286

P-PROPATH: Pure Substances and Mixtures with Fixed Composition

2.30 i-Butane
Equations for thermodynamic properties have been cited from reference [1].

2.30.1 Temperature Scale
International practical temperature scale 1968 (IPTS-1968)

2.30.2 The Names of Substance, Library File and Single Shot Program
Name of Substance:
Library File for UNIX:
Library File for DOS,Windows95/NT:
Single Shot Program for UNIX:
Single Shot Program for DOS,Windows95/NT:

i-Butane, Isobutane
libjic4h10.a
JIC4H10.LIB
ic4h10-ss
IC4H10–SS.EXE

2.30.3 Important Constants and Others
Molecular Formula:
Relative Molecular Mass:
Gas Constant:(CH3 )2 CHCH3
58.1243
143.05 J/(kg·K)

Critical Constants:
Critical Pressure:
Critical Temperature:
Critical Speciﬁc Volume:

3.65489×10 6Pa (36.5489 bar)408.00 K (134.85 ◦C)
4.46×10 −3m3 /kg

Triple Point:
Pressure:
Temperature:

0.018893 Pa (0.18893×10 −6 bar)113.55 K (−159.60 ◦C)

Reference State:
Zero is assigned to the speciﬁc internal energy at the triple point.

2.30.4 Formula
Equation of State:
Equation (6) in a function form of P = P (ρ, T ) in reference [1]. Here P = pressure, ρ= density and T =temperature.
Vapor Pressure:
Equation (2) in reference [1].
Properties at Vapor-Liquid Equilibrium:
Equation (3) for speciﬁc volume of saturated liquid and equation (4) for speciﬁc volume of saturated vapor,equations (14) and (18) for speciﬁc entropy, equations (15) and (18) for speciﬁc enthalpy, and equation (16) for
isobaric speciﬁc heat, respectively. All of these have been cited from refernce [1].
Pressure and Temperature on Melting Line:
Equation (1) in reference [1].

References[1] R.D.Goodwin, Isobutane: Provisional Thermodynamic Functions from 114 to 700K at Pressures to 700
bar, National Bureau of Standards, NBSIR 79-1612 (September 1979)

i-Butane

287
Table II–2.30–1 i−Butane Function

No.
194
8A
8B
82
8C
8D
234

Name ofFunction
AIPPT(P,T)
AJTPT(P,T)
AKPD(P)AKPDD(P)AKPT(P,T)
AKTD(T)
AKTDD(T)
ALAPP(P)
ALAPT(T)
ALHP(P)

5

ALHT(T)67
8
910111213
1415
9290919316

ALMPD(P)ALMPDD(P)
ALMPT(P,T)
ALMTD(T)ALMTDD(T)
AMUPD(P)AMUPDD(P)AMUPT(P,T)
AMUTD(T)AMUTDD(T)BPPT(P,T)
BSPT(P,T)
BTPT(P,T)
BVPT(P,T)
CPPD(P)

17

CPPDD(P)18

CPPT(P,T)

19

CPTD(T)

20

CPTDD(T)21

CRP(‘A’)

Function and Argument(s)Range of Argument(s)ALHP: Latent Heat of Vaporization [J/kg]
P∗: Pressure [Pa], [bar]ALHT: Latent Heat of Vaporization [J/kg]
T∗: Temperature [K], [◦C]

0.018893≤P≤3.65489×106 [Pa]0.18893×10−6 ≤P≤36.5489 [bar]113.55≤T≤408 [K]−159.6≤T≤134.85 [◦ C]

CPPD: Isobaric Speciﬁc Heat of Saturated
Liquid [J/(kg·K)]
P∗: Pressure [Pa], [bar]
CPPDD: Isobaric Speciﬁc Heat of Saturated
Vapor [J/(kg·K)]
P∗: Pressure [Pa], [bar]Isobaric Speciﬁc Heat [J/(kg·K)]
P∗: Pressure [Pa], [bar]T∗: Temperature [K], [◦C]

