Energy conversion machines

Thermodynamic cycle

a. Otto cycle
b. Diesel cycle


a. Otto cycle



Processes that occur are:
1-2 : adiabatic compression
2-3 : combustion isokhorik
3-4 : Expansion / job step adiabatic
4-1 : Step waste isokhorik

At first the mixture of air and fuel vapor flow from the carburetor to the cylinder when the piston moves down (step input). Subsequently a mixture of air and gasoline vapor is adiabatically compressed in the cylinder when the piston moves upward (compression stroke or emphasis). Because it is adiabatically compressed the mixture increases in temperature and pressure. At the same time, spark plugs, so sprinkle a mixture of air and gasoline vapors on fire. When burned, the temperature and gas pressure increase. Gas at high temperature and high pressure it expands against the piston and push the piston down (slender expansion). Subsequently the burned gas discharged through the exhaust valve and flow toward the drain pipe (removal step). Inlet valve is open longer and fourth steps are repeated again.
 The purpose of the adiabatic compression stroke or the emphasis was to increase the temperature and pressure of a mixture of air and gasoline vapor. Combustion processes at high pressure will result in temperature and pressure (P = F / A) is very large. As a result, the thrust (F = PA) generated during the process of expansion become very large. Motor or car engine becomes more powerful. Although it is not pressed, a mixture of air and gasoline vapor can burn when the spark plug sparks. But the temperature and pressure of the burned gas is so high that the thrust generated is also small. As a result, a less powerful engine.

The process of transformation of energy and energy transfer in a combustion engine in four steps above can be explained like this: When there is a combustion process, chemical energy in gasoline + potential energy turns into heat in the air hot alias. Most of the heat transformed into mechanical energy of the piston rod and crankshaft, some heat is discharged through the discharge pipe (exhaust). Most of the mechanical energy of the piston rod and the crankshaft turned into mechanical energy of the vehicle (vehicle moving), a small turn into heat while the hot heat aka arise because of friction.

In thermodynamics, the Otto cycle has 4 pieces of thermodynamic processes which consist of 2 pieces isokhorik process (fixed volume) and 2 adiabatic processes (heating equipment).

b. Diesel cycle




The image above shows the PV diagram for the ideal Diesel cycle, where p is pressure and v is the specific volume. These four ideal Diesel cycle:
Process 1 to 2 is isentropic compression
Process 2 to 3 is reversible constant pressure heating
Process 3 to 4 is isentropic expansion
Process 4 to 1 is reversible constant volume cooling
At first the air is adiabatically compressed (1-2), then heated at constant pressure - injector (injector) and there was a diesel spray combustion (2-3), the burned gases have adiabatic expansion (3-4), cooling at constant volume - the burned gas discharged into the drain pipe and a new air, into the cylinder (4-1).
Working Principle


Gas pressure of combustion fuels and air will push the piston is connected to the crank shaft using the shaft, so that the piston can move back and forth (reciprocating). Back and forth motion of the piston is converted into rotational motion by crank shaft (crank shaft). And reverse rotation of the crankshaft is also converted into alternating motion of the piston on the compression stroke.