The CYCLE_D package simulates vapor compression refrigeration cycles that use pure refrigerants or blends of refrigerants. The model can simulate a basic subcritical or transcritical refrigeration cycle, both with or without a liquid-line/suction-line heat exchanger. In addition, the model can simulate a subcritical two-stage economizer cycle, a subcritical three- stage economizer cycle, and a subcritical two-stage compression cycle with intercooling. Calculations are based on refrigerant properties as represented in the NIST Reference Fluid Thermodynamic and Transport Properties Program REFPROP, Version 10.0 . Simulation results are presented in terms of coefficient of performance (COP), volumetric capacity, thermodynamic parameters, and thermodynamic charts.