Fundamental studies on effect of ozone injection to the internal-combustion engine - FTIR spectra of hydrocarbon compound exposed to ozone -
Yagyu, Yoshihito; Nobuya, Hayashi; Kawasaki, Hiroharu; Ohshima, Tamiko; Suda, Yoshiaki; Baba, Seiji
Japan

<1. Introduction> Alternative energy sources for automobile, such as hydrogen, bio-diesel fuel (BDF), dimethyl ether (DME) and ethanol, are widely studied and some of them have been developed to a practical level. Also, effective uses of a fuel to an internal combustion engine have been studied. It was reported that cetane number improved when ozone was injected to a compression ignition engine (T. Tachibana et. al: Combustion and flame, 85, 515 (1991)). We analysed the FTIR spectra of the mixture gas composed of petrol and air/O2 exposed to discharge.
<2. Experiment> The gases were blended in the jar that was simply copied induction stroke of a four-stroke cycle engine. Discharge was generated on the surface of a discharge element that was made of thin-gritted tungsten electrode fixed on BaTiO3 plate. The discharge voltage was applied by high AC voltage power supply (Logy Electric Co., LHV-13AC) and varied from 8.0 to 13.0 kV (with 9~11 kHz in frequency). The mixture gas was analysed by FTIR (Shimadzu, FTIR-8900) with 24 m long-path distance gas cell.
<3. Results and discussion> The FTIR spectra of the mixture gas indicated that the by-product at 1750 cm-1 was generated and also around 890cm-1 and 970cm-1 were disappeared after injecting air/O2 exposed to discharge. It is found that the composition of the vaporised petrol was chemically changed with the discharged air/O2. The generation rate of the by-product around 1750 cm-1 strongly relates with ozone concentration. It was suggested that ozone is the major molecule reacting with vaporised petrol. A candidate for the by-product detected at around 1750 cm-1 is C8H16O or/and C8H16O2 because they indicate similar FTIR spectra of the by-product. The air exposed to discharge tended to easily produce the by-product in the fact that the generation rate of air was about 10 % higher than O2. Other gases in the discharged air maybe assist to generate the by-product. Moreover, unconsumed ozone was observed when injected ozone was more than approximately 2 g/m3 in this study.
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