In this early type of torpedo propulsion system, compressed gas and fuel combust to drive the engine. Because it lacks a water injection mechanism to cool the combustion chamber and generate additional steam mass, it runs at extremely high temperatures. This design limits the total power output and range compared to later steam-injected systems.
Heard on the job
The dry heater design was dropped because the combustion chamber couldn't handle the thermal stress without water injection.
Insider tip
Engineers quickly moved away from dry heaters in torpedo design because adding a water spray not only cooled the engine but massively increased the expanding fluid volume for better efficiency.
Do not mix it up with
- Wet heater: A wet heater injects water into the combustion chamber to cool the engine and produce steam for extra power, whereas a dry heater relies solely on gas expansion.