Overview
SIST EN ISO 20765-2:2018 is an international standard developed by CEN and ISO that specifies a method for the calculation of thermodynamic properties of natural gases, manufactured fuel gases, and similar mixtures. Part 2 of this standard provides a comprehensive approach to compute the volumetric and caloric properties of these gases in single-phase conditions-whether in the gas, liquid, or supercritical (dense fluid) state. This standard facilitates accurate property determination over extended ranges of temperature, pressure, and composition, essential for gas analysis, processing, and transportation.
The standard is particularly valuable for the gas industry as it enables the reliable calculation and comparison of different property parameters, such as density, enthalpy, heat capacity, and speed of sound, across various operational scenarios, including those beyond the scope of traditional methods.
Key Topics
- Thermodynamic Properties Calculation: EN ISO 20765-2 defines detailed methodologies for calculating both volumetric (e.g., density and compression factor) and caloric (e.g., enthalpy, heat capacity) properties for single-phase fluids.
- Extended Ranges of Application: The standard supports property calculation for a wide range of gas mixtures, including those with atypically high levels of nitrogen, carbon dioxide, ethane, or hydrogen, and for pure components and binary or multi-component mixtures.
- Helmholtz Free Energy Approach: The calculation method is based on the Helmholtz free energy function, allowing comprehensive thermodynamic property derivation from fundamental principles.
- Accuracy and Uncertainty: EN ISO 20765-2 offers high accuracy, with volumetric property uncertainty typically ≤0.1%. This reliability extends to caloric properties and the speed of sound within homogeneous states.
- Component Analysis: A detailed and accurate molar composition analysis is required-typically using a 21-component model-which covers all major and most minor natural gas constituents.
Applications
SIST EN ISO 20765-2:2018 serves various practical purposes in the natural gas and fuel gas sectors:
- Gas Transmission and Distribution: Supports pipeline operators and network designers by providing accurate property values for safety assessments, network modeling, and system optimization.
- LNG Production and Processing: Facilitates the precise calculation of liquefied natural gas properties under varying temperature and pressure conditions, crucial for storage, transportation, and conversion processes.
- Gas Analysis and Quality Control: Enhances laboratory and industrial measurement accuracy for gas composition and behavior, supporting compliance with industry regulations and contractual obligations.
- Research and Product Development: Enables process engineers and researchers to simulate and optimize systems involving gas mixtures with atypical or variable compositions.
- Environmental and Safety Applications: Assists in evaluating scenarios like carbon dioxide sequestration and hydrogen-rich gas streams for emerging energy and environmental technologies.
Related Standards
Implementing SIST EN ISO 20765-2:2018 often involves cross-referencing other international standards for a complete and robust approach:
- ISO 20765-1: Natural gas - Calculation of thermodynamic properties - Part 1: Gas phase properties for transmission and distribution applications.
- ISO 7504: Gas analysis - Vocabulary.
- ISO 14532: Natural gas - Vocabulary.
- ISO 80000-5: Quantities and units - Part 5: Thermodynamics.
These standards collectively ensure the consistency and reliability of gas property calculations and terminology across the industry.
Keywords: SIST EN ISO 20765-2:2018, natural gas, thermodynamic properties, single-phase properties, volumetric properties, caloric properties, gas analysis, Helmholtz free energy, natural gas standard, gas mixture calculation, LNG, CEN, ISO standards, gas phase, liquid phase, dense fluid, extended range gas properties.
