ISO 17584:2005
(Main)Refrigerant properties
Refrigerant properties
ISO 17584:2005 specifies thermophysical properties of several commonly used refrigerants and refrigerant blends. ISO 17584:2005 is applicable to the refrigerants R12, R22, R32, R123, R125, R134a, R143a, R152a, R717 (ammonia), and R744 (carbon dioxide) and to the refrigerant blends R404A, R407C, R410A, and R507. The following properties are included: density, pressure, internal energy, enthalpy, entropy, heat capacity at constant pressure, heat capacity at constant volume, speed of sound, and the Joule-Thomson coefficient, in both single-phase states and along the liquid-vapour saturation boundary. The numerical designation of these refrigerants is that defined in ISO 817.
Propriétés des fluides frigorigènes
General Information
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 17584
First edition
2005-12-15
Refrigerant properties
Propriétés des fluides frigorigènes
Reference number
ISO 17584:2005(E)
©
ISO 2005
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ISO 17584:2005(E)
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ISO 17584:2005(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 Calculation of refrigerant properties . 2
4.1 General. 2
4.2 Pure-fluid equations of state . 3
4.3 Mixture equation of state . 5
4.4 Implementation . 7
4.5 Alternative implementation. 7
4.6 Certification of conformance. 7
5 Specifications for individual refrigerants. 7
5.1 General. 7
5.2 R744 — Carbon dioxide. 7
5.3 R717 — Ammonia . 11
5.4 R12 — Dichlorodifluoromethane. 14
5.5 R22 — Chlorodifluoromethane. 18
5.6 R32 — Difluoromethane . 22
5.7 R123 — 2,2-dichloro-1,1,1-trifluoroethane .26
5.8 R125 — Pentafluoroethane . 30
5.9 R134a — 1,1,1,2-tetrafluoroethane. 33
5.10 R143a — 1,1,1-trifluoroethane . 37
5.11 R152a — 1,1-difluoroethane . 40
5.12 R404A — R125/143a/134a (44/52/4). 44
5.13 R407C — R32/125/134a (23/25/52). 47
5.14 R410A — R32/125 (50/50) . 50
5.15 R507A — R125/143a (50/50) . 53
Annex A (normative) Requirements for implementations claiming conformance with this
International Standard. 56
Annex B (informative) Calculation of pure-fluid thermodynamic properties from an equation
of state . 58
Annex C (informative) Calculation of mixture thermodynamic properties from an equation of state . 61
Annex D (informative) Literature citations for equations of state and verification values. 63
Annex E (informative) Variation of mixture properties due to composition tolerance . 68
Bibliography . 70
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ISO 17584:2005(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 17584 was prepared by Technical Committee ISO/TC 86, Refrigeration and air-conditioning,
Subcommittee SC 8, Refrigerants and refrigeration lubricants.
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ISO 17584:2005(E)
Introduction
This document, prepared by ISO/TC 86/SC 8/WG 7, is a new International Standard. It is consistent with and
is intended to complement ISO 817. The purpose of this International Standard is to address the differing
performance ratings due to the differences between multiple property formulations, which is a problem
especially in international trade. The fluids and properties included in this International Standard represent
those for which sufficient high-quality data were available. While the working group recognizes the desirability
of including additional fluids, such as the hydrocarbons, and including the transport properties of viscosity and
thermal conductivity, the data and models for these were judged insufficient at this time to be worthy of
designation as an International Standard. Therefore, the working group decided to prepare the present
International Standard, incomplete though it might be, in a timely fashion rather than delay it awaiting
additional data. The working group is continuing its efforts to add additional fluids and additional properties to
this International Standard. It is anticipated that this International Standard will undergo regular reviews and
revisions.
For applications such as performance rating of refrigeration equipment, having all parties adopt a consistent
set of properties is more important than absolute accuracy. But consensus is easiest to achieve when high-
quality property data are available.
With this in mind, the Working Group has taken as its starting point the results of Annex 18 Thermophysical
Properties of the Environmentally Acceptable Refrigerants of the Heat Pump Programme of the International
[7]
Energy Agency (McLinden and Watanabe ). Annex 18 reports the comprehensive evaluations of the
available equations of state and recommended formulations for R123, R134a, R32, R125, and R143a. Wide
participation was invited in this process, and anyone could submit an equation of state for evaluation. The
formulations for R123, R134a, R32, and R143a adopted in this International Standard are the same as those
recommend by Annex 18. (The recent equation of state for R125 adopted in this International Standard was
shown to be more accurate than the older formulation recommended by Annex 18.)
