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CYCLE_D: NIST Vapor Compression Cycle Design Program, Version 5.1.1; User’s Guide



Piotr A. Domanski, J S. Brown, Eric W. Lemmon


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. CYCLE_D operates in a Microsoft Windows environment that facilitates evaluating the performance of selected working fluids at different operating conditions. Calculations are based on refrigerant properties as represented in the NIST Reference Fluid Thermodynamic and Transport Properties Program – REFPROP, Version 9.1 [1].
Natl Std. Ref. Data Series (NIST NSRDS) - NIST.NSRDS.49
Report Number


air conditioning, coefficient of performance, refrigerant, thermodynamics, vapor compression


Domanski, P. , Brown, J. and Lemmon, E. (2017), CYCLE_D: NIST Vapor Compression Cycle Design Program, Version 5.1.1; User’s Guide, Natl Std. Ref. Data Series (NIST NSRDS), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed April 25, 2024)
Created March 9, 2017, Updated November 10, 2018