Specialists from different countries are conducting research in the field of the use of new types of fuel and energy sources in road transport. This is due to a significant increase in the number of vehicles and increasing environmental pollution.
to the most efficient and promising species motor fuel include natural gas, hydrogen, propane-butane mixture, methanol, etc.
A promising automotive fuel is any chemical energy source, the use of which in traditional or developing automobile engines allows to solve the energy problem to some extent and reduce harmful effect on the environment. Based on this, five main conditions for the prospects of new energy sources are formulated:
availability of sufficient energy resources;
the possibility of mass production;
technological and energy compatibility with transport power plants;
acceptable toxic and economic indicators of the energy use process;
safety and security of operation.
There are several different classifications of promising automotive fuels. Of great practical interest is the energy classification, which is based on the calorific value of traditional liquid carbon fuel.
For traditional liquid hydrocarbon fuel the highest energy density, so the car running on it has a small size and mass of the fuel tank and fuel equipment and does not require a complex fueling and storage system. Hydrocarbon gases and hydrogen have a higher mass energy intensity, but due to their low density, they have significantly worse volumetric energy indicators. Therefore, the use of these fuels is possible only in a compressed or liquefied state, which in some cases greatly complicates the design of the car.
Hydrogen fuel. Great hopes are placed on hydrogen fuel as the fuel of the future. This is due to its high energy performance, the absence of most toxic substances in combustion products and a virtually unlimited resource base. It is with hydrogen that the promising development of energy is associated.
In terms of mass energy intensity, hydrogen exceeds hydrocarbon fuels by about 3 times; alcohols - 5-6 times. But due to its very low density, its energy density is low. Hydrogen has a number of properties that greatly complicate its use: it liquefies at 24K; has a high diffusion capacity; makes high demands on contacting materials, explosive. However, despite this, scientists in many countries are working on the creation of vehicles running on hydrogen fuel. Numerous schemes of its possible use in a car are divided into two groups: hydrogen as the main fuel and as additives to modern motor fuels. The main difficulty in using hydrogen in a liquefied state is its low temperature. Typically, liquid hydrogen is transported in double-walled cryogenic tanks, the space between which is filled with insulation. For the safe operation of liquid hydrogen, complete sealing of the fuel supply system and ensuring the release of excess pressure are necessary.
Hydrogen technology, hydrogen energy - they are being talked about more and more persistently for the reason that this chemical element is the basis of the only fuel known today that does not form the notorious carbon monoxide during combustion and therefore is the least environmentally harmful. In addition, its reserves in nature are practically inexhaustible. That is why for many years attempts have been made to use hydrogen for internal combustion engines. The Moscow Automotive Institute, Bauman Moscow State Technical University and a number of other institutes worked in this direction back in the 1930s.
During the Great Patriotic War, the idea of hydrogen fuel was practically applied to cars in the air defense forces on the Leningrad front.
In the postwar years, Academician E. A. Chudakov and Professor I. L. Varshavsky used hydrogen to power a single-cylinder engine in the Automobile Laboratory of the USSR Academy of Sciences. Academician VV Struminsky and other researchers dealt with this problem. However, the experiments then did not receive a wide scope. They became more relevant and resumed later. Only in the USA by 1976. 15 experimental design groups conducted research on this topic, which created 42 varieties of "hydrogen" engines. Similar searches have been launched by scientists from Germany and Japan.
Such a great interest in hydrogen as a fuel is explained not only by its environmental benefits, but also by its physicochemical properties: its calorific value is three times higher than that of petroleum products, the flammability of the mixture with air has wide limits, hydrogen has a high flame propagation speed and low ignition energy - 10-12 times lower than gasoline.
In our country, extensive work on the use of hydrogen for automobile engines is being actively carried out by many research centers.
The method for obtaining this chemical element using the so-called energy-accumulating substances has been developed in detail by the Institute of Mechanical Engineering Problems of the Academy of Sciences of Ukraine, which also conducts fundamental research combustion processes of hydrogen-air and gasoline-hydrogen-air mixtures, develops circuit diagrams power plant vehicle with different methods of storing new fuel on board.
Hydrogen as a motor fuel has some features due to its properties. Wide flammability limits allow for better control of engine performance. As a result, it is possible to increase efficiency at partial loads - a mode in which an automobile engine "lives" for quite a long time. The calorific value of a homogeneous mixture of hydrogen and air is lower than that of gasoline. Therefore, the power of the engine on hydrogen, to a greater extent than when using gasoline, depends on the method of mixture formation.
Studies of the detonation resistance of gasoline-hydrogen-air and hydrogen-air mixtures have shown that their tendency to detonation largely depends on the excess air coefficient. And in this regard, when using hydrogen as a fuel, other patterns were revealed than for gasoline. The study of the operation of engines on hydrogen-air and gasoline-hydrogen-air mixtures showed a high stability of the working process. Comparing the limits of change of the optimal ignition timing when operating on hydrogen and gasoline, it can be seen that in the first case it significantly depends on the excess air coefficient. When the mixture is enriched, the most favorable ignition timing is significantly reduced. Therefore, when operating on hydrogen, the engine needs other adjustments of this parameter.
Finally, during the combustion of hydrogen, the exhaust gases do not contain such harmful components as CO, hydrocarbons, and PbO. Only one toxic component remains in the exhaust - NO (and then in smaller quantities than when running on gasoline). When using hydrogen as an additive, the content of harmful components is sharply reduced due to the completeness of combustion. In addition, the need to use harmful anti-knock lead additives in gasoline is reduced.
Experiments have shown that internal combustion engines can successfully operate both on pure hydrogen and on its mixture with gasoline vapor. It is curious that even a 10% addition (of the mass of fuel consumed) of hydrogen can have a significant impact, reducing the toxicity of exhaust gases and improving economic performance. It greatly expands the flammability limits of the mixture, which creates the conditions for effective control of the combustion process. In practice, this means the possibility of stable operation on very lean gasoline-hydrogen-air mixtures with a large excess air ratio, which ensures significant savings in gasoline. Considering the fact that the engine in urban conditions runs up to 30% of the time at idle or part-load modes, one can imagine what economic benefits the use of hydrogen brings. And engine operation at high excess air ratios is accompanied by almost complete combustion of the mixture, and, consequently, there are no toxic components in the exhaust gases. The Institute of Mechanical Engineering Problems of the Academy of Sciences of Ukraine has already developed automobile power plants operating on hydrogen fuel. For them, hydrogen is obtained from water (using energy-accumulating substances based on metal oxides), as well as from hydrides - substances capable of absorbing hydrogen when cooled, and giving it away when heated.
It is necessary to bind hydrogen with hydrides in the interests of safety, since when leaking from cylinders, it forms, mixing with air, an explosive mixture that is highly flammable (remember frequent accidents airships with tanks filled with hydrogen). But more important is the fact that hydrides are a more rational method of storing hydrogen on board a car in terms of volumetric indicators.
The general scheme of the fuel power plant: hydrogen fuel, obtained as a result of the interaction of energy storage substances with water, is supplied by the power system to the engine. Engine power is controlled by the components fed into the reactor to release the bound hydrogen.
The power plant can be made both in open and closed cycles. In the first case, only containers for energy storage substances and water are placed on board the vehicle, and combustion products are emitted into the atmosphere. In a closed cycle, a heat exchanger and a condenser are additionally introduced, allowing the use of water vapor from exhaust gases. The water entering the reactor with energy storage substances again serves as a source for hydrogen production. Thus, in a closed cycle, water serves as the "carrier" of fuel, and energy-accumulating substances serve as energy. Hydrogen fuel in both cycles can be used in pure form or as additives (5--10% by weight). In the latter case, the gasoline supply system remains on the machine. The “extraction” of hydrogen from water takes place in a reactor containing energy storage substances. The simplest is a permanent reactor, in which the pressure is maintained by adjusting the supply of components to the reaction zone.
The process of obtaining fuel in it does not occur instantly, that is, it has some inertia. The hydrogen liberated in the reactor must therefore be supplied to the motor through a gearbox-regulator that maintains optimum pressure in front of the supply nozzles.
According to the developed methods for testing using energy storage substances based on metal oxides, as well as using hydrides, serial cars"Moskvich" and "VAZ".
The first experiment (the use of energy-accumulating substances - the Moskvich car) - the gasoline supply system was left unchanged. Two reactors 1 are mounted on the machine, which provide hydrogen production from water, and a reducer 5, designed to dose the fuel supply at different engine operating modes.
Batch reactors have a constant load of energy storage substances based on silicon or aluminum with controlled water supply. Pumps high pressure 4, driven by an electric motor, supply water from the tank through a heater and filter to the reactor, where it is sprayed by nozzles. Check valves are installed in the water system to prevent the penetration of hydrogen into it when the water supply is interrupted. In addition, it has a tap 3, which switches the water supply from one reactor to another. All units of this experimental setup are mounted on a common frame and placed in the trunk.
Installation with the use of energy-accumulating substances to supply the engine with hydrogen: 1 - batch reactors; 2 -- water tank; 3 - valve for supplying water to the reactor; 4 - a block of pumps with an electric drive; 5 -- reducer in the hydrogen supply system
Hydrogen from the reactors is supplied to a valve installed on dashboard, with which the driver connects the operating reactor 1 with the hydrogen supply system. The latter consists of a reduction gear, a moisture separator, gas meter and a reducer for regulating the supply of hydrogen (controlled by a special pedal). Fuel is introduced into the intake manifold, just before the intake valve.
To operate on hydrogen obtained from hydrides, the gasoline supply system was also retained and an additional hydrogen storage and supply system was installed (VAZ car). It consists of a hydride tank 1 heated by exhaust gases, a gearbox with an all-mode vacuum regulator 9 hydrogen consumption and mixer 8, made on the basis of a serial carburetor. The system automatically regulates the rate of hydrogen evolution by hydride (control unit 10, pressure switch 2, damper with electromagnetic drive 7 on the exhaust pipe), maintains the hydrogen pressure in the system constant, regardless of the engine mode. The hydride tank is water cooled when charging.
Installation using hydrides: 1 - hydride tank; 2 -- pressure switch; 3 -- filling valve; 4 -- the exhaust pipe of the hydride tank; 5 -- muffler; 6 -- petrol tank; 7 -- electromagnetic damper drive; 8 - mixer; 9 -- regulator of pressure and flow of hydrogen; 10 -- electronic control unit
The use of hydrogen as an additional fuel for carburetor engines opens up the possibility of a fundamentally new approach to the organization of the working process. With minimal modification of the engine, mainly related to the power supply system, it is possible to achieve a significant increase in its fuel efficiency (the operating consumption of gasoline is reduced by 35–40%) and reduce the toxicity of exhaust gases.
Table 13 Toxicity of exhaust gases,
Water-fuel emulsions. The use of water in the working process of an internal combustion engine is not a novelty in recent years. Water injection has been used to power internal combustion engines on low octane fuels as early as the 1930s.
Now the main attention in the use of water as a fuel additive is given to the possibility of improving the efficiency and reducing the toxicity of vehicle exhaust gases.
Water-fuel emulsions are liquid fuels with tiny drops of water evenly distributed over the fuel volume. The emulsion is prepared directly on the vehicle. To prevent separation of the emulsion, an emulsifier is added to the fuel in the amount of 0.2--0.5%. The water content in the water-fuel emulsion can reach 30--40%.
The use of water-fuel emulsions is possible both in carburetor and diesel engines. But in carbureted engine the use of water-fuel emulsions in some cases leads to a deterioration in some indicators (in particular, fuel efficiency), failures when the throttle is fully opened, and interruptions when driving at low speed. Best Results gives the use of water-fuel emulsions on diesel engines. The supply of water to the combustion chamber provides additional atomization of the fuel due to crushing by superheated water vapor. The specific fuel consumption is reduced by 4--10%.
The addition of water to the fuel makes it possible to reduce the content of certain toxic substances in the exhaust gases by reducing the maximum temperatures in the combustion chamber, the value of which determines the amount of NOx. When using water-fuel emulsions, the amount of NOx can be reduced by 40-50%. The opacity of exhaust gases also decreases, since soot, in the presence of water vapor, interacts with them to form carbon dioxide and nitrogen. The emission of CO remains practically unchanged compared to the operation of an internal combustion engine on fuel without the addition of water, and the emission of SpNsh slightly increases. This type of fuel has not yet found wide application in road transport, as the design of the car becomes more complicated, a number of problems arise when operating in winter period, the effect of water on the working conditions and durability of an internal combustion engine has not been sufficiently studied.
synthetic alcohols. As a fuel for the internal combustion engine of automobiles, methanol and ethanol have been used both in pure form and as part of multicomponent mixtures.
The most widespread cars running on alcohol fuel are in Brazil, which imports 80-85% of petroleum products, paying for them in foreign currency. Fuel costs are growing from year to year and amount to billions of dollars. Therefore, the country announced with enthusiasm the president announced in 1975. transport alcoholization project. fuel tanks brazilian cars refuel with a mixture of alcohol and gasoline in a ratio of 1: 4.
Over time, it is planned to transfer the entire fleet to the use of ethyl alcohol instead of gasoline. Alcohol is obtained from sugar cane (Brazil is the world's largest producer of this crop). It is possible to obtain up to 80 tons of biomass from 1 hectare per year. Plantations, occupying 2% of the country's territory, will be enough to meet the need for new fuel.
According to experts, 1 liter of alcohol costs 30-35% cheaper than gasoline.
Mexico, the second most populous country in Latin America, is poised to follow Brazil's lead. In the US, there is also interest in the production of fuel alcohol from wood, agricultural and other waste.
From an energy point of view, the advantage of alcohol fuels is high efficiency working process and high anti-knock resistance of the fuel, but the calorific value of alcohols is about half that of gasolines. The low energy content of alcohols leads to an increase in the specific fuel consumption.
The use of alcohols requires a relatively small change in the design of the car. The main measures are to increase the volume of fuel tanks and install devices that ensure a stable engine start in any weather. It also requires the replacement of some metals and gasket materials, in particular the plastic lining of the methanol tank. This is due to the high corrosiveness of alcohols and the need for more thorough sealing of the fuel supply system, since methanol is a neurovascular poison. The use of a benzomethanol mixture puts forward a number of other specific requirements. In particular, the requirements for the saturated vapor pressure of gasoline are being tightened, since even with a 5% addition of methanol, it increases significantly. To avoid separation of the mixture, during its storage, transportation and use, it is necessary to observe a certain temperature and prevent water from entering it. Certain synthetic materials used in fuel systems and in automotive systems nutrition, proved to be unstable to the benzomethanol mixture. When transferring the car from gasoline to benzomethanol mixture, I had to change throughput jets, while slightly increasing the overall fuel consumption. At the same time, it was found that a mixture with a methanol content of up to 15% does not worsen the main technical and operational indicators trucks. The high anti-knock performance of alcohols makes it possible to increase the compression ratio of an internal combustion engine up to 14-15 units.
The use of alcohol fuels reduces the content of toxic substances in exhaust gases, which is explained by the lower combustion temperature of alcohol fuel.
Since the beginning of the 1970s, when the energy and environmental situation has sharply worsened, almost all industrialized countries have launched a broad search for alternative energy sources that can replace gasoline and diesel fuel. Among alternative fuels Special attention attention is paid to hydrogen: its use for internal combustion engines makes it possible to solve both raw materials and environmental problems, and to do this without a radical restructuring of the technical base of modern engine building. In particular, studies have shown that the use of hydrogen as the main or additional fuel for engines with forced ignition of a charge increases their fuel efficiency by 30–40% and sharply reduces the toxicity of exhaust gases, since the motor properties allow engines to operate on lean mixtures with high-quality power regulation. Abroad, work on the creation of automobile "hydrogen" internal combustion engines has been carried out by advanced developed countries for a long time and quite successfully. In particular, car company Daimler-Benz (Germany) manufactured cars and minibuses based on production models, whose engines are powered by both gasoline with the addition of hydrogen and "pure" hydrogen. Of the three methods of hydrogen storage acceptable for motor vehicles - compressed to 20 MPa, liquefied at a temperature of 20 K, or chemically bound in metal hydrides - the last one was used on experimental cars of the Daimler-Benz company.
The decisive influence of transport on the state of the environment requires special attention to the use of new environmentally friendly fuels. These include, first of all, liquefied or compressed gas.
In world practice, compressed natural gas containing at least 85% methane is most widely used as a motor fuel.
The use of associated petroleum gas is less common; which is a mixture of mainly propane and butane. This mixture may be in a liquid state at ordinary temperatures under pressure up to 1.6 MPa. To replace 1 liter of gasoline, 1.3 liters of liquefied petroleum gas is required, and its economic efficiency in terms of equivalent fuel costs is 1.7 times lower than that of compressed gas. It should be noted that natural gas, unlike petroleum gas, is not toxic.
The analysis shows that the use of gas reduces emissions of: carbon oxides - 3-4 times; nitrogen oxides - 1.5-2 times; hydrocarbons (excluding methane) - 3-5 times; soot particles and sulfur dioxide (smokyness) of diesel engines - 4-6 times.
When operating on natural gas with an excess air ratio a=1.1, PAH emissions from the combustion of fuel and lubricating oil (including benzo(a)pyrene) in the engine amount to 10% of emissions from gasoline operation. Natural gas engines already meet all modern standards for the content of gaseous and solid components in exhaust gases.
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Toxic Exhaust Components |
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Type of fuel |
(without methane) |
Benzopyrene |
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Gasoline (engines with neutralization) | |||||
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Diesel fuel | |||||
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Gas + diesel fuel | |||||
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propane butane | |||||
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nature, compressed | |||||
Special mention should be made of hydrocarbon emissions, which undergo photochemical oxidation in the atmosphere under the influence of ultraviolet radiation (accelerated in the presence of NOx). The products of these oxidative reactions form the so-called smog. In gasoline engines, the main amount of hydrocarbon emissions is ethane and ethylene, and in gas engines - methane. This is due to the fact that this part of the emissions gasoline engines It is formed as a result of cracking of gasoline vapors in the non-combustible part of the mixture at high temperatures, and non-combustible methane is not subjected to any transformations in gas engines.
