Abstract <p>This paper presents an analysis of the effect of the original dryness degree on the operating parameters and performance of an oil-free refrigerating rotary-vane compressor operating in a wet steam environment using various approaches in determining the discharge factor through the ends. The calculation is based on the equation of the first law of thermodynamics for an open system, the Clapeyron–Clausius equation, and the equation of state of a real gas. When determining the discharge factor of a two-phase flow through the ends, two approaches were considered: the approach proposed by V.I. Alyoshin, taking into account the coefficient of sealing the gap by a liquid, and that proposed by M.E. Deutsch, which takes into account the theoretical and actual steam flow factors through the nozzle. The analysis of the results showed that the discrepancy in the performances of the refrigerating rotary-vane compressor operating in the wet-steam region, such as indicator power and feed ratio, calculated using two approaches, ranges from 1 to 15%. Based on the analysis, it is recommended, with allowance for the accepted assumptions, to use V.I. Alyoshin’s approach to study the characteristics of a rotary-vane refrigerating compressor operating in a wet steam environment.</p>