Epsilon Open Archive

Abstract

Non-road mobile machinery is used for a range of different operations with varying engine load characteristics. Fuel consumption and emission amounts from such machinery are dependent on the operation performed. The engine load during many of the operations performed is largely transient in nature. However, the majority of fuel consumption and emission data reported in the literature are based on static measurements and engine load patterns not representative of the real use of the vehicle. Emission data derived from the average annual use of agricultural tractors, based on three different typical areas of use, were compared with emission data obtained from European and international standards. The results showed that the emission amounts obtained from the engine load cycles stipulated in European and international emissions regulations were not representative of the real use of non-road mobile machinery. Furthermore, operations can be performed using a variety of different approaches depending on factors such as vehicle characteristics and driver behaviour. An engine load simulation model was developed and the results from the simulations showed that by using different driving strategies or transmission characteristics, it was possible to affect the emissions for a specific operation without affecting the fuel consumption or duration of the operation. Changes in engine speed and torque, i.e. transients, are likely to affect the fuel consumption and formation of emissions due to periods of time lags in e.g. the fuel injection system or the boost pressure. During normal operations a decrease in the fuel efficiency due to transient loads was detected. The fuel consumption increased with up to 13% compared with the corresponding steady-state condition. In order to study the effects of transients, special transient test cycles were developed. At high transients, both in engine speed and torque, the effects on fuel consumption and emissions were substantial. For example emissions of particulate matter increased with up to twelve times. Based on these results, a mathematical model was developed that could derive transient fuel consumption and emission amounts for all types of operations using a limited amount of emission measurements.