A method and a system for determining the specific gas constant and the stoichiometric air fuel ratio of a fuel gas for a gas engine

A system for determining a specific gas constant and a stoichiometric air fuel ratio of a fuel gas for a gas engine, the system comprising:

• means for keeping a pressure essentially constant in an inlet manifold of the gas engine, so that the pressure is not varying more than a pre-determined threshold;
• means for determining a first λ value downstream the gas engine while the engine is operated at a first time period of gas injection into the inlet manifold;
• means for changing said first time period of gas injection into the inlet manifold to a second time period of gas injection into the inlet manifold;
• means for determining a second λ value downstream the gas engine after said changing of the time period of gas injection into the inlet manifold;
• and
• means for determining the specific gas constant and the stoichiometric air fuel ratio of the fuel gas based on said determined first and second λ value.

A vehicle comprising a system for determining a specific gas constant and a stoichiometric air fuel ratio of a fuel gas for a gas engine, the system comprising:

• means for keeping a pressure essentially constant in an inlet manifold of the gas engine, so that the pressure is not varying more than a pre-determined threshold;
• means for determining a first λ value downstream the gas engine while the engine is operated at a first time period of gas injection into the inlet manifold;
• means for changing said first time period of gas injection into the inlet manifold to a second time period of gas injection into the inlet manifold;
• means for determining a second λ value downstream the gas engine after said changing of the time period of gas injection into the inlet manifold;
• and
• means for determining the specific gas constant and the stoichiometric air fuel ratio of the fuel gas based on said determined first and second λ value.

A computer program product comprising computer program code stored on a non-transitory computer-readable medium, said computer program product for determining a specific gas constant and a stoichiometric air fuel ratio of a fuel gas for a gas engine, said computer program product comprising computer instructions to cause said at least one control unit to perform the following operations:

• keeping a pressure essentially constant in an inlet manifold of the gas engine, so that the pressure is not varying more than a pre-determined threshold;
• determining a first λ value downstream the gas engine while the engine is operated at a first time period of gas injection into the inlet manifold;
• changing said first time period of gas injection into the inlet manifold to a second time period of gas injection into the inlet manifold;
• determining a second λ value downstream the gas engine after said changing of the time period of gas injection into the inlet manifold;
• and
• determining the specific gas constant and the stoichiometric air fuel ratio of the fuel gas based on said determined first and second λ value.