Numerical Analysis of Concentration Fluctuation in a Sampling Tube for Fast-Response Flame Ionization Detector

Abstract

To measure concentration fluctuation accurately by a fast-response flame ionization detector (FFID), the frequency response function should be known, and measured signals need to be compensated appropriately. In the present study, we numerically analyzed the convection and diffusion equations of concentration developing in a laminar pipe flow. Then, we have obtained the response functions of the cross-sectional mean concentration at several downstream locations by varying the frequency of concentration fluctuation at the inlet of the pipe. It is found that the theoretical and numerical results are in good agreement. Based on the response function obtained, we may compensate the attenuated concentration signals rationally.