Mass analysis of CH4/SO2 gas mixture by low-pressure MEMS gas sensor

Abstract

The mass analysis of natural gas for the extraction and separation of the undesirable component such as sulfur dioxide is significant for industrial applications. In this research, numerical simulations are performed to investigate the capability of the Knudsen thermal force for the detection of sulfur dioxide in CH4/SO2 gas mixture. Recently, a new micro gas sensor (MIKRA) is introduced to apply this force for measurement of the pressure. In fact, this device operates due to temperature difference inside a rectangular enclosure with heat and cold arms at low pressure condition. In order to simulate a rarefied gas inside the micro gas detector, Boltzmann equations are applied to obtain high precision results. To solve these equations, Direct Simulation Monte Carlo (DSMC) approach is used as a robust method for the non-equilibrium flow field. This study has focused on the effect of various concentrations of the CH4/SO2 gas mixture and reveals the main mechanism of force generation inside the device. Our findings show that value of generated Knudsen force significantly changes when the fraction of SO2 in CH4/SO2 gas mixture is varied. This indicates that this micro gas sensor could precisely detect the concentration of sulfur dioxide gas inside a low-pressure CH4/SO2 gas mixture.