Engine control system, method for controlling a dual fuel engine, and non-transitory computer-readable medium

A method for controlling an engine configured to receive a primary fuel and a secondary fuel, the method comprising:

• determining a first adjustment to a start of injection to satisfy an engine knock threshold and a NOx level threshold for the engine;
• adjusting the start of injection based on the first adjustment to the start of injection;
• determining a first adjustment to a substitution rate of the secondary fuel to satisfy the engine knock threshold;
• adjusting the substitution rate of the secondary fuel based on the first adjustment to the substitution rate of the secondary fuel;
• determining, based on the first adjustment to the substitution rate of the secondary fuel, a second adjustment to the start of injection to adjust the start of injection to approximately a target start of injection, wherein an adjustment to the target start of injection is determined to adjust an exhaust temperature of the engine to be within a target range of the exhaust temperature;
• and controlling the engine based on the first adjustment to the start of injection, the first adjustment to the substitution rate of the secondary fuel, and the second adjustment to the start of injection.

A non-transitory processor-readable medium storing code representing instructions to be executed by one or more processors, the instructions comprising code to cause the one or more processors to:

• determine that an engine knock level does not satisfy an engine knock threshold for an engine in a dual fuel engine system,
• determine a first adjustment, based at least on a difference between the engine knock level and the engine knock threshold and based on a NOx level threshold, to a start of injection to attain an adjusted engine knock level below the engine knock threshold;
• adjust the start of injection based on the first adjustment;
• determine a second adjustment, based at least on a difference between the start of injection and a target start of injection, to a substitution rate of a secondary fuel to initiate injection closer to the target start of injection and maintain approximately the adjusted engine knock level;
• adjust the substitution rate and the start of injection based on the second adjustment;
• determine a third adjustment, based at least on a difference between the substitution rate and a target substitution rate, to an air-to fuel ratio to attain an adjusted substitution rate closer to the target substitution rate and maintain approximately the adjusted engine knock level;
• wherein an adjustment to the target start of injection is determined to adjust an exhaust temperature of the engine to be within a target range of the exhaust temperature;
• and
• adjust the air-to-fuel ratio and the substitution rate based on the third adjustment.