HHI introduces ammonia dual-fuel marine engine

South Korea’s HD Hyundai Heavy Industries (HHI) has developed a high-pressure direct injection ammonia dual-fuel engine for marine applications.

PHOTO: A model of HD Hyundai's ammonia dual-fuel engine. HHI

Ammonia dual-fuel engines can typically use conventional fuels in addition to ammonia. This engine can be used on ammonia carriers as well as container ships for propulsion or auxiliary power, according to the company.

It will be equipped with selective catalytic reduction technology to reduce nitrogen oxides and unburned ammonia emissions. Additionally, it will be integrated with ammonia scrubber technology to further minimise the release of unburned ammonia gas.

The engine has received class approvals from the American Bureau of Shipping, DNV, Lloyd’s Register, RINA, ClassNK, and Korea Register. HHI added that the engine will be available commercially once “the detailed examination and suitability review” is completed.

High-pressure vs low-pressure engines

The low-pressure injection method mixes ammonia and air before they enter the combustion chamber. The mixture is then fed into the combustion chamber, where it is compressed and ignited to create combustion, HHI explains.

In contrast, the high-pressure direct injection system, like the one used in this engine, compresses air in the engine's combustion chamber and then injects ammonia fuel at high combustion pressure.

High-pressure injection allows for better control over the combustion process, which can improve the engine’s fuel efficiency. It can also increase the engine’s power output due to more precise and intense combustion.

Need for pilot fuel

Ammonia as a fuel requires a pilot fuel, such as diesel, for ignition because its high auto-ignition temperature makes it difficult to ignite and sustain combustion.

Swiss engine maker Winterthur Gas & Diesel (WinGD), which has also commercialized ammonia dual-fuel technology, claims that low-pressure engines need less pilot fuel due to the pre-chamber mixing.

When using ammonia, high-pressure engines typically require 0.5% to 8% of pilot fuel relative to the total energy consumption needed for engine operation. In comparison, low-pressure engines can require around 0.5% to 1% of pilot fuel relative to their total energy consumption, according to WinGD's website.

HHI has not yet specified the amount of pilot fuel required for its ammonia dual-fuel engine.

By Konica Bhatt

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