Starting in February, Volvo Trucks will be conducting field testing of methane-diesel engines in commercial operations in cooperation with several Swedish customers.  The trucks will be the Volvo FL and FE 7-liter models using Volvo’s Euro-5 diesel engines.

Converted to gas operation, the trucks have special tanks added for the compressed natural gas (CNG or methane) and a second fuel system is put in place to inject the gas into the inlet manifold.  This allows a methane-injection into the diesel stream, boosting fuel economy with the methane (CNG) being the primary ignition and the diesel the “starter” igniter.

Normally, diesel engines inject diesel into the cylinder and use compression to pressurize the fuel, causing it to ignite.  With the new CNG injection, a small amount of diesel is injected along with natural gas.  The cylinder’s compression ignites the diesel, which in turn ignites the natural gas, creating combustion to push the cylinder back upwards, completing the cycle.

To the driver, nothing much changes except at the fuel station, where much less diesel is required and a refuel of natural gas is added.   This new system is also easier to install and retrofit to existing trucks as it requires no overhaul of the engine block nor replacement of most major components.

Volvo hopes that the testing will show significant improvements in fuel economy, with preliminary tests showing a possible savings of up to 60%.  Sweden was chosen as the testing ground because of it’s already-present infrastructure for biogas throughout the country.

This is the first of the tests announced last year by Volvo.

Related posts:

1. Sturman Electro-Hydraulic Valvetrain Exceeds 40% Peak Efficiency in NG Engines
2. Volvo Begins Sales of Heavy-Duty Dual-Fuel FM MethaneDiesel (LNG)