The use of ice slurries as secondary refrigerants is a very promising technology. The aim of this paper is to evaluate the contribution of second law analysis to the study of a phase changing secondary refrigerant in cooling systems. The first step of the work presented here consists of two parts: the first involves the calculation of enthalpies and entropies and the second is an entropy/exergy analysis of a heat exchanger. This work attempts to provide a thermodynamic criterion in order to choose the kind of fluid and the inflow conditions that are more suitable for a particular application. It presents the establishment of the method and the results that have been obtained for an ethyl alcohol-water mixture.