Unsaturated hydrocarbons, such as ethylene, are most easily oxidized under the influence of ultraviolet radiation. Limit hydrocarbons, including methane, are more stable, because require harder (short-wavelength) radiation for a photochemical reaction. In the spectrum of solar radiation, the component that initiates the oxidation of methane has such a low intensity compared to the initiators of the oxidation of other hydrocarbons that practically no oxidation of methane occurs. Therefore, in the restrictive standards for automotive emissions in a number of countries, hydrocarbons are taken into account without methane, although the conversion is carried out for methane.
Thus, despite the fact that the amount of hydrocarbons in the exhaust gases of engines using natural gas fuel is the same as in gasoline engines, and in gas diesel engines it is often higher, the effect of air pollution by these components with gas fuel is several times less. than with liquid.
It is also important to keep in mind that the use of gas fuel increases the motor resource of the engine - by 1.4-1.8 times; service life of spark plugs - 4 times and engine oil - 1.5-1.8 times; overhaul run - 1.5-2 times. This reduces the noise level by 3-8 dB and the refueling time. All this ensures a quick payback of the costs of transferring vehicles to gas motor fuel.
The attention of specialists is attracted by the safety issues of using gas motor fuel. In general, an explosive mixture of gas fuels with air is formed at concentrations of 1.9-4.5 times. However, gas leaks through leaky connections pose a certain danger. In this regard, liquefied petroleum gas is the most dangerous, because. the density of its vapor is greater than that of air, and for compressed air it is less (respectively, 3: 1.5: 0.5). Consequently, after leaving leaks, compressed gas leaks rise up and disappear, while liquefied gas leaks form local accumulations and, like liquid petroleum products, “spill”, which, when ignited, increases the fire.
In addition to liquefied or compressed gas, many experts predict a great future for liquid hydrogen, as an almost ideal, from an environmental point of view, motor fuel. A few decades ago, the use of liquid hydrogen as a fuel seemed quite remote. In addition, the tragic death on the eve of the Second World War of the hydrogen-filled airship "Hindenburt" so tarnished the public reputation of the "fuel of the future" that it was excluded from any serious projects for a long time.
The rapid development of space technology again forced us to turn to hydrogen, this time already liquid, as an almost ideal fuel for the exploration and development of world space. However, the complex engineering problems associated with both the properties of hydrogen itself and its production have not disappeared. As a transport fuel, it is more convenient and safer to use hydrogen in liquid form, where, in terms of one kilogram, it exceeds kerosene by 8.7 times in calories and liquid methane by 1.7 times. At the same time, the density of liquid hydrogen is less than that of kerosene by almost an order of magnitude, which requires much larger tanks. In addition, hydrogen must be stored at atmospheric pressure at a very low temperature - 253 degrees Celsius. Hence the need for appropriate thermal insulation of tanks, which also entails additional weight and volume. The high combustion temperature of hydrogen leads to the formation of a significant amount of environmentally harmful nitrogen oxides if the oxidizing agent is air. And finally, the notorious security issue. It still remains serious, although it is now considered greatly exaggerated. Separately, it should be said about the production of hydrogen. Almost the only raw materials for hydrogen production today are the same fossil fuels: oil, gas and coal. Therefore, a true breakthrough in the global fuel base based on hydrogen can only be achieved by fundamentally changing the way it is produced, when water becomes the feedstock, and the Sun or the force of falling water becomes the primary source of energy. Hydrogen is fundamentally superior to all fossil fuels, including natural gas, in its reversibility, that is, its practical inexhaustibility. Unlike fuels extracted from the ground, which are irretrievably lost after combustion, hydrogen is extracted from water and burns back into water. Of course, in order to obtain hydrogen from water, energy must be expended, and much more than can be used later in its combustion. But this does not matter if the so-called primary energy sources are in turn inexhaustible and environmentally friendly.
A second project is also being developed, where the Sun is used as a source of primary energy. It is estimated that at latitudes of ± 30-40 degrees, our luminary heats up about 2-3 times stronger than in more northern latitudes. This is due not only to the higher position of the Sun in the sky, but also to a slightly thinner atmosphere in the tropical regions of the Earth. However, almost all of this energy quickly dissipates and disappears. Obtaining liquid hydrogen with the help of it is the most natural way of accumulating solar energy with its subsequent delivery to the northern regions of the planet. And it is no coincidence that the research center organized in Stuttgart has the characteristic name "Solar Hydrogen - Energy Source of the Future". Installations that accumulate sunlight are supposed to be located in the Sahara, according to the specified project. The heavenly heat thus concentrated will be used to drive steam turbines that generate electricity. The further links of the scheme are the same as in the Canadian version, with the only difference being that liquid hydrogen is delivered to Europe via the Mediterranean Sea. The fundamental similarity of both projects, as we see, is that they are environmentally friendly at all stages, including even the transportation of liquefied gas by water, since the tankers again run on hydrogen fuel. Already, such world-famous German companies as Linde and Messergrisheim, located in the Munich area, produce all the necessary equipment for the production, liquefaction and transportation of liquid hydrogen, with the exception of cryogenic pumps. Huge experience in the use of liquid hydrogen in rocket and space technology has been accumulated by the MBB company, located in Munich and participating in almost all prestigious Western European space exploration programs. The company's research equipment in the field of cryogenics is also used on American space shuttles. The well-known German airline Deutsche Airbus is developing the world's first airbus flying on liquid hydrogen. In addition to environmental considerations, the use of liquid hydrogen in conventional and supersonic aviation is preferable for other reasons. Thus, the take-off weight of the aircraft is reduced by about 30%, all other things being equal. This in turn allows for a shorter takeoff run and a steeper takeoff curve. As a result, noise is reduced - this is the scourge of modern airports, often located in densely populated areas. The possibility of reducing the frontal resistance of the aircraft by means of a strong cooling of its nose parts, which meet the air flow, is also not ruled out.
