| In recent years, Fischer-Tropsch diesel fuel (F-T) as an excellent alternative fuel for diesel engine has attracted considerable attention. To shed light of the main drawbacks in F-T application, series of investigations have been carried out in this work, which cover the spray and combustion characteristics of F-T diesel, the effects of F-T on the engine performance and exhaust pollutants in detail and the comprehensive evaluations of F-T particle matter toxicity. The data derived from this study will provide the scientific fundamentals for the acceptance of F-T in the future, and the main contributions are listed as follows:1. The effects of the fuel injection pressure and ambient pressure have been studied on the spray characteristics of F-T, such as spray angle and spray tip penetration etc.. F-T spray distance increases with an enhancement of injection pressure, and drops with an increase of ambient pressure. The incremental fuel injection pressure and ambient pressure results in an increase of spray angle. Under the same conditions, the spray tip penetration of F-T is shorter than that of low sulfur diesel (LSD), while the spray angle of F-T is larger than that of LSD. Moreover, the differences of combustion characteristics between F-T and LSD have been compared. During the pilot injection period, except for a lower heat release peak for F-T, the ignition delay and combustion duration period of F-T are shorter than those of SLD by 14% and 50%, respectively. However, the similar combustion characteristics for both F-T and SLD can be observed during the main injection period.2. Using a high-pressure common rail diesel engine, the influences of F-T on the engine properties and regulated exhaust pollutants have been investigated. Compared with SLD, F-T leads to a decrease by 1.1% in engine rated power, a decrease by 7.1% in full-load specific fuel consumption, and an increase by 4.5% in thermal efficiency respectively. At European steady state cycle (ESC), the particle matter (PM)、carbon monoxide (CO)、hydrocarbon (HC) and nitrogen oxide (NOx) emissions for F-T are lower than those for SLD by 25.5%, 33.9%, 39.3% and 11.7%, respectively. The use of F-T hardly affects the number concentration of PM, but the particle size for F-T is smaller than that for SLD.3. Carbonyl compounds (CBCs) and polycyclic aromatic hydrocarbons (PAHs) from the exhaust emissions of F-T diesel engine are analyzed qualitatively and quantitatively with advanced chemical analysis approaches. The total amount of CBCs yielded by F-T is higher than that by LSD. Among all of the CBCs arising from F-T, formaldehyde, acetaldehyde and acetone are found to be the most abundant carbonyl, and the sum of the three carbonyls accounts for over 70% of the total CBCs. Individual emission of the three carbonyls decreases with the increase of engine load. The total amount of PAHs produced by F-T is lower than that by LSD. Among all of PAHs for F-T, phenanthrene, fluoranthene and pyrene are found to be the most abundant. The sum of the three constitutes over 80% of the total PAHs. On the whole, each of the three gives a dropping trend with the increase of engine load.4. Toxicities of particulate materials (PMs), resulting from the combustion of F-T, LSD and the mixture of both in diesel engine, have been evaluated by the containing cell proliferation, cycle and apoptosis, migration in vitro, protein expression, as well as the enzyme-linked immunosorbant assay (ELISA) of human bronchial epithelial cells (HBE). The results obtained show that there are no significant differences in toxicities among three kinds of PMs. Nevertheless, these PMs inhibit the cell growth, influence the formation of cell DNA, promote the cell early apoptosis, and impair the ability of the cell invading the nutrition region. |
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