1. Ch. 10 Heat Transfer in Engines
Contents
10.1 Energy distribution
10.2 Engine temperatures
10.3 Heat transfer in intake & exhaust system, combustion chamber
10.6 Engine operating variables on heat transfer
10.7 Cooled engines and modern trends

2. 10.1 Energy distribution
1. For any engines

3. 10.2 Engine temperatures 1. a typical temperature distribution
Temperatures of a typical SI engine as s function of time after cold start-up
Typical temperature in an SI engine

4. 10.3 Heat transfer in intake system
1. a typical temperature distribution
Steady state temperature of intake valves : ˚C
Hot spot in intake manifold to accelerate fuel evaporation

5. 10.4 Heat transfer in combustion chamber
1. heat transfer through a cylinder wall

6. 10.4 Heat transfer in combustion chamber
Cooling of piston
Convection to the oil
Conduction by the piston rings
Conduction down the connecting rod to the oil

7. 10.5 Heat transfer in exhaust system
Exhaust temperatures of SI engine : ˚C with extremes of ˚C
Exhaust temperatures of CI engine : ˚C

8. 10.6 Engine operating variables on heat transfer
Engine size: larger engine more efficient
Engine speed: as engine speed is increased, heat transfer increases
Load: as load is increased mass flow rate of air and fuel goes up and heat transfer goes up.
Spark timing
Equivalence ratio
Evaporative cooling-water injection
Inlet air temperature
Coolant temperature
Engine materials
Compression ratio
Knock
Swirl and squish

9. 10.7 Cooled engine Cooling system of water-cooled engine
Air cooled aircraft engine

10. Radiator of a water-cooled engine