0.018893≤P≤3.65489×106 [Pa]0.18893×10−6 ≤P≤36.5489 [bar]CPTD: Isobaric Speciﬁc Heat of Saturated
Liquid [J/(kg·K)]
T∗: Temperature [K], [◦C]
CPTDD: Isobaric Speciﬁc Heat of Saturated
Vapor [J/(kg·K)]
T∗: Temperature [K], [◦C]
CRP: Critical Constants
H: ‘A’=‘H’: 752.5×103 [J/kg] Speciﬁc EnthalpyP∗: ‘A’=‘P’: 3.65489×106 [Pa], 36.5489 [bar]Pressure
S: ‘A’=‘S’: 4.791×103 [J/(kg·K)] Speciﬁc EntropyT∗: ‘A’=‘T’: 408.0 [K], 134.85 [◦ C] Temperature
V: ‘A’=‘V’: 4.46×10−3 [m3 /kg] Speciﬁc Volume0.018893≤P≤3.65489×106 [Pa]0.18893×10−6 ≤P≤36.5489 [bar]0.018893≤P≤70×106 [Pa]TMLP(P)≤T≤700 [K]
0.18893×10−6 ≤P≤700 [bar]TMLP(P)≤T≤426.85 [◦ C]
113.55≤T≤408 [K]−159.6≤T≤134.85 [◦ C]
113.55≤T≤408 [K]−159.6≤T≤134.85 [◦ C]
one of ‘H’, ‘P’, ‘S’, ‘T’ and ‘V’288

P-PROPATH: Pure Substances and Mixtures with Fixed Composition
Table II–2.30–1 i−Butane Function (cont’d)

No.
7A
76

Name ofFunction
CVPD(P)
CVPDD(P)77

CVPT(P,T)

7B
78

CVTD(T)
CVTDD(T)

2A
2B
22
2C
2D
89

EPSPD(P)EPSPDD(P)EPSPT(P,T)
EPSTD(T)EPSTDD(T)FC(‘A’)

9A
96
95
9B
97
23

GAMPD(P)GAMPDD(P)GAMPT(P,T)
GAMTD(T)GAMTDD(T)HPD(P)

24

HPDD(P)

71
25

HPS(P,S)
HPT(P,T)26
27

HPX(P,X)
HTD(T)28

HTDD(T)

29
84

HTX(T,X)
IDENTF(‘A’)

66
68

PLDT(T)
PMLT(T)

85
86
81
87
88
99

PRPD(P)PRPDD(P)
PRPT(P,T)
PRTD(T)
PRTDD(T)PSBT(T)

Function and Argument(s)Range of Argument(s)CVPDD: Isochoric Speciﬁc Heat of Saturated
Vapor [J/(kg·K)]
P∗: Pressure [Pa], [bar]Isochoric Speciﬁc Heat [J/(kg·K)]
P∗: Pressure [Pa], [bar]T∗: Temperature [K], [◦C]

0.018893≤P≤3.65489×106 [Pa]0.18893×10−6 ≤P≤36.5489 [bar]CVTDD: Isochoric Speciﬁc Heat of Saturated
Vapor [J/(kg·K)]
T∗: Temperature [K], [◦C]

113.55≤T≤408 [K]−159.6≤T≤134.85 [◦ C]

FC: Fundamental Constants
M: ‘A’=‘M’: 58.1243 Relative Molecular Mass
R: ‘A’=‘R’: 143.05 [J/(kg·K)] Gas Constant

one of ‘M’ and ‘R’

HPD: Speciﬁc Enthalpy of Saturated Liquid [J/kg]
P∗: Pressure [Pa], [bar]HPDD: Speciﬁc Enthalpy of Saturated Vapor [J/kg]
P∗: Pressure [Pa], [bar]0.018893≤P≤3.65489×106 [Pa]0.18893×10−6 ≤P≤36.5489 [bar]0.018893≤P≤3.65489×106 [Pa]0.18893×10−6 ≤P≤36.5489 [bar]Speciﬁc Enthalpy [J/kg]
P∗: Pressure [Pa], [bar]T∗: Temperature [K], [◦C]

