Assignment 6

1-List down different TC and locate examples from GT Power

Following are some of the types turbochargers
a-Fixed Geometry Turbocharger
b-Wastegate Turbocharger(WGT)
c-Variable Geometry Turbine(VGT)
d-2-stage Turbocharger
e-Variable Geometry Compressor(VGC)
f-E-Turbo

Explore tutorial number 6 and 7

Step1: Copy and Paste Di_1cyl model 5 more times ,attach engine crancktrain and list firing order of different cylinders . Attch Intercooler assembly as on the Assignment 1. Modify the inlet and exhaust manifols as in the tutorial.

Step2:

Add the intercooler effectiveness controller and setup required input and output control signals.

Step3:

Delete the comp-out part ,add the compressor with desired compressor map and eventually setup a compressor inlet pipe and environment object.

Step4:

Similarly add turbine and turbine outlet pipe and environment.

Step5:

Caliberate the compressor and turbine if required. Eventually add a mechanical shaft with specific inertia to connect the compessor and the turbine.

Plot operating points on compressor and turbine maps

The example used for the question is SI_4cyl_GDI_Turbo-WOT

Compressor Map

Turbine Map

In which application Variable Geometry Turbine is beneficial?

Applications where we need to avoid the discomfort due to turbo lag e.g. passenger cars.

Explore example- Diesel VGT EGR and understand the modeling part

The Engine

Engine is a four cylinder compression ignition deisel engine, with common rail direct injection system and heat trensfer model as WOSHNIGT in engine cylinder whereas DI_Pulse as combustion model.

This engine uses a multiple injection system that can be divided into pre and main injection.Pre-Injections are predominantly used to rduce combustion noise.

During pre-injection a small quantity of fuel is injected and undergoes homogenous combustion, this raises the temperature of the cylinder and reduces the ignition delay for the main injection, in turn reducing the premix combustion peak. This results in quieter operation of the engine. The reduced ignition delay also advances the combustion which improves the efficiency. However this leads to an increase in soot production due to longer diffusion combustion duration. The NOx also increases due to the increase in cylinder temperature since the combustion is advanced (Badami et al., 2002).

Pre-Mass is the mass of fuel sprayed at the pre-injection phase. The quantity of the fuel sprayed is the function of target bmep in the cylinder.

Start of Injection for pre-injection phase is the function of rpm of engine and brake mean effective pressure.

Similarly Injection rate maps are given as a function of Rail Pressure and time.

Similarly, for the main part of injection a 50 mg of fuel is injected, Start of Injection is the function of Engine RPM and BMEP, whereas injection rate profile are given as a function of rail pressure and time.

Finite Element Method is used to model the Cylinder walls.

DI- Pulse Combustion model is used.

The Intecooler

A semi-predictive model is used to model the intercooler, as the heat exchanger effectiveness values are known.

Inlet Manifold

It is model using aluminium as a material along with the conduction objects as shown in the images below to correctly model the changing compressor outputs .

Exhaust Manifold

Similarly Exhaust Maniflod is model using cast along with the conduction objects as heat transfer in the exhaust manifold could effect the turbine effeciency.

EGR Control

After Treatment

This step is modelled using a Diesel Oxygen Catalyst (DOC) and Deisel Particulate Filter (DPF) without the chemistries involved.