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A notable reduction in NOx, CO2 and soot emissions is a critical factor for success of modern diesel engines. Therefore it is the aim of MAN Diesel & Turbo to develop the best technologies and measures to assure efficient operation of our eninges with full compliancet of the International Maritime Organisation – IMO Tier II and *IMO Tier III (*optional Selective Catalytic Reduction).
The 32/44 common rail injection system uses the latest MAN Diesel & Turbo common rail technology which allows flexible setting of injection timing, duration and pressure for each cylinder. This flexibility allows the fuel consumption and emissions of the 32/44CR to be optimised on its operating profile. Due to constant development of our safety concept the redundant high pressure pumps guarantee further operation of the engine even in the event of high pressure pump malfunction.
A special, patented feature for common rail engines, called boost injection, was introduced parallel with release of the IMO Tier II engines. SaCoS is able to detect a load increase at the engine at early stage and to improve the load response of the engine significantly by activation of a boost injection in the common rail control.
The 32/44CR is equipped with the newest generation of MAN Diesel & Turbo’s engine management system. SaCoSone breaks down all functions of modern engine management into one complete system. Through integration on the engine, it forms one unit with the drive assembly.
The use of MAN Diesel & Turbo turbochargers equipped with the latest high efficiency compressor wheels can alleviate the NOx-SFOC trade off. The higher pressure ratio increases the efficiency of the engine and thus compensates the increase in SFOC normally associated with lower NOx emissions. The higher pressure ratio also increases the scope for Miller valve timing.
To reduce the temperature peaks which promote the formation of NOx, early closure of the inlet valve causes the charge air to expand and cool before start of compression. The resulting reduction in combustion temperature reduces NOx emissions.
Variable valve timing enables variations in the opening and closing of the inlet valves. It can be used to compensate the increase in SFOC associated with lower NOx emissions. VVT is an enabling technology of variable Miller valve timing. A strong Miller effect under high load operation results in an improvement in the NOx-SFOC trade-off. At low load the Miller valve timings are reduced to attain higher combustion temperatures and thus lower soot emissions.