RU2549745C2 - Operation of two-stroke ice running on hydrogen and with application of exhaust power in pulsating pipe - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: invention relates to machine building, particularly, to propulsion engineering. Invention consists in that fuel mix consists of hydrogen and oxygen and includes water liquid phase, liquid and gaseous nitrogen. Fuel mix is pre-cooled by liquid nitrogen prior to its feed to engine cylinder. Combustion products are discharged via pulsating pipe into atmosphere after fuel mix combustion. Application of hydrogen in fuel mix allows pre-cooling of fuel mix by liquid nitrogen, increase in mix compression ratio at knock-free engine operation and decrease in compression ratio. Besides, high compression ratio allows addition of extra heat produced by fed hydrogen to combustion product expansion and increase in cycle efficiency thanks to exhaust of combustion products into pulsating pipe.

EFFECT: higher efficiency.

9 cl, 3 dwg

Description

The invention relates to mechanical engineering, namely engine building, in particular the organization of the processes of the cycle of an internal combustion engine (ICE) and the development of systems for supplying the fuel mixture to the engine.

The aim of the invention is to increase the efficiency of the cycle of a two-stroke ICE with forced arson of the fuel mixture in the combustion chamber due to improved processes; compression of the working fluid, heat supply and expansion of the working fluid using pulsation pipes during the discharge of combustion products.

It is well known that the maximum efficiency of a heat-utilizing device for generating mechanical energy can be obtained by implementing the Carnot cycle and is determined only by the temperature range between the heating and cooling sources [1], and the larger this difference, the higher the cycle efficiency.

The process of compressing the working fluid at a lower temperature level has a particularly large effect on cycle efficiency, and the minimum work of compression will correspond to the isothermal process at ambient temperature.

As a result of thermodynamic analysis of piston ICE cycles, considered in [2] with various methods of heat input (with constant volume, constant pressure and mixed), it was shown that the main factor affecting the increase in cycle efficiency is the compression ratio of the motor. However, the use of hydrocarbon fuel in ICE does not allow to increase this indicator for ICE with spark ignition above (6-11) and for ICE operating on the Diesel cycle (15-22).

In the first case, the compression ratio is limited mainly by the detonation resistance of light gasolines, and in the second, the longer burning of heavy diesel fuel due to the increased carbon content in it and its partial (not burnt) emission into the atmosphere.

The consequence of the use of hydrocarbon fuel in the implementation of the considered ICE cycles is a significant loss of heat discharged into the atmosphere by the stream of exhaust gases. So, the values of exhaust gas temperatures for ICE with spark ignition are in the region of 600 K and for ICE operating on a 850 K diesel cycle.

In addition, in real internal combustion engines operating on hydrocarbon fuels, there is an incomplete use of heat associated with heat losses in the walls of the combustion chamber and a significant burn-out in the process of expansion of the combustion products. This in turn leads to additional costs of mechanical energy for compressing a fresh portion of the mixture at a higher temperature due to its heating from the hot walls of the combustion chamber.

As a result, the effective efficiency in the well-known massively used ICEs and operating on the Otto and Diesel cycles does not exceed (33 and 40)%, respectively.

Attempts to improve the thermodynamic efficiency of the ICE cycle, undertaken in a number of patents using wave processes to intake systems and exhaust systems [3; four; 5; 6; 7; 8], as well as the use of separation devices for the release of oxygen from the air [9; 10] are ineffective and the main reason for this is the consequence of the use of hydrocarbon fuels based on gasoline and diesel fuel.

So intake systems according to [3; 4] provide mainly an increase in the density of the air-fuel mixture in the engine cylinder and, as a direct consequence, an increase in engine power, but they do not significantly affect the increase in the efficiency of the cycle as a whole.

Similarly, the use of wave processes in the conversion of exhaust energy in the exhaust pipe [11; 12; 13; fourteen; 15], is also ineffective, since the use of exhaust energy is associated with numerous losses in a large transformation chain — losses in the receiver (resonator) and turbocharger.

