BS ISO 17584 -pdf download – Refrigerant properties.
NOTE An equation of stale most commonly expresses pressure or Helmholtz energy as a functIon of temperature, density, and (tot a blencll coinpoebon. Other thermodynamic properties are obtained through Integration andor ditlerentialion 01 the equation of slate
35 fluid
refrIgerant
substance, present in liquId and/or gaseous states, used for heat transfer in a refrigerating system
NOTE The fluid absorbs heat at a low temperature and low presswe, then releases the heat at a higher temperature and a higher pressure, usually through a change 01 state.
3.6
liquid-vapour saturation
state at which liquid and vapour phases of a fluid are in thermodynamic equilibrium with each other at a common temperature and pressure
NOTE Such Mates exist from the triple point to the o’itical point.
3.7
transport properties
viscosity, thermal conductivity, arid diffusion coefficient
thermodynamic properties
density, pressure, fugacity, internal energy, enthalpy, entropy, Gibbs arid Helmholtz energies, heat capacthes, speed of sound, and the Joule-Thomson coefficient, in both single-phase states and along the liquid-vapour saturation boundary
3.9
thermophysical properties
all of me thermodynamic, transport, and other miscellaneous properties
3.10
triple point
slate at which solid, liquid, and vapour phases of a substance are ii thermodynamic equilibrium
4 Calculation of refrigerant properties
4.1 General
This International Standard specifies properties br the retrigerants listed in Clause 1. These properties are derived from experimental measurements. It is not practical, however, to crectly reference the experimental data; they may not be available at all conditions of interest and some properties, such as entropy. cannot be measured directly. Furthermore, a simple tabulation, even for properties (such as vapour pressure) that are directly measurable, is not convenient for modem engineering use. Thus, some means to correlate the data is required to allow calculation of the properties at a desired thermodynamic state.
The properties enumerated in this International Standard are calculated from specified equations of state, although alternative algorithms are allowed. The properties themselves constitute this International Standard. The equations of state servo as a convenient moans to roprosenl and reproduce the properties. The properties enumerated in the tables in this International Standard thus represent only a subset of the properties specified by this Iriternationat Standard; the fuil range of conditions is given for each fluid in Clause 5. An equation of state is a mathematical equation that is a complete and thermodynamically consistent representation of the thermodynamic properties of a fluid. These equations have been selected based on the following criteria:
a) accuracy in reproducing the available experimental data;
b) applicability over wide ranges of temperature. pressure, and density:
c) proper behavior on extrapolation beyond the available experimental data; and
d) preference has been given to fully documented and pub’ished formulations.
4.2 Pure-fluid equations of state
An equation of state for a pure fluid may express the reduced molar Helmholtz energy, A, as a function of temperature and density. The equation is composed of separate terms arising from ideal-gas behaviour (subscript 1d) and a “residual or real-fluid (subscript ar”) contribution as given in Equation (1):
where R is the gas constant. Equations of this form may be written on either a molar basis or a mass basis. For a consistent representation in this International Standard, the equations of state originally published on a mass basis have been converted to a molar basis. The “residual” or real-fluid contribution is given by Equation (2).
BS ISO 17584 -pdf download – Refrigerant properties
