PROSESSI DAVRI (sikl) dar termodinamika, prosessest, ki dar jarayoni on sistemai fiziki (masalan, bug) ba yak qator tagiirot duchor shuda, boz ba holati avvalaash barmegardad.
Prosessi davri dar taraqqiyoti fizika, khimiya va tekhnika roli muhim bozid. Hisobu kitobi yak qator prosesshoi davrii muvozinat tarikhan avvalin metodi tadqiqoti termodinamiki bud. In metod imkon dod, ki dar asosi tadqiqi sikli korii moshini idealii harorati (sikli Karno) ifodai matematikii qonuni duyumi termodinamika va shkalai haroratii termodinamiki tartib doda shavad.