RU2391523C2 - Operating method of internal combustion engine and device for method's implementation - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: air and fuel is supplied to cylinders. Fuel-air mixture is compressed. Combustible mixture is burnt. Steam is supplied to cylinders. As a result, combustion products and steam is expanded. Useful mechanical work is carried out during movement of pistons, waste gas and steam is discharged from cylinders and their heat is recovered by water heating and steam generation in recovery system. Steam is supplied to engine cylinders in expansion stroke (working travel). Steam introduced to engine cylinders is pre-heated, steam is introduced at the beginning of working travel at maximum pressure and temperature of gases, and waste steam-gas mixture is supplied to heat recovery system consisting of steam generator and superheater. Device for implementation of the method of internal combustion engine operation includes mechanisms for performing working processes, systems of gas distribution, fuel, air feed, waste gas outlet, heat recovery system of waste gas for generation of water vapour and is equipped with a valve or an atomiser with possibility of introduction of superheated steam to engine cylinders in expansion stroke (working travel). Heat recovery system of waste gas and steam includes steam generator, superheater and control gas valve installed before the outlet of waste gas to atmosphere.

EFFECT: increasing engine efficiency, reducing toxicity level of waste gas, improving operating reliability of heat-stressed elements.

2 cl, 2 dwg

Description

The invention relates to the field of power engineering, engine building, mainly to internal combustion engines, for example, carburetor, diesel.

A known method of operation of an internal combustion engine and a device for its implementation (see the description of the invention to the patent of the Russian Federation No. 2093692, CL F02B 47/02, 10/20/1997), including the recovery of heat from the cooling system and heat of exhaust gases to increase engine power, Efficiency by 20%, reduction of harmful emissions into the atmosphere. Due to the heat of the cooling system and the heat of the exhaust gases in the heat exchanger-boiler, high-pressure water vapor is generated in an amount of 20-40% relative to the amount of air sucked into the cylinders, fuel is mixed in it in a vapor state, and before the start of the combustion process the steam-fuel mixture and air are supplied into the engine cylinders.

The main disadvantage of this method and device for its implementation is that the introduction of steam into the cylinders of the engine is allowed in small quantities due to the difficulty of the process of ignition of the combustible mixture, the deterioration of the effective combustion of the fuel, leading to significant chemical and mechanical incompleteness of combustion, due to the large quantity heat of fuel spent on heating water vapor in the combustion chamber. This limitation reduces the possible degree of heat recovery of exhaust gases, the possibility of increasing engine efficiency.

The main disadvantage of the device for implementing this method is the complexity of the design of two-phase steam-fuel devices for introducing the mixture into the cylinders, significantly complicating the design of the engine as a whole, its operation at start-up and at variable operating modes.

There is also a known method of operating an internal combustion engine and a device for its implementation, adopted as a prototype (see the description of the invention to the patent of the Russian Federation No. 2168030, class F02B 47/02, 05.27.2001), including the recovery of heat from exhaust gases to increase engine efficiency by gasification (evaporation) of liquid fuels before feeding them into the cylinders, as well as additional boosting and cooling of the engine by intensifying the cycle by injecting catalyst-water into the working chamber-cylinders at the expansion stroke (stroke) at the highest pressure ha and in the loop. The injection of catalyst water into the cylinder chambers also reduces exhaust emissions.

The main disadvantage of this method is the low degree of heat recovery of the exhaust gases, and hence a low increase in engine efficiency. A large amount of introduced catalyst water into the cylinder chambers in the expansion stroke (stroke) to increase the engine efficiency is unacceptable, as this will lead both to a positive factor - a useful increase in the mass of expanding gases, and a negative one - a significant decrease in the efficiency of combustion products due to decrease in temperature and pressure, heat content of the mixture due to heat consumption for water evaporation, steam overheating.

Other disadvantages of this method and device for its implementation are: the lack of heat recovery of exhaust gases and devices, heat exchangers for heating the catalyst water before being introduced into the cylinders, the significant cost of preparing the catalyst water, as well as the complexity of the design.

Thus, the considered methods of operation of engines and devices for their implementation do not allow the full use of the heat of exhaust gases, most of which is lost in the environment.

An object of the invention is: to increase the efficiency of an internal combustion engine (for example, a diesel engine, internal combustion engine with positive ignition, a carburetor or an engine with liquid fuel injection into the intake system, etc.), to reduce the toxicity of exhaust gases, to increase the reliability of heat-stressed engine elements.

The technical problem is solved in that in the method of operation of an internal combustion engine, which includes supplying air and fuel to the cylinders, compressing air, air-fuel mixture, burning the combustible mixture, expanding the combustion products, performing useful mechanical work when the pistons move, exhausting the exhaust gases from the cylinders, recovering their heat by heating water, the formation of steam in heat exchangers, the introduction of steam into the engine cylinders is carried out in the expansion stroke (stroke).

In the method, the steam introduced into the engine cylinders is preheated with respect to a pressure exceeding the gas pressure in the cylinders before the steam is introduced.

In the device for implementing the method of operation of an internal combustion engine containing mechanisms for carrying out work processes, a gas distribution system, fuel, air, exhaust gas recovery, heat recovery of exhaust gases to generate water vapor, there are valves for introducing superheated steam into the engine cylinders in an expansion stroke (working stroke), an independent system of heat recovery of exhaust gases and steam, including a superheater and a gas control valve installed in front of the release of exhaust gases into the atmosphere.

Figure 1 shows the combined comparative schematized reliability of heat-stressed engine elements due to a significant reduction in the duration and absolute temperature of the gases in the cylinders.

In the known method of engine operation, adopted as a prototype, the injection of catalyst-water in the expansion stroke does not allow to achieve such an effect as in the proposed method, for the following reasons: a significant decrease in useful work and efficiency due to a significant decrease in pressure and temperature of the expanding gas-vapor mixture, its performance caused by the high consumption of heat content of the combustion products for water evaporation; a negligible fraction of the heat of the exhaust gas spent on heating the water, that is, a small degree of recovery.

The engine variant of FIG. 2, operating according to the proposed method, consists of cylinders 1, pistons 2, cylinder heads 3, air intake pipes 4, fuel tank 5, carburetor 6 of known design. On the cylinder head there are nozzles for introducing the air-fuel mixture with inlet valves 7 of a known design, spark plugs 8 of a known design, exhaust pipes of a gas-vapor mixture with exhaust valves 9 of a known design, of which the exhaust gas mixture enters an independent heat recovery system consisting of a steam generator 10, a superheater 11, the return tank of water condensate 12 of a known design, a water purification apparatus 13 of a known design to make up for condensate loss, p tatelnogo high pressure pump 14 of known construction, the gas regulating valve 15 installed before an exit of exhaust gases into the atmosphere.

Superheated steam through the steam line 16 enters the valves 17 for direct introduction into the engine cylinders in the expansion stroke (stroke).

We consider the method of operation of the engine and the device for its implementation on the passage of one cycle. For the starting point of the cycle reference we take point a ″ (Fig. 1) - the end of the intake stroke of the air-fuel mixture, the piston is in the "BDC", all valves are closed by means of known systems, mechanisms.

When the piston moves to the TDC, a polytropic compression process occurs with increasing pressure and temperature of the air-fuel mixture.

When the piston approaches the “TDC”, the fuel mixture is forcedly ignited by means of a spark plug. When the piston is in the “TDC”, point c ″ (FIG. 1), the compression stroke is completed, the combustion process continues. The process of combustion of the bulk of the fuel occurs with an increase in pressure and temperature, while there is also a preliminary expansion, a slight increase in the volume of gases, point z ″ (Fig. 1), then the expansion stroke (stroke) continues. At the point z ″ at maximum pressure per cycle, superheated steam is introduced into the engine cylinder by means of valves, while the expansion of gases and steam in the cylinder continues with the completion of useful work at constant pressure, as is customary for the considered option. The expansion process with the introduction of steam into the cylinder can take place with other changes in parameters. The introduction of steam ends at the point to ″ (Fig. 1), then the expansion stroke (stroke) continues along the polytropic and ends approximately at the position of the piston in "BDC", the point at ″ (Fig. 1). When the piston approaches the "BDC", the exhaust valves are opened by means of known mechanisms, the cycle of exhaust gas and steam release begins under the influence of the pressure drop in the cylinder and the environment, which lasts when the piston moves to the "TDC". Exhaust gases and steam leaving the cylinder enter the exhaust pipe and then into the heat recovery system. At the end of the exhaust stroke, the exhaust valves are closed and the inlet valves are opened by means of known mechanisms and systems when the piston moves to the "BDC" in the cylinder, in which the vacuum is created, the air-fuel mixture is sucked in under the influence of environmental pressure, formed using a carburetor and other known mechanisms and systems. The intake stroke ends when the piston approaches the "BDC", point a ″, the cycle ends. From the exhaust pipe, the exhaust gases and steam enter the recuperative superheater, are partially cooled and then go to the steam generator, in which the steam-gas mixture is further cooled, and partial condensation of water vapor from it on the heat transfer surface; Further, the exhaust gas and the remaining non-condensed water vapor are discharged through the control gas valve into the atmosphere. Water condensate from the steam generator enters the condensate return tank, from where it is again fed through a high-pressure feed pump of a known design to the steam generator, in which water is converted to saturated steam and enters the superheater, in which it overheats and flows through the steam line to the valves and then directly to the engine cylinder . The replenishment of the non-condensable part of the water vapor from the vapor-gas mixture is carried out by introducing into the condensate return tank an additive of industrial water that has passed the water purification apparatus of known design. The degree of condensation of water vapor from a gas-vapor mixture depends on its pressure and is regulated by a gas valve.