In the proposed method, there is the possibility of a significant improvement in factors affecting the effective ICE efficiency due to the use of fuel consisting of hydrogen and oxygen extracted from gaseous air and preliminary cooling of the fuel with liquid nitrogen including its injection into the combustion chamber before the compression of the fuel mixture.

The use of hydrogen as fuel allows you to stably, at the right time in the cycle and for a short period of time, burn all the hydrogen in the fuel mixture and clearly regulate its combustion during the expansion of combustion products.

In addition, the unique properties of hydrogen as fuel [16] allow its combustion to occur in super-lean fuel mixtures. So when using air as an oxidizing agent, the minimum concentration of hydrogen with stable flammability and combustion of hydrogen is in the range (4.1-5)%, which dramatically improves the efficiency of ICE. For comparison, the values of the most super-lean mixtures in the form of an excess air coefficient for a gasoline engine are 1.25, and for a hydrogen ICE is 10.

In the proposed method, the main factors for increasing the effective internal combustion engine efficiency are: pre-cooling with liquid nitrogen the gaseous oxygen and hydrogen supplied to the engine cylinder, injection of liquid nitrogen into the engine cylinder, the implementation of the controlled process of hydrogen combustion and the inclusion in the expansion process of the combustion products of processes occurring in the pulsating pipe [ 17], by which a complete expansion of the combustion products is achieved.

Liquid nitrogen, supplied directly to the engine cylinder before the compression process of the fuel mixture, allows you to bring the compression process closer to the isothermal process and reduce the work of its compression.

In addition, the use of a pulsation pipe in the exhaust of combustion products makes it possible to use the energy of the exhaust and to cool the exhaust gases to produce water condensate and nitrogen gas for reuse in the cycle as a working fluid.

This is achieved by the fact that the pulsation pipe due to the exhaust process allows you to use a deeper expansion of the combustion products and implement the heat pump cycle. So the exhaust of the engine into the pulsation pipe allows you to create a temperature gradient along the length of the pulsating pipe, the cold end of which is connected to the exhaust windows of the engine, and at the hot end of the pulsation pipe there is a heat rejection device.

In an idealized setting, when the engine consumes hydrogen and oxygen, cooled by liquid nitrogen, and also with the injection of liquid nitrogen into the engine cylinder as a working fluid, the exhaust into the atmosphere from the hot end of the pulsation pipe will consist of non-condensed water vapor and gaseous nitrogen.

In the established mode of operation of the pulsation pipe, water vapor and gaseous nitrogen are discharged into the atmosphere from the hot end through the throttle opening, the amount of which is determined, respectively, by the flow of hydrogen and the flow rate of liquid nitrogen supplied directly to the engine cylinder.

With this method of preparation and supply of fuel (a mixture of chilled oxygen and hydrogen), as well as nitrogen, a double effect is observed:

1. The work of compression of the working mixture — oxygen, hydrogen and nitrogen in the ICE cycle — is reduced due to the reduced temperature of the mixture before compression begins. Saving mechanical energy by compressing the working mixture is a net gain and increases engine efficiency.

2. There is the possibility of a sharp increase in one of the main factors affecting the efficiency of the internal combustion engine - the compression ratio during detonation-free operation of the engine. This is achieved by lowering the temperature of the working mixture before compression in the combustion chamber and shifting the process towards isothermal, the self-ignition temperature of the mixture (detonation) will correspond to a higher compression ratio (or the degree of pressure increase).

The application of these measures, depending on the degree of cooling of the working mixture with liquid nitrogen and its partial injection directly into the cylinder, the compression ratio can be increased by 10 or more times.

Figure 1 - presents one of the devices of a power plant based on a push-pull ICE with hydrogen as fuel and with a pulsating exhaust pipe.

The power plant consists of a two-stroke ICE 42, in the cylinder 32 of which there is an inlet window 27 for oxygen supply and an outlet window 41 for exhaust exhaust.

In the head of the combustion chamber 30 of the cylinder 32 is installed an adjustable controllable valve 12 for supplying hydrogen and a device 13 for controlling the process of expansion of the products of combustion, which is, for example, capillary channels, at the ends of which there is a common collector.

