Cylinder Bypass Valve For High Fuel Efficiency

MaK offers the option of retrofitting a cylinder bypass valve (CBV) for diesel-mechanical propulsion systems with controllable pitch propellers. Through this retrofit, a reduction in fuel consumption of up to 20 % can be achieved, provided that the engine is operated at a fuel-efficient part load.

With a CBV implemented, charge air is taken from the charge air duct. Via the electro-pneumatically controlled valve, this charge air is fed back into the exhaust gas manifold and thus to the power turbine. This ensures that sufficient boost pressure is still available in the part-load range at variable engine speeds and that the turbocharger does not reach its surge limit, as this would result in very inefficient combustion or even an engine standstill.

The CBV is electro-pneumatically controlled, which makes it possible to operate the engine at medium power with variable speed in a similar operating mode as a system with a fixed propeller. The lower fuel consumption results from propeller efficiency increasing at lower speeds and higher pitches. In other words, less propulsion power is required for the same ship speed, and the engine's load is reduced, resulting in less fuel having to be injected.