Further discussion on uncertainty evaluation of indirect measurement of natural gas calorific value: uncertainty evaluation of compression factor under reference condition

The uncertainty of compression factor on reference condition is a big source to the uncertainty evaluation of indirect calorific value measurement according to the earlier study, it contributes a lot to the uncertainty of calorific value. On the other hand, the uncertainty of compression factor on reference condition is also applied in the volumetric measurement of natural gas. The calculation formula of natural gas is analyzed and derived in order to get the evaluation formula of compression factor. With the help of reference article, the uncertainty source is evaluated as type A or type B uncertainty. These two steps make a whole procedure to the uncertainty evaluation of compression factor on reference condition. The influence of different uncertainty of composition on the uncertainty of compression factor is tested by simulative calculation. With difference orders of magnitude composition uncertainty, compression factor uncertainty comes out to be quantitative.