IC_engines_PPT

I.C. Engines Overview

Definition

• An internal combustion engine (I.C. Engine) is a device where the combustion of fuel occurs with an oxidizer (air) in a combustion chamber.

• It converts the chemical energy of the fuel into mechanical work.

Importance

• Used in various applications including:

  • Automobiles

  • Power generation

  • Aviation

Classification of I.C. Engines

Based on Fuel Used

• Petrol Engine

• Diesel Engine

• Gas Engine

• Bi-fuel Engines

Based on Ignition Method

• Spark Ignition (SI) Engine

• Compression Ignition (CI) Engine

Based on Working Cycle

• Two-Stroke Engine

• Four-Stroke Engine

Based on Cylinder Arrangement

• Inline

• V-type

• Opposed Cylinder

Based on Cooling Method

• Air-cooled

• Water-cooled

Based on Speed

• High-speed

• Medium-speed

• Low-speed

Components of I.C. Engines

Basic Components

• Cylinder: Contains the fuel-air mixture and combustion process.

• Piston: Transfers energy from expanding gases to the crankshaft.

• Crankshaft: Converts reciprocating motion into rotational motion.

• Connecting Rod: Links the piston and crankshaft.

Additional Components

• Valves: Control intake of air-fuel mixture and exhaust gases.

• Spark Plug (for SI Engine): Ignites the air-fuel mixture.

• Fuel Injector (for CI Engine): Sprays fuel into the combustion chamber.

• Flywheel: Stabilizes engine rotation.

Working Principles of I.C. Engines

Spark Ignition (SI) Engine

• Fuel and air are mixed in a carburetor.

• Mixture is compressed and ignited by a spark plug.

• Commonly used in petrol engines.

Compression Ignition (CI) Engine

• Air is compressed, raising its temperature.

• Fuel is injected into the hot air, causing ignition.

• Commonly used in diesel engines.

Two-Stroke Engine Working Procedure

• Compression and Intake: The piston moves upward from Bottom Dead Center (BDC) to Top Dead Center (TDC). The air-fuel mixture is compressed.

• Power and Exhaust: The piston moves downward, the mixture ignites and expands, forcing the piston down generating power. The exhaust port opens to release gases.

• Transfer: Fresh mixture is transferred from the crankcase to the cylinder.

Four-Stroke Engine Working Procedure

(a) Intake Stroke

• Draws in the air-fuel mixture or air.

• Intake valve opens; piston moves from TDC to BDC.

(b) Compression Stroke

• Compresses the air-fuel mixture.

• Intake valve closes; piston moves from BDC to TDC.

(c) Power Stroke (Expansion Stroke)

• Ignition occurs, expanding gases push the piston down.

(d) Exhaust Stroke

• Expels burned gases.

• Exhaust valve opens and the piston moves from BDC to TDC.

SI Engine vs. CI Engine

Two-Stroke vs. Four-Stroke Engines

Hydro-Electric Power Plant Overview

Key Projects

• Koyna Hydroelectric Project: Largest completed plant in India (1,960 MW).

• Tehri Hydro Electric Power Plant: Highest in India (2,400 MW capacity).

• Srisailam Hydro Power Plant: Third largest on Krishna River.

• Nathpa Jhakri Hydroelectric Power Plant: Largest underground project in India.

Primary Components

• Reservoir: Stores water, provides necessary head.

• Dam: Controls water flow and creates pressure head.

• Control Gate: Regulates water released in the penstock.

• Penstock: Directs water to turbines under high pressure.

• Turbine: Converts water energy to mechanical energy.

• Generator: Converts mechanical energy into electrical energy.

• Powerhouse: Houses turbines, generators, and auxiliary equipment.

• Transformer: Steps up voltage for transmission.

• Tailrace: Discharges water back to the river.

Advantages and Disadvantages of Hydroelectric Power

Advantages

• No fuel requirement; free energy from water.

• Clean source of energy.

• Low running charges; minimal maintenance required.

• Flexible use for irrigation.

Disadvantages

• High capital costs for dam construction.

• Transmission costs; located in remote hilly areas.

• Dependent on water availability; vulnerability to droughts.

Classification of Turbines

Based on Energy Utilization

1. Impulse Turbines: Utilize kinetic energy (e.g., Pelton Wheel).

2. Reaction Turbines: Utilize both pressure and kinetic energy (e.g., Francis and Kaplan Turbines).

Based on Flow Direction

• Axial Flow Turbines: Water flows along axis (e.g., Kaplan).

• Radial Flow Turbines: Water flows perpendicular to axis (e.g., Pelton and Francis).

• Mixed Flow Turbines: Water flows at an angle.

Based on Head at Inlet

• High Head: >250 m (e.g., Pelton).

• Medium Head: 45-250 m (e.g., Francis).

• Low Head: <45 m (e.g., Kaplan).

Based on Specific Speed

• Low Specific Speed: Up to 30 m/s (e.g., Pelton).

• Medium Specific Speed: 50-250 m/s (e.g., Francis).

• High Specific Speed: >250 m/s (e.g., Kaplan).

Turbine Types Summary

Pelton Wheel Turbine (Impulse)

• Construction: Features buckets, nozzle, casing.

• Performance: Rated head 80-1600 m, flow 0.1-20 m3/s.

• Efficiency: 89%.

Francis Turbine (Reaction)

• Construction: Spiral casing, guide vanes, runner.

• Performance: Rated head 10-300 m, flow 0.3-100 m3/s.

• Efficiency: 93%.

Kaplan Turbine (Reaction)

• Construction: Adjustable blades, guide vanes.

• Performance: Rated head 2-70 m, flow 1-200 m3/s.

• Efficiency: 93%.

Summary of Differences Among Turbines