Simulation approach of chamber purging experiment by nitrogen gas

Abstract

Chamber purging is usually required in a gas sensing research, in order to make a perfect dry air condition (Relative Humidity/RH = 0%) in the chamber. An experiment shows that RH of the cylindrical chamber (volume = 7.5 cm3) never touch 0% (only 32% and 4%) although it was purged by 100 and 300 sccm of synthetic air (consists of 20% O2 and 80% of N2). It was also obtained the same condition when N2 gas was used instead of synthetic air. In order to understand this experiment’s results, a simulation has been done. The simulation approach using a box-form chamber (volume = 9.6 cm3) shows that the combination of the diffusion-convection process of N2 gas is responsible for the results of the chamber purging experiment instead of pure diffusion or pure convection. For the future step, it is needed further investigation (experiment and simulation) in order to reach 0% RH.