This document discusses supercharging and turbocharging of internal combustion engines. It begins by explaining that supercharging and turbocharging aim to increase engine power output by supplying air or air-fuel mixture at a pressure higher than ambient pressure, thus increasing density and mass of the intake charge. It then describes the three main types of superchargers - centrifugal, roots, and vane types - and compares their characteristics. Turbocharging is introduced as using a gas turbine powered by exhaust gases to drive the supercharger, avoiding the need for a mechanical linkage. The principles of exhaust gas turbocharging for a single-cylinder engine are illustrated. Effects of supercharging such as increased power output and torque are also outlined.

1. INTERNAL COMBUSTION ENGINES-II Supercharging & Turbocharging
University of Petroleum & Energy Studies Dehradun

2. I C ENGINES - II Supercharging & Turbocharging
Introduction
ȐPurpose : higher power , lower emissions
•Power output of naturally aspirated engine depend :
- Amount of Air
- Air utilization
- Engine speed
- Amount of fuel admitted
- Combustion characteristics
- Engine thermal efficiency

3. I C ENGINES - II Supercharging & Turbocharging
Introduction
•Brake Horse Power of Engine :
bhp = [ pbm x Vs x n x K ] / 60000
where;
pbm : brake mean effective pressure, N / m2
Vs : swept vol. of engine, m3
n : no. of power strokes or cycles
K : no. of cylinders
Power out put can be increased by means of increasing
mean effective pressure

4. I C ENGINES - II Supercharging & Turbocharging
Increase in bmep of a given engine capacity
•Supplying air or air- fuel mixture at higher than ambient pressure
- this will increase density
- thereby mass of charge; air or air- fuel mixture
- resulting in increase in power out put
The method of supplying air or air- fuel mixture at a
pressure higher than the pressure at which the
engine naturally aspirate,by means of device is
called supercharging

5. I C ENGINES - II Supercharging & Turbocharging
ȐSupercharging
- increase power w/o increase in sfc
- some power consumed but net power increases
- engine to withstand higher forces of
supercharging
- higher pressure & temperature may result in
knocking and require better anti - knock fuel
- applications; marine, automotive, genset, racing cars, engines working at high altitudes, etc.

6. I C ENGINES - II Supercharging & Turbocharging
Types of Superchargers
Supercharger is a pressure - boosting device
A centrifugal, axial or displacement type compressor is normally used
Superchargers driven by engine crankshaft are called mechanically driven superchargers
Superchargers driven by a gas turbine using exhaust gases are called Turbochargers
There are three types of superchargers;
- Centrifugal type - Roots type - Vane type

7. I C ENGINES - II Supercharging & Turbocharging
Centrifugal Type of Supercharger
•Supplying air or air- fuel mixture

8. I C ENGINES - II Supercharging & Turbocharging
Root’s Type of Supercharger
•Supplying air or air- fuel mixture

9. I C ENGINES - II Supercharging & Turbocharging
Vane Type of Supercharger
•Supplying air or air- fuel mixture

10. I C ENGINES - II Supercharging & Turbocharging
Comparison between the three Superchargers
- The required characteristics of centrifugal type has limitations & are suitable for only low speeds
- The root’s type is simple in construction, minimum maintenance and longer life
- The vane type has problem of wear of the tips of vanes over a period of time
- Depending upon the application, the type of supercharger should be decided

11. I C ENGINES - II Supercharging & Turbocharging
Methods of Supercharging
- Independently driven compressor or blower
- Ram effect
- Under piston compression
- Engine driven compressor or blower

12. I C ENGINES - II Supercharging & Turbocharging
Effects of Supercharging
- Higher induction of charge & out put
- Better atomization of fuel and its mixing with air
- Better scavenging of combustion products
- Better torque characteristics over speed range
- Quicker acceleration of vehicle
- More smoother & complete combustion with
reduction in knock tendency
- Usage of poor ignition quality fuel
- improved cold starting

13. I C ENGINES - II Supercharging & Turbocharging
Effects of Supercharging
- Reduced exhaust smoke
- Reduced specific fuel consumption in
turbocharging
- Increased mechanical efficiency
- Increased thermal stresses, heat losses, gas
loading, valve overlap
- Increased cooling requirements of pistons and
valves

14. I C ENGINES - II Supercharging & Turbocharging
ȐTurbocharging
- The supercharger driven by gas turbine uses
energy in the exhaust gases
- No mechanical linkage between the engine and
the supercharger
- The major parts of a turbocharger ;
turbine wheel, turbine housing, turbo shaft,
compressor wheel, compressor housing,
bearing housing.

15. I C ENGINES - II Supercharging & Turbocharging
 Principle of Exhaust Turbocharging of a
Single- Cylinder Engine

16. I C ENGINES - II Supercharging & Turbocharging
•Charge Cooling
- Air charge when compressed becomes hot and leaves compressor at much higher temperature (60 to 90 C) than ambient air temperature
- When air gets heated it expands and density reduces therefore mass of air entering cylinder becomes lesser. This reduces oxygen for combustion. Hot air also increases operating temp.
- Charge is cooled by intercooling, and/or after cooling to overcome complexity of hot air

17. INTERNAL COMBUSTION ENGINES-II
Course Outlines ADEG-222 LTP-3 1 1
I: BASIC THEORY
II: FUEL INJECTION SYSTEM
III: AIR MOTION, COBUSTION & COMBUSTION CHAMBERS
IV: SUPERCHARGING and TUBOCHARGING
V: DIESEL ENGINE TESTING & PERFORMAMCE