Influence of the Thermophysical Fluid Properties of the New Ozone-Safe Refrigerants on Performance.
Influence of the Thermophysical Fluid Properties of the
New Ozone-Safe Refrigerants on Performance.
(1546 K)
Didion, D. A.
International Journal of Applied Thermodynamics, Vol.
2, No. 1, 19-35, March 1999.
Keywords:
refrigerants; ozone; azeotropic mixtures; thermophysical
properties; two-phase flow; vapor compression cycle;
zeotropic
Abstract:
The selection a working fluid as a refrigerant for the
vapor compression cycle is discussed. For thermodynamic
performance to be optimized particular attention must be
paid to the fluid's critical point and molar heat
capacity. To achieve a reasonable balance between
volumetric capacity, which implies equipment size, and
coefficient of performance, which is efficiency, it is
necessary to select a fluid with a critical point such
that the application's condenser will operate in a
reduced temperature range of approximately 0.7 to 0.9.
It is also necessary to select fluids within a rather
limited range of molar heat capacity values. The
specifics as to how these properties effect the cycle's
performance are presented in detail. For a better
matching of the working fluid to a given application,
both azeotopic and zeotropic mixtures of fluids are
used. The characteristics and performance advantages and
disadvantages of these mixtures are discussed.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899