Objective China current standardized algorithms lack consistency in simultaneously ensuring reasonable uncertainty bounds and computational efficiency when determining viscosity, Joule-Thomson coefficient and isentropic exponent for natural gas applications under varying operational conditions. To improve the measurement accuracy of orifice plate flowmeters across diverse operating scenarios, this study proposes a unified computational framework for precisely determining these thermodynamic properties in flow measurement applications.

Method Combined with the natural gas composition in China, this work carried out the standard adaptability analysis for viscosity, Joule-Thomson coefficient, and isentropic exponent by comparing the calculated values of the equations in ISO 20765-5: 2022 Natural gas—Calculation of thermodynamic properties-Part 5: Calculation of viscosity, Joule-Thomson coefficient, and isentropic exponent with the data from the working conditions in China as well as literature research.

Result The equations in ISO 20765-5:2022 were applicable for calculating viscosity, Joule-Thomson coefficient, and isentropic exponent of pipeline natural gas in China under both the recommended and exceeded conditions outlined in ISO 20765-5:2022.

Conclusion The transformation of ISO 20765-5:2022 will be conducive to improving the algorithm standard system and calculation efficiency of viscosity, Joule-Thomson coefficient, and isentropic exponent in the natural gas metering process in China, and providing a crucial standard guarantee for the natural gas flow metering.