With growing concern about GHG emissions the use of natural gas as fuel has been seen as a very interesting alternative. Natural gas, whose main constituent is methane, due to its higher ratio of hydrogen/carbon and its higher content of energy has a potential to generate about 22% less carbon dioxide emissions compared to diesel considering the same combustion efficiency. According to tests conducted so far, substituting a portion of the diesel fuel with natural gas in a compression ignition internal combustion engine gives an efficiency equivalent as that of the same engine running just on diesel, maintaining the same torque and power curve.
Controlling the torque in the dual fuel engine with diesel and CNG is an absolute necessity. This allows not only converting a required driver demand torque into actuator signal but also calculating if a change in operating point of any of the torque controlling factors is needed so that the driver demand can be immediately realized. This paper describes the result of measurements performed to evaluate the possibility of using a semi-empirical torque model along with a torque structure to control a dual-fuel engine.
