Assignment 6

Types of the turbocharger:

1. Single Turbo
2. Sequential turbo
3. Twin scroll Turbo
4. Variable geometry turbo
5. Variable twin scroll turbo
6. Electric turbo

TURBOCHARGER EXAMPLE IN GT POWER:

The following are the examples from the gt-power:

• Fixed geometry turbocharger:

this is the simplest form of the turbocharger in which the geometry of the turbocharger is fixed. the speed of the turbocharger also can't be controlled.

• Variable Geometry turbocharger or VGT:

In this type of turbocharger, the geometry of the turbocharger can be controlled according to the speed. This helps in reducing the chances of mechanical failure and also helps to start the engine at low speed by closing the gates.

BENEFITS OF VARIABLE GEOMETRY TURBINE:

The VGT turbo engines are beneficial when they are used in turbo diesel engines to compensate for the performance loss when the engine is equipped with an Exhaust Gas Recirculation System. The typical application is in passenger car application where we are required to start the engine without the lag by adjusting the kinetic energy entering the turbines.

• Wastegate turbo charger:

  In this type of turbocharger, the amount of exhaust gas going to the turbocharger can be controlled using pressure sensors. if the pressure increases above the limit then the small opening called Wastegate opens and thus the pressure gets back to its limited value.

EXPLORING TUTORIAL 6 AND TUTORIAL 7: -

• This is a 6 cylinders direct injection diesel engine with an intercooler system. The main function of the intercooler is to cool down the hot air from the compressor.
• In this model, a Twin Scroll Turbine is assumed and the assumed data is fed into the inlet and outlet boundary condition.

• This is the model of 6 cylinders Direct injection along with an Intercooler and Turbocharger system. In this model, the turbocharger is attached to the Cylinders' exhaust.
• Here the turbine maps and compressor maps are defined by the manufacturer which defines the working of the Compressor and Turbine.

Compressor Map:-

Turbine Map:-

Q4. In which application Variable Geometry Turbine is beneficial?

VGT devices are used to increase boost pressure at low speed, reduces response time, increase available torque, decrease the boost at high engine speeds to prevent over boosting, reduce engine emission, improve fuel economy and increase the overall turbocharger operating range.

Q5. Explore example- Diesel VGT EGR and understand the modeling part.

Compressor Map of VGT EGR:-

• The engine is a 4-cylinder, four-stroke, direct injection, 2L diesel engine. A predictive combustion model is being used with detailed injection profiles.

• The intake system consists of the air piping upstream of the compressor inlet and contains a simple model of an airbox.

• The intercooler is present which cools the compressed air.

• The exhaust gas recirculation system is present to decrease the temperature of cylinders by mixing with the incoming air.

• Exhaust gases enter the turbine radially and before entering the turbine there are some guiding through which we change the area to allow the required flow. Depending on the available kinetic energy and the required pressure ratios we can change the amount of kinetic energy going to the turbines.

• VGT is defined in terms of rack position and for each rack position, the turbine maps are provided. An electronic controller controls the rack position and for different speed load conditions we have different possibilities of boost pressures. Here the boost pressure is provided as wireless signals.