Thermodynamic Correlations, k – Exponents, Speed of Sound, and COP Data for Binary Refrigerant Mixtures

Authors : Athina STEGOUSAGİA, M DAMANAKİS

Pages : 15-22

View : 11 | Download : 8

Publication Date : 2004-03-01

Article Type : Research Paper

Abstract :Our study covers thermodynamic performance quantities for binary refrigerant mixtures of R-32/R-134a with compositions of 20/80%, 30/70%, 40/60% by mass for a wide range of thermodynamic conditions insert ignore into journalissuearticles values(pressure: 0.2 - 3.0 MPa, temperature: 240 - 480 oK and saturated conditions);. The primary thrust of the study is the calculation of coefficient of performance insert ignore into journalissuearticles values(COP); values for refrigeration systems. Additional attention is also given to speed of sound data and to isentropic process changes. The relevant COPs are derived based on a simplified reference refrigeration cycle with one stage compression and throttling, saturated vapor and no liquid sub-cooling prior to the throttling valve. The COP values are given for various condensing and evaporating temperatures. For all calculations, a Peng – Robinson type equation of state is used to determine the necessary fluid properties. The enthalpy, entropy, and constant-pressure and constant-volume specific heats as well as the k-type isentropic change exponents are presented for all mixtures for the range of thermodynamics conditions listed above. Comparisons are made illustrating the influence of pressure and temperature on the k-type exponents kp,v, kT,v, and kp,T, and on the ratio of specific heats k insert ignore into journalissuearticles values(k = cp/cv);. Furthermore, graphs with speed of sound data for this extended range of conditions are also given.
Keywords : R 32 R 134a mixtures, enthalpy, entropy, constant pressure and constant volume specific heats, isentropic exponents, coefficient of performance, speed of sound