Heat Engine Processes
Cycle | Process 1-2 (Compression) |
Process 2-3 (Heat Addition) |
Process 3-4 (Expansion) |
Process 4-1 (Heat Rejection) |
Notes |
---|---|---|---|---|---|
Power cycles normally with external combustion - or heat pump cycles: | |||||
Bell Coleman | adiabatic | isobaric | adiabatic | isobaric | A reversed Brayton cycle |
Carnot | isentropic | isothermal | isentropic | isothermal | |
Ericsson | isothermal | isobaric | isothermal | isobaric | the second Ericsson cycle from 1853 |
Rankine | adiabatic | isobaric | adiabatic | isobaric | Steam engine |
Scuderi | adiabatic | variable pressure and volume |
adiabatic | isochoric | |
Stirling | isothermal | isochoric | isothermal | isochoric | |
Stoddard | adiabatic | isobaric | adiabatic | isobaric | |
Power cycles normally with internal combustion: |
|||||
Brayton | adiabatic | isobaric | adiabatic | isobaric | Jet engines the external combustion version of this cycle is known as first Ericsson cycle from 1833 |
Diesel | adiabatic | isobaric | adiabatic | isochoric | |
Lenoir | isobaric | isochoric | adiabatic | Pulse jets (Note: Process 1-2 accomplishes both the heat rejection and the compression) |
|
Otto | adiabatic | isochoric | adiabatic | isochoric | Gasoline / petrol engines |
Each process is one of the following:
- isothermal (at constant temperature, maintained with heat added or removed from a heat source or sink)
- isobaric (at constant pressure)
- isometric/isochoric (at constant volume), also referred to as iso-volumetric
- adiabatic (no heat is added or removed from the system during adiabatic process which is equivalent to saying that the entropy remains constant, if the process is also reversible.)
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