RU2053390C1 - Method of operation of internal combustion engine - Google Patents

Abstract

FIELD: internal combustion engines. SUBSTANCE: water is injected into cylinders in all modes of operation, starting included. Amount of water is determined in accordance with relationship G_в= n•K•G_т at n = Q_т/i_п-i_в, where Q_т is heat of combustion of fuel, G_т is fuel consumption, K is coefficient characterizing the fraction of heat escaping to cooling system 0.16-0.36 i_в is enthaply of water corresponding to temperature of injection; i_п is enthalpy of steam corresponding to exhaust gas temperature. EFFECT: enhanced efficiency and reliability of engine operation.

Description

 The invention relates to mechanical engineering, in particular engine manufacturing, and in particular to methods of operation of internal combustion engines using water in a duty cycle.

There is a known method of ICE operation, in which an increase in efficiency is ensured by equalizing the power of duty cycles when they are carried out on fuel and water. The disadvantage of this method of engine operation is that the alignment of the power of the duty cycles is carried out by reducing the total diesel power, which generally leads to underutilization of its capabilities and is mainly aimed at maintaining the reliable operation of the piston-cylinder group. Furthermore, the method only affects engine operating conditions, ie. E. When the temperature of the combustion chamber surface reaches 250-300 ^{° C,} which significantly reduces the possibility of using the method for a number of diesel engines.

There is a known method of operating an internal combustion engine by injecting fuel and water into the combustion chamber, in which a decrease in the heat stress of the parts and an improvement in starting properties is achieved by injecting water, the amount of which is set according to the given dependence. The specified method of operation, selected as a prototype, contains a number of disadvantages. Firstly, the method is applicable only to engines equipped with boost systems and does not apply to naturally aspirated modifications. Secondly, the above dependence, which establishes the amount of injected water, involves constant monitoring of a number of parameters, which requires a reliable adjustment system, which generally complicates the power plant. Third, the water injection is carried out at ^about 30 crank angle before TDC, which imposes certain restrictions, not allowing to take full advantage of the gas-vapor mixture more efficiently. In addition, the possibility of injecting water in partial modes is limited by both the boost pressure and the maximum combustion pressure, which also reduces the possibility of increasing the efficiency of the engine by injecting fuel and water.

где Q_т теплота сгорания топлива;
G_т расход топлива;
К коэффициент, характеризующий долю тепла, уходящего в систему охлаждения, 0,16 0,36;
i_в энтальпия воды, соответствующая температуре впрыска;
i_п энтальпия пара, соответствующая температуре отработавших газов.The proposed method consists in the fact that, in contrast to the known method of engine operation by injecting fuel and water into the combustion chamber, water is injected at all engine operating modes, and its amount is set in accordance with the following relationship:
G _in = n · K · G _t , with n

where Q _{t the} calorific value of the fuel;
G _t fuel consumption;
K coefficient characterizing the proportion of heat leaving the cooling system, 0.16 0.36;
i _{in the} enthalpy of water corresponding to the injection temperature;
i _{p the} enthalpy of steam corresponding to the temperature of the exhaust gases.

 The essence of the invention lies in the fact that numerous known methods and devices involving the injection of water into the combustion chamber of an engine are mainly aimed at increasing the efficiency of the engine and are achieved by optimizing the gas-vapor situation in the combustion chamber, i.e., ensuring macro- and micro-mixture formation, resulting in is the reduction of toxicity, heat stress, hard engine operation, etc. However, the injection of water into the combustion chamber, in addition to the manifestation of these effects, allows It differently organizes heat flows in the engine, i.e. change the heat balance of the engine in the direction of increasing its efficiency. Indeed, the injection of water with appropriate mixing of its vapor phase with fuel significantly increases the efficiency of the diesel engine, however, the amount of water supplied is limited by a change in the flow of heat stress towards the overcooling of engine parts. This situation is observed both in water-cooled engines, where heat is removed both in the cooling system and in the water injected onto the walls of the combustion chamber. It is obvious that the injection of water into the engine cylinder in large (in comparison with the known methods) quantities in accordance with the proposed dependence allows the water system to be abandoned in water-cooled engines, since the heat will be removed from the cylinder walls directly with water, the vapor phase of which will be further contribute to a greater manifestation of effects (reduction of toxicity, heat stress, etc.) achieved in the known methods using water in the work cycle.

The advantages of the proposed method also include the fact that the use of water, the amount of which is determined by the dependence G _in = n · k · G _t , is acceptable for all engine operating modes, including the starting mode, where there is no water cooling system, on the one hand and injecting into the combustion chamber together with the fuel, for example, a heated charge of water, on the other hand, greatly facilitates starting the engine. It is also important that the amount of water injected into the combustion chamber in accordance with the proposed dependence is proportional to the supplied dose of fuel and does not require special control systems.

 Finally, internal cooling of the engine will be more effective than external (with a water system), since heat is removed directly on the surface of the cooled parts without the existing temperature gradient between the cooling liquid and the cooled parts of the piston-cylinder group. Moreover, the use of the method allows the widespread use of heat recovery of exhaust gases by heating the injected water with them, thereby further reducing the temperature of the exhaust gases.

где Q_т теплота сгорания топлива;
G_т расход топлива;
K коэффициент, характеризующий долю тепла, уходящего в систему охлаждения;
i_в энтальпия воды, соответствующая температуре впрыска;
i_п энтальпия пара, соответствующая температуре отработавших газов.The engine according to the proposed method is as follows. Water is injected into the combustion chamber of the engine before or simultaneously with the supply of the fuel dose, while the amount of water supplied is set in accordance with the dependence
G _in = n · K · G _t , with n

where Q _{t the} calorific value of the fuel;
G _t fuel consumption;
K is a coefficient characterizing the fraction of heat leaving the cooling system;
i _{in the} enthalpy of water corresponding to the injection temperature;
i _{p the} enthalpy of steam corresponding to the temperature of the exhaust gases.

The water injected into the cylinder of the engine during fuel combustion evaporates, cooling the walls of the combustion chamber. The steam is mixed with the combustion products of the fuel and performs the mechanical expansion work. In this case, there are effects when using water: antiknock properties allow to increase the compression ratio without increasing the octane number, reduces the toxicity of gases, heat stress of parts, etc. The new property that manifests itself in this case is that the injection function performs cooling of the cylinder-piston group water into the combustion chamber, i.e. previously removed engine heat to the water cooling system in the amount of 0.16 0.36 of the total combustion of fuel heat is not carried away from the engine, but is involved in the completion of useful work, thereby increasing engine efficiency
The effectiveness of the proposed technical solution is confirmed by carried out for two specific types of engines for calculating the heat balance.

1. The diesel engine, the power of 300 kW, the cylinder 8, the maximum combustion pressure of 11.52 MN / m ^2, temperature ^of 2140 K, α = 1,55 (Table. 1).

 It follows from the calculation that with the joint injection of fuel and water in the ratio 56: 44, the proportion of heat equivalent to efficient operation increases by 12% (from 39.46% to 52.5%).

2. The engine carburetor, the power of 55.2 kW, four cylinder, the maximum combustion pressure of 6.41 MNm / m ² and a temperature of ^about 2733 K, α = 0,9, ε = 9 (Table. 2).

 And in this case, the injection of water increases the fraction of heat equivalent to efficient operation, which suggests an increase in engine efficiency.

 Thus, the use of the proposed technical solution allows not only to achieve the effects that occur in known methods and devices, but by switching from external to internal heat extraction from the walls of the combustion chamber to increase the effective operation of the engine while reducing weight and size parameters, which can contribute to the creation of a significant effect in the national economy.

Claims (1)

METHOD OF WORKING THE INTERNAL COMBUSTION ENGINE by injecting fuel and water into the combustion chamber at maximum, nominal and partial modes, characterized in that water is additionally injected at the starting engine operation mode and its quantity G _in is determined for all operating modes in accordance with the dependence
G _in = n × K × G _t ,
wherein

where θ _t is the calorific value of fuel;
G _t - fuel consumption;
K = 0.16 - 0.36 - coefficient characterizing the proportion of heat leaving in the cooling system;
i _в - enthalpy of water corresponding to the injection temperature;
i _p is the vapor enthalpy corresponding to the temperature of the exhaust gases.

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