This product gives results of a project to quantify the advantages and disadvantages of using ammonia with a secondary brine refrigerant compared to R-22 in supermarket refrigeration applications. Project objectives were achieved by numerical experiments using simulations. Mechanistic models of refrigeration system components were used, based on fundamental principles, accepted heat transfer/pressure drop correlations, and available manufacturers' data. Available thermodynamic and transport property data correlations for ammonia and R-22 were used in the models. The parameters of these models were varied to determine their effect on system performance and locate optimum values. A modular approach was used in which each component was separately modeled, allowing simple changes in system configurations. The combined component models resulted in a large set of coupled nonlinear algebraic equations for the quasi-steady systems that did not involve brine storage. The system involved differential and algebraic equations. These equations were solved using the general-purpose simulation programs EES and TRNSYS. EES is a robust nonlinear equation-solving program with built-in thermophysical property data. TRNSYS is a sequential modular simulation program that uses schemes to solve coupled algebraic and differential equations.