The book describes methods for calculating, modeling and optimizing cryogenic units: recuperative and regenerative heat exchangers, condensers-evaporators, distillation columns, adsorbers. The issues of determining the kinetic parameters of heat and mass exchange described by differential equations, calculating quasi-static modes of operation of systems of heat exchangers, the use of information theory in calculating distillation columns are covered. Factual materials, examples illustrating the methods are given.