1. The problem statement, all variables and given/known data 2. Relevant equations N/A 3. The attempt at a solution I am confused what 5-5b and 5b-6 represent in the above TS diagram. I know that 1-2 is compression, 2-3 is cooling, 3-4 is compression and 4-5 is regeneration (since these are indicated in the block diagram) but as for 5-5b and 5b-6 it is less clear. I mean 5-6 is the combustion chamber but what is the significance of the 5-5b and 5b-6 segments? Why have they split it up like this?