Figure 2 presents one of the variants of the device 13. The device includes a set of parallel capillary channels 44 (or a porous heat-accumulating packing, such as copper or nickel), the inlet openings of which begin on the inner surface of the head of the combustion chamber 30, and the ends exit into a common hydrogen cavity 45 (collector) with an adjustable volume.

To initiate ignition of the fuel mixture in the head of the combustion chamber 30, an arson device 29, for example, an electric spark plug, is mounted.

In the hydrogen storage and supply system for a two-stroke ICE, one of the versions of the metal hydride hydrogen storage and supply system according to the patent [18] is implemented.

The device consists of metal hydride elements 3, compactly located in the casing of the metal hydride module 2 connected to a hydrogen collector 4 from which hydrogen is extracted through a pipe 10 through a shut-off valve 11 using a piston compressor or a mechanical vacuum pump 7, through a pipe 8, through a shut-off valve 9 and beyond , being cooled in the heat exchanger 43, enters through an adjustable controlled valve 12 and a device 13 for controlling the process of supplying heat to the engine cylinder.

As a hydride forming material, alloys based on magnesium or titanium can be used, for example, an alloy of magnesium and nickel in various proportions, as well as with the addition of various alloying additives.

To supply heat from the environment to the metal hydride elements 3 in order to extract hydrogen from them, a fan 1 is installed. Hydrogen filling of the metal hydride modules is carried out through a pipe 6 through a shut-off valve 5, while the released heat in the metal hydride elements is also discharged into the environment using a fan 1.

The oxygen production and supply system consists of a compressor 21 for compressing atmospheric air (arrow B) entering through the air intake 20, a system for separating air 22 into oxygen and nitrogen. Oxygen from the air separation system 22 through a pipe 46 enters through a throttle controlled valve 24 into an oxygen pulsation pipe 25 and then through a heat exchanger 47 to the inlet window 27 of the engine cylinder.

The thermal regime of the oxygen pulsation pipe 25 is controlled by a thermocouple 26.

Nitrogen from the air separation system is discharged into the atmosphere through the pipe 23 (arrow A _B ).

The storage system and supply of liquid nitrogen is a Dewar vessel 16, for filling which liquid nitrogen has a neck 14.

For supplying liquid nitrogen, for example, a pumping system is used, with which, by means of a mechanical pump 15, the liquid nitrogen entering through the pipe 17 is divided into two streams, one of which enters the engine cylinder through a controlled valve 19 and an inlet window 27, and the other stream through an adjustable valve 18 enters the heat exchanger 28 to cool the cold end of the oxygen pulsation pipe 25, then through the connector a enters the heat exchanger 33 to cool the cold end of the pulsation pipe 36 for exhaust gases and further through connector b, it enters the heat exchanger 43 to cool the hydrogen entering the engine cylinder.

The nitrogen exiting the heat exchanger 43 is discharged into the atmosphere (arrow A).

The hot end of the pulsation pipe 36 is equipped with a cooler 37 and a throttle hole 38.

The thermal regime of the pulsation pipe 36 is controlled by thermocouples 39 and 40.

Figure 3 presents a picture of the thermal state of the pulsation pipe, for example, for exhaust gases, in the form of a temperature dependence on the length of the pipe.

For the operation of the device of the power plant shown in FIG. 1, it is necessary to charge metal hydride elements 3 with hydrogen and fill the Dewar vessel 16 with liquid nitrogen.

Hydrogen filling of metal hydride elements is carried out at a gas station.

When refueling with hydrogen, the refueling pipe 6 is connected to a hydrogen source, for example to a balloon system, the shutoff valve 11 is closed, the shutoff valve 5 is opened, through which hydrogen enters the metal hydride elements 3.

The heat released in the metal hydride elements in the process of their saturation with hydrogen is discharged into the environment using the included fan 1.

At the end of the process of refueling metal hydride elements with hydrogen, the filling valve 5 is closed, the filling pipe is disconnected from the filling station and the fan 1 is turned off.

The Dewar vessel is filled with liquid nitrogen according to the standard technique for filling the Dewar vessels with liquid nitrogen.

