Corresponding states treatment of refrigerants and cryogenic fluids

International Journal of Mechanical Engineering Education

Saha

Dutta

et al. 2012

This paper lists the values of slope properties of entropy, enthalpy and exergy along isotherms, isochors, isobars and isentropes in terms of properties that can be primarily measured, namely pressure, volume, temperature, their slopes derivable from equations of state and one of the specific heats in the ideal gas state. It is also shown that all these slopes can be expressed in terms of a coefficient of thermal expansion and isothermal compressibility as well. These could be useful as an educational tool in chemical and mechanical engineering.

“…Every liquid has a point along the saturation curve where the product Tρ f is maximum. This occurs at about 0.82T c , where T c is the critical temperature [7]:…”

Section: Table 3 Slopes Of Exergy With P V T H and Smentioning

confidence: 99%

Thermodynamic Property Slopes from Primary Measurements

International Journal of Mechanical Engineering Education

Saha

Dutta

et al. 2012

“…The procedure adopted is nearly the same as that described by Srinivasan and Krishna Murthy [8] with the change that the reduced fluidity is made dimensionless and its power is allowed to vary for each fluid (instead of 0.5 used by them) where cP~= A + BTD (1) ~D = 1/qD (2) qD = fac. q fac is the viscosity reduction factor given by…”

Section: Development Of Correlationmentioning

confidence: 99%

“…A review of the relative effects of these correlations has been presented by Latini et al [6] and Takahashi [7]. A relation between fluidity and dimensionless temperature has been developed by Srinivasan and Krishna Murthy [ 8 ] for CFCs and HCFCs in the methane family and CFCs of the ethane family.…”

Section: Introductionmentioning

confidence: 99%

Saturated liquid viscosity correlations for alternative refrigerants

Khan

1996

Int J Thermophys

Self Cite

This article presents dimensionless equations for the temperature dependence of the saturated liquid viscosity of R32, R123, R124, R125, R134a, R141b, and R152a valid over a temperature range of engineering interest. The correlation has the form m" -A ~D-+BTD where ~D is the dimensionless fluidity (l/r/D) and TD is a dimensionless temperature, n, A, and B are evaluated for each of the above refrigerants based on a least-squares fit to experimental data. This equation is found to provide an improved fit over those existing in the literature up to To = 0.8.

“…The parameters that characterize the physical magnitude of interactions are the depth of the potential well in the intermolecular potential energy distribution function, kT* (where k is the Boltzmann constant), and the molecular length parameter (a) which describes the size of a molecule and the dipole moment (\i). T* and a can be calculated from the saturated liquid density data (Srinivasan & Murthy, 1985). It may be recalled that R-12 and R-ll are polar fluids (\i ~ 0.5 DU).…”

Section: Molecular Considerationsmentioning

confidence: 99%

CFC Alternatives — A Fresh Look

1992

Envir. Conserv.

This article examines, through a molecular perspective, the ‘ozone-friendly’ refrigerants R-134a and R-123 vis-à-vis R-12 and R-11, which are targeted to be phased out under the Montreal Protocol on Substances that Deplete the Ozone Layer, Final Act (1987). It appears that the molecular weight, size parameter, and dipole moment, of R-134a and R-123, may induce a pronounced effect on the chemical equilibrium of ice particles in the polar stratospheric clouds and subsequently influence the photochemical reactions therein.Non-polar, high-molecular-weight perfluoropropane (R-218), could be a better substitute for R-12, while R-134, which is a non-polar HFC of the ethane family, could also be a candidate although its molecular weight is lower than that of R-12. The search for a good substitute for R-11, however, must continue.