The choice of the steam jet ejector system, which transforms the thermal energy of motive steam, will primarily depend on the final vacuum to be achieved. The net result of these energy transformations is an increase of the absolute pressure of the mixture on discharge to several times the pressure at which it entered the ejector inlet. A new approach of mathematical correlations performance of thermal vapor compressor (TVC) is presented. The performance of TVC is studied. The results of the mathematical model of TVC mixing ratios and performance diagram are very close approach to the Power's lines. Published by Elsevier B.V.