All of the above allows us to conclude that the transition to hydrogen fuel, first of all in aviation, and then in land transport, will become a reality already in the first years of the new century. By that time, technical problems will have been overcome, distrust of hydrogen as an overly dangerous fuel has been finally eliminated, and the necessary infrastructure has been created.
Throughout the world, fossil fuels continue to be used as an energy source everywhere, which, although environmentally improving every year, pollution from the exhaust of which remains one of the main environmental problems. This makes scientists and engineers think about the possibility of using alternative fuels as other energy sources.
There are many such developments, but not so many types of environmentally friendly fuels are moving into serial use.
compressed air pressure
The pneumatic actuator was developed in France and India almost simultaneously. Now such cars are already being mass-produced. For movement, the force generated by compressed air is used. Such a vehicle develops a speed of up to 35 km / h (using a meager amount of fuel up to 90 km / h). Consumption compressed air in gasoline equivalent is about one liter per 100 kilometers.
alcohol engine
Ethanol or ethyl alcohol is one of the most common alternative fuels. In the USA and Brazil about 32 thousand filling stations sell ethyl fuel. More than 230 million vehicles worldwide use it. The substance obtained during the fermentation of various crops provides a sufficient amount of energy, and its combustion products do not cause any harm to the environment.
Biodiesel or vegetable oil energy
Design diesel engine by itself is more efficient than gasoline. And if you fill it with vegetable oil, then it is also environmentally friendly. We are talking about specially processed oil. You can get such fuel even at home, using simple technological processes. This technology has many advantages: there is no need to change the design of engines on already assembled cars, renewable resources are used for its production, and the exhaust is completely safe for the environment.
Hydrogen engine
At the beginning of the 21st century, a hydrogen engine was developed. Technologically, it is possible to use hydrogen fuel in conventional engine internal combustion, but then the power drops by 60 - 82%. If you make the necessary changes in the ignition system, then, on the contrary, the power will only increase by 117%, in this case, an increase in the output of nitrogen oxides leads to burning of the pistons and valves, and the entry of hydrogen into a reaction with other materials leads to rapid wear engine. An improved version of it in the future could possibly even use water as a fuel. In addition, hydrogen is highly volatile, so it is difficult to store it in liquid form, in fuel tank BMW Hydrogen ( the car in the image) in just a week of non-use, half a tank of hydrogen fuel evaporates.
electric motor
There is a type of engine that produces no exhaust at all - electric. Technology begins its history in the 19th century. Popularity electric motor trams and trolleybuses contributed as urban transport, but in this case, transport needed a constant electric current in the form of wires. The electric car never gained popularity at the time, although it appeared earlier than the car with an internal combustion engine. Now electric vehicles are being mass-produced, electric filling stations for them are being equipped in cities, and the technology is gaining popularity.
hybrid car
Particularly popular are hybrid cars with the simultaneous use of an electric motor and an internal combustion engine, which allows the car to be driven both from an electric charge and from conventional fuel. hybrid cars, of course, do not completely rid the atmosphere of harmful emissions, but reduce the amount of exhaust gases, while allowing you to significantly save fuel and reduce performance.
The Moscow government has decided to entrust the distribution of ecological fuels and energy sources in the city's motor transport to certain auto enterprises. , which is not much different from gasoline, is less practical than alternative fuels.
The enterprises carried out work on already experimental models of cars that are adapted to the use of compressed natural gas, that is, methane.
Half of all vehicles in the company's fleet run on alternative fuels.
Until now, such equipment has never been used in Russian cities, the experience that is being actively acquired now allows one to obtain the necessary knowledge that will create conditions for the expansion and implementation of innovations in all regions of the country.
In the near 1960s, almost all highly developed countries had an energy sector that depended on oil. Western countries won for a set of cheap oil exports, a barrel cost them about $5. Which resulted in quite high . 13 years later, the organization of the Arab oil exporting countries imposed an embargo on the import of oil into the United States of America, this was due to the fact that in the war between Israel and Syria and Egypt, North America supported Israel. After this incident, those countries that called themselves highly developed came to the conclusion that the current economic plans are no longer effective, it is urgent to develop new ones, taking into account completely different types of fuel. The weakest point was the transport industry, which used hydrocarbon fuels.
Another reason for the search for an alternative to oil was that its production became more expensive every year, and its reserves in the bowels of the earth were consumed at a very high rate, and could disappear altogether in about 50 years.
The most interesting thing is that gas engine not at all a novelty of our time, since it was invented back in the very distant 19th century by an engineer from France, Lenoir, he worked, of course, on gas. Nowadays, using alternative fuels in cars, gas is most often used.
Do not confuse it with household gas, because when refueling a car, gas stations use special components of propane-butane, this is liquefied petroleum gas. Its use is cheaper, and environmentally friendly, compared to gasoline. Cars are refueled at special complexes for refueling with alternative types of fuel.
The best fuel for vehicles.
Natural gas, methane, is what bypasses both gasoline and petroleum gas in terms of performance. They are usually filled with cars by those who want to travel twice as much for the same money, more distance.
Does not provoke soot, engine oil is not subject to change. Much less damage is done to pistons and cylinders, good engine performance. No soot, engine oil does not liquefy. Less wear of pistons and cylinders, improves engine life. Oil soot, plus soot, oxidizes the oil, significantly reducing lubricating properties.
There are very few specialized points where you can refuel without problems. There is a network of gas stations. Lots of places to fill up.
Does not require any processing, suitable for use in its original form. A mixture that requires certain proportions, taking into account the seasons. Oil refineries are required.
Delivery is carried out by gas transport routes. They are transported by special tractors. Just like propane-butane, it is delivered to gas stations in tanks.
Explored deposits should be enough for humanity for about 200 years. Since gas is extracted from oil, it will last for about 50 years. Produced from oil, stock no more than 50 years.
Pretty cheap and requires little investment. It has average price. Unstable cost, in the sense that it only grows every year.
Expensive equipment, very few specialists. Russian Federation, installation and production, as well as the repair of installations. Not cheap equipment. No need for additional equipment.
