auxiliary engine · auxiliary system

Wärtsilä W20

The Wärtsilä 20 is a compact medium-speed, four-stroke marine diesel engine widely used aboard ships as an auxiliary engine driving a generator, and in smaller vessels for propulsion. The number 20 refers to the cylinder bore of 20 centimetres, placing it at the smaller end of Wärtsilä's medium-speed range, and it is offered in various cylinder numbers to suit different power requirements. Its compactness, reliability and worldwide support have made it one of the more common auxiliary engines in the fleet. As an auxiliary engine, its main task is generating the electrical power a ship needs for cargo systems, machinery, navigation equipment, lighting and accommodation. Coupled to an alternator to form a generating set, several such engines are typically installed so that they can run in parallel and share the electrical load, with the ship's power management system starting and stopping sets as demand changes and providing redundancy against the failure of any one unit. In smaller ships and in some diesel-electric or propulsion arrangements, engines of this class also contribute to driving the vessel. Being a four-stroke medium-speed engine, the Wärtsilä 20 runs faster and is far more compact than the low-speed two-stroke main engines of large ships, while still being built for durability and long service life with planned maintenance. It can be configured to run on marine distillate fuels and, in appropriate versions, heavier fuels, and it is designed to meet the applicable IMO nitrogen-oxide emission standards. Routine care involves maintenance of the fuel injection equipment, valves, turbocharger, and cooling and lubrication systems. The Wärtsilä 20 is representative of the dependable small-to-medium marine engine that supplies the electrical power on which almost everything aboard a ship depends, and its reliability is important to the safe and continuous operation of the vessel. Its long production history and large installed base mean that spare parts, technical support and experienced service engineers are readily available around the world, which matters greatly for a machine whose continuous, dependable operation underpins the electrical supply to the entire ship and therefore the working of almost every other system aboard.