Theory about turbocharger & supercharger -working principle -types -working -purpose -advantages -disadvantages

1. SHREY SHIROMANI (140050119110)

2.  A supercharger is an air compressor that increases
the pressure or density of air supplied to an
internal combustion engine. This gives each intake
cycle of the engine more oxygen, letting it burn
more fuel and do more work, thus increasing
power.
 Power for the supercharger can be provided
mechanically by means of a belt, gear, shaft, or
chain connected to the engine's crankshaft.

3. Air inlet

4. 1. To overcome the effect of high altitude, as in the case of
aircrafts and stationary engine ties in mountains.
2. To reduce the weight of an engine per kW or power
developed, as in the case of racing cars.
3. To reduce the size of the engine to fit into a limited space, as
in the case of locomotives or marine engines.
4. To increase the power output of an existing engine to meet
greater power demands.

5. 1. Power output: Supercharging produces more power because
the supercharger supplies air at a pressure and density
higher than atmospheric with has the effect of increasing
volumetric efficiency.
2. Mechanical efficiency : The mechanical efficiency of a
supercharged engine is higher than that of one not
supercharged.
3. Fuel consumption : It provides better mixing of fuel and air
which results in a specific reduction of fuel consumption
and the thermal efficiency increases.
4. Scavenging : In supercharged engine , the pressure of
charge is higher than the exhaust pressure & hence
scavenging is possible

6. Based on the use of compressor
 Centrifugal type
 Roots type
 Vane type

7.  The roots type supercharger is by far the oldest, dating back
to before the 20th century. However, it has been continuously
updated since it was first invented and used, and has
managed to hold its own in modern times in several areas.
 Originally, roots type superchargers push extra oxygen into
engines by using meshed-lobe rotors with two lobes. These
rotors rotate in opposite directions, trapping air in pockets
and forcing it from the inlet to the compressor chamber,
where it is compressed and moved into the engine. Modern
designs use the same basic principal, but usually use rotors
with three or even four lobes, as well as other upgrades that
can improve efficiency in dramatic ways.

8. ROOTS BLOWER SUPERCHARGER

9.  Centrifugal superchargers are similar to many pumps or fans.
They pull air through an intake using an impeller, which
collects air and forces it out into a progressively smaller area,
compressing it and leading to an engine, where it is put to
work.
 Centrifugal superchargers use their special features to their
advantage, but not without drawbacks. In general, they are
excellent at moving a large volume of air. As a result of this,
they are among the most efficient and effective
superchargers. Centrifugal superchargers have comparatively
few moving parts. As a result of this, they are quite reliable,
requiring little maintenance. They also generate much less
heat than their more complicated equivalents. Unfortunately,
they put a limited amount of pressure on this air, unlike the
other kinds of superchargers. They also perform less
effectively at lower RPM.

11.  The screw type supercharger works in a similar way to the
roots type supercharger. Screw type superchargers work by
using two counter rotating screws, rather than rotors. While
this seems similar enough to a roots type supercharger, it
actually offers very different advantages and disadvantages.
 Screw type superchargers are very good at moving air — they
lose very little of it due to their design. Additionally, they can
compress air as they move it using their screws. However,
these advantages are not without cost. Screw type
superchargers are significantly less powerful before reaching
high RPM — and if used on an engine that never reaches high
RPM, they will not ever achieve their potential.

13. 1. Compressor driven by engine
2. Compressor driven by turbine
3. Compressor driven by external source of power
4. Compressor driven by engine shaft & free turbine
5. Direct coupling between engine, compressor &
turbine

14.  Increased horsepower: adding a supercharger to any engine is
a quick solution to boosting power.
 No lag: the supercharger’s biggest advantage over a
turbocharger is that it does not have any lag. Power delivery
is immediate because the supercharger is driven by the
engine’s crankshaft.
 Low RPM boost: good power at low RPM in comparison with
turbochargers.
 Price: cost effective way of increasing horsepower.

15.  Less efficient: the biggest disadvantage of superchargers is
that they suck engine power simply to produce engine power.
They’re run off an engine belt connected to the crankshaft, so
you’re essentially powering an air pump with another air
pump. Because of this, superchargers are significantly less
efficient than turbochargers.
 Increases knocking tendency of engine.
 Increases the strain on engine & running gear.
 Mechanical & gas loading increases with an increase in
supercharging.
 Reliability: with all forced induction systems (including
turbochargers), the engine internals will be exposed to higher
pressures and temperatures, which will of course affect the
longevity of the engine. It’s best to build the engine from the
bottom up to handle these pressures, rather than relying on
stock internals.

16.  A turbocharger, is a turbine-driven forced induction device that
increases an internal combustion engine's efficiency and power
output by forcing extra air into the combustion chamber. This
improvement over a naturally aspirated engine's power output is
due to the fact that the compressor can force more air—and
proportionately more fuel—into the combustion chamber than
atmospheric pressure (and for that matter, ram air intakes)
alone.
 The key difference between a turbocharger and a
conventional supercharger is that a supercharger is mechanically
driven by the engine, often through a belt connected to
the crankshaft, whereas a turbocharger is powered by a turbine
driven by the engine's exhaust gas. Compared to a mechanically
driven supercharger, turbochargers tend to be more efficient,
but less responsive. Twin charger refers to an engine with both a
supercharger and a turbocharger.

19. 1. Constant pressure turbocharging
 The various cylinders discharge their exhaust into a common
manifold at pressures higher than atmospheric pressure.
 These exhaust gases undergo expansion in exhaust valves, to an
approximately constant pressure in the common manifold and then
enter the turbine.
 This allows the conversion of blow-down energy (internal energy) to
work in the turbine. Higher the pressure ratio of turbine, higher is
the recovery of blow-down energy.

20. 2. Pulse Turbocharging:
 In this significant part of blow down energy is converted into
exhaust pulses as soon as exhaust valve opens.
 These pulses enter the turbine through narrow exhaust pipes
where this energy is utilized and so a large part of energy is
recovered.
 Separate exhaust pipes are used so that the exhaust process
of various cylinders do not interfere with each other.
3. Pulse Convertor Turbocharging:
 This method provides advantages of both constant pressure
and pulse turbocharging simultaneously.
 The arrangement involves connecting the different branches
of exhaust manifolds together in a specially designed venturi
junction called pulse converter before the turbine.

21.  Significant increase in horsepower.
 Power vs. size: allows for smaller engine displacements to
produce much more power relative to their size.
 Better fuel economy: smaller engines use less fuel to idle, and
have less rotational and reciprocating mass, which improves
fuel economy.
 Higher efficiency: turbochargers run off energy that is
typically lost in naturally-aspirated and supercharged engines
(exhaust gases), thus the recovery of this energy improves
the overall efficiency of the engine.

22.  Turbo lag: turbochargers, especially large turbochargers, take
time to spool up and provide useful boost.
 Boost threshold: for traditional turbochargers, they are often
sized for a certain RPM range where the exhaust gas flow is
adequate to provide additional boost for the engine. They
typically do not operate across as wide an RPM range as
superchargers.
 Power surge: in some turbocharger applications, especially
with larger turbos, reaching the boost threshold can provide
an almost instantaneous surge in power, which could
compromise tire traction or cause some instability of the car.
 Oil requirement: turbochargers get very hot and often tap
into the engine’s oil supply. This calls for additional
plumbing, and is more demanding on the engine oil.
Superchargers typically do not require engine oil lubrication.