Department of Mechanical Engineering

K Pavan Kumar,11781A0347,IV year, mechanical Dept,SVCET, Chittoor.

Presented by

Twin Turbo Technology

Introduction :

The power out put of an engine depends upon the amount of air inducted per unit time

and the degree of utilization of this air , and the thermal efficiency of the engine.

Indicated engine Power

IP=P*L*A*n*K/60000

Where,

IP= indicated power (kW)

P=indicated mean effective pressure(N/m2)

L=length of stroke

A= area of piston

n= no of power stroke, for 2-s engine-N and for 4-s engine N/2, N= rpm

K= No of cylinders

Three possible methods utilized to increase the air

consumption of an engine are as follows:

Increasing the piston displacement: This increases the size and weight of the engine, and introduces additional cooling problems.

Running the engine at higher speeds: This results in increased mechanical friction losses and imposes greater inertia stresses on engine parts.

Increasing the density of the charge: This allows a greater mass of the charge to be inducted into the same volume.

Definition

The most efficient method of increasing the power of an engine is by

supercharging, i.e. increasing the flow of air into the engine to enable

more fuel to be burnt.

A Supercharger is run by the mechanical drive, powered by engine power .

A turbocharger uses the otherwise unused energy in the exhaust gases todrive a turbine directly connected by a co-axial shaft to a rotarycompressor in the air intake system.

Introduction :

The parameters which take the centre stage of the competition in car

today are efficiency, power, and environmental safety.

One technology that is going to be the heart of the future diesel cars is

TWIN TURBO technology.

Unlike the Bi-Turbo mechanism, this Twin Turbo is a combination of

two turbo chargers mounted serially rather than in parallel.

The only car in India, which has this facility, is Hyundai i20.

Super Charger

Turbo Charger( schematic diagram)

Need of turbocharger and super

charger

For ground installations, it is used to produce a gain in the power out put of the engine.

For aircraft installations, in addition to produce a gain in the power out put at sea-level, it also enables the engine to maintain a higher power out put as altitude is increased.

Turbo Charger

A turbocharger is practically a turbine that is fuel-driven.

A turbocharger, often called a turbo, is a small radial fan pump driven

by the energy of the exhaust flow of an engine.

A turbocharger consists of a turbine and a compressor on a shared axle.

The turbocharger increases the pressure at the point where air is

entering the cylinder, a greater mass of air (oxygen) will be forced in as

the inlet manifold pressure increases.

Working principle of a turbocharger:

A turbocharger is a small radial fan pump driven by the energy of theexhaust gases of an engine.

A turbocharger consists of a turbine and a compressor on a sharedshaft.

The turbine converts exhaust to rotational force, which is in turn usedto drive the compressor.

The compressor draws in ambient air and pumps it in to the intakemanifold at increased pressure, resulting in a greater mass of airentering the cylinders on each intake stroke.

Where the turbocharger is located in the car

0

2

3

41

Four-stroke cycle of an SI engine equipped with a

supercharger turbocharger, plotted on p-v coordinates.

Thermodynamic analysis of turbocharged engine

cycle

Net work output Wnet= work done by piston + Gas exchange work= area A + area

Area A=

Area B= work done by turbocharger=

Wnet = Work done per unit of air mass.Where, p0 = atmospheric pressure,p1= pressure after compression,T0= atmospheric air temperature,V1= volume of boosted air,rp =pressure ratio,r = compression ratio, cp=Specific heat of air

and η = turbocharger efficiency,

Selection process of turbocharger

Illustration of the concept of a turbocharger.

•Compressor air inlet,Point1- p1, T1•Compressor air out let, point2-p2, T2•Turbine exhaust gas inlet, point 3-p3,T3•Turbine exhaust gas outlet-P4, T4

The compressor efficiency = ( theoretical temperature rise across the compressor)/(the actual temperature rise). ec is always less than 1.0.

The turbine efficiency = ( the actual temperature drop across the turbine )/(the theoretical temperature drop). The turbine efficiency is also always less than 1.0.

The mechanical efficiency of the turbocharger

Types of Turbo Chargers

Single Turbo Charger

Twin – Turbo Charger

Single Turbo Charger

Single Turbo, a single turbo

requires all 8 cylinders in

order to build some boost.

Produces good results for drag

racing, which needs extremely

high power.

Single Turbo Charger

Single turbo engines are easier

to set up.

There are super large single

setups that can support up to

1500BHP, can create real

power but there is that

unwanted lag.

Doesn't take up much space in

the car.