As comparative calculations of the efficiency of internal combustion engines with forced ignition of the air-fuel mixture and diesel engines show, the increase in the efficiency of engines working according to the proposed method, compared with engines operating according to the known method, is approximately 40-75%.

As an example, we present the results of the calculation of a carburetor 4-stroke 4-cylinder internal combustion engine operating according to the known method and according to the proposed one. The calculated indicator diagrams are presented in figure 1

Working conditions and calculation results for an engine operating according to a known method: the net calorific value of liquid fuel is adopted N = 44 MJ / kg; compression ratio E = 8.5; Ra = 0.09 MPa; Pc = 1.58 MPa; Pz = 6.18 MPa; excess air ratio - 1.0; temperature after fuel combustion, at the beginning of the expansion stroke Tz = 2720 K; Tv = 1480 K; Pb = 0.41 MPa; effective engine power Ne = 51.1 kW; fuel consumption Gt = 15.1 kg / h; air consumption Gb = 223.6 kg / h; the amount of exhaust gas Gg = 238.5 kg / h; effective efficiency - 0.28.

Working conditions and calculation results for an engine operating according to the proposed method: N = 44 MJ / kg; E = 8.5; Ra ″ = 0.09 MPa; Pc ″ = 1.58 MPa; Pz ″ = 6.18 MPa; Tz ″ = 2720 K; excess air ratio - 1.0; Ne = 50.55 kW; Gt = 8.4 kg / h; St = 124.8 kg / h; Gg = 133.2 kg / h; the amount of superheated steam introduced at maximum pressure per cycle Pz ″ -Gpar = 148.9 kg / h; effective efficiency - 0.49; superheated steam pressure Рпе = 6.5 MPa; superheated steam temperature Тпе = 793 К (520 ° С). Pressure and temperature of the gas-vapor mixture at the end of the steam injection process: Pк = Pz ″; Tc ″ = 1450 K (1177 ° C). The pressure and temperature of the vapor-gas mixture at the end of the expansion process (stroke): Rv ″ = 0.72 MPa; Tw ″ = 927 K (654 ° C).

The efficiency of the engine operating by the proposed method is 75% higher than the efficiency of the engine operating by the known method.

An important factor is also that when the engine is operating according to the proposed method, the temperature of the gas mixture after steam is introduced decreases from 2720 K to 1450 K - by more than 1000 K. This leads to a significant decrease in the heat stress of cylinders, pistons, cylinder heads, engine blocks, to increase reliability, engine life. The use of valves for introducing only steam into the cylinder instead of valves for the steam-fuel mixture simplifies their design. A significant reduction in the duration and absolute value of the high temperature of the gases in the cylinders due to the introduction of steam in the expansion stroke also leads to a decrease in heat loss in the engine cooling system, into the environment, and an increase in efficiency.

Claims (2)

1. The method of operation of the internal combustion engine, which consists in supplying air and fuel to the cylinders, compressing the air-fuel mixture, burning the combustible mixture, supplying steam to the cylinders, as a result of which the expansion of the combustion products and steam, performing useful mechanical work during movement pistons discharge exhaust gases and steam from the cylinders and recover their heat by heating water and generating steam in the recovery system, the steam being supplied to the engine cylinders being extended in tact ia (working stroke), characterized in that the steam introduced into the engine cylinders is preheated, the steam is introduced at the beginning of the working stroke at the highest gas pressure and temperature, and the spent steam-gas mixture is fed to a heat recovery system consisting of a steam generator and a superheater. 2. A device for implementing a method of operating an internal combustion engine, comprising mechanisms for carrying out work processes, a gas distribution system, fuel, air, exhaust gas, an exhaust gas heat recovery system for generating water vapor, characterized in that it is provided with a valve or nozzle with the possibility introducing superheated steam into the engine cylinders in the expansion stroke (stroke), and the heat recovery system for exhaust gases and steam includes a steam generator, superheat spruce and gas control valve installed in front of the exhaust gas to the atmosphere.

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