Real driving emissions of tractors during field work and on the test stand

Exhaust gas emission limits from non-road mobile machinery (NRMM) such as tractors, excavators or loaders have been increasingly tightened in recent years. But there is only little knowledge about the emission behaviour under real-life operating conditions of diesel and rapeseed oil fuel compatible tractors of the latest emission stage IV. Besides mitigation of greenhouse gas (GHG) emissions from agricultural machines, also other limited and not limited exhaust gas emission components are relevant, to perform optimization processes entirely. Considering this, comprehensive knowledge is necessary about real emission behaviour of mobile machinery. By using a portable emission measurement system PEMS Semtech Ecostar, which was set up in a sturdy box for off-road use, the emission components NOX, CO, HC and CO₂ as well as the exhaust mass flow are measured. In this work a methodology is suggested to transfer in-field recorded engine parameters of ploughing into test cycles. The test cycles are applied at the tractor, which is connected to an eddy current brake with its PTO shaft. A high congruency in emission behaviour between infield recorded and on the test stand replicated values can be observed for three repetitions. The specific emission values for all measurements with rapeseed oil fuel are under the limit values for test cycles according to the EU Regulation 2016/1628 or ISO 8178. Furthermore, regarding results neither significant differences between the use of rapeseed oil and diesel fuel nor divergences of PEMS and stationