FUEL CONSUMPTION AND EMISSION MODELLING BY POWER DEMAND

A fuel consumption model based upon the instantaneous power demand experienced by a vehicle has been developed from chassis dynamometer experiments on 177 in-use Australian vehicles. When applied to an individual vehicle, the model provides aggregate fuel consumption estimates for on-road driving which are within 2 per cent of the actual measured fuel usage. Emission rate models for hydrocarbons and nitrogen oxides which are of the same form as the fuel consumption model are also presented. The vehicle model can be applied in any traffic situation provided on-road power demand is known. On-road instantaneous power demand is derived from the vehicle's mass, drag, velocity, acceleration and road gradient. 1929 km and 2778 links of traffic driving pattern data for both urban and non-urban trips are reviewed. Correlations between the link power and traffic parameters are presented and it is shown that vehicle link fuel consumption and emissions can be accurately calculated from vehicle mass, engine capacity, link average velocity, link average positive inertial power, link altitude change and link trip time. In the non-urban case, link power, and hence fuel consumption and emissions, are not dependent upon positive inertial power. Road gradients in Sydney are shown to contribute only 5 per cent on average to the total trip power demand and in terms of the fleet averaged fuel consumption, this represents an increase of only 3 per cent. For the abstract of the covering entry see TRIS no. 378221. (Author/TRRL)