• Journal of Energy Engineering
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• v.17 no.4
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• pp.182-188
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• 2008

This paper is to compare the carbon-balanced and liner air-fuel ratio determination methods for alternative fuels. In the previous work, expansion of Eltinge chart, unburned hydrocarbon compensation, comparison of the results from various methods were discussed. It has been also concluded that Eltinge method might be regarded as the most general equation of AFR determination among the existing ones. In the recent years, however, increasing demand for the environmental preservation, including global warming-up protection, and energy conservation lead to introduce the alternative fuel to the internal combustion engine. Therefore, the exact calculations of AFR for these fuels are needed. Especially, for the fuel that contains oxygen, all AFR calculation equations except Eltinge have to be re-formulated. In this paper, the AFR for alternative fuel were calculated by re-formulated carbon balance, accuracy of which was already confirmed, and linear equations, which are newly proposed by statistical method for each fuel. The results show that AFRs based on carbon balance have a little more error compared with gasoline, however, the accuracy is enough for this formula to apply to various fuel. The proposed linear equation also have excellent accuracy below $\lambda=1.2$.