How do the engines breathe in diesel submarines?

A dieselsubmarineis a very good example of ahybrid vehicle. Most diesel subs have two or more diesel engines. The diesels can runpropellersor they can rungeneratorsthat recharge a very largebatterybank. They can also work in combination, one engine driving a propeller and the other driving a generator.

The sub must surface (or cruise just below the surface using a snorkel) to run the diesel engines. Once the batteries are fully charged, the sub can head underwater. The batteries powerelectric motorsthat drive the propellers.Battery operationis the only way a diesel sub can actually submerge.

The limits of battery technology severely constrain the amount of time a diesel sub can stay underwater. This is the huge benefit of using nuclear power in a sub. Nuclear generators need no oxygen, so a nuclear sub can stay underwater for weeks at a time. SeeHow Nuclear Power Worksfor a description.

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