Research progress of the primary gas calorimeter

The progress on the primary gas calorimeter is reviewed. In the whole system of the traceability of the energy metering of natural gas, the primary gas calorimeter was employed for the determination of the calorific value of pure gases, the basic data for the calculation of the calorific value of natural gas based on their composition, which makes the calorific value traceable to SI units. On the other hand, the primary gas calorimeter can also be used to determine the calorific values of mixed gases for the calibration or validation of other measurement methods. There are two stages for the development of the primary gas calorimeter. In the first stage, the original Rossini gas calorimeter and other work followed were founded, and the uncertainty of calorific value of methane is about 0.15%. In the second stage, the revised Rossini gas calorimeter has been founded and its uncertainty is about 0.05%. But the determination of the calorific value of other pure gases except methane and mixed gases by the primary gas calorimeter remain to explore.