Aftertreatment systems for dual-fuel engines

A controller for use in an aftertreatment system, the controller comprising:

• a determination module configured to determine an operating mode of a dual-fuel engine;
• an operation module configured to operate the dual-fuel engine in a stoichiometric operating condition when the dual-fuel engine is operating in a natural gas mode or a dual-fuel mode, and to operate the dual-fuel engine in a lean operating condition when the dual-fuel engine is not operating in the dual-fuel mode or the natural gas mode;
• a dosing module configured to control the injection of urea into exhaust downstream from the dual-fuel engine, the dosing module communicating with the operation module to determine when to allow the injection of the urea;
• and
• a fuel injection module configured to control an air-fuel ratio in the dual-fuel engine based upon the operating mode of the dual-fuel engine.

An aftertreatment system configured to be used with a dual-fuel engine operable in a plurality of operating modes, the aftertreatment system comprising:

• a three-way catalyst positioned downstream of the dual-fuel engine, the three-way catalyst configured to receive exhaust from the dual-fuel engine;
• a selective catalytic reduction catalyst communicatively connected to the three-way catalyst and positioned downstream of the dual-fuel engine;
• and
• a controller configured to determine the operating mode of the dual-fuel engine,
• wherein the controller operates the dual-fuel engine in a stoichiometric operating condition when the dual-fuel engine is in a dual-fuel mode or a natural gas mode, and wherein the controller operates the dual-fuel engine in a lean operating condition when the dual-fuel engine is not in the dual-fuel mode or the natural gas mode.