The filling tube from the liquid nitrogen tank is introduced into the filling neck 14 and the filling process is carried out. In this case, the shutoff valve 18 and the controlled valve 19 for supplying liquid nitrogen are closed, and the pump for supplying cryogenic liquid 15 is turned off. At the end of the filling, the filling tube is removed from the neck 14 of the Dewar vessel, and the neck 14 is closed.

Consider the cycle processes of a two-stroke ICE in the device of the power plant shown in Fig.1.

1. The processes occur when the piston moves upward from the bottom dead center (BDC) to the top dead center (TDC).

At the beginning of this movement, due to the reflected wave in the oxygen pulse tube 25, the engine cylinder is filled with the cooled combustion products of the reflected wave, a portion of oxygen dosed by a controlled valve 24, and a dosed portion of liquid nitrogen using a controlled valve 19.

Similarly, due to the reflected wave and the pulsation pipe 36, the filling of the engine cylinder with combustion products from the previous process ends: with gaseous nitrogen and water vapor in the mainly dropping state. Part of the gaseous nitrogen and non-condensed water vapor is discharged into the atmosphere through the throttle hole 38 (arrow VG).

Simultaneously with these processes, hydrogen is supplied to the engine cylinder, which enters through an adjustable controllable valve 12 and a control device 13 for supplying heat to the combustion chamber of the engine. Part of the hydrogen remains in the cavity 45 (figure 2) with an adjustable volume.

With the further movement of the piston up due to the supply of the main mechanical energy from the engine shaft, the fuel mixture (hydrogen and oxygen), nitrogen (liquid and gaseous) and water are compressed in the droplet state.

Near the TDC position, the fuel mixture is set on fire.

2. The processes that occur when the piston moves from TDC to BDC can be represented in the form of five stages carried out sequentially:

- After arson of the fuel mixture in the combustion chamber, combustion products with high pressure and temperature are formed.

At this stage, a process close to isobaric takes place, in which gases push the piston down, and the energy of expansion of the gases is transmitted to the engine shaft.

- In the process of expansion of the combustion products, hydrogen temporarily located in the storage cavity 45 with a controlled volume enters through the capillary channels into the combustion chamber, but due to the significant hydraulic resistance of the capillary channels, it burns out as it arrives with some delay. The heat released at this stage increases the gas expansion energy transmitted to the engine shaft, which is characteristic of a process close to isothermal.

- After the combustion of the additionally supplied hydrogen, a stage comes close to the adiabatic process of expansion and cooling of the combustion products. At the end of this stage, the energy transfer to the motor shaft ends.

- The next stage of the adiabatic process is associated with the conversion of the expansion energy of the combustion products in the pulsation tubes and obtaining a temperature gradient at their ends. At this stage, no energy is diverted to the motor shaft.

When the piston reaches the window 41, there is a further expansion of the gases in the pulsation pipe 36 and a partial exhaust of the combustion products into the atmosphere in the form of heated nitrogen gas and water vapor through the throttle opening 38.

When the piston reaches the window 27, there is also a further expansion of the combustion products and mixing with the gases in the oxygen pulse tube 25.

The expansion of the combustion products without performing work in both pulsation pipes 36 and 25 leads to heating of the gases at the ends of the pipes and cooling of the gases at the beginning of the pipes connected to the cylinder windows.

- At the last stage, when the piston is near the BDC, the return of compression waves in both pulsation pipes and filling of the engine cylinder with mixtures begins.

- From an oxygen pulsation pipe 25 with cooled products of combustion, as well as oxygen supplied through a controlled valve 24, and liquid nitrogen from a controlled valve 19.

- From the exhaust pulsation pipe 36 with chilled combustion products, including condensed water vapor.

- From the control device 13 of the heat supply process, hydrogen enters the combustion chamber of the engine through an adjustable controlled valve 12.

Further, when the piston passes the bottom dead center and moves it up, the cycle repeats.

Used sources

1. Technical thermodynamics: Textbook for high schools / V.A. Kirillin, V.V. Sychev, A.E. Sheindlin. - 4th edition - M .: Energoatomizdat, 1983.

