HOW DIESEL

Overview of Diesel Engines
(How Diesel Engine Work)

1)   Working Principle Diesel Engines

Engine / diesel engine (diesel engines) is a form of internal combustion engine (internal combustion engines) in addition to gasoline engines and gas turbines. Diesel engine called the compression ignition engine (compression ignition engines) due to ignition of fuel caused by the temperature of compressed air in the combustion chamber. On the other hand motors
called motor gasoline spark ignition (spark ignition engines)   due to ignition of fuel caused by electrical sparks from spark plugs. Fires and pengatomisasian (atomizing) fuel in diesel motor is not the same as the gasoline motor.   In the gasoline motor fuel and air mixture carburetor melelui inserted into the cylinder and burned by electric ignition of the spark plug. On diesel engine which sucked by the piston and inserted into the combustion chamber just air, the air is further compressed until it reaches a high temperature and pressure. Moments before the piston reaches top dead center (TDC) of diesel fuel is injected into the combustion chamber. With temperature and air pressure in the cylinder is high enough then the particles will be flaming fuel by itself to form a combustion process. In order to burn diesel fuel alone, it would require a compression ratio of 15-22 and compressed air temperature of approximately 600 º C.Although not required for diesel engine ignition systems as well as the gasoline motor, but the diesel engine fuel injection system takes the form of injection pump (injection pump) and the atomizer (injector) and other auxiliary equipment. Fuel that sprayed flammable nature must have its own   (Self ignition). 

2)   Advantages and Disadvantages of diesel engines  

Diesel motor also has advantages over gasoline motors, namely:

a) The use of more fuel-efficient, because efficiency heat better, more efficient operating costs because diesel is cheaper.

b) longer durability and less interference, because it does not use the ignition system

c) The type of fuel is used more

d) Operation is more convenient and suitable for large vehicles, due to variations in the moment of change happens to a smaller rate of speed.

In addition, the diesel engine has disadvantages, namely:

a) The sound and vibration incurred greater (almost 2 times) than gasoline motors. This is due to the very high pressure (nearly 60 kg/cm2) at the time of combustion

b) The weight per unit of power and greater production costs, because the materials and construction is more complicated for a high compression ratio

c) Preparation of the injection pump more carefully so maintenance is more difficult

d) Requires the capacity of the battery and the starter motor is great to be able to rotate the crankshaft with high compression.

Briefly the working principle of 4 stroke diesel engine are as follows:

a) suction step, ie when the piston moves from TDC to BDC. The air sucked through the suction valve while the exhaust valve is closed.

b) compression step, ie when the piston moves from BDC to TDC to compress air which sucked, because both the suction valve and the exhaust valve is closed, so that the pressure and temperature of air in the cylinder to rise.

c) Step effort, when   suction valve and the exhaust valve is closed, the fuel particles are sprayed by the atomizer mixes with the air pressure and high temperature, so there was burning. In this step the piston starts moving from TDC to BDC because the combustion takes place gradually,

d) Step waste, when the piston moves from TDC to BDC continues with suction valve closed and the exhaust valve is open, so that ex-burning gas pushed out.

  3)   Diesel engine combustion process

The combustion process is divided into four periods:

a) Period 1: Time delayed combustion (ignition delay) (AB)

In this period called the preparatory phase combustion, because the particles are injected fuel mixes with air in the cylinder for easy burning.  

b) Period 2: Propagation of fire (BC)

In the second period the mixture of fuel and air will burn in some places. Flame will travel at high speed so it seems a mixture of burning time, thus causing the pressure in the cylinder rises.   This period is often referred to this period is often called the burning letup.

c) Period 3: Direct Combustion (CD)

As a result of the flame in the cylinder, the fuel is injected directly on fire. Combustion can be controlled directly from the amount of fuel injected, so this period is often called controlled burning period.

d) Period 4: Burning up (DE)

Injection ends at point D, but not burning all the fuel. So even though the injection had ended, burning still persists.When burning up too long, the high exhaust gas temperature will cause thermal efficiency drops.