A similar comparison of mixture models reported by Annex 18 facilitated the dissemination and adoption of a
new mixture modelling approach. This model is based on Helmholtz energies for each of the mixture
components, and it is the approach used in the NIST REFPROP refrigerant property database (Lemmon
[5]
et al. ) and in the extensive tabulation of properties published by the Japan Society of Refrigerating and Air
[12] [2]
Conditioning Engineers (Tillner-Roth et al. ). The Lemmon and Jacobsen model (implemented in the
[12]
REFPROP database) is simpler than the Tillner-Roth et al. model in that it avoids the ternary interactions
terms required in the Tillner-Roth model, with practically the same representations of the experimental data.
For these reasons, as well as the widespread use of REFPROP, the Lemmon and Jacobsen model was
adopted as the basis for the mixture properties specified in this International Standard.
The one significant disadvantage of the formulations adopted here is their complexity. In recognition of this,
this International Standard allows for “alternative implementations” for the properties. These can take the form
of simpler equations of state that may be applicable over limited ranges of conditions or simple correlations of
single properties (e.g., expressions for vapour pressure or the enthalpy of the saturated vapour). This
International Standard does not restrict the form of such alternative implementations, but it does impose
requirements, in the form of allowable tolerances (deviations from the standard values), given in Annex A,
which alternative implementations shall satisfy.
The question of allowable tolerances for alternative implementations generated the most controversy among
the working group. In the working group discussions, some felt that the tolerances should be fairly large to
encompass as many formulations in common use as possible. But others argued that this would defeat the
very purpose of this International Standard, which was to harmonize the property values used across the
industry. The concept of alternative implementations with their allowable tolerances was not intended to
sanction the continued use of “incorrect” data but, rather, to provide for fast, application-specific equations that
would be fitted to the properties specified in this International Standard. In the end, fairly strict tolerances were
selected. The experiences and recommendations of the European Association of Compressor Manufacturers
(ASERCOM) carried significant weight. They had experience with simplified property equations that were fitted
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ISO 17584:2005(E)
to, and closely matched, several of the same equations of state recommended in this International Standard.
They recommended strict tolerances.
These tolerances do not necessarily represent the uncertainty of the original experimental data or of the
equation of state in fitting the data. The allowable tolerances specified in Annex A were selected to result in
“reasonable” differences in quantities derived from these properties, for example, a cycle efficiency or
compressor rating. For example, the tolerances specified in Annex A result in an overall variation of
approximately 2,5 % in the efficiency of an ideal refrigeration cycle operating between an evaporator
temperature of − 15 °C and a condenser temperature of 30 °C. By comparison, ISO 817 specifies that the
primary energy balance for compressor tests agree with flow data within 4 %.
The tolerances are relative (i.e. plus or minus a percentage) for some properties and absolute for others (e.g.
plus or minus a constant enthalpy value). Properties such as enthalpy and entropy, which can be negative,
demand an absolute tolerance; any allowable percentage variation would be too strict at values near zero.
The allowable tolerances for enthalpy and entropy are scaled by the enthalpy and entropy of vapourisation for
each fluid. This scaling arose from a cycle analysis which revealed that a constant tolerance resulted in
greatly differing sensitivities of the cycle efficiency depending on the enthalpy and entropy of vapourisation. By
scaling the tolerance to the vapourisation values, a greater tolerance is allowed for fluids, such as ammonia,
with high heats of vapourisation.
The tolerances apply to individual thermodynamic states. In cycle and equipment analyses, it is the
differences in enthalpy and/or entropy between two different states that are important. However, it is not
possible to specify, in a simple way, allowable tolerances based on pairs of states because of the large
number of possible pairs of interest.
The values of C and C approach infinity at the critical point, but the actual values returned by the equation of
v p
state are large numbers that vary from computer to computer due to round-off errors in the calculations.
According to critical-region theory, the speed of sound is zero at the critical point; all traditional equations of
state (including the ones in this International Standard), however, do not reproduce this behaviour. Rather
than list values that are inconsistent with either the theory or the specified equations of state, these points are
not included as part of this International Standard.
The values of the gas constant, R, vary from fluid to fluid. Similarly, the number of significant figures given for
the molecular mass, M, vary. The values for R and M are those from the original equation of state source from
the literature. These values are adopted to maintain consistency with the original sources. The various values
−6
of R differ by less than 5 × 10 (equal to parts per million, a deprecated unit) from the currently accepted
value of 8,314 472 J/(mol·K) and result in similarly small differences in the properties. The compositions of the
refrigerant blends (R400- and R500-series) are defined on a mass basis, but the equations of state are given
on a molar basis. The mass compositions have been converted to the equivalent molar basis and listed in
Clause 5; a large number of significant figures are given for consistency with the tables of “verification values”
given in Annex D.
This International Standard anticipates regular reviews (see Clause 6) and will be reviewed every five years.
