Errata of ISO 12213-2: 2006 and AGA Report 8:

1992

Masahiro Ishibashi

NMIJ/AIST

4th workshop CFVN, Poitiers

20 Sep., 2013

Gas Flow Standards Sec., Fluid Flow Div.,

(Compressibility factor of natural gas)

Calculation of Z factor of NG

AGA8-92DC equation .... most accurate method

Calculation of Z factor of NGZ of ISO sample gases calculated

Gas1 is OK.

Gas2~0.2%

Gas3~0.3%

Gas4~0.15%

Gas5~1%

Gas6~0.5%

exactly according to the ISO.

Calculation of Z factor of NGConflictions

between ISO text equation, AGA text equation and ISO sample program

AGA :

ISO:

missing x2

?

Calculation of Z factor of NGConflictions

between ISO text equation and ISO sample program

ISO:

AGA :

J from I

?

x2 when i<>j

?

AGA8-92DC equationErrata

Any other ISO equations are fine.

N

i

N

jji

uijnijji

u

nn KKEBxxTaB nn

1 1

23*18

1

2thenif

1thenif18

1

21

1

2123*

cj

cjiKKEBxxcTaB

n i ijji

uijnijji

un

nn

(B.1)

1

1 1

255

2

1

255 1N

i

N

ijjiijji

N

iii EEUxxExU

8

1

19

1

255

221

1

255 12i ij

jiijjii

ii EEUxxExU

(B.6)

By modified AGA8-92DC equation

All sample error.

220 Z values / 10 gases

Calculation agreed with the sample values, but...

Hoping #1 is the case..., but I’m theoretically not sure...

two (or three?) possibilities.

Equations Sample Values

case #1

case #2

wrong correct

correct wrong

wrongwrongcase #3