How Does a Marine Oil Cooler Work? (The Standard Design)
The most common type is the Shell and Tube Heat Exchanger. Here’s how it works:
The Components:
- Shell: A large cylindrical outer vessel.
- Tubes: A bundle of tubes running through the inside of the shell.
- Tube Plates: End plates that seal the tube bundle into the shell.
- Cooling Fluids:
- Tube Side (Inside the Tubes): Seawater is pumped through the tubes. It is kept contained within the tubes because it is corrosive and prone to fouling.
- Shell Side (Outside the Tubes): Hot Oil from the engine or gearbox is pumped into the shell and flows around the outside of the tubes.
The Process:
- Hot Oil In: Oil, heated by the engine (reaching ~65-75°C / ~150-167°F), enters the shell of the cooler.
- Cold Seawater In: Cold seawater is pumped through the tubes.
- Heat Exchange: Heat from the hot oil transfers through the walls of the tubes into the cooler seawater.
- Cooled Oil Out: The oil, now cooled to its ideal temperature (~45-55°C / ~113-131°F), exits the shell and is pumped back to the engine.
- Warm Water Out: The now-warm seawater is discharged overboard.
A thermostatic valve (or bypass valve) automatically regulates the flow of oil either through the cooler or around it to maintain a perfectly consistent oil temperature.