I am very new to using the HYSYS process modelling software and would appreciate if somebody could possibly answer a simple question. For an assignment i was working on, i needed to reference the critical temperature and pressure for a hydrocarbon mix. For the particular stream, i used the "critical properties" utility, which displayed "true" and "pseudo" temperatures and pressures. What is the difference between these values? How is the pseudo value calculated? If anybody is able to shed some light on this issue, i'd be greatly appreciative Thanks, Dan.