Any interested party requesting the inclusion of additional refrigerant(s) to this International Standard or
requesting the revision of one or more fluids specified in this International Standard should petition the
ISO/TC 86 secretariat.
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INTERNATIONAL STANDARD ISO 17584:2005(E)
Refrigerant properties
1 Scope
This International Standard specifies thermophysical properties of several commonly used refrigerants and
refrigerant blends.
This International Standard is applicable to the refrigerants R12, R22, R32, R123, R125, R134a, R143a,
R152a, R717 (ammonia), and R744 (carbon dioxide) and to the refrigerant blends R404A, R407C, R410A,
and R507A. The following properties are included: density, pressure, internal energy, enthalpy, entropy, heat
capacity at constant pressure, heat capacity at constant volume, speed of sound, and the Joule-Thomson
coefficient, in both single-phase states and along the liquid-vapour saturation boundary. The numerical
designation of these refrigerants is that defined in ISO 817.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 817, Refrigerants — Designation system
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
algorithm
procedure for the computation of refrigerant properties
NOTE An algorithm is most often a computer program. An algorithm may also consist of one or more single-property
correlations as allowed under 4.4.
3.2
blend
mixture of two or more chemical compounds
3.3
critical point
state at which the properties of the saturated liquid and those of the saturated vapour become equal
NOTE Separate liquid and vapour phases do not exist above the critical point temperature for a pure fluid. This is
more completely referred to as the “gas-liquid critical point” as other “critical points” can be defined.
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ISO 17584:2005(E)
3.4
equation of state
mathematical equation that is a complete and thermodynamically consistent representation of the
thermodynamic properties of a fluid
NOTE An equation of state most commonly expresses pressure or Helmholtz energy as a function of temperature,
density, and (for a blend) composition. Other thermodynamic properties are obtained through integration and/or
differentiation of the equation of state.
3.5
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 pressure, then releases the heat at a higher temperature
and a higher pressure, usually through a change of 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 states exist from the triple point to the critical point.
3.7
transport properties
viscosity, thermal conductivity, and diffusion coefficient
3.8
thermodynamic properties
density, pressure, fugacity, internal energy, enthalpy, entropy, Gibbs and Helmholtz energies, heat capacities,
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 the thermodynamic, transport, and other miscellaneous properties
3.10
triple point
state at which solid, liquid, and vapour phases of a substance are in thermodynamic equilibrium
4 Calculation of refrigerant properties
4.1 General
This International Standard specifies properties for the refrigerants listed in Clause 1. These properties are
derived from experimental measurements. It is not practical, however, to directly 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 modern 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 serve as a convenient means to represent 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 International Standard; the full range of conditions is given for each fluid in
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ISO 17584:2005(E)
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 published 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 “id”) and a “residual” or “real-fluid” (subscript “r”) contribution as given in Equation (1):
A
φ==φφ+ (1)
id r
RT
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):
lm
td
⎡ kk⎤⎡ ⎤
kk
φτ=−Nδ expαδ−ε exp−βτ−γ (2)
() ( )
r ∑kkk kk
⎢ ⎥⎢ ⎥
⎣ ⎦⎣ ⎦
k
where
τ is the dimensionless temperature variable T*/T;
T* is the reducing parameter which is often equal to the critical parameter;
δ is the dimensionless density variable ρ/ρ*;
ρ* is the reducing parameter which is often equal to the critical parameter;
N are numerical coefficients fitted to experimental data;
k
α , β , ε and γ are parameters optimized for a particular fluid or group of fluids by a selection
k k k k
algorithm starting with a large bank of terms or by use of a non-linear fitting process;
t , d , l and m are exponents optimized for a particular fluid or group of fluids by a selection algorithm
k k k k
starting with a large bank of terms or by use of a non-linear fitting process.
The ideal-gas contribution can be represented in one of several ways. One representation is in terms of the
heat capacity of the ideal-gas state, as given in Equation (3):
TT C
⎛⎞
hs RTρ11
p,id
ref ref
φ=− −1l+n + CTd− dT (3)
⎜⎟
id p,id
∫∫
TT
RT R p RT R T
ref ref
⎝⎠ref
where
h is the arbitrary reference enthalpy for the ideal gas at the reference state specified by T ;
ref ref
s is the arbitrary reference entropy for the ideal gas at the reference state specified by T and p .
ref ref ref
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ISO 17584:2005(E)
In this International Standard, the h and s are chosen to yield a reference state for enthalpy of 200 kJ/kg
ref ref
and for entropy of 1 kJ/(kg·K), both for the saturated liquid at 0 °C. Such values of h and s are informative
ref ref
only; different values, corresponding to different reference state conventions, are acceptable.
