阅读说明：本技术 基于电动增压的高背压柴油机功率恢复方法及其实施装置 (Electric supercharging-based high back pressure diesel engine power recovery method and implementation device thereof ) 是由 杨名洋 马泽泰 邓康耀 石磊 崔毅 张琨 于 2021-09-30 设计创作，主要内容包括：一种柴油机技术领域的基于电动增压的高背压柴油机功率恢复方法及其实施装置,功率恢复方法包括以下步骤：利用涡轮流量公式计算得出涡前压力；利用涡轮能量公式计算得出涡轮所能提供的能量；利用涡轮与压气机之间的能量平衡公式与压气机效率公式,结合计算求出电动压气机后压力和电动压气机后实际温度；利用能量公式计算出电动压气机所需要的能量；根据计算得出的电动压气机所需要的能量值,通过变频电机对电动压气机转速进行调节。在本发明中,电动压气机串接在低压级,当柴油机处于高排气背压的环境时,根据排气背压调节驱动电机转速,提高进气压力,以达到在高排气背压下柴油机进气量的补充,从而可以实现柴油机功率的恢复。(A high back pressure diesel engine power recovery method based on electric supercharging and an implementation device thereof belong to the technical field of diesel engines, and the power recovery method comprises the following steps: calculating to obtain the pressure before the vortex by using a turbine flow formula; calculating the energy provided by the turbine by using a turbine energy formula; calculating the rear pressure of the electric compressor and the rear actual temperature of the electric compressor by combining an energy balance formula between the turbine and the compressor and an efficiency formula of the compressor; calculating the energy required by the electric compressor by using an energy formula; and adjusting the rotating speed of the electric compressor through a variable frequency motor according to the calculated energy value required by the electric compressor. In the invention, the electric compressor is connected in series with the low-pressure stage, when the diesel engine is in an environment with high exhaust back pressure, the rotating speed of the driving motor is adjusted according to the exhaust back pressure, and the air inlet pressure is improved, so that the air inlet amount of the diesel engine is supplemented under the high exhaust back pressure, and the power recovery of the diesel engine can be realized.)

1. A power recovery method of a high-backpressure diesel engine based on electric supercharging is characterized by comprising the following steps:

firstly, the turbine flow formula is utilized to calculate and obtain the pressure P before the vortex₃：

Secondly, the energy E provided by the turbine is calculated by using a turbine energy formula_T：

Thirdly, the energy balance formula between the turbine and the compressor and the efficiency formula of the compressor are combined to calculate and obtain the back pressure P of the electric compressor₁' and actual temperature T after electric compressor₁'：

Fourthly, calculating the energy E required by the electric compressor by using an energy formula_C1：

Fifthly, adjusting the rotating speed of the electric compressor through a variable frequency motor according to the calculated energy value required by the electric compressor;

wherein the content of the first and second substances,mass flow through the turbine in kg/s; t is_TIs the pre-vortex temperature in K; a. the_TIs the turbine flow area in m²；P₄Is the exhaust back pressure in Pa; p₃Is the preswirl pressure in Pa; e_TFor turbine liftingThe energy supplied is in units of J; eta_TTo turbine efficiency;the unit is kg/s for the mass flow passing through the compressor; t is₁' is the actual temperature after the electric compressor, and the unit is K; p₁' is the back pressure of the electric compressor, and the unit is Pa; p₂The unit is Pa for the back pressure of the gas compressor; eta_C2The adiabatic efficiency of the compressor is high; eta_C1The heat insulation efficiency of the electric compressor is improved; t is_1sThe temperature after isentropic compression of the electric compressor is expressed in K; t is₁The unit is K and is the front temperature of the electric compressor; e_C1The unit is J for the energy required by the compressor;the unit is kg/s for the mass flow passing through the compressor; p₁The unit is Pa for the front pressure of the electric compressor; r is a gas constant, and the value of R is 8.314J/(mol.K); k is a turbine end adiabatic polytropic index and takes the value of 1.33; gamma is the adiabatic polytropic exponent at the end of the compressor, and the value is 1.4.

