Abstract
Heavy road vehicles contribute markedly to the air pollution as well as energy consumption of road traffic. However, information about their fuel consumption and air polluting emissions in a format that relates to their real-world operations and duty-cycles is very scarce, even if there is a growing need for that amongst both public and private parties. To alleviate this need, VTT has since 2002 worked with a full-scale chassis dynamometer suitable for simulations of heavy truck and bus operations. The facility allows accurate determination of energy consumption and exhaust pollution over any transient duty-cycle. Furthermore, even uphill/ downhill gradients are included, allowing very realistic simulations of real-world routes.
When performing simulations on a chassis dynamometer, important key issues are correct setting of the vehicle road load, and use of a duty-cycle that relates itself to the real-world operations of the vehicle. VTT has developed methodology how to experimentally determine the road load of a complete heavy vehicle, and how to record in-use duty cycles over actual operations, and how to prepare both to be used as parameters in chassis dyno measurements.
In experiments with heavy trucks from 18 tonnes up to 60 tonnes of GVW, marked difference between energy consumption and emissions has been established between comparable vehicles from different manufacturers. Also the assessment suggests that using truck/full trailer combinations with the highest total vehicle load allowed in Sweden and Finland (60 tonnes) may not be energy efficient compared to slightly smaller, 42 tonnes semi-trailers, especially in terms of energy used per tonn-kilometers.
Supplying unbiased, reliable and to some degree harmonised information on the environmental performance and energy consumption has also recently been taken on the agenda of the European co-operative platform ERA-NET, where an action group (ENT9) has been established to build a framework for such assessment and provide public information.
Keywords:Heavy vehicles, emissions, energy use, real-world, dynamometer testing