Method and apparatus for cooling an engine

A method for cooling an engine, the method comprising:

• increasing the pressure of a liquid coolant from a first pressure to a second pressure;
• after increasing the pressure of the liquid coolant, contacting components of the engine to be cooled with the liquid coolant so that the liquid coolant at least partially evaporates and forms a vapor with a particular state;
• after the vapor with the particular state forms, feeding the vapor to a throttle so as to reduce the pressure of the liquid coolant to a third pressure;
• determining the particular state of the vapor upstream of the throttle based on the temperature and the third pressure of the liquid coolant downstream of the throttle, and based on the second pressure of the liquid coolant upstream of the throttle under an assumption that the throttle is an adiabatic throttle such that enthalpy of the liquid coolant remains constant as the liquid coolant passes the throttle;
• and
• adjusting a desired vapor state based on the determined particular state of the vapor upstream of the throttle.