Definition A generating station in which diesel engine is used as the prime mover for the generation of electrical energy is known as diesel power station.
Diesel power plant • Introduction: • Diesel power plants produce power in the range of 2 to 50 MW. • They are used as standby sets for continuity of supply such as hospitals, telephone exchanges, radio stations, cinema theatres and industries. • They are suitable for mobile power generation and widely used in railways and ships. • Generally 2 stroke diesel engine used for power generation.
USES OF DIESEL ENGINES TODAY, DIESEL ENGINES ARE USED TO PROVIDE POWER IN A VARIETY OF APPLICATIONS IN MANY INDUSTRIES
Advantages and Disadvantages of DPP Advantages (a) The design and layout of the plant are quite simple. (b) It occupies less space as the number and size of the auxiliaries is small. (c) can be located at any place. (d) It can be started quickly and it can pickup load in a short time. (e) There are no standby losses. (f) It requires less quantity of water for cooling. (g) The overall cost is much less than that of steam power station of same capacity. (h) The thermal efficiency of the plant is higher than that of a steam power station. (i) It requires less operating staff. Disadvantages (a) The plant has high running charges as the fuel (diesel) used is costly. (b) The plant doesn’t work satisfactorily under overload conditions for a longer period. (c) The plant can only generate small power. (d) The cost of lubrication is generally high. (e) The maintenances charges are generally high
Fundamental of Diesel Engine Four Stroke Cycle • Intake / Suction Compression Power / Expansion Exhaust
Four stroke cycle theory Intake stroke Piston moving down Intake valve open Exhaust valve closed
Four stroke cycle theory Compression stroke Piston moving up Intake valve closed Exhaust valve closed
Four stroke cycle theory Power stroke Piston moving down Intake valve closed Exhaust valve closed
Four stroke cycle theory Exhaust stroke Piston moving up Intake valve closed Exhaust valve open
Four-Stroke Cycle Diesel Engine • The piston travels from one end of the cylinder to the other four times during each cycle. • The fuel is ignited at the beginning of the third stroke of each cycle. • Intake air flows into each cylinder through intake valves in the cylinder head. • Exhaust gases leave through exhaust valves. • On the intake stroke, atmospheric pressure pushes air into the cylinder through the intake valve. • The exhaust stroke forces burned gases out through the exhaust valve. • During the compression and power strokes, both valves are closed.
Two-Stroke Cycle Diesel Engine • They have only two strokes per cycle. • The fuel is ignited on every other stroke of the piston. • In the two-stroke diesel engine, air is forced in and exhaust gases are forced out on a single stroke. • Usually a blower forces air into the cylinder through intake ports. • The incoming air pushes remaining exhaust gases out of the cylinder through an exhaust valve.
High torque output Smooth running Quieter operation Lower emissions output More forgiving to poor operational practices Higher horse power availability Heavier construction No Gas/Oil mixing Advantages & Disadvantagesto a 4-Stroke Cycle Engine Disadvantages: • Advantages: • Heavy • Limited slope operation • More moving parts
Low torque output Erratic running Characteristic Noisy Higher emissions output Gas/Oil mixing Advantages & Disadvantagesto a 2-Stroke Cycle Engine Disadvantages: • Advantages: • Lighter • Can be operated in all positions • Less moving parts • Higher horse power per cc displacement
2 Stoke Engines part names Still uses a flywheel (not shown) Cylinder Combustion chamber Exhaust port No Valve Train Crankcase Reed valve Piston Connecting Rod Crankshaft Intake port Transfer port