0.018893≤P≤70×106 [Pa]TMLP(P)≤T≤700 [K]

HTD: Speciﬁc Enthalpy of Saturated Liquid [J/kg]
T∗: Temperature [K], [◦C]HTDD: Speciﬁc Enthalpy of Saturated Vapor [J/kg]
T∗: Temperature [K], [◦C]

113.55≤T≤408 [K]−159.6≤T≤134.85 [◦ C]
113.55≤T≤408 [K]−159.6≤T≤134.85 [◦ C]

IDENTF: CHARACTER TYPE FUNCTION
for Package Identiﬁcation (Length 20)
C: ‘A’=‘C’: ‘(CH3)2CHCH3’ Molecular Formula
S: ‘A’=‘S’: ‘I-BUTANE’ Name of Substance
V: ‘A’=‘V’: ‘10.1’ Version Number

one of ‘C’, ‘S’ and ‘V’

PMLT∗: Pressure on Melting Curve [Pa], [bar]T∗: Temperature [K], [◦C]

113.55≤T≤133.107 [K]−159.6≤T≤−140.043 [◦ C]

0.018893≤P≤70×106 [Pa]TMLP(P)≤T≤700 [K]
0.18893×10−6 ≤P≤700 [bar]TMLP(P)≤T≤426.85 [◦C]

0.18893×10−6 ≤P≤700 [bar]TMLP(P)≤T≤426.85 [◦C]

i-Butane

289
Table II–2.30–1 i−Butane Function (cont’d)

No.
30

Name ofFunction
PST(T)

72
73
313233

PSTD(T)
PSTDD(T)SIGP(P)
SIGT(P)
SPD(P)34

SPDD(P)35

SPT(P,T)36
37

SPX(P,X)
STD(T)38

STDD(T)

39
67
69

STX(T,X)
TLDP(P)
TMLP(P)

64
6H
65
6S
98
70
41

TPH(P,H)
TPH2(P,H)
TPS(P,S)
TPS2(P,S)TPSEUP(P)TPV(P,V)
TRPL(‘A’)

100
40

TSBP(P)TSP(P)

7475
42

TSPD(P)TSPDD(P)UPD(P)43

UPDD(P)

7944

UPS(P,S)
UPT(P,T)45

UPX(P,X)

Function and Argument(s)Range of Argument(s)PST∗: Saturation Pressure [Pa], [bar]T∗: Temperature [K], [◦C]

113.55≤T≤408 [K]−159.6≤T≤134.85 [◦ C]

SPD: Speciﬁc Entropy of Saturated Liquid[J/(kg·K)]
P∗: Pressure [Pa], [bar]SPDD: Speciﬁc Entropy of Saturated Vapor[J/(kg·K)]
P∗: Pressure [Pa], [bar]Speciﬁc Entropy [J/(kg·K)]
P∗: Pressure [Pa], [bar]T∗: Temperature [K], [◦C]

0.018893≤P≤3.65489×106 [Pa]0.18893×10−6 ≤P≤36.5489 [bar]STD: Speciﬁc Entropy of Saturated Liquid[J/(kg·K)]
T∗: Temperature [K], [◦C]
STDD: Speciﬁc Entropy of Saturated Vapor[J/(kg·K)]
T∗: Temperature [K], [◦C]

113.55≤T≤408 [K]−159.6≤T≤134.85 [◦ C]

TMLP∗: Temperature on Melting Curve [K], [◦ C]
P∗: Pressure [Pa], [ bar]0.018893≤P≤70×106 [Pa]0.18893×10−6 ≤P≤700 [bar]TRPL∗: Properties at Triple PointP∗: ‘A’=‘P’: 0.018893 [Pa], 0.18893×10−6 [bar]PressureT∗: ‘A’=‘T’: 113.55 [K], −159.60 [◦ C] Temperature

one of ‘P’ and ‘T’

TSP∗: Saturation Temperature [K], [◦ C]
P∗: Pressure [Pa], [bar]0.018893≤P≤3.65489×106 [Pa]0.18893×10−6 ≤P≤36.5489 [bar]UPD: Speciﬁc Internal Energy of Saturated
Liquid [J/kg]
P∗: Pressure [Pa], [bar]UPDD: Speciﬁc Internal Energy of Saturated
Vapor [J/kg]
P∗: Pressure [Pa], [bar]0.018893≤P≤3.65489×106 [Pa]0.18893×10−6 ≤P≤36.5489 [bar]Speciﬁc Internal Energy [J/kg]
P∗: Pressure [Pa], [bar]T∗: Temperature [K], [◦C]

0.018893≤P≤70×106 [Pa]TMLP(P)≤T≤700 [K]

0.018893≤P≤3.65489×106 [Pa]0.18893×10−6 ≤P≤36.5489 [bar]0.018893≤P≤70×106 [Pa]TMLP(P)≤T≤700 [K]
0.18893×10−6 ≤P≤700 [bar]TMLP(P)≤T≤426.85 [◦C]

113.55≤T≤408 [K]−159.6≤T≤134.85 [◦ C]

0.018893≤P≤3.65489×106 [Pa]0.18893×10−6 ≤P≤36.5489 [bar]0.18893×10−6 ≤P≤700 [bar]TMLP(P)≤T≤426.85 [◦C]

290

P-PROPATH: Pure Substances and Mixtures with Fixed Composition
Table II–2.30–1 i−Butane Function (cont’d)No.
46

Name of
Function
UTD(T)

47

UTDD(T)

48
49

UTX(T,X)
VPD(P)50

VPDD(P)

80
51

VPS(P,S)
VPT(P,T)

52
53

VPX(P,X)
VTD(T)54

VTDD(T)

55
8E
8F
83

VTX(T,X)
WPD(P)WPDD(P)
WPT(P,T)

8G
8H
56
57
58
59
60
61
62
63

WTD(T)WTDD(T)
XPH(P,H)
XPS(P,S)
XPU(P,U)
XPV(P,V)XTH(T,H)
XTS(T,S)XTU(T,U)XTV(T,V)

Function and Argument(s)Range of Argument(s)UTD: Speciﬁc Internal Energy of Saturated
Liquid [J/kg]
T∗: Temperature [K], [◦ C]
UTDD: Speciﬁc Internal Energy of Saturated
Vapor [J/kg]
T∗: Temperature [K], [◦ C]

113.55≤T≤408 [K]−159.6≤T≤134.85 [◦ C]

VPD: Speciﬁc Volume of Saturated Liquid [m3/kg]
P∗: Pressure [Pa], [bar]VPDD: Speciﬁc Volume of Saturated Vapor [m3 /kg]P∗: Pressure [Pa], [bar]0.018893≤P≤3.65489×106 [Pa]0.18893×10−6 ≤P≤36.5489 [bar]0.018893≤P≤3.65489×106 [Pa]0.18893×10−6 ≤P≤36.5489 [bar]Speciﬁc Volume [m3 /kg]P∗: Pressure [Pa], [bar]T∗: Temperature [K], [◦ C]

0.018893≤P≤70×106 [Pa]TMLP(P)≤T≤700 [K]

VTD: Speciﬁc Volume of Saturated Liquid [m3 /kg]
T∗: Temperature [K], [◦ C]
VTDD: Speciﬁc Volume of Saturated Vapor [m3 /kg]
T∗: Temperature [K], [◦ C]

113.55≤T≤408 [K]−159.6≤T≤134.85 [◦ C]
113.55≤T≤408 [K]−159.6≤T≤134.85 [◦ C]

Velocity of Sound [m/s]P∗: Pressure [Pa], [bar]T∗: Temperature [K], [◦ C]

0.018893≤P≤70×106 [Pa]TMLP(P)≤T≤700 [K]

113.55≤T≤408 [K]−159.6≤T≤134.85 [◦ C]

0.18893×10−6 ≤P≤700 [bar]TMLP(P)≤T≤426.85 [◦C]

0.18893×10−6 ≤P≤700 [bar]TMLP(P)≤T≤426.85 [◦C]