Effect of ambient pressure on local concentration measurement of transient hydrogen jet in a constant-volume vessel using spark-induced breakdown spectroscopy. (13th April 2015)

• Record Type: Journal Article
• Authors: Abdul Rahman, Md Tasyrif; Kawahara, Nobuyuki; Tsuboi, Kazuya; Tomita, Eiji
• Is Part Of: International journal of hydrogen energy. Volume 40:Number 13(2015)
• Page Start: 4717
• Page End: 4725
• Publication Date: 2015-04-13
• Subjects: Hydrogen -- Direct injection -- Spark ignition -- Spark induced breakdown spectroscopy -- Local fuel concentration -- Ambient pressure; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2015.01.121
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: We report an investigation of the effects of the ambient pressure on fuel concentration measurements of an injected jet of hydrogen using spark-induced breakdown spectroscopy (SIBS) in a constant-volume vessel. Measurements were carried out using hydrogen injected into a nitrogen environment with different ambient pressures, and the local concentrations were measured at various spark locations. The optical emission from the spark discharge at 501 nm (corresponding to nitrogen) and 656 nm (corresponding to hydrogen) was observed using SIBS. Spectrally resolved emission from the plasma was detected simultaneously using a spectrometer. The potential to determine the hydrogen/nitrogen ratio in the spark gap using was demonstrated. Spectral calibration was carried out using a hydrogen/nitrogen mixture, and hydrogen was injected at a pressure of 5.0 MPa into nitrogen with ambient pressures in the range 0.5–1.5 MPa. The results show an increase in the background radiation, as well as of the peaks corresponding to hydrogen and nitrogen atomic emission lines, as the ambient pressure increased. An increase in the density of nitrogen inside the chamber influenced the structure of the hydrogen jet, slowing the spray and reducing penetration, which altered the equivalence ratio at the location of the spark. When the spark occurred during injection, the behavior of the hydrogen jet was quasi-steady state; when the spark timing followed the injection, however, an unsteady state was observed. Highlights: Atomic emission spectrum of hydrogen Hα (656 nm) and nitrogen N(I)(501 nm) was observed with SIBS sensor. Effect of ambient pressure on mixing ratio was determined from spectral ratio of Hα and N(I). Distribution of the equivalence ratio was obtained in the hydrogen jet. Ambient pressure affected the hydrogen jet structure and hydrogen/nitrogen mixing.