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http://dx.doi.org/10.3795/KSME-B.2013.37.12.1167

Evaluation of Critical Flow Function by Using Helmholtz Free Energy for Natural Gas Flow Measurement  

Ha, Young-Cheol (Gas Quality and Flow Measurement Lab, R&D Division, Korea Gas Corporation)
Her, Jae-Young (Gas Quality and Flow Measurement Lab, R&D Division, Korea Gas Corporation)
Publication Information
Transactions of the Korean Society of Mechanical Engineers B / v.37, no.12, 2013 , pp. 1167-1173 More about this Journal
Abstract
This study aimed to calculate the CFFs (critical flow functions) of a sonic nozzle bank with a 12-nozzle package within 1 s. Toward this end, the Helmholtz free energy of natural gas was formulated by using the AGA8-dc equation of state in a form without integral terms, and thereafter, thermodynamic properties such as the enthalpy, entropy, speed of sound, and heat capacity, which are used in CFF calculation, were derived in analytical form. As a result, the calculation time of CFFs was improved from 6.7 s in a previous study to 0.6 s per 12-nozzle package and kept almost constant regardless of the number of components in natural gas. Furthermore, it was confirmed that the calculated CFF values were in agreement with the results of a CFF international comparison test carried out under ISO management in 1998-1999.
Keywords
Critical Flow Function; Natural Gas; Flow Measurement; Helmholtz Free Energy; Sonic Nozzle; Critical Flow Venturi Nozzle; Calibration;
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  • Reference
1 Savidge, J. L. and Starling, K. E. 1994, "Compressibility Factors of Natural Gas and Other Related Hydrocarbon Gases," AGA Report No. 8, American Gas Association, Arlington, Virginia (USA).
2 Park, K. A., 1998, Korea Research Institute of Standards and Science, Daejon City, Private Communication.
3 Johnson, A. N., 2004, "Uncertainty and Traceability for the CEESI Iowa Natural Gas Facility," J. Res. Natl. Inst. Stand. Technol., Vol. 109, No. 3, pp. 345-369.   DOI
4 Ha, Y. C. and Her, J. Y., 1999, "Evaluation of Critical Flow Factor in Natural Gas Flow Measurement Using Sonic Nozzle and International Comparison Results," Trans. Korean Soc. Mech. Eng. B, Vol. 23, No. 7, pp. 911-917.
5 Kunz, O., Klimech, R., Wagner, W. and Jaeschke, M., 2007, "The GERG-2004 Wide-Range Equation of State for Natural and Other Mixtures," GERG Technical Monograph 15, Groupe Europeen de Recherches Gazieres, Reihe 6 Nr. 557(Germany).
6 Schley, P., Jaeschke, M. and Busch, C., 1998. "Berechnung kaorische Zustandsgroben von Erdgasen mit," gwf-Gas/Erdgas Vol. 139, No. 11, pp. 714-719.
7 Aly, F. A. and Lee, L. L., 1981, "Self Consistent Equations for Calculating the Ideal gas Heat Capacity, Enthalpy and Entropy," Fluid Phase Equilibria, Vol. 6, pp. 169-179.   DOI   ScienceOn
8 Macfall, R. L., 1984, "Sonic Nozzle Flow Calculations for Natural Gas Using a Generalized Equation of State," Master thesis, University of Oklahoma, Norman, Oklahoma(USA).
9 Jaeschke, M. and Schley, P., 1995, "Ideal-Gas Thermodynamic Properties for Natural-Gas Applications," Int. J. Thermophys. Vol. 16, No. 6, pp 1381-1392.   DOI