BASICS OF HEAT ENGINE AND ITS CLASSIFICATION

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BASICS OF HEAT ENGINE AND ITS CLASSIFICATION

HEAT ENGINE:
A HEAT ENGINE IS A DEVICE WHICH TRANSFORMS THE CHEMICAL ENERGY OF A FUEL INTO THERMAL ENERGY AND USES THIS ENERGY TO PRODUCE MECHANICAL WORK.

IT IS CLASSIFIED INTO TWO TYPES:
  •  EXTERNAL COMBUSTION ENGINE
  • INTERNAL COMBUSTION ENGINE

1.       EXTERNAL COMBUSTION ENGINE:
IN THIS ENGINE, THE PRODUCTS OF COMBUSTION OF AIR AND FUEL TRANSFER HEAT TO A SECOND FLUID WHICH IS THE WORKING FLUID OF THE CYCLE.
EXAMPLES:
  • IN THE STEAM ENGINE OR A STEAM TURBINE PLANT, THE HEAT OF COMBUSTION IS EMPLOYED TO GENERATE STEAM WHICH IS USED IN A PISTON ENGINE (RECIPROCATING TYPE ENGINE) OR A TURBINE (ROTARY TYPE ENGINE) FOR USEFUL WORK.
  • IN A CLOSED CYCLE GAS TURBINE, THE HEAT OF COMBUSTION IN AN EXTERNAL FURNACE IS TRANSFERRED TO GAS, USUALLY AIR WHICH THE WORKING FLUID OF THE CYCLE. 

2.       INTERNAL COMBUSTION ENGINE:
IN THIS ENGINE, THE COMBUSTION OF AIR AND FUELS TAKE PLACE INSIDE THE CYLINDER AND ARE USED AS THE DIRECT MOTIVE FORCE. IT CAN BE CLASSIFIED INTO THE FOLLOWING TYPES:


a.       ACCORDING TO THE BASIC ENGINE DESIGN
·         RECIPROCATING ENGINE (USE OF CYLINDER PISTON ARRANGEMENT)
·         ROTARY ENGINE (USE OF TURBINE)

b.       ACCORDING TO THE TYPE OF FUEL USED
·         PETROL ENGINE
·         DIESEL ENGINE
·         GAS ENGINE (CNG, LPG)
·         ALCOHOL ENGINE (ETHANOL, METHANOL ETC)

c.        ACCORDING TO THE NUMBER OF STROKES PER CYCLE
·         FOUR STROKE
·         TWO STROKE ENGINE

d.       ACCORDING TO THE METHOD OF IGNITING THE FUEL
·         SPARK IGNITION ENGINE
·         COMPRESSION IGNITION ENGINE
·         HOT SPOT IGNITION ENGINE

e.       ACCORDING TO THE WORKING CYCLE
·         OTTO CYCLE (CONSTANT VOLUME CYCLE) ENGINE
·         DIESEL CYCLE (CONSTANT PRESSURE CYCLE) ENGINE
·         DUAL COMBUSTION CYCLE (SEMI DIESEL CYCLE) ENGINE

f.         ACCORDING TO THE FUEL SUPPLY AND MIXTURE PREPARATION
·         CARBURETTED TYPE (FUEL SUPPLIED THROUGH THE CARBURETTOR)
·         INJECTION TYPE (FUEL INJECTED INTO INLET PORTS OR INLET MANIFOLD, FUEL INJECTED INTO THE CYLINDER JUST BEFORE IGNITION)

g.       ACCORDING TO THE NUMBER OF CYLINDER
·         SINGLE CYLINDER
·         MULTI-CYLINDER ENGINE

h.       METHOD OF COOLING
·         WATER COOLED
·         AIR COOLED

i.         SPEED OF THE ENGINE
·         SLOW SPEED
·         MEDIUM SPEED
·         HIGH SPEED ENGINE

j.         CYLINDER ARRANGEMENT
·         VERTICAL
·         HORIZONTAL
·         INLINE
·         V-TYPE
·         RADIAL
·         OPPOSED CYLINDER OR PISTON ENGINES.
k.       VALVE OR PORT DESIGN AND LOCATION
·         OVERHEAD (I HEAD)
·         SIDE VALVE (L HEAD); IN TWO STROKE ENGINES: CROSS SCAVENGING, LOOP SCAVENGING, UNIFLOW SCAVENGING

l.         METHOD GOVERNING
·         HIT AND MISS GOVERNED ENGINES, QUANTITATIVELY GOVERNED ENGINES
·         QUALITATIVELY GOVERNED ENGINE

m.     APPLICATION
·         AUTOMOTIVE ENGINES FOR LAND TRANSPORT
·         MARINE ENGINES FOR PROPULSION OF SHIPS
·         AIRCRAFT ENGINES FOR AIRCRAFT PROPULSION
·         INDUSTRIAL ENGINES
·         PRIME MOVERS FOR ELECTRICAL GENERATORS.

                            


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