St 0 X ni Ii S1 1 Ji TJ

i d0 '

/A

~d20 "

/A

' d0 '

/A

d20 "

/A

' d20 "

S

[ dT2 J

S

dSdT

Equation (28) covers region 3 of IAPWS-IF97 defined by the following range of temperature and pressure, see Fig. 1:

623.15 K < T < T(p)^) p( T)Eq.(5) < p < 100 MPa . In addition to the properties in the stable single-phase region defined above, Eq. (28) also yields reasonable values in the metastable regions (superheated liquid and subcooled steam) close to the saturated liquid and saturated vapor line.

Computer-program verification

To assist the user in computer-program verification of Eq. (28), Table 33 contains test values of the most relevant properties.

Table 33. Thermodynamic property values calculated from Eq. (28), for selected values of Tand pa

T = 650 K, T = 650 K, T = 750 K, p = 500 kg m-3 p = 200 kg m-3 p = 500 kg m-3

T = 650 K, T = 650 K, T = 750 K, p = 500 kg m-3 p = 200 kg m-3 p = 500 kg m-3

Table 33. Thermodynamic property values calculated from Eq. (28), for selected values of Tand pa

p/ MPa

0.255 837 018

X

102

0.222 930 643

X

102

0.783 095 639

X

102

h/ (kJ kg-1)

0.186 343 019

X

104

0.237 512 401

X

104

0.225 868 845

X

104

u/ (kJ kg-1)

0.181 226 279

X

104

0.226 365 868

X

104

0.210 206 932

X

104

s/(kJ kg-1 K-1)

0.405 427 273

X

101

0.485 438 792

X

101

0.446 971 906

X

101

cp/(kJ kg-1 K-1)

0.138 935 717

X

102

0.446 579 342

X

102

0.634 165 359

X

101

w/ (m s-1)

0.502 005 554

X

3 103

0.383 444 594

X

3 103

0.760 696 041

X

3 103

a It is recommended to verify programmed functions using 8 byte real values for all three combinations of T and p given in this table.

a It is recommended to verify programmed functions using 8 byte real values for all three combinations of T and p given in this table.

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