The distinction among Performance parameters and criteria

It is significant to note that whereas performance parameters just give a measure of plant performance, it is performance criteria that give a yardstick against that the real performance can be judged. After a plant is planned, built and operated, it is essential to ask how much improved the performance could have been. Performance criterion, not performance parameters, is able of giving the answers. Such criteria cannot outcome from practical experiment, as all real-life procedures are to some degree imperfect. They are resulting from the application of the laws of thermodynamics to reversible procedures.