DIFFERENCE BETWEEN
TURBOCHARGER AND SUPERCHARGER
Turbochargers
were originally known as turbosuperchargers when all forced induction devices were classified as
superchargers. Nowadays the term "supercharger" is
usually applied only to mechanically driven forced induction devices. 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.
In
contrast to turbochargers, superchargers are mechanically driven by the engine. Belts, chains, shafts, and gears are
common methods of powering a supercharger, placing a mechanical load on the
engine. For example, the
supercharger uses about few horsepower. Yet the benefits outweigh the costs,
for that few horsepower to drive the
supercharger the engine generates an additional horsepower(3 times more). This
is where the principal disadvantage of a supercharger becomes apparent; the
engine must withstand the net power output of the engine plus the power to
drive the supercharger.
WORKING OF TURBOCHARGER
The basic idea is that the exhaust drives the turbine,
which is directly connected to the
compressor, which increases the flow of air into the engine(cylinder). This can
be explained in the following steps:-
i. Atmospheric cool air enters the engine's air intake and heads
toward the compressor.
ii. The compressor fan helps to suck air in.
iii. The compressor squeezes and heats up the incoming air and
blows it out again.
iv. Hot, compressed air from the compressor passes through the
heat exchanger, which cools it down.
v. Cooled, compressed air enters the cylinder's air intake. The
extra oxygen helps to burn fuel in the cylinder at a faster rate.
vi. Since the cylinder burns more fuel, it produces energy more
quickly and can send more power to the wheels via the piston, shafts, and
gears.
vii. Waste or exhaust gas from the cylinder exits through the
exhaust outlet.
viii. The hot exhaust gases blowing past the turbine fan make it
rotate at high speed.
ix. The spinning turbine is mounted on the same shaft as the compressor.
So, as the turbine spins, it makes the compressor to spin as well.
x. The exhaust gas leaves the car, so wasting less energy.
WORKING OF SUPERCHARGER
A supercharger is a belt driven device that forces air
into an internal combustion engine. It consists of a drive belt, drive, the
driven gears inside, and a centrifugal compressor wheel. The belt drives the
gear and compressor wheel. The compressor wheel pumps air into the engine. The
intake air comes in from the back, and goes out of the bottom, the belt drives
the wheel in the front.
Supercharger are installed on top of the intake manifold
on V-type engines and on the side of inline engines. Since they’re belt driven,
supercharger speed is dependent on engine speed and is most efficient at higher
engine speeds. There are two main types of supercharger positive displacement and dynamic
compression
Positive-displacement
pumps deliver a nearly fixed volume of air per revolution at all speeds (minus
leakage, which is almost constant at all speeds for a given pressure, thus its
importance decreases at higher speeds). Major types of positive-displacement pumps include:-
i. Roots type.
ii. Lysholm twin-screw.
iii. Sliding vane.
iv. Scroll-type supercharger, also known as the G-Lader.
Dynamic compressors rely
on accelerating the air to high speed and then exchanging that velocity for
pressure by diffusing or slowing it down. Major types of dynamic compressor
are:-
i. Centrifugal type.
ii. Multi-stage axial-flow.
iii. Pressure wave supercharger.
ADVANTAGES OF
TURBOCHARGER OVER SUPERCHARGER
i. Some superchargers(especially Roots type) has lower adiabatic efficiency as compared to turbochargers.
ii. Roots superchargers impart significantly more heat to the
air than turbochargers.
iii. For a given volume and pressure of air, the turbocharged
air is cooler, and as a result denser, containing more oxygen molecules, and
therefore more potential power than the supercharged air.
iv. In practical application the disparity between the two,
turbochargers often produces 15% to 30% more power based solely on the
differences in adiabatic efficiency.
