Volvo FM MethaneDiesel
Unlike all other gas-driven trucks the Volvo MethaneDiesel is a 13-litre (460 hp) truck with an explicit environmental profile, developed primarily for regional distribution. It has the ability to perform also long-haul transports in a cost-effective manner. The qualities of the new Volvo FM MethaneDiesel add unique flexibility to the truck fleet since each truck will offer a substantially larger range of operation compared with traditional gas vehicles. Its unique ability to run on diesel only, if gas supply temporarily is a problem, further adds to its flexibility.
Engine: Volvo D13
The new Volvo FM MethaneDiesel represents a giant step forward in the field of gas-driven, commercial heavy vehicles. By utilising liquefied gas in the diesel engine, it enables longer and heavier transports – a unique quality for a gas truck. In addition, this truck delivers fuel efficiency similar to the diesel truck, resulting in up to 25% lower fuel consumption compared with traditional gas vehicles. And, should gas not be available, it runs smoothly on diesel as well. The Volvo methane-diesel principle enables heavy-duty diesel engines to operate substantially on natural gas or biogas. On a regional or long-haul route, this means up to 75 % gas and 25 % diesel. With the basic diesel engine fully intact, retaining its original energy efficiency, the truck is able to run entirely on diesel at any time.
How it works
Injection of gas into the cylinder is made by a multipoint gas injection system installed in an injector plate. Pilot amounts of diesel are injected directly in the cylinder to ignite the gas. A special dual-fuel ECU, integrated with the standard engine control unit, performs real-time control to optimise diesel substitution.
The engine starts on diesel and goes into MethaneDiesel mode when the coolant temperature reaches a sufficient temperature. The diesel is ignited by compression ignition and in turn ignites the gas and air mixture. The combustion process is optimised by accurate control of both diesel and gaseous fuels and by a turbo air bypass valve that controls the intake air to achieve desired air/fuel ratio. To protect the engine from varying gas properties in Europe, two knock sensors are mounted on the engine block. They monitor the engine block for frequencies of vibration associated with knock. If knock is detected, the ECU will alter the diesel injection timing and air/fuel ratio to stop it from occurring. If knock persists the engine returns to diesel-mode to protect the engine.
The engine will continue in MethaneDiesel mode provided that adequate air-fuel ratio conditions can be met to sustain efficient gas combustion. The engine air-flow is constantly monitored. At low torque levels, for example at idle, the presence of too much air makes the air-fuel ratio too lean to sustain combustion of gas. At such light-load conditions the engine will run on diesel only. Therefore, best gas use is achieved when the vehicle duty cycle is reasonably loaded.
The engine is equipped with a dedicated methane catalyst optimised for methane oxidation, in addition to the diesel exhaust after treatment system.