Positive size-effect on the sensitivity of a planar counter-current micro flame ionization detector

To reduce fuel gas consumption, a planar counter-current micro flame ionization detector (μFID) has been developed for mobile applications. In this work, the effect of flame chamber size on the μFID sensitivity is investigated. An FEM model is presented, which predicts sensitivity. The model shows that smaller chambers result in more confined flammable mixtures. Flame observations confirm that smaller chambers generate brighter flames. In addition, sensitivity turns out to be inversely proportional to the distance between the opposing nozzles. Consequently, the smallest flame chamber is most sensitive. At a fourth of the hydrogen consumption (7.5 ml/min), sensitivity is only two times smaller (7.3 mC/gC) than conventionally.