Food can be cooked faster in a pressure cooker since the boiling point of water increases with pressure. The pressure cooker consists of a pressurized pot which has controlled vent at a specified pressure above atmospheric pressure. It is typical for the pressure of venting to be about 15 pounds per square inch above atmospheric pressure. That raises the boiling point to about 121°C or 257 °F.
Since atmospheric pressure is about 14.7 lb/in2, then a gauge pressure of 15 lb/in2 amounts to about a doubling of absolute pressure. The nature of the variation of saturation vapor pressure with temperature places the boiling point at about 121°C.
Heat engine concepts