Decalin, which is promising a gas-to-liquid (GTL) fuel through its efficient direct conversion from methane, has properties appropriate for a diesel fuel. With neat decalin, smoke is remarkably reduced without sacrifices in brake specific energy consumption (BSEC) when compared with ordinary diesel fuel, and low nitrogen oxide (NOx) is maintained by exhaust gas recirculation (EGR) and at retarded fuel injection timings. The lower smoke emission with decalin is due to its lower ignitability, making it possible to complete fuel injection early in the combustion stage and to decrease the quantity of fuel directly injected into the hot flame zone. With 20% addition of either cyclohexane or n-hexane to decalin, BSEC and smoke improve while NOx increases slightly. In particular, cyclohexane addition significantly reduces smoke emissions. Compared with ordinary diesel fuel, the tradeoffs between smoke and NOx and between BSEC and NOx are remarkably improved with decalin—cyclohexane blends and the application of EGR.
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