Methodology to enable efficient flex fuel operation with natural gas, hydrogen, and their blends

A system, comprising:

• a fuel storage system fluidly connected to an engine by a main fuel line;
• a pressure sensor connected to the fuel storage system;
• an air handling system fluidly connected to a downstream side of the engine by a main exhaust passage;
• a main intake passage fluidly connected to an upstream side of the engine;
• an oxygen sensor interfacing with the main exhaust passage;
• and
• a controller electrically coupled to the engine and the oxygen sensor, the controller including
• a processor and a memory, the memory storing instructions that, when executed by the processor, cause the processor to:
• perform a fuel identification routine to determine a composition of a fuel blend in the fuel storage system at startup of the engine, wherein the fuel blend comprises an amount of hydrogen and an amount of natural gas;
• determine, using a fuel-engine relationship, target operating conditions corresponding to the composition of the fuel blend for operation of the engine, wherein the target operating conditions comprise a target air-fuel ratio;
• use the oxygen sensor to measure a residual oxygen concentration in an exhaust gas stream in the main exhaust passage;
• calculate, from the residual oxygen concentration, an operating air-fuel ratio;
• adjust one or more engine operating conditions until the operating air-fuel ratio equals the target air-fuel ratio;
• measure, using the pressure sensor, a measured fuel pressure of the fuel blend upon engine startup and after re-fueling occurring at a time prior to engine startup;
• and
• determine if the measured fuel pressure is greater than a fuel pressure at engine shutoff occurring at a time prior to re-fueling and prior to engine startup,
• wherein, when the measured fuel pressure is greater than the fuel pressure at engine shutoff, performing the fuel identification routine.