There is no possibility of methane theft at gas stations or from car tanks. You can't steal from gas stations. Easy to resell.
Almost does not change its properties with decreasing temperature. Properties drop as temperature drops Small changes in properties if temperature drops.
Has the highest 4 class of safety. Not very safe, as it has only the 2nd security class. Stable security, 3rd class.
The conclusion suggests itself, methane has only three drawbacks, if compared with other types of fuel. Problems with specialists are easy to solve, and the high cost of equipment still pays off over time, for a set of the same savings. Methane is the fuel that has the best performance among other fuels.
Today, almost all cars can be filled with methane, but in the 90s, it was believed that it was intended for trucks and buses. It was placed in special steel cylinders that could withstand a pressure of 200 atmospheres. But the weight of a cylinder of 100 kilograms scared away motorists, so few people transferred their "beast" to this fuel. Now it's as simple as any other fuel.
Today, steel cylinders have been replaced by less durable composite alloys, reliability has become a victim of lightness, that is, less cylinder weight. Cylinders, like steel, withstand pressure and high temperatures. The explosiveness is overestimated, methane is able to ignite only when the temperature reaches 600 degrees, while gasoline is at 250, not to mention its vapors, which are enough for 170 degrees.
Application in European countries
Widespread use is increasing by leaps and bounds. Now there are 10 million LPG machines. Russia is the leader in the supply of gas fuel on the Western market.
Modern factories are necessarily engaged in the development and production of one or two models of gas cylinders. Audi cars, Honda, Toyota and others. All of them are beginning to establish the production of cars.
Energy benefits have been assessed different countries, with different economic conditions. Auto capable of using gas fuel, can be found from the USA to Asia. In Russia, there are very few factory gas-filled cars, most often you can find gasoline counterparts converted to gas.
Cars with such an alternative fuel as gas are well produced in countries such as Germany and the Czech Republic. This is due to the fact that the first one has an excellent refueling infrastructure, the second one is planned to be replaced with more economical analogues of 10% of the fuel. Italy is a country that already has widespread use of LPG vehicles. More than 779 thousand GBA, traveling through the expanses of this country.
Road transport as a source of environmental pollution. Reasons for the formation of toxic components in the exhaust gases of internal combustion engines
IN last years In connection with the increase in the density of traffic in cities, the pollution of the atmosphere by combustion products of engines has sharply increased. The exhaust gases of internal combustion engines (ICE) consist mainly of harmless fuel combustion products - carbon dioxide and water vapor. However, in relatively small quantities they contain substances that have toxic and carcinogenic effects. These are carbon monoxide, hydrocarbons of various chemical composition, nitrogen oxides, which are formed mainly during high temperatures and pressure.
During the combustion of hydrocarbon fuels, the formation of toxic substances occurs, associated with the combustion conditions, the composition and state of the mixture. In positive ignition engines, the concentration of carbon monoxide reaches high values due to the lack of oxygen to completely oxidize the fuel when they are running on a fuel-rich mixture.
When driving in the city and on roads with a variable slope and frequently changing speeds with the gear engaged and the throttle open, the engines have to work about 1/3 of the travel time in the forced idle mode. At forced idle, the engine does not give up, but, on the contrary, absorbs the energy accumulated by the car. At the same time, fuel is irrationally consumed, the increased absorption of which leads to the greatest emission of toxic CO and CH gases into the atmosphere.
Automobile exhaust gases are a mixture of approximately 200 substances. They contain hydrocarbons - unburned or incompletely burned fuel components, the proportion of which increases sharply if the engine is running at low speeds or at the moment of increasing speed at the start, i.e. during traffic jams and at red traffic lights. It is at this moment, when the accelerator is pressed, that the most unburned particles are released: about 10 times more than during normal engine operation. The unburned gases also include ordinary carbon monoxide, which is formed in one quantity or another wherever something is burned. The exhaust gases of an engine running on normal gasoline and under normal operation contain an average of 2.7% carbon monoxide. With a decrease in speed, this share increases to 3.9%, and at low speed, up to 6.9%.
The main operational factors affecting the level of harmful engine emissions are the factors characterizing the condition of the parts of the cylinder-piston group (CPG). Increased wear parts of the CPG and deviations from their correct geometric shape cause an increase in the concentration of toxic components in the exhaust gases (EG) and crankcase gases (CG).
The basic part of the CPG, on which the performance and environmental friendliness of the engine depends, is the cylinder, since the tightness of the combustion chamber depends on the sealing ability of the ring in conjunction with the cylinder. From technical condition cylinders and piston rings mainly depends on the intensity of the growth of gaps between the rings and piston grooves. Thus, monitoring and adjusting the gap between the ring and the cylinder during operation is a significant reserve for reducing the amount of harmful impurities in the exhaust gas and exhaust gas by improving the conditions for fuel combustion and reducing the amount of oil remaining in the over-piston space.
Toxic emissions of internal combustion engines are exhaust and crankcase gases. With them, about 40% of toxic impurities from the total emission enter the atmosphere. The content of hydrocarbons in the exhaust gases depends on the technical condition and adjustments of the engine and at idle ranges from 100 to 5000% or more. With a total small amount of crankcase gases equal to 2-10% of exhaust gases in general pollution atmosphere, the proportion of crankcase gases is about 10% for few worn out engines and grows up to 40% when operating an engine with worn cylinder-piston group, because the concentration of hydrocarbons in the crankcase gases is 15-10 times higher than in the spent engine. The number of CGs, as well as their chemical composition depend on the state of the CPG parts that seal the combustion chamber. The penetration of gases from the cylinder into the crankcase and back depends on the size of the gaps between the rubbing parts of the CPG. At the same time, the proportion of hydrocarbons with carcinogenic properties increases due to increased oil waste and increased crankcase gas flow through a closed crankcase ventilation system.
By reaching the limit of engine wear, emissions increase by an average of 50%. On the example of accelerated tests carried out at NAMI, it was found that engine wear increases emissions of hydrocarbons by 10 times. The bulk of the engines increased opacity EG falls on engines that have passed overhaul.
