Combining the four fundamental transformations into closed sequences gives the cycles that lie behind real machines. Each cycle is named after whoever studied it or the machine that realises it, and is characterised by the recipe of processes that make it up.
| Cycle | Processes | Application |
|---|---|---|
| Carnot | 2 isothermals + 2 adiabatics | ideal thermodynamics |
| Otto | 2 isochorics + 2 adiabatics | petrol engine |
| Brayton-Joule | 2 isobarics + 2 adiabatics | gas turbine, jet |
| Diesel | 1 isobaric + 1 isochoric + 2 adiab. | diesel engine |
The Carnot cycle is the ideal reference cycle, against which every other engine is measured. The other three correspond to real engines: the Otto cycle to the petrol engine, the Brayton-Joule cycle to gas turbines and jet engines, the Diesel cycle to the engine of the same name. The difference between them lies in how combustion takes place — at constant volume (Otto), at constant pressure (Brayton), or in a combination of the two (Diesel).
The three named cycles in the - diagram: Otto (2 isochorics + 2 adiabatics), Brayton-Joule (2 isobarics + 2 adiabatics), Diesel (1 isobaric + 1 isochoric + 2 adiabatics).
Linked notes
Topics: Termodinamica · Macchine termiche Concepts: Trasformazioni termodinamiche · Ciclo di Carnot Methods: Diagramma P-V e ln P - ln V Objects: Macchina termica
Related exercises: Problema — Vero o falso su reversibilità e cicli · Problema — Dimostrazione del rendimento di Carnot · Problema — Ciclo di Carnot nel piano ln P – ln V