The study on refrigeration systems in this paper was made at the Technical University of Civil Engineering of Bucharest (U.T.C.B) - Colentina Laboratories Complex. The chosen topic is aiming to contribute to the theoretical basis and practical research in terms of development and use of ecological refrigerants. The ecological refrigerants proposed in this scientific work are chemicals obtained by mixing in different proportions of various current ecological refrigerants with one or more natural or synthetic substances that have zero values of ozone depletion potential (ODP) and low global warming potential (GWP). The results of the simulations from this paper performed with the help of the high-performance program EES (Engineering Equation Solver) for the refrigerants: R 134a, R1234yf, MV3T, MV3TN (mixteres of R 134a, R1234yf) in the case of the air-water heat pump. An important objective was the realization of an experimental stand air-water heat pump, designed to determine the performance of the refrigeration system operating with the refrigerant R134a and to find new ecological refrigerants of mixture type MV3T, MV3TN. From the ecological point of view the MV3TN mixture (GWP = 560) is the most advantageous compared to R134a (GWP = 1430). The comparative study of these facilities followed the coefficient of performance (COP/EER) and also the TEWI factor (Total Equivalent Warming Impact – in respect with EN 378-1).