The ever-increasing pressure to reduce both costs and emissions is a great challenge for engine builders, the latest example being the newly imposed IMO Tier III regulations. With these regulations, the International Maritime Organization focuses further on the strong reduction of combustion emissions, especially on nitrogen oxides (NOx). Compliance with IMO Tier III regulations basically requires a reduction of NOx emissions by 80 per cent compared to Tier I within assigned emission control areas (ECA areas). Outside of the ECA zones, the requirements are relaxed to known Tier II values. From the point of view of an engine builder, there is a well-known trade-off between NOx formation and fuel efficiency. This trade-off can be alleviated by the application of a state-of-the-art high performance turbocharger – the new TCT series.
The core components for achieving the ambitious performance targets are the compressor and the turbine. MAN’s turbocharger engineering department has thus ventured into developing new designs, which are specifically optimised for IMO Tier III requirements in whatever solution customers require. The development is based on state-of-the-art computational flow simulations (CFD) that make it possible to achieve multiple targets at the same time: wide compressor maps, high flow-rates, high stability margins and exceptionally high efficiencies at design point as well as at part load. The promising simulations have been verified by an extensive test programme.
Besides further, newly-developed components such as a lightweight silencer, proven designs from MAN Diesel & Turbo’s 80-year heritage of turbocharger experience have been carried over to the TCT turbocharger. This includes basic layout concepts, as well as sub-assemblies such as bearings. Thus, a high degree of maturity of the entire system can be expected from the very start of its service life. The readiness of the technology has already been demonstrated in an elongated validation process on our test rigs in Augsburg, as well as in an extensive field-test program.
The TCT series is specifically designed for two‑stroke engines. The newly developed components, together with an optimised lightweight and compact design of the entire turbocharger, are the basis for high specific-flows enabling a significant reduction in size. An up-to-30 per cent decrease in weight, compared to previous turbocharger series, as well as a strong increase in the lowest eigen frequency facilitate engine integration and further improve vibrational behaviour. Special attention has been paid to reducing the cost of ownership. Maintenance friendliness, long design lives and long service intervals have been primary objectives during the entire development phase.
The TCT series provides the performance and flexibility to fit any requirement that current or future engine concepts may require. With specifically designed compressor wheels and a wide choice of turbine tuning options, a solution can easily be found. In summary, TCT offers a cost-effective package for the charging system of two-stroke engines in a demanding IMO Tier III environment.
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