Question: One thermodynamic cycle used in internal combustion engines is the Humphrey cycle. The episode is shown in the attached PV plane. The cycle consists of four sub-processes which are AB: adabatic, BC: isochoric, CD: adiabatic and D-A: isobaric. In which sub-processes does the system release or receive heat? And in which sub-processes does the system work or is it done? There is no need to justify the answers.