This project deals with the study of a quasi-isothermal scroll compression/expansion obtained by spray injection of water. The spray injection process is first described from the theoretical point of view as it concerns the droplets formation and breakup processes, both directly related to the evaporation. A simulation of spray injection is also performed using Ansys CFX. The last part deals with an experimental application in the laboratory of the system studied. Results are presented and discussed both for CFD simulation and experimental part.