Turbo Charge Modelling - IC-Engine Calibration Using GT-Power and GT-Suite.

IC-Engine Calibration Using GT-Power and GT-Suite

Assingment:6 (Turbo Charge Modelling)

Objective:

1. List down different TC and locate examples from GT Power
2. Explore tutorial number 6 and 7
3. Plot operating points on compressor and turbine maps
4. In which application Variable Geometry Turbine is beneficial?
5. Explore example- Diesel VGT EGR and understand the modeling part

Description:

Turbocharger is a turbine-driven force induction device that increases an internal combustion engine's efficiency and power output by forcing extra compressed air into the combustion chamber. The function of turbocharger is to compress more air flowing into the engine's cylinder. When air is compressed the oxygen molecules are packed closer together. This increases in air means that more fuel can be added for the same size naturally aspirated engine.

1. Different types of Turbocharger and locating examples from GT Power:-

Types of Turbocharger:

1. Fixed Type Turbocharger.
2. Waste gate Turbocharger.
3. Variable Geometry Turbine.

Locating types of Turbocharger from GT Power:

1. Fixed Type Turbocharger.

Procedure:

• Firstly open GT-ISE > click on TUTORIALS > go to MODELLING_APPLICATIONS > select ENGINE_PERFORMANCE > now select " 07-TURBOCHARGING " > finally click on " Turbo_Step5-final.gtm " > opens the model.

Model Map-

1. Waste gate Turbocharger.

Procedure:

• Firstly open GT-ISE > click on EXAMPLES > go to Engine_1D_Gas_Exchange_Combustion > select DIESEL > now select " Diesel_WG Controller " > finally click on " Diesel_WGController.gtm > opens the model.

Model Map-

1. Variable Geometry Turbine.

Procedure:

• Firstly open GT-ISE > click on EXAMPLES > go to Engine_1D_Gas_Exchange_Combustion > select DIESEL > now select " Diesel_VGT_EGR " > finally click on " Diesel_VGT_EGR.gtm > opens the model.

Model map-

2. Exploring tutorial number 6 and 7:-

Tutorial No-6

Here, this tutorial explains how to model the 6 cylinder direct injection engine with the intercooler system. In this model, instead of using turbocharger we used EndEnvironment parts. At the outlet we have two entries i.e. we can have two entrie but the turbocharger used is only one. As this is a single stage. As we have two entries this is called Twin Scroll Turb0. This type of arrangement is more suitable for 6 cylinder because here 1st set of 3 cylinders are grouped as one and rest 3 cylinders are grouped seperately, they these both groups will not interact with eachother. All these clinders are directly linked to the EndEnvironment parts.

Engine Performance:

Tutorial No-7

In this tutorial, the complete modelling is done by splitting into multiple steps.

• In the first step,the basic 6 cylinder direct injection engine with the intercooler system and End Environment parts are modeled. For the basic modelling, in the outlet we have two entries i.e. we can have two entries but the turbocharger used is only one.
• Then slightly modify by changing the Environment parts i.e. removing comp-out-1(at inlet) and add compressor at the inlet. After adding the compressor set with the desired compressor map. Then to the compressor add a compressor driver, inlet pipe and environment near the inlet.
• Similarly, first remove the outlets and add turbine(out) along with the turbine outline pipe and environment parts. Also add compressor driver sor connecting both the turbines .The rest of the model remains same in this step.
• Now set both the compressor and turbine as per the requirement. Also connect compressor and the turbine by using a mechanical. This shaft helps to transmit the energy produced in the turbine to run the compressor and hence no extrnal energy is required to run the compressor.

Engine Performance:

3. Plotting operating points on compressor and turbine maps:-

Compressor Map:

Turbine Map:

4. In which application Variable Geometry Turbine is beneficial :-

The Variable Geometry Turbine allows significant flexibility over the pressure ratio across the turbine. In diesel engines, this flexibility can be used for improving low speed torque characteristics reducing turbocharger lag and driving EGR flow. VGT are mainly used to boost up pressure at low speed, reduces response time and helps to increase the available torque.

5. Explore- Diesel_VGT_EGR(example) and understanding the modeling part:-The above model includes the concepts of VGT, intercooler, EGR circuit along with the cooler, boost control, EGR Rate control and exhaust after treatment device modeling.

This engine consist of 4-cylinders. for this case the engine speed is specified as per the requirement by the user and then the engine torque is calculated. The combustion is modeled by DIPulse method. This combustion model generally predicts the combustion rate and associated emissions for direct-injection doiesel engines with single and multi-phase injection events.Here, the In-cylinder heat transfer is modeled by using Woschni Model. A FE model is used to predict the cylinder head,and piston temperatures.

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 various possibilities to boost pressure. we can provide signals wireless.

The intake system generally include the air piping upstream of the inlet-compressor and also contains Air box.The box is modeled as a group pf various inter connected flowsplits that show the total volume of the air box.For both inlet and outlet of the air box, the bell mount orifice connections are used to model smooth transitions.

An intercooler is a mechanical device used to cool a gas after compression. Intercooler is generally located to the downstream of the compressor outlet. The intercooler is an air -air intercooler that ois modeled using a semi predictive method based on heat exchanger effectiveness. An intercooler typically takes a form of heat exchanger that removes waste heat in a gas compressor.

The intake manifold is modeled with aluminum using heat conduction objects to calculate the wall temperatures. The initial temperatures and pressuresare specified at the expected boost pressure in order to decrease the convergence time.

The EGR system includes an exhaust gas recirculation system to transport exhaust gases from the exhaust manifold back to the intake manifold. The flow of EGR is driven by positive pressure difference between the exhaust manifold and intake manifold and also is controlled by an orifice connection i.e. EGR VALVE. Because of the high EGR rates, it is desirable to cool the EGR gases using a heat exchanger i.e. EGR cooler.

The exhaust system is modeled below the turbine outlet. The geometry of Diesel Oxidation Catalyst(DOC) is modeled using 'Catalyst Brick' part. The inlet and outlets of the DOC must be modeled using flowsplits because the DOC is effectively a bundle of very small pipes. Just below the DOC there is a Diesel Particulate Filter(DPF). Downstreams of the DOC ther is a muffler.

Conclusion:

• Various types of Turbocharger are studied and locating examples from GT Power.
• Tutorial 6 and 7 are explored.
• Therefore the modelling of Diesel VGT EGR is studied.