Why brayton cycle is not used in reciprocating engine?

Answer 1

The Brayton

Cycle originally was used as a reciprocating, not a turbine, engine and in fact was used to power the U.S.

Navy's first engine powered submarine.

The drawback to reciprocating Brayton

engines is that they operate on low pressure ratios (typically 3:1 for a recuperated cycle) and require a large volume flowrate

of air to make power. Turbines can turn at very high speed and can move large volumes of air in a fairly compact package. Reciprocating engines turn much slower and so, with a Brayton

cycle, they become fairly large.

Nevertheless, there are enough advantages that you will soon see reciprocating Brayton

engines back in commercial operation, particularly for sub-mW

electric power generators. Turbines have blade leakage and windage

losses that become significant at smaller sizes. Another very important consideration is that turbine

engines are expensive to build while reciprocating engine construction is universal and inexpensive. Maintaining reciprocating engines in remote areas only requires skills that are generally available from local mechanics while maintaining turbines requires specialized skill. Finally, although it may be much larger than a turbine counterpart, a reciprocating Brayton

electric generator can have the compressor, expander, and synchronous generator all on a single shaft and can thus avoid the expense, noise, and maintenance of a high speed gearbox.

Turbines will remain the preferred configuration for the majority of Brayton

engines, but reciprocating Brayton

engines have a place that is now becoming more appreciated.