2. The device for implementing the power recovery method of the electrically supercharged high-back-pressure diesel engine comprises an air inlet main pipe, air inlet branch pipes, a diesel engine, air outlet branch pipes and an air outlet main pipe, wherein the inlets of the air inlet branch pipes are connected with the outlets of the air inlet main pipe, the outlets of the air inlet branch pipes are connected with the inlet of an air inlet passage of the diesel engine, the inlets of the air outlet branch pipes are connected with the outlet of an air exhaust passage of the diesel engine, and the outlets of the air outlet branch pipes are connected with the inlet of the air outlet main pipe, and the device is characterized by further comprising an electric compressor, a compressor, an intercooler, a turbine, an air outlet back-pressure valve, a bypass pipe, a bypass valve, an upper computer, a control module, a variable frequency motor, a gear box oil outlet pipe, a radiating fin, a gear box oil inlet pipe and a cooling oil tank, wherein the electric compressor, the compressor and the intercooler are sequentially arranged on the air inlet main pipe along the air inlet direction, and the turbine and the air outlet back-pressure valve are sequentially arranged on the air outlet main pipe along the air flow direction, two ports of the bypass pipe are respectively communicated with the front and rear exhaust main pipes of the turbine, the bypass valve is arranged on the bypass pipe, and the compressor and the turbine are connected together through a connecting shaft; the upper computer, the control module and the variable frequency motor are connected through a wire harness; the variable frequency motor is connected with a gear box, and the gear box is connected with the electric compressor; the business turn over hydraulic fluid port of gear box is connected with the export that the gear box goes out oil pipe, the entry that the gear box advanced oil pipe respectively, and the business turn over hydraulic fluid port of fin is connected with the export that the gear box advanced oil pipe, the entry that the gear box goes out oil pipe respectively, and the cooling oil tank is arranged on the gear box advances oil pipe.

3. The device for implementing the power recovery method of the high-backpressure diesel engine based on electric supercharging of claim 2, wherein the variable frequency motor is connected with a gear box through a belt, and the gear box is coupled with the electric compressor.

4. The device for implementing the power recovery method of the high-back-pressure diesel engine based on the electric supercharging of claim 2, wherein the height of the cooling fins and the cooling oil tank is lower than that of the electric compressor.

Technical Field

The invention relates to a power recovery method and an implementation device thereof in the technical field of diesel engines, in particular to a power recovery method and an implementation device of a high-back-pressure diesel engine with a variable frequency motor based on electric supercharging.

Background

Since the 50 s, diesel engines have been widely used in the fields of marine main power, marine power generation, and the like due to their large power range, low fuel consumption, simple and convenient maintenance, and high reliability. Under the special working condition of underwater work, because the exhaust pipe of the diesel engine is positioned at a certain depth below the sea level, the diesel engine faces the environment with high exhaust back pressure, and the highest back pressure range can be as high as about 1.65 bar-1.85 bar generally.

Studies have shown that high back pressure environments have a severe impact on diesel power characteristics. When the exhaust back pressure is increased from 1.0bar to 1.65bar, the output power of the diesel engine is greatly reduced, the maximum reduction amplitude can reach 52.9 percent, and the exhaust temperature, the pressure and the smoke intensity of the diesel engine are all rapidly increased. Analysis of engine operating parameters proves that the main reasons are pumping loss and rapid increase of residual exhaust gas coefficient caused by high back pressure, insufficient exhaust energy before the supercharging turbine, and reduction of air inflow, further increase of combustion duration and increase of after-combustion proportion.

At present, medium and large diesel engines used for ship power have widely adopted an exhaust gas turbocharger technology to improve the output power of the diesel engine. The power of the turbine depends on the pressure and temperature of the engine exhaust at the inlet end and the environment at the outlet end, the environment condition at the outlet end of the turbine is obviously different from the environment condition under the atmospheric backpressure condition under the fluctuation high backpressure condition, and the performance of the supercharger can be changed violently. Therefore, it is difficult to satisfy the power recovery of the diesel engine under high back pressure by the turbocharger alone.

In order to meet the power requirement of ships, the diesel engine needs to have multiple back pressure working condition adaptability, can provide long-time and stable high-power output under the working conditions of fluctuation and high back pressure and under the working conditions of common atmosphere, and simultaneously, various parameters such as exhaust temperature, maximum pressure in a cylinder and the like cannot exceed design indexes so as to ensure the operation reliability of the diesel engine. However, there is no related patent in the prior art.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a high-backpressure diesel engine power recovery method based on electric supercharging and an implementation device thereof, which can meet the diesel engine power recovery under steady-state high backpressure and can realize the follow-up control of a motor under fluctuating high backpressure.

The invention is realized by the following technical scheme, and the power recovery method of the high back pressure diesel engine based on electric supercharging comprises the following steps:

firstly, the turbine flow formula is utilized to calculate and obtain the pressure P before the vortex₃：

Secondly, the energy E provided by the turbine is calculated by using a turbine energy formula_T：

Thirdly, the energy balance formula between the turbine and the compressor and the efficiency formula of the compressor are combined to calculate and obtain the back pressure P of the electric compressor₁' and actual temperature T after electric compressor₁'：

Fourthly, calculating the energy E required by the electric compressor by using an energy formula_C1：

Fifthly, adjusting the rotating speed of the electric compressor through a variable frequency motor according to the calculated energy value required by the electric compressor;

wherein the content of the first and second substances,mass flow through the turbine in kg/s; t is_TIs the pre-vortex temperature in K; a. the_TIs the turbine flow area in m²；P₄Is the exhaust back pressure in Pa; p₃Is the preswirl pressure in Pa; e_TEnergy provided to the turbine in units of J; eta_TTo turbine efficiency;the unit is kg/s for the mass flow passing through the compressor; t is₁' is the actual temperature after the electric compressor, and the unit is K; p₁' is the back pressure of the electric compressor, and the unit is Pa; p₂The unit is Pa for the back pressure of the gas compressor; eta_C2The adiabatic efficiency of the compressor is high; eta_C1The heat insulation efficiency of the electric compressor is improved; t is_1sThe temperature after isentropic compression of the electric compressor is expressed in K; t is₁The unit is K and is the front temperature of the electric compressor; e_C1The unit is J for the energy required by the compressor;the unit is kg/s for the mass flow passing through the compressor; p₁The unit is Pa for the front pressure of the electric compressor; r is a gas constant, and the value of R is 8.314J/(mol.K); k is a turbine end adiabatic polytropic index and takes the value of 1.33; gamma is the adiabatic polytropic exponent at the end of the compressor, and the value is 1.4.

The implementation device of the invention comprises an air inlet main pipe, air inlet branch pipes, a diesel engine, air outlet branch pipes, an air outlet main pipe, an electric compressor, a compressor, an intercooler, a turbine, an air outlet back pressure valve, a bypass pipe, a bypass valve, an upper computer, a control module, a variable frequency motor, a gear box oil outlet pipe, a radiating fin, a gear box oil inlet pipe and a cooling oil tank, wherein the inlet of the air inlet branch pipe is connected with the outlet of the air inlet main pipe, the outlet of the air inlet branch pipe is connected with the inlet of an air exhaust passage of the diesel engine, the inlet of the air outlet branch pipe is connected with the outlet of an air exhaust passage of the diesel engine, the outlet of the air outlet branch pipe is connected with the inlet of the air outlet main pipe, the electric compressor, the compressor and the intercooler are sequentially arranged on the air inlet main pipe along the air inlet direction, the turbine and the air outlet back pressure valve are sequentially arranged on the air outlet main pipe along the air outlet direction, two end ports of the bypass pipe are respectively communicated with the air outlet main pipes in front and back of the turbine, the bypass valve is arranged on the bypass pipe, and the gas compressor and the turbine are connected together through a connecting shaft; the upper computer, the control module and the variable frequency motor are connected through a wire harness; the variable frequency motor is connected with a gear box, and the gear box is connected with the electric compressor; the business turn over hydraulic fluid port of gear box is connected with the export that the gear box goes out oil pipe, the entry that the gear box advanced oil pipe respectively, and the business turn over hydraulic fluid port of fin is connected with the export that the gear box advanced oil pipe, the entry that the gear box goes out oil pipe respectively, and the cooling oil tank is arranged on the gear box advances oil pipe.

Further, in the invention, the variable frequency motor is connected with the gear box through a belt, and the gear box is coupled with the electric compressor.

Further, in the present invention, the height of the heat radiating fins and the cooling oil tanks is lower than that of the electric compressor.

In the invention, the gear box is coupled with the electric compressor, the air cooling device is used for cooling the gear box, the variable frequency motor is used for controlling the rotating speed of the electric compressor, and the control module is matched with the control program to realize the control of the variable frequency motor. The electric compressor is connected in series at a low-pressure stage to realize the recovery of air inflow; the electric compressor is connected with the high-pressure compressor in series, so that the purpose of high pressure ratio is achieved. The control module and the control program can realize the real-time control and monitoring of the rotating speed of the variable frequency motor. The control module feeds the motor information back to the control program, the control program monitors in real time, and a user can adjust the rotating speed of the variable frequency motor randomly according to requirements. The control program can be provided with an external interface, and a user can write the rotating speed control of the variable frequency motor according to the use condition and access the control program to realize the control of the variable frequency motor under different conditions.

Compared with the prior art, the invention has the following beneficial effects: the invention has reasonable design, simple structure and convenient installation; the air inflow of the diesel engine can be recovered under the condition of high back pressure, so that the power recovery of the diesel engine is realized; the motor follow-up control in different back pressures and fluctuating back pressures can be realized, and the application range is wide.

Drawings

FIG. 1 is a flow chart of a method of the present invention;

FIG. 2 is a schematic structural diagram of an apparatus for practicing the present invention;

FIG. 3 is a schematic view of the installation of a variable frequency motor of the device of the present invention;

wherein: 1. the device comprises an air inlet main pipe, 2, air inlet branch pipes, 3, a diesel engine, 4, air outlet branch pipes, 5, an air outlet main pipe, 6, an electric compressor, 7, a compressor, 8, an intercooler, 9, a turbine, 10, an air outlet back pressure valve, 11, a bypass pipe, 12, a bypass valve, 13, an upper computer, 14, a control module, 15, a variable frequency motor, 16, a gear box, 17, a gear box oil outlet pipe, 18, a cooling fin, 19, a gear box oil inlet pipe, 20, a cooling oil tank, 21, a motor belt pulley, 22, a mounting base, 23, an electric compressor support, 24, a tension pulley, 25 and an electric compressor fixing plate.

Detailed Description

The following embodiments of the present invention are described in detail with reference to the accompanying drawings, and the embodiments and specific operations of the embodiments are provided on the premise of the technical solution of the present invention, but the scope of the present invention is not limited to the following embodiments.

Examples

The specific structure of the whole implementation device is shown in fig. 2 and fig. 3, and comprises an air inlet main pipe 1, an air inlet branch pipe 2, a diesel engine 3, an air outlet branch pipe 4, an air outlet main pipe 5, an electric compressor 6, a compressor 7, an intercooler 8, a turbine 9, an exhaust back pressure valve 10, a bypass pipe 11, a bypass valve 12, an upper computer 13, a control module 14, a variable frequency motor 15, a gear box 16, a gear box oil outlet pipe 17, a cooling fin 18, a gear box oil inlet pipe 19, a cooling oil tank 20, a motor belt pulley 21, a mounting base 22, an electric compressor support 23, a tension pulley 24 and an electric compressor fixing plate 25, wherein the inlet of the air inlet branch pipe 2 is connected with the outlet of the air inlet main pipe 1, the outlet of the air inlet branch pipe 2 is connected with the inlet of the diesel engine 3, the inlet of the air outlet branch pipe 4 is connected with the outlet of the diesel engine 3, the outlet of the air outlet branch pipe 4 is connected with the inlet of the air outlet main pipe 5, an electric compressor 6, a compressor 7 and an intercooler 9 are sequentially arranged on an air inlet main pipe 1 along an air inlet direction, a turbine 9 and an exhaust back pressure valve 10 are sequentially arranged on an exhaust main pipe 5 along an exhaust flow direction, two ports of a bypass pipe 11 are respectively communicated with the exhaust main pipe 5 in front of and behind the turbine 9, a bypass valve 12 is arranged on the bypass pipe 11, and the compressor 7 and the turbine 9 are connected together through a connecting shaft; the upper computer 13, the control module 14 and the variable frequency motor 15 are connected through a wire harness; the variable frequency motor 15 is connected with a gear box 16, and the gear box 16 is connected with the electric compressor 6; the oil inlet and outlet of the gear box 16 are respectively connected with the outlet of the gear box oil outlet pipe 17 and the inlet of the gear box oil inlet pipe 19, the oil inlet and outlet of the cooling fin 18 are respectively connected with the outlet of the gear box oil inlet pipe 19 and the inlet of the gear box oil outlet pipe 17, and the cooling oil tank 20 is arranged on the gear box oil inlet pipe. The inverter motor 15 is connected to a gear box 16 via a belt, and the gear box 16 is coupled to the electric compressor 6. The heights of the radiating fins 18 and the cooling oil tank 20 are lower than that of the electric compressor 6, and the rotating speed ratio between the variable frequency motor 15 and the electric compressor 6 is 1: 15. The variable frequency motor 15 and the electric compressor bracket 23 are both arranged on the mounting base 22; the motor belt pulley 21 is arranged at the front end of the variable frequency motor 15, and the motor belt pulley 21 is connected with a tensioning pulley 24 and a gear train of the gear box 16 through a belt; the electric compressor 6 is mounted on the top of the electric compressor bracket 23 through an electric compressor fixing plate 25.

In the implementation process of the invention, when the diesel engine 3 is under the working condition of high exhaust back pressure, the control program starts the variable frequency motor 15 to drive the electric compressor 6 to supplement air to the diesel engine 3, thereby recovering the power of the diesel engine 3; when the back pressure fluctuates, the variable frequency motor 15 can be adjusted in real time by the control program, so that the variable frequency motor is suitable for different working conditions. During operation, the gear box 16 is lubricated and cooled by the air cooling device to ensure that the temperature of the electric compressor 6 is not too high during high-speed operation.

In the implementation process, firstly, the pressure P in front of the turbine 9 is calculated by using a turbine flow formula₃：

Then, the energy E provided by the turbine 9 is calculated by using a turbine energy formula_T：

Then, the energy balance formula between the turbine 9 and the compressor 7 and the compressor efficiency formula are combined to calculate and obtain the back pressure P of the electric compressor 6₁' and actual temperature T after electric compressor 6₁'：

Then, the energy E required by the electric compressor 6 is calculated by using an energy formula_C1：

Finally, adjusting the rotating speed of the electric compressor 6 through the variable frequency motor 15 according to the calculated energy value required by the electric compressor 6;

wherein the content of the first and second substances,is a streamThe mass flow through the turbine 9 is in kg/s; t is_TIs the temperature before the turbine 9 in K; a. the_TIs the flow area of the turbine 9, in m²；P₄Is the exhaust back pressure of the turbine 9 in Pa; p₃Is the pressure before the turbine 9, in Pa; e_TEnergy provided to the turbine 9 in units of J; eta_TIs the efficiency of the turbine 9;the mass flow rate of the gas flowing through the gas compressor 7 is kg/s; t is₁' is the actual temperature after the electric compressor 6, and the unit is K; p₁' is the back pressure of the electric compressor 6, and the unit is Pa; p₂The back pressure of the compressor 7 is expressed in Pa; eta_C2The adiabatic efficiency of the compressor 7; eta_C1The heat insulation efficiency of the electric compressor 6 is high; t is_1s' is the temperature after isentropic compression by the electric compressor 6, and the unit is K; t is₁The temperature before the electric compressor 6 is expressed by K; e_C1The unit is J for the energy required by the compressor 7;is the mass flow rate of the flow through 7 and has the unit of kg/s; p₁The unit is Pa for the front pressure of the electric compressor 7; r is a gas constant, and the value of R is 8.314J/(mol.K); k is a turbine end adiabatic polytropic index and takes the value of 1.33; gamma is the adiabatic polytropic exponent at the end of the compressor, and the value is 1.4.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.