The New X Generation Low-Speed Engines from W(a)rtsil(a)
The launch of the W(a)rtsil(a) X-engines marks the introduction of a new generation of lowspeed engines to the market. The new engines have been developed out of the requirements for lowest Total Cost of Ownership and highest reliability, while manufacturing cost for W(a)rtsil(a)’s licensees is reduced from the onset of the design. The new engine types are being developed for the actual IMO Tier II NOx legislations, and the technologies required for the forthcoming Tier III NOx limits are already considered in the engine design for a later effortless integration. As of January 2013, the X generation engine family comprises of six different engine types that either just entered into operation or are currently in different stages of their development, with further engines in planning. These engines are the small bore W-X35 andWX40, the W-X62 and W-X72 for the medium segment and the new large bore W-X92 engine, which are described in this paper. The latest X-engine model, the W-X82, is described in paper no. 326. Differences and commonalities between the advanced X engines and the well proven RTA/RT-flex design are highlighted in the present paper. Furthermore, power ranges including extended layout field engine ratings, vessel applications, as well as engine availability are shown. To ensure undisputable reliability and short development time, most of the design concepts of the X-engines were derived from the very popular RT-flex82C/T engines. Where needed, e.g. due to manufacturing limitations, or where possible to optimise the manufacturability, engine specific design concepts were selected. Such are the two-part crankshaft with dual cylinder distance for the bigger cylinder numbers of W-X92 or the through-flow oil cooling of the W-X35/40 pistons. All new two-stroke engines of the X type feature the well-known flex system - W(a)rtsil(a)’s fully variable, electronically controlled fuel injection and exhaust valve operation, independent of engine load - which has readily proven its advantages on the RT-flex engine series. Extremely slow stable running speeds, optimised Brake Specific Fuel Consumption (BSFC) versus NOx trade-off, smokeless operation at all loads and various tuning possibilities are amongst the most important. The fuel injection valves of W-X35 and W-X40 feature a conventional nozzle, whereas the injectors for the mid and large bore engines feature the FAST (Fuel Actuated Sackless Technology) slide valve nozzle with minimised sack volume for even optimised fuel consumption. The X-engines feature extra long strokes, leading to extra low engine speeds. This allows the selection of a larger propeller with higher propulsion efficiency. Furthermore, the bigger stroke-to-bore ratios lead to a better internal efficiency of the engine. The extra long stroke in combination with the fully flexible fuel injection and exhaust valve actuation and the different tuning possibilities gives ship owners, shipyards and engine builders the possibility to select the propulsion system with the lowest fuel consumption. By January 2013 a total of seventeen W-X35 and WX40 engines have been ordered and two are sailing already in the field. While the design work on the W-X62 is almost finished, the W-X72 and the W-X92 are still under development. Up to date, Chinese shipyards have ordered in total fourteen W6X72 for applications in bulk carriers and container vessels.
Marc Spahni Andreas Kyrtatos Ronald de Jong
W(a)rtsil(a),Switzerland
国际会议
上海
英文
1-16
2013-05-13（万方平台首次上网日期，不代表论文的发表时间）