WinGD ramps up testing of X-DF-A engine

After obtaining approval in principle for its X-DF-A engine from Bureau Veritas in December 2023, WinGD expects the 52-bore X52DF-A to be available for delivery from Q1 2025.

The engine designer is developing an X52DF-A engine first to satisfy an order for two engines for LPG/ammonia carriers being built for Exmar LPG. It is also developing an X72DF-A engine as part of a collaboration with Belgian shipowner CMB for a series of ammonia-fuelled 210,000dwt bulk carriers.

Other models will roll out progressively, depending on market demand, in 2026 and 2027. The roll-out of upgrade packages for specific engine bore sizes will follow, typically 6-12 months after the newbuild design is completed.

Engine performance

Meanwhile, dedicated single cylinder engine tests are being undertaken this year. The X‑DF‑A engine will operate on the Diesel principle, maintaining the same rating field as WinGD’s existing X‑engines. Simulations have already indicated that it will be possible to stay below 5% pilot fuel rate up to 100% engine load. Fuel changeover from diesel to ammonia will take place when the engine is running at 25-80% engine CMCR power, with developments ongoing to reduce that minimum.

“Diesel mode efficiency is the same as a pure diesel engine,” says Fabio Cococcetta, program manager future fuels, WinGD. “In ammonia mode, the efficiency is improved by up to 2% compared to the pure diesel engine.”

The ammonia fuel is delivered to the engine at high pressure (85 bar), and the modifications required to WinGD’s existing diesel engine technology for use with ammonia include an ammonia fuel injection system, an additional servo oil rail for the ammonia injection system, an additional servo oil supply unit, modifications to the cylinder cover, adaption of piping and slight modifications to bedplate, gears and cylinder jacket.

In February this year, WinGD and Mitsubishi Shipbuilding completed the initial design of an ammonia fuel supply system. As well as the fuel supply system – including a fuel valve unit, fuel conditioning and all related piping – the concept includes an ammonia catching system as well as purging and venting arrangements. ClassNK granted Approval in Principle for the systems in April 2024.

Fuel safety measures

The fuel valve unit comes under WinGD’s responsibility and specifications will be delivered to certified suppliers. As a safety precaution, to ensure the tightness of valves and the proper functioning of components, the fuel valve unit performs an ammonia leakage test before the engine starts operating on ammonia fuel.

Cococcetta says WinGD has applied the gas-safe machinery space concept to all X-DF-A engines. “Gas-safe machinery space is defined as an area in which a single failure cannot lead to an ammonia release into the machinery space. For (ammonia) fuel piping, this is accomplished with a double-wall piping system, which means any leakage in any part of the fuel pipe and ammonia is contained in the secondary enclosure (outer piping of the double-wall), thereby ensuring ammonia is properly redirected to the catch technology and not released into the engine room, rendering it safe for personnel and environment.”

To further improve the system safety and manage toxicity of ammonia, WinGD developed an efficient purging mechanism. After any transfer from ammonia mode to diesel or when ammonia is required to be removed from the fuel lines due to failure conditions, the purging mechanism ensures the lines are fully clear of any residual ammonia, thereby ensuring safe maintenance.

“Explosion risks are low for ammonia but also well managed, leveraging WinGD know-how on dual-fuel engines (diesel and LNG). All these measures provide a high level of confidence to shipowners and operators in our WinGD XDF-A (Ammonia) engine,” says Cococcetta.

NOx levels can be kept within IMO Tier II levels without aftertreatment and, with existing abatement technology, Tier III emission levels can be reached. Where an SCR is installed and Tier III NOx performance is not needed, the SCR unit can be employed to reduce ammonia emissions without urea dosing.

N2O is another potential emission from ammonia combustion, with significant greenhouse warming potential. In the absence of IMO-defined limits, WinGD has ensured that the combustion and injection system design dramatically reduce CO2-equivalent emissions without additional aftertreatment.

WinGD expects ammonia to become a mainstream sustainable marine fuel and energy carrier by mid-century.