Seawater Heat Exchanger For Mitsubishi 6D22TC Marine Engine

Seawater heat exchanger for Mitsubishi 6D22TC Marine Engine

A seawater heat exchanger isolates your marine engine's closed cooling loop from raw, corrosive seawater. It allows the engine coolant to shed heat overboard without letting harsh saltwater ruin internal engine blocks or run the engine too cold.

How the System Works
Raw Water Circuit: A belt or gear-driven pump pulls seawater through a hull seacock and strainer to filter out debris.
Coolant Circuit: A separate internal pump circulates fresh, treated coolant around the hot engine cylinders.
Heat Transfer: The fluids pass each other inside the exchanger (using tubes or plates), transferring heat from the coolant to the seawater before the water is safely discharged through the exhaust.

Common Type
Shell and Tube: The industry standard. It utilizes a bundle of tubes housed in an outer shell; engine coolant runs through the shell, while raw seawater flows through the tubes.
Plate Heat Exchanger: A more compact alternative utilizing pressed metal plates that provide highly efficient heat transfer in smaller spaces.

Materials & Maintenance
Seawater is highly corrosive and erosive, which is why proper materials and maintenance are non-negotiable:
Corrosion-Resistant Metals: Units use premium materials like cupronickel (Cupronickel 90/10 or 70/30), stainless steel 316L, or highly durable titanium to withstand saltwater.
Sacrificial Anodes: Many exchangers use zinc anodes to absorb galvanic corrosion. These must be monitored and replaced regularly.
Flushing & Descaling: Routine flushing with fresh water after saltwater use helps prevent salt and marine-growth buildup.