Page 101 - Essentials of physical chemistry

The First Law of Thermodynamics 63

Fuel nozzle
Rocker arms
Valve spring
Exhaust valve
Fuel line

Inlet valve

Inlet manifold Exhaust
manifold
Cylinder
Push rods
Water head
jackets
Piston
Fuel pump

Wristpin

Cylinder
liner
Camshaft
Frame

Camshaft drive Bearing cap

Connecting rod

Crankpin bolt
Crankpin

Main
bearing
Bedplate
Crankshaft
Crankcase

FIGURE 4.3 Detail of diesel engine design. (From Kates, E. J., Diesel and High-Compression Gas Engines,
Fundamentals, 2nd Edn., American Technical Society, Chicago, IL, 1965, 8th printing 1966, p. 41. With the
permission of Power Magazine.)

isooctane) to burn slower than the linear n-octane while the heavier diesel fuel needs to use n-cetane
or similar faster burning fuels. This is an interesting problem in combustion chemistry to match the
rate of the combustion to the mechanical timing of the engine. Early diesel engines characteristically
produced a sooty exhaust of incompletely burned fuel but in the last 5 years design modifications
have produced diesel engines that have much cleaner exhaust.
The diesel engine is a very good example of a quasi-adiabatic process. Yes, the engine does get
hot and requires a system of cooling water, but it is the air that enters the engine on each cycle that
we will consider. We only need the first law here to start the analysis:
DU ¼ 0 þ w: