What generator systems are cooled by marine dry coolers?

Marine dry coolers are widely used to cool generator-related systems on ships and offshore platforms where seawater use is limited, restricted, or undesirable. They provide closed-loop, air-cooled heat rejection, improving reliability, corrosion resistance, and environmental compliance.

Generator Systems Cooled by Marine Dry Coolers

1. Engine Jacket Water (HT / LT Cooling Circuits)

Primary application

Marine generators typically use two freshwater cooling loops:

• HT (High-Temperature) jacket water: 80–90 °C

• LT (Low-Temperature) circuit: 35–45 °C

Marine dry coolers reject heat from these closed freshwater loops by transferring it to ambient air.

Why dry coolers are used

• Eliminates seawater fouling and corrosion

• Reduces dependence on plate heat exchangers and sea chests

• Ideal for coastal, river, ice-class, and offshore vessels

Typical generators

• Diesel generator sets (DG)

• Gas generator sets

• Dual-fuel marine generators

2. Charge Air Cooler (CAC) / Aftercooler Circuit

Turbocharged marine generators require cooling of compressed intake air.

Dry coolers are used to cool:

• Freshwater loop serving charge air coolers

• Indirectly controlling intake air temperature

Benefits

• Stable engine performance

• Improved fuel efficiency

• Reduced NOₓ emissions

• Lower maintenance compared to seawater-cooled CACs

3. Lubricating Oil Cooling System

Marine dry coolers are frequently used to cool:

• Generator lube oil cooler freshwater loop

• Gearbox oil circuits (for gensets with PTOs)

Advantages

• Precise oil temperature control

• No oil-to-seawater contamination risk

• Reduced plate cooler failures

4. Generator Stator and Rotor Cooling

For medium- and high-voltage marine generators, dry coolers remove heat from:

• Generator stator water cooling circuits

• Air-to-water generator cooling loops

Common in

• Offshore platforms

• FPSOs

• Naval vessels

• Large electric propulsion ships

Dry coolers ensure stable electrical performance under continuous load.

5. Exhaust Gas Heat Recovery Systems (Secondary Cooling)

In CHP or waste heat recovery configurations:

• Dry coolers dissipate excess heat from exhaust gas boilers

• Serve as heat rejection for ORC or thermal oil systems

Used when recovered heat cannot be fully utilized onboard.

6. Emergency and Standby Generator Cooling

Marine dry coolers are increasingly specified for:

• Emergency generators

• Harbor / standby gensets

Reasons:

• Independence from seawater systems

• Guaranteed cooling even when sea valves are closed

• Simplified compliance with safety regulations

7. Gas Generator Auxiliary Cooling (LNG / Offshore)

For gas-powered marine generators, dry coolers cool:

• HT/LT engine circuits

• Gas valve units (GVU) cooling loops

• Ignition and control cabinet cooling circuits

This is common on:

• LNG carriers

• Offshore gas platforms

• Hybrid power vessels

Typical Marine Generator Types Using Dry Coolers

• Diesel generator sets (IMO Tier II / III)

• Dual-fuel generators

• Gas engine generators

• Emergency gensets

• Shaft generators (with auxiliary cooling)

• Hybrid power modules

Why Marine Dry Coolers Are Preferred

• No seawater corrosion or biofouling

• Reduced maintenance and lifecycle cost

• Suitable for harsh marine atmospheres

• Environmentally compliant (no thermal discharge)

• Reliable operation in shallow, polluted, or icy waters

Typical Installation Locations

• Upper deck

• Funnel casing

• Engine room ventilation zone

• Offshore module skids

Designed for:

• Salt spray resistance

• Vibration and shock loads

• Marine classification (DNV, ABS, LR, BV)

Summary

Marine dry coolers are used to cool engine jacket water, charge air cooling loops, lube oil systems, generator stator cooling, exhaust heat recovery circuits, and emergency generator systems. They are especially valuable where seawater cooling is unreliable, high-maintenance, or restricted, making them a standard solution for modern marine and offshore generator installations.