Well-known Thermodynamic Cycles
In practice, simple idealized thermodynamic cycles are usually made out of four thermodynamic processes. Any thermodynamic processes may be used. However, when idealized cycles are modeled, often processes where one state variable is kept constant are used, such as an isothermal process (constant temperature), isobaric process (constant pressure), isochoric process (constant volume), isentropic process (constant entropy), or an isenthalpic process (constant enthalpy). Often adiabatic processes are also used, where no heat is exchanged.
Some example thermodynamic cycles and their constituent processes are as follows:
| 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 |
Read more about this topic: Thermodynamic Cycle
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