The heat capacity of the ideal gas state, C may be represented as a function of temperature by the general
,
p id
form consisting of separate summations of polynomial (empirical) and exponential (theoretical) terms, as given
in Equation (4):
2
C
uuexp
()
p,id
t kk
k
=+ccT +a (4)
0∑∑kk
2
R
⎡ ⎤
kk exp u −1
()
k
⎣ ⎦
where
b
k
u = ; (5)
k
T
c , a , b and t are numerical coefficients and exponents fitted to data or derived from theoretical
k k k k
calculations.
A second representation of the ideal-gas contribution is given directly in terms of the Helmholtz free energy,
as shown in Equation (6):
t
k
⎡ ⎤
φτ=+dd + lnδ+ddalnτ+τ + ln 1− exp−τλ (6)
()
id 1 2 3 ∑kk∑ k
⎣ ⎦
kk
where
d and d are adjusted to yield the desired reference state values for the enthalpy and entropy;
1 2
d , d , a , λ and t are either empirical or theoretical parameters.
3 k k k k
Equation (6) is functionally equivalent to Equations (3) to (5), and an ideal-gas contribution in the form of
Equation (6) may be converted to the heat capacity form as given by Equation (7):
t
k 2
*
C ⎛⎞
uuexp()
T
p,id kk
=+dd11− tt− +a (7)
()⎜⎟
3∑∑kk k k
2
⎜⎟
RT
⎡ ⎤
kk⎝⎠ exp u −1
()
k
⎣ ⎦
where
*
λ T
k
u = (8)
k
T
The equations of state for certain fluids may also include special terms to represent the behaviour very close
to the critical point. These are of the form of Equation (9):
b
k
φ = N δ∆ Ψ (9)
crit ∑ k
k
where
a
k
2
2
⎡⎤
∆θ=+ B δ−1 (10)
()
k
⎢⎥
⎣⎦
12β
( )
k
2
⎡⎤
θτ=−()11+ A(δ−) (11)
k
⎢⎥
⎣⎦
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ISO 17584:2005(E)
22
⎡⎤
Ψ=−expCDδτ−1− −1 (12)
() ( )
kk
⎢⎥
⎣⎦
Equation (9) is added to the normal terms in Equation (1). The N , A , B , C , D , α and β are adjustable
k k k k k k k
parameters fitted to data. Among the fluids in this International Standard, only the equation of state for R744
(carbon dioxide) includes these critical region terms.
Alternately, an equation of state may express pressure as an explicit function of temperature and molar
density. One form is that of a modified Benedict-Webb-Rubin (MBWR) equation of state, as given in
Equation (13):
915
kk22 2 −17
pa=+ρρexp−ρ aρ (13)
()
∑∑kkcrit
kk==110
where the a are functions of temperature resulting in a total of 32 adjustable parameters that are fitted to the
k
experimental data. For a complete description of the thermodynamic properties, the MBWR equation is
combined with an expression for the ideal-gas heat capacity, such as Equation (4) or (5).
In this International Standard, pressure-explicit equations of state [such as Equation (13)] are transformed into
the Helmholtz-energy form to maintain a consistent representation. The pressure is related to the Helmholtz
energy using the thermodynamic identity shown in Equation (14):
⎛⎞∂A
p=− (14)
⎜⎟
∂V
⎝⎠
T
Thus, the Helmholtz energy can be evaluated from the pressure by an integration over volume, using
Equation (15):
AT,ρ ∞
()
⎛⎞p
r
==φρ− − dV (15)
r ⎜⎟
∫
V
RT RT
⎝⎠
Equation (15) is then combined with an ideal-gas contribution given by Equations (3) to (5) to yield a complete
description of the thermodynamic properties. Among the fluids in this International Standard, the equations of
state for R123 and R152a have been transformed in this manner.
An equation of state or the ideal-gas heat capacity may also be expressed in other forms, but the forms
represented by Equations (1) through (15) encompass all those specified in this International Standard.
Methods for computing pure-fluid thermodynamic properties from an equation of state are given in Annex B.
4.3 Mixture equation of state
Thermodynamic properties of mixtures are calculated by applying mixing rules to the Helmholtz energy of the
mixture components together with a separate mixture function. The reduced Helmholtz energy of the mixture
is a sum of ideal-gas and residual contributions as given by Equation (16):
A
φφ== +φ (16)
mix mix,id mix,r
RT
The ideal gas part is given by Equation (17):
n
⎡⎤
φφ=+xx lnx+f+f /T (17)
mix,id ∑ ii,id i i 3 4
⎣⎦
i=1
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ISO 17584:2005(E)
where
x is the mole fraction of component i in the n-component mixture;
i
x ln x are terms arising from the entropy of mixing of ideal gases.
i i
The parameters f and f are used to shift the thermodynamic surface such that the reference state for
3 4
enthalpy is 200 kJ
...
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