The degree of decompression of the combustion chamber depends on the wear of the parts of the CPG, the deviation of their macrogeometry from the correct geometric shape. With an increase in the leakage of the combustion chamber, an increase in CO and CH and a decrease in CO2 occur as a result of deterioration in the conditions of fuel combustion. In addition to reducing the quality of the organization of the working process, the gaps between the ring and the cylinder, as well as the gaps between the ring and the piston groove, lead to an increase in the amount of oil that has entered the over-piston space, to an increase in the deviation from the given dynamics of heat release during the combustion process, and, consequently, to an increase in the total mass of toxic emissions. Oil makes up 30-40% of the solid particles in the exhaust gas.
The basic part of the CPG is the cylinder, on which the economic and environmental feasibility of operating the engine depends. The wear of the cylinder liners has a pronounced oval shape, the major axis of which is located in the swing plane of the connecting rod. The reason for the formation of ovality of the cylinders is mainly the increased load of the pistons on the sleeves in the plane of the swing of the connecting rods. The imperfection of the cylinder block assembly technology also affects the ovality of the cylinders. A change in the macrogeometry of the cylinders (ovality and taper) after the engine is assembled also leads to a deterioration in the fit of the piston rings to the cylinder mirror. It is known that when installing sleeves in blocks various brands ICE, ovality in the cylinders increases by 2-3 times.
It is very important to note that the nature of the distortion of the macrogeometry of cylinder liners after assembly and during operation is the same for most designs of cylinder blocks with “ wet shells". The major axis of the oval of the cylinder formed during assembly, in the stop zone of the upper compression ring at the top dead center of the piston, has the same direction as the major axis of the oval formed during operation. This character of the deformation of the cylinders is explained by the greater deformation of the block in places between the bores for the sleeves.
Reducing the ovality of the cylinders helps to reduce the wear rate of the piston rings and grooves, which generally improves the operation of the piston rings and improves the sealing of the combustion chamber. It is known that the replacement oil scraper rings after the development of the marginal resource, restores to some extent average level engine toxicity. Undoubtedly, if, when replacing rings, the ovality of the cylinders is adjusted to the level of the limit value for the manufacture of new liners, then the effect will be much more significant.
The development of new methods of mixing and dissolution and mathematical description of the effect of the corresponding additives and additives in petroleum fuels will significantly reduce the time for the development of new compositions of alternative fuels and the prediction of their physicochemical properties, which will make it possible to improve the engine workflow when using new alternative fuels.
An analysis of domestic and foreign literature showed that the development of the transition to new types of fuel will go through three main stages. At the first stage, standard petroleum fuels, alcohols, additives of hydrogen and hydrogen-containing fuels, gaseous fuels and various combinations of them will be used, which will solve the problem of partial savings petroleum fuel. The second stage will be based on the production of synthetic fuels, similar to petroleum, produced from coal, oil shale, etc. At this stage, the problems of long-term supply of the existing fleet of engines with new types of fuel will be solved. The final, third stage will be characterized by a transition to new types of energy carriers and power plants (hydrogen-powered engines, the use of nuclear energy).
The conversion of internal combustion engines to hydrogen and hydrogen-containing fuel is a complex socio-economic process, which will require a major restructuring of a number of industries, therefore, at the first stage, the most acceptable option is the operation of diesel engines with the addition of hydrogen-containing fuels. Extremely limited information in the literature on the features of the combustion of hydrocarbon fuels with hydrogen and ammonia additives in diesel engines does not allow an unambiguous answer to the question of the effect of hydrogen-containing fuels on the performance of a diesel engine.
Also, the issue of the use of synthetic liquid fuel (GTL) produced from coal in diesel engines has been extremely poorly studied. Various literature data do not allow an unambiguous assessment of the effect of GTL on the working process, due to the fact that its physicochemical properties are very dependent on the feedstock and processing technology.
Alcohols are the most likely source of motor fuel, but their extremely poor motor properties should be taken into account when they are used in diesel engines. The applied methods of using alcohol fuels require additional complication of the design (installation of carburetors, spark plugs or a second fuel system), or an increase in the cost of fuel (the use of additives that increase the cetane number). The most optimal in this situation may be the method of using solutions of ethanol or methanol with diesel fuel in diesel engines.
The study of the influence of various types of alternative fuels was carried out for several types of high-speed diesel engines with different mixing methods, so it was necessary to obtain as complete information as possible on the course of fuel supply, combustion, soot formation, toxicity, etc. Therefore, an automated system for recording and processing information based on a PC was developed and implemented. For this complex, an application software package was developed, including a program for collecting information from various sensors during tests, programs for processing the data obtained for the analysis of the indicator diagram, the results of optical indication, fuel supply and calculation of mode parameters.
For the simultaneous supply of a cyclic portion of diesel fuel and gas into the cylinder, the author developed a special dual-fuel nozzle, which was supplemented by a separate line consisting of a gas supply fitting and channels in the nozzle and atomizer body. In the channel of the nozzle body is made check valve pressed against the seat by a spring. A cylindrical insert with a screw thread on the surface is pressed into the atomizer channel, which forms a mixing-accumulation chamber connected to the under-needle cavity of the nozzle atomizer.
On the basis of the developed injector, a fuel system diesel engine, which allows you to supply various types of gaseous additives to the fuel.
It is most effective to consider the features of the working process when using alternative fuels, having information about the spatial distribution of soot concentration and temperature fields. To date, there is mainly a two-dimensional representation of the temperature-concentration inhomogeneity in the diesel cylinder. As a result, the problem of experimental study of the spatial distribution of temperature fields and soot concentrations was set. The original experimental equipment for determining the mass concentration of soot, based on the optical indication of cylinders, and software-implemented methods for determining temperature fields were used in the work.
Computational studies of gas solubility (hydrogen, ammonia, etc.) were based on the following assumptions: firstly, the dissolution process takes place in the mixing-accumulating chamber and nozzle atomizer; secondly, the dissolution proceeds in accordance with the surface renewal model, i.e. the fuel-gas contact surface is updated at a frequency equal to the frequency fluctuations in fuel pressure in the high pressure injection pipeline.