Twin-Turbo Charger

The secret behind "twin-turbo" is

the clever two-stage forced

aspiration principle.

The revolutionary twin-turbo

technology, the next big step

forward in the development of

modern diesel engines for

passenger cars.

Twin-Turbo Charger

The car with the Twin-Turbo mechanism gives more power, more torque,better mileage, and a comprehensive pollution free engine than its rivals.

ENGINE SPEED BELOW 1800 RPM:

By using a small high-pressure turbocharger for the first

stage, the engine responds readily to the gas pedal at lower

speeds without suffering from "turbo lag".

Up to 1800 rpm this high-pressure turbocharger works

alone and compresses the intake air at up to 3.2 bar boost

pressure.

ENGINE SPEED BETWEEN 1800 -

3000 RPM:

Between 1800 and 3000 rpm, a larger low pressure turbocharger joins

in - both turbines run together in this engine speed range.

The exhaust from the cylinder will drive the first turbo charger and

come to the second. This will leads to the working of the second stage

turbo charger it affects in the intake air. This intake air which is needed

for the combustion is sucked in and goes to the first stage turbo charger

which will pressurized the air and goes to the cylinders.

ENGINE SPEED ABOVE 3000 RPM:

Above 3000 rpm, only the larger turbocharger continues to deliver

charge air to the cylinders.

The complex control of both chargers is via a valve in the engine's

exhaust system, controlled by engine speed and load.

POTENTIAL OF THE TWIN TURBO-

CHARGER

The enormous potential of a twin-turbo engine can be seen

from the mean effective pressure values it achieves.

Whereas traditional turbo-diesels have a mean effective

pressure of 17 to 19 bars, the 1.9-litre twin-turbo reaches

26 bars.

EFFICIENCY: 212 hp from 1.9-liter engine with fuel consumption of only 6.0

l/100 km

Compared with a naturally aspirated diesel engine, power outputs can

be raised by up to 50 percentages without increasing fuel consumption.

Alternatively, consumption can be reduced by as much as a quarter

without loss of power.

This high-tech engine delivers a peak power output of 156 kW (212 hp)

from just 1.9 litters displacement.

With this engine the Vectra OPC accelerates from 0 to 100 in 6.5 seconds;

the top speed is an electronically regulated 250 km/h.

At 6.0 litters per 100 km in the European test cycle

Vectra OPC

Type of Twin-Turbo

After the revolution of the two-stage turbo-charger, there are two ways in

which the turbo-charger can be mounted. They are parallel and

sequential.

Parallel:

Sequential:

APPLICATIONS:

Everybody knows mechanical superchargers are good for low-end output but

short of efficiency at high rev, while exhaust turbochargers works strongly at

high rev but reluctantly at low rev. For decades engineers dreamed of

combining supercharger and turbocharger together. This was tried once in

history – the 1985 Lancia Delta S4 rally car.

1985 Lancia Delta S4 rally car

APPLICATIONS:

In 2005, Volkswagen finally introduced a production unit toits Golf 1.4 TSI. Called "Twin charger" system.

APPLICATIONS:

The only car in India, which has this facility, is Hyundai i20.

Advantages

The environmental safety standard is the major consideration today, this

technology is EURO V ready.

Even though the car delivers a much higher power than its counterparts, it still

maintains the conventional 16.5 KMpL as mileage.

At 1500 rpm, both chargers contribute about the same boost pressure, with a

total of 2.5 bars. (If the turbocharger works alone, it can only provide 1.3 bars

at the same rev.)

In the 1.4-litre Golf, the Twin charger system produces 170 horsepower and

177 lbft of torque. That's equivalent to a 2.3-litre normally aspirated engine

but it consumes 20% less fuel.

Advantages

The more increase the pressure of the intake air above the local atmosphericpressure (boost), the more power the engine produces. Automotivesuperchargers for street use typically produce a maximum boost pressurebetween 0.33 to 1.0 bar, providing a proportionate increase in power.

Engines burn air and fuel at an ideal (stoichiometric) ratio of about 14.7:1,which means that if you burn more air, you must also burn more fuel.

This is particularly useful at high altitudes: thinner air has less oxygen, reducingpower by around 3% per 1,000 feet above sea level, but a supercharger cancompensate for that loss, pressurizing the intake charge to something close tosea level pressure.

Disadvantages

Cost and complexity

Detonation

Parasitic losses

Space

Turbo lag

CONCLUSION:

From this, it is clear that the vehicle, which use thisadvanced technology, has proved to be more efficient andmore powerful. So let’s hope that the recent automobile willuse this technology and gets modernized.