Objective The aims are to measure the calorific value of natural gas accurately and achieve a fair and accurate natural gas trade.

Methods Based on the principle of the fixed-mass open flame combustion method, a direct measurement experimental platform of natural gas calorific value is designed, which has an extended uncertainty better than 0.3% (k=2). Based on the theoretical formula of calorific value, a mathematical model for measuring the calorific value of natural gas is established. Considering the economic cost comprehensively, the measurement equipment with appropriate technical indicators is selected. The uncertainty of the direct measurement experiment platform of natural gas calorific value is evaluated by taking methane as the gas sample, the feasibility of the development of the experimental platform is confirmed, and the contribution rate of each uncertainty component is analyzed.

Results The uncertainty of measuring methane calorific value is 0.27%(k=2).

Conclusions The uncertainty of measuring methane calorific value meets the value traceability of the calorific value of the commonly used 1.0 level and below calorific value meter, which lays a foundation for the establishment of the experimental platform.