One of the ways to overcome the difficulties of preparing mixtures of diesel fuel with alternative ones is the use of a third component - a joint solvent of diesel fuel and alcohol. The co-solvent must have the properties of diesel fuel and alcohol, i.e. its molecule must have both polar properties and an aliphatic component in order to form bonds with hydrocarbons.
Attempts to use hydrogen as a fuel for internal combustion engines have been known for a long time. For example, in the 1920s, the option of using hydrogen as an additive to the main fuel for internal combustion engines of airships was studied, which made it possible to increase their flight range.
The use of hydrogen as a fuel for internal combustion engines is a complex problem that includes a wide range of issues:
Possibility of converting modern engines to hydrogen;
Studying the working process of engines when working on hydrogen;
Definition best ways regulation of the workflow ensuring minimum toxicity and maximum fuel efficiency;
Development of a fuel supply system that ensures the organization of an effective workflow in the cylinders of the internal combustion engine;
Development of efficient methods of hydrogen storage on board vehicles;
Ensuring the environmental efficiency of using hydrogen for internal combustion engines;
Ensuring the possibility of fueling and accumulating hydrogen for engines.
The solution of these issues has a variant level, however, general state research on this problem can be considered as a real basis for the practical application of hydrogen. This is confirmed by practical tests, studies of variant engines running on hydrogen. So, for example, the company "Mazda" relies on hydrogen rotary piston engine.
Research in this area is distinguished by a wide range of options for using hydrogen for engines of external and internal carburetion, using hydrogen as an additive, partially replacing the fuel with hydrogen, and operating the engine only on hydrogen.
An extensive list of studies determines the need for their systematization and critical analysis. The use of hydrogen is known in engines running on traditional petroleum based fuels, as well as in combination with alternative fuels. So, for example, with alcohols (ethyl, methyl) or with natural gas. It is possible to use hydrogen in combination with synthetic fuels, fuel oils and other fuels.
Research in this area is known for both gasoline engines and diesel engines, as well as for other types of engines. Some authors of works on this subject believe that hydrogen is an inevitability and it is necessary to better prepare to meet this inevitability.
Distinctive feature hydrogen is its high energy performance, unique kinetic characteristics, environmental friendliness and virtually unlimited resource base. In terms of mass energy intensity, hydrogen exceeds traditional hydrocarbon fuels by 2.5-3 times, alcohols - by 5-6 times, ammonia - by 7 times.
The qualitative impact on the working process of the internal combustion engine of hydrogen is determined, first of all, by its properties. It has a higher diffusion capacity, more speed combustion, wide flammability limits. The ignition energy of hydrogen is an order of magnitude less than that of hydrocarbon fuels. The real working cycle determines a higher degree of perfection of the ICE working process, the best indicators of efficiency and toxicity.
To accommodate existing designs piston internal combustion engines, gasoline and diesel engines to operate on hydrogen as the main fuel, certain changes are necessary, first of all, the design of the fuel supply system. It is known that the use of external mixture formation leads to a decrease in the filling of the engine with fresh oxidizer, and hence a decrease in power by up to 40%, due to the low density and high volatility of hydrogen. When using internal mixture formation, the picture changes, the energy intensity of the charge of a hydrogen diesel engine can increase up to 12%, or can be provided at a level corresponding to the operation of a diesel engine on a traditional hydrocarbon fuel. diesel fuel. Features of the organization of the workflow hydrogen engine determined by the properties of hydrogen air mixture, namely: ignition limits, ignition temperature and energy, flame front propagation velocity, flame extinguishing distance.
In almost all known studies of the working process of a hydrogen engine, difficult-to-control ignition of the hydrogen-air mixture is noted. The effect on pre-ignition by introducing water into the intake piping or by injecting "cold" hydrogen has been investigated with positive results.
Residual gases and hot spots of the combustion chamber intensify the pre-ignition of the hydrogen-air mixture. This circumstance requires additional measures to prevent uncontrolled ignition. At the same time, the low ignition energy over a wide range of excess air ratio makes it possible to use existing systems ignition when converting engines to hydrogen.
Self-ignition of the hydrogen-air mixture in the engine cylinder at a compression ratio corresponding to diesel engines does not occur. For self-ignition of this mixture, it is necessary to provide a temperature of the end of compression of at least 1023K. It is possible that the air mixture is ignited from the pilot portion of hydrocarbon fuel, due to an increase in the temperature of the end of compression by the use of pressurization or heating at the air charge inlet.
Hydrogen as a diesel fuel is characterized by high speed propagation of the flame front. This speed can exceed 200 m/s and cause a pressure wave to travel in the combustion chamber at speeds in excess of 600 m/s. High speed combustion of hydrogen-air mixtures, on the one hand, should have a positive effect on increasing the efficiency of the working process, on the other hand, this predetermines high values of the maximum pressure and temperature of the cycle, higher rigidity of the hydrogen engine working process. An increase in the maximum pressure of the cycle leads to a decrease in the engine life, and an increase in the maximum temperature leads to the intensive formation of nitrogen oxides. It is possible to reduce the maximum pressure by deforming the engine or burning hydrogen as it is supplied to the cylinder during the power stroke. Reducing the emission of nitrogen oxides to an insignificant level is possible by depleting working mixture or by using the water supplied to the inlet pipeline. So, at a > 1.8, the emission of nitrogen oxides is practically absent. When water is supplied by mass 8 times more than hydrogen, the emission of nitrogen oxides is reduced by 8 ... 10 times.
CNG is allowed directly in city blocks of residential and public buildings. Moreover, in many countries it is allowed to refuel vehicles with natural gas in underground garages. 1.6. Manufacture of gas equipment for cars. Nowadays, Italy has intercepted the glory of the world's best manufacturer of gas auto equipment. And now in the world market the greatest demand is ...
The model, which received the designation "H2R", develops a speed of over 300 km / h. A new direction in hydrogen fuel engine building, based on the use of the Stirling engine, seems promising. This engine until the end of the XX century. not widely used in motor vehicles due to the more complex design compared to the internal combustion engine, greater material consumption and cost. ...
