Author :
Mardolcar, U.V. ; Santos, F.J.V. ; De Castro, C. A Nieto
Author_Institution :
Departamento de Fisica e Nucleo de Ternofisica, Instituto Superior Tecnico, Lisbon, Portugal
Abstract :
This paper reviews our research, from experimental measurements of the relative permittivity on new and alternative refrigerants, to theoretical interpretation of the data and density functional and density functional self-consistent reaction field calculations for a series of HFC molecules. Experimental measurements were obtained as a function of temperature and pressure for Class B refrigerants - HCFC-123, HCFC-142b, HCFC-141b and Class A refrigerants - HFC-32, HFC-134a, HFC-152a, HFC-143a, HFC-227ea, HFC-245fa, HFC-365mfc and some mixtures of them: HFC-125/143a/134a (R-404A), HFC-32/125/134a (R-407C), HFC-125/143a (R-507), HFC-32/125 (R-410A). Density functional and density functional self-consistent reaction field calculations were performed for CHF2CF3 (HFC-125), CH2FCF3 (HFC-134a), CH3CF3 (HFC-143a), CH2F2 (HFC-32), and CHF2CH3 (HFC-152a). A particular emphasis has been given to the calculation of dimerisation energies, rotational potentials, polarisabilities and dipole moments.
Keywords :
SCF calculations; association; density functional theory; molecular moments; permittivity; polarisability; refrigerants; reviews; rotational states; density functional self-consistent reaction field calculations; dimerisation energies; dipole moments; permittivity; polarisabilities; refrigerants; review; rotational potentials; Capacitance measurement; Dielectrics; Electrical resistance measurement; Impedance; Instruments; Parasitic capacitance; Permittivity measurement; Pressure measurement; Refrigerants; Temperature measurement;
