquid fuel (diesel, gasoline). For today three ways of storage of hydrogen onboard a vehicle are known: in the compressed look, in the liquefied condition and in the form of metalhydrides. Any of the listed ways of storage of hydrogen doesn’t allow to lift over 5-6 % of a ratio of weight of fuel and weight of necessary capacities. The similar ratio for liquid types of fuel makes 80 % and more. Therefore, for preservation of a stock of a course of traditional liquid fuel when using hydrogen it is necessary on 500 kg and more to increase mass of a vehicle.
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