2. Car engines. V.M. Arkhangelsk, M.M. Wichert, A.N. Voinov, Yu.A. Stepanov, V.I. Trusov, M.S. Howah. Ed. M.S. Hovaha. M .: Mechanical Engineering, 1977.

3. RF patent No. 2034164 C1.

4. RF patent No. 2312235 C1.

5. RF patent No. 1209905 A1.

6. RF patent No. 1193278 A1.

7. RF patent No. 1359449 A1.

8. RF patent No. 1716184 A1.

9. RF patent №2126896 C1.

10. RF patent No. 2209322 C2.

11. RF patent No. 1372078 A1.

12. RF patent No. 1359450 A1.

13. RF patent No. 1502863 A1.

14. RF patent No. 1583647 A1.

15. RF patent No. 1617168 A1.

16. Hydrogen is the fuel of the future. A.N. Podgorny, I.L. Warsaw K .: “Science. Dumka ", 1977.

17. Theory and calculation of cryogenic systems: A textbook for universities in the specialty "Cryogenic Engineering" A.M. Arkharov, I.M. Marfenina, E.I. Mikulin. - M.: Mechanical Engineering, 1978.

18. RF patent No. 2381413 C2.

Claims (9)

1. The method of operation of a two-stroke internal combustion engine, the cycle of which consists of the following processes: compression of the fuel mixture based on hydrocarbon fuel and air; heat supply due to the combustion of fuel in the mixture and the formation of combustion products with high values of temperature and pressure; expanding the combustion products and expelling the expansion energy to the engine shaft, characterized in that the fuel mixture consists of hydrogen and oxygen, includes the liquid phase of water, liquid and gaseous nitrogen, and before the fuel mixture is fed into the engine cylinder, it is pre-cooled with liquid nitrogen and after the combustion of the fuel mixture, the combustion products are discharged through the pulsation pipe into the atmosphere. 2. The method according to p. 1, characterized in that before compressing the fuel mixture with liquid nitrogen, all its components are cooled - hydrogen, oxygen and part of the combustion products returned from the pulsation tubes to the engine cylinder. 3. The method according to p. 1, characterized in that in the process of extracting hydrogen from metal hydride elements, the heat of the environment is used using a fan system. 4. The method according to p. 1, characterized in that the supply of hydrogen from the metal hydride elements to the engine is carried out using a device for increasing the pressure of hydrogen or a mechanical vacuum pump. 5. The method according to p. 1, characterized in that the supply of liquid nitrogen can be carried out by a pumping system. 6. The method according to p. 1, characterized in that in the process of compression of the fuel mixture, part of it enters through the capillary channels into the cavity of the collector and burns with some delay in the process of expansion of the combustion products. 7. The method according to p. 1, characterized in that the process of expanding the products of combustion with the removal of energy to the engine shaft consists of five stages that are carried out sequentially when the piston moves to the bottom dead center: a stage close to the isobaric process in which the main part burns hydrogen with decreasing gas pressure and temperature at the end of this stage; a stage close to the isothermal process of gas expansion, with the supply of heat due to the combustion of hydrogen accumulated in the reservoir cavity; a stage close to the adiabatic process, with a further decrease in pressure and temperature; the stage of exhaust of the combustion products into the pulsation pipes and the stage of filling the engine cylinder with oxygen, hydrogen, liquid nitrogen and the combustion products returned from the pulsation pipes - gaseous nitrogen and condensed water vapor. 8. The method of operation of a two-stroke internal combustion engine, the cycle of which consists of the following processes: compression of a fuel mixture consisting of hydrogen and oxygen, a liquid phase of water, liquid and gaseous nitrogen; heat supply due to the combustion of hydrogen in the mixture and the formation of combustion products with high values of temperature and pressure; expanding the combustion products and diverting the expansion energy to the engine shaft, characterized in that the energy of the exhaust of the combustion products is used to produce cold using pulsation tubes to cool the combustion products and reuse them as a working fluid. 9. The method according to p. 8, characterized in that the pulsation pipes at the hot ends are equipped with coolers.

Images