Question

Can someone explain to me when you can use a regenerator in a gas turbine engine? Thanks!

Answer 1

A regenerator is a 'counter-flow, heat exchanger' meaning it helps decrease fuel (energy) consumption. 'The thermal efficiency of the Brayton cycle increases as a result of regeneration since the portion of energy of the exhaust gases that is normally rejected to the surroundings is now used to preheat the air entering the combustion chamber.'

To read more about it, you can access the references below.

Source: http://www.waset.org/journals/waset/v68/v68-130.pdf
http://www.britannica.com/EBchecked/topic/226481/gas-turbine-engine/45718/Intercooling-reheating-and-regeneration