Modeling of two-phase hydrodynamic phenomena with a refrigerant (Freon) has been carried out for several years because of the lower cost of experimentation with this working fluid. Freon-12a modeling of the critical-heat-flux condition, a coupled hydrodynamic thermal phenomenon, has recently been reported. The effort described here represents an extension of the critical-heat-flux modeling work using Freon-22.b A recently proposed correlation method, comparing Freon and water data, has been modified, and good agreement is shown between water and Freon-22 test results in a round tube with and without a twisted ribbon insert. The modeling technique is also extended to cover inlet subcooling and the operating pressure effect. In addition, some liquid-metal and water critical-heat-flux data are compared.