COMPARING TURBOCHARGER AND SUPERCHARGER

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.