Waste heat recovery system and control

A method for operating a waste heat recovery (WHR) system including at least two pressure circuits, each pressure circuit including at least one heat exchanger, each of the at least two pressure circuits providing a working fluid to the respective at least one heat exchanger and to an expander having a plurality of inputs, comprising separate input ports, corresponding to a number of the at least two pressure circuits, the method comprising:

• receiving, at a controller, a first pressure value and a first temperature value from a first sensor positioned at one of an inputs of the expander;
• determining, at the controller, a superheated temperature value from the first pressure value based on at least one characteristic of the working fluid;
• determining, at the controller, whether the first temperature value is greater than the superheated temperature value;
• and
• controlling, by the controller responsive to determining that the first temperature value is greater than the superheated temperature value, at least one of a pump pumping the working fluid or a bypass valve positioned across the pump to increase a flow of the working fluid.

A system, comprising:

• an engine;
• and
• a waste heat recovery (WHR) system, comprising:
• at least two pressure circuits, each pressure circuit including at least one heat exchanger receiving at least one fluid associated with the engine, the at least two pressure circuits providing a working fluid to the respective at least one heat exchanger and to an expander having a plurality of inputs, comprising separate input ports, corresponding to a number of the at least two pressure circuits, and
• a controller communicably coupled with the at least two pressure circuits, the controller configured to:
• receive a first pressure value and a first temperature value from a first sensor positioned at one of an inputs of the expander;
• determine a superheated temperature value from the first pressure value based on at least one characteristic of the working fluid;
• determine whether the first temperature value is greater than the superheated temperature value;
• and
• control, responsive to determining that the first temperature value is greater than the superheated temperature value, at least one of a pump pumping the working fluid or a bypass valve positioned across the pump to increase a flow of the working fluid.