Metod för uppskattning av bränslebesparing vid hybridisering av en stadsbuss

Abstract

This study was conducted within the framework of a project employment at the consulting firm LTC AB, as a part of a client dialogue with an external bus manufacturer. The consulting firm and various stakeholders in the bus industry identified a need for a simple model in order to compare buses from different manufacturers with one another. During this dialogue, the need for more unbiased operating figures emerged. These figures are commonly provided by each manufacturer. This led to the following question: Is it possible to develop a simple method to calculate and compare the fuel consumption of vehicles with different powertrains, including an electrically hybridized bus, if so – how could such a method be designed and what would the results be? The method is baes on calculating the energy needed to overcome the resistances a bus is exposed to when it runs in a cycle, and further to define what type of engine that can be used in a possible scenario to overcome this resistance. The results of the study show that it is possible to develop and use a simplified method for comparing the fuel consumption of different vehicles and that a hybrid bus consume significantly less amounts of fuel than a conventional bus in city traffic. The method contains simplified and justified adjustments of input data that can be used in loops, for example to skip gears in a fuel-saving operation. The method also identifies other differences, for instance in acceleration performance. The potential consequence of applying the method is a better comparison between buses having different powertrains in terms of fuel consumption. The basic operation functions of the vehicle were taken from various handbooks and can be upgraded with more detailed data from real vehicles and/or cycles to be more precise. Due to the fact that the various components of the bus are complex, all of the components are simplified. The simplification was made using logical reasoning in order to obtain functional basic components. The timeframe of the study and the limited access to more detailed data resulted in restrictions concerning the possibility to conduct further in-depth studies on the various components.