Diesel layout with its five systems

A diesel power plant is a CI engine–alternator set supported by five essential auxiliary systems: air intake, cooling, fuel, lubrication and exhaust (plus starting and governing).

Layout

       Air filter --> Supercharger
                         |
 Bulk tank -> Filter -> Day tank -> Inj. pump
                         |            |
                         v            v
                    +-------------------+
 Lube tank->pump--> |   DIESEL ENGINE   |==> ALTERNATOR
 ->filter->cooler   +-------------------+
        ^  return     |              |
        +-------------+              v
                      |          Silencer -> Stack
         Jacket water v
   Cooling tower <- Heat exchanger <- Pump

(i) Air intake system

Supplies clean air for combustion. Air passes through air filters (oil-bath or dry type) that remove dust, then through ducts and often a supercharger/turbocharger that raises air density so more fuel can be burnt per stroke. Intake is placed outside the engine room, away from exhaust, and a silencer reduces suction noise. Dirty air would cause rapid wear of liners and rings.

(ii) Cooling system

Removes 25–35 % of the fuel heat that passes to cylinder walls, head and pistons. Water is pumped through the jackets, then to a heat exchanger or radiator; the heat is finally rejected in a cooling tower or spray pond. Closed (soft-water) systems are preferred to prevent scaling. Proper cooling keeps metal temperatures and lube-oil temperatures safe.

(iii) Fuel supply system

Oil from tankers goes to bulk storage tanks, then is transferred through filters to a day tank. From there the fuel injection pump pressurises and meters the oil, and injectors atomise it into the hot compressed air. Heaters are used for heavy oil. Governor controls the quantity injected according to load.

(iv) Lubrication system

An oil pump draws oil from the sump/tank and supplies it under pressure through filters and an oil cooler to main bearings, crank pins, gudgeon pins, camshaft and cylinder walls. Oil reduces friction and wear, cools parts, seals the piston rings and carries away dirt. Oil drains back to the sump and is recirculated.

(v) Exhaust system

Discharges hot exhaust gases from the cylinders to the atmosphere through the exhaust manifold, silencer (muffler) and stack. The silencer reduces noise; flexible joints isolate vibration and allow expansion. The exhaust heat (about 30 % of fuel energy) may be recovered in a waste-heat boiler or used to drive the turbocharger. The stack must be high enough to disperse fumes.