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Performance supercharged diesel generators

2014-04-01 16:44      Click:

 (1) Improve the performance of the supercharged diesel generator

After using the exhaust gas turbocharger diesel generators, which improves performance mainly in the following aspects.

① improved dynamic performance supercharged engine backward volume increased amount of oil also increased, thus greatly increasing the power of the diesel engine, the general increase engine power by 30% -100%; Meanwhile, the average effective after the turbocharged diesel engine elevated pressure, much higher than the average mechanical pressure loss increases. Within a certain range, the mechanical supercharger improves the efficiency of the diesel engine V-0 Accordingly, supercharging performance of the diesel engine so that the power is greatly improved.

② After improving economic performance supercharged engine excess air ratio increased, help to improve burn tender process and improve the thermal efficiency of the diesel engine ŋu instruction cycle and mechanical efficiency ŋm

Is increased accordingly. Thus reducing diesel fuel consumption rate tender, generally up to 3% - 12%

After ③ improved emission performance boost, because the increased intake air, mixed gas thinning, so that harmful emissions HC, CO and smoke have declined. After pressurization, however, since the intake air temperature rise, NOx increase in harmful emissions. In this case, the use of a turbocharged and intercooled technology that measures taken so pressurized hot air cooled cooling cylinder backward people, then it will reduce NOx. So on the whole, the supercharger helps reduce emissions.

After ④ improved combustion and exhaust noise supercharger, intake increases the compression pressure and temperature, so that the ignition delay shortened tender material, tender roast pressure rise rate dropped providers, with the result that tender roast noise down. As the exhaust can be further expanded in the turbine, so the exhaust noise is decreased.

Meanwhile, turbocharged diesel engine with improved power and economy indicators, mechanical and thermal loads diesel will increase accordingly. Increased mechanical load bearing crank linkage and severe stress, increased wear. But the most important limitation turbocharged diesel engine or heat load conditions, due to the increased amount of air and pressurized injection after children, the total energy increases too burned to make heat load increase; Meanwhile, the supercharger into the engine cylinder compression air temperature is increased, so that the maximum firing temperature and the tender cycle average temperature increase; density and because of the working fluid increases, the working fluid is increased to heat the wall surfaces, which are set so that the piston, cylinder, cylinder head, discharge. valves and other parts of the thermal load to increase, thereby limiting the increase of the engine supercharging.

(2) changes in the structural parameters of the diesel generator

For a high degree of supercharged diesel engines, changes in its structure could be great, or even need to adapt to a high degree of re-designed pressurized. As the body and the main parts in the structure should be strengthened through various parts of the piston may be oil cooling, fuel, gas distribution, cooling, lubrication should be reconsidered.

For the supercharged engine is not high, the basic structure of turbocharged diesel engine with non-supercharged models belong to the same family, it is easy for the main components and non-supercharged supercharged two models on the same processing line organization production. To meet the increasing demands of the power booster to reduce the mechanical load and the thermal load, the supercharger is still need for such changes necessary to make the model.

① adjust supply system, increasing the amount of oil to increase the amount of circulating oil, if still non-pressurized fuel pump, fuel is bound to increase sustainable angle, the combustion process stretched economy deteriorated. Shorten the duration of supply methods are: increasing the plunger diameter, increasing the feed rate (so fuel pump cam profile steepening) and increasing the nozzle orifice diameter, etc.. Improving and increasing injection pressure nozzle diameter can also increase the penetration of oil mist guarantee in the case of increasing the density of the air cylinder has enough range to meet the needs of fit between the oil-beam, air and combustion chamber size.

Limit the maximum explosion pressure from the viewpoint of reducing the fuel injection timing should be appropriate, namely to reduce the amount of fuel burned before TDC. However, reducing excessive fuel injection timing, can burn a lot to continue to inflate online, so turbo diesel economy and working conditions deteriorate.

② change the valve timing reasonable increase in re-board valve angle, can enhance the scavenging effect of the cylinder, helps to reduce the surface temperature of the combustion chamber parts, inflatable coefficient increases, improved working conditions of the turbine. However, re-board valve angle is not too large. Research shows that when the valve overlap angle over 800 crank angle after its scavenging effect will not be further improved. Moreover, the overlap angle is too large will make the scavenging air volume is increased, adding to the workload of the compressor, causing the engine at low speed, low load exhaust backflow, which accelerates the performance of the machine and variable conditions unfavorable; same time, when the overlap angle is too large, in order to avoid touching the valve and the piston to the top of the deep pits dug in the piston, so that the combustion deterioration.

③ reduce the compression ratio, increasing the excess air ratio in order to reduce the outbreak of the pressure, the compression ratio can be appropriately reduced 1 --- 2 units. Much reduced, not only worsen the whole economy, it will start to poor performance.

Increasing the excess air factor, to reduce the thermal load, to improve economy. Usually the excess air ratio increases about 10% -30%.

④ I branch exhaust pipe located in the pulse turbocharging system, in order to take full advantage of the pulse can t, so that all exhaust interfere with each other, the exhaust pipe must branch. Principles branch is connected to an exhaust pipe of each cylinder exhaust must not overlap each other (or re-surplus rarely).

⑤ pressurized cooling air to the turbocharger outlet to the pressurized air cooling, while the density can be improved inflatable suppliers to increase engine power; ju of the other, and also reduces the average temperature of the engine compression cycle starting point, thereby reducing the diesel engine exhaust gas temperature and heat load. Practice shows that the pressurized air each lower l or, the average temperature of the diesel engine cycle can be reduced 25.300C, the pressure turbocharger outlet to population ratio is 1.5-2, the gas volume can be compared without using pressurized air-cooled diesel engine 10% -18%.

The method of cooling the charge air, water or air is generally indirect cooling, the turbocharger via the compressed air after cooling in the cold engine in a cooler one.

⑥ intake, the engine exhaust system is pressurized, typically to increase the volume of the intake pipe, to reduce the fluctuation of the inlet pressure, thereby improving the compressor efficiency and improved machine performance diesel pump. Arrangement of the exhaust pipe shall be changed, as described in section accordingly occur.

⑦ After cooling water and lubricating oil road diesel turbocharger, the capacity of the pump should be adjusted to improve the pump speed, increasing the radiator cooling area, increasing the diameter of the fan, the fan blade angle improvement, and other measures to increase the fan speed to reduce heat load, while increasing the pump capacity, increasing oil cooler cooling area, improve the crankcase ventilation.

(3) the basic characteristics of the diesel engine combined with a turbocharger operation

When the diesel engine turbocharger joint work, there is no mechanical contact with each other, they transfer energy to flow through the air or gas stream. Because diesel compressor different conditions require different supply capacity, the ability to do work in the turbine exhaust from diesel exhaust rational organization, and the power turbine to the compressor are all consumed. You can also say that some of the diesel needed to power the air flow and pressure ratio basin, just a compressor to be provided. In order to make the diesel engine turbocharger can well fit, so they work satisfactorily in a variety of conditions, there are two things to do. First, according to the specific conditions of diesel engines (such as maximum torque rated conditions or conditions), determine its position (ie, the appropriate choice based on engine type supercharger) on the compressor characteristic curve; second is to solve the diesel engine the entire operation region and to achieve a good fit booster. Here is the premise selected turbocharger, supercharger choose poorly, the diesel engine may not reach the expected boost results.

Optional booster, the engine according to the specific conditions required for the air flow (including the scavenging air amount) and the pressure ratio, it is judged that the condition of a compressor located on the characteristic curve, the point so that the gas pressure falls high efficiency characteristic curve area machine can initially selected turbocharger models.

The piston engine type, the blades of the turbine and compressor such machinery, the structure is determined by the angle of the blade leading edge of the flow parameters of the design conditions. When the working gas flow changes caused by changes in market conditions, will allow the gas inflow direction deviation angle of the direction of the blade leading edge structure, the occurrence of impact damage, high efficiency blade machine area is narrowed, it is impossible to make all engine operating conditions are in high efficiency compressor work area, only take into account the specific conditions of the diesel engine.

Each has a turbocharger to determine the scope of work. In the small flow range compressor surge limit by at large flow range, compressor efficiency decreases due to excessive nor restricted; in the high-speed, high-load range of the turbocharger, exhaust gas may be due to the high energy, so the mechanical strength of the turbocharger exceeds the allowable rotational speed, or the exhaust gas temperature is too high, exceeding the turbine blades can withstand the temperature, turbocharger speed, or by the over-temperature limit. Which determines the turbocharger a roughly determine the scope of work.

Within this scope of work permitted, according to a joint position with the engine running, you can determine with turbocharger and diesel is good.

If the joint operation of the compressor characteristic curve with the line and not ideal, the need for local adjustment, the common approach is to change the cross-sectional area of the turbine outlet nozzle ring. For example, reducing the cross-sectional area of the outlet nozzle ring can make the joint line running from the area toward the high efficiency compressor inefficiencies area (closer to the surge line). However, these adjustments are limited, if the best fit line with the joint operation of the compressor are very far, only to replace the turbocharger model is appropriate.

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