Designing and Numerical Analysis of Capillary Tube Thermal Mass Flowmeter as a Residential Natural Gas Meter

Accurate natural gas measurement is an important issue especially in domestic usage levelCapillary tube thermal mass flow meter is one of the most common types of mass flow meters which are mostly used for low mass flow rates. In this work, a capillary tube flow meter was simulated numerically. A three-dimensional steady state heat transfer in its sensor tube was numerically analyzed and the sensitivity of this type of flow meter was investigated. In order to validate the simulation approach and conditions taken in this study, the simulation was also accomplished for Nitrogen, for which experimental data was available in the literature, leading to satisfactory results. Considering all the possible effective parameters, the uncertainty of the flow meter was also calculated. Numerical results show that the maximum amount of uncertainty in measurement for this type of flow meter is less than 1.24% that is acceptable for residential customers.