Using gas-chromatography, the authors developed a unique technique called ‘NPgram’ to characterize the hydrocarbon fuel oil. The notation ‘NPgram’ stands for Normal Paraffin gram.
It is obtained by plotting the weight percent of a group of hydrocarbons, which are located within the range of retention values of two successive normal paraffins (Cn-1 and Cn), against the carbon number (n). As the carbon number (n) corresponds to the boiling point range of a group of compounds, NPgram (C-NPgram) actually represents a boiling point distribution, when it is applied for fuel oils composed of aliphatic compounds.
In this work we applied this C-NPgram technique to characterize coal derived oils which are mostly composed of aromatics. And analogous to C-NPgram, the carbon number distributions of S, N, Cl and O-compounds in coal derived oils were also shown. We defined them by ‘S-NPgram’, ‘N-NPgram’, ‘Cl-NPgram’ and ‘O-NPgram’. The NPgrams of these heterogeneous compounds were obtained by plotting the amount of heterogeneous compounds determined by a GC-AED (Atomic Emission Detector) against the carbon number (n).

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Given that the atmospheric emission of CO₂ is the worst cause of global warming, improving automobile fuel consumption can have positive effects on the reduction of CO₂ emissions. The idling stop campaign has been suggested to accomplish this goal because it can decrease the fuel consumption and the exhaust emissions for all conventional gas engine vehicles. To measure the fuel consumption effect of short-time idling stops with the traffic signal, a comparative study has been conducted using two 1498 cc gas engine vehicles and their road performance has been analyzed. Based on our analyses, we have formulated the following equation that can predict the amount of fuel saved when the idling stop campaign is exercised:
F_s=I× (∑T_is)-S₂× (N_is)
where F_s (cc): Saved fuel consumption, I (cc/s): Idling fuel consumption, T_is (s): Idling Stop period, S₂ (cc): Additional fuel consumption by restarting, N_is: Idling stop times.
Also we have proposed a new evaluation parameter, i.e., limited effecting idling stop time (LEIST) and used it as an index for the maximum efficiency duration of idling stop.Our performance test showed I=0.17 (cc/s) and S₂=1.2 (cc), which indicated the tested vehicle's LEIST was 7.0 seconds, a close approximation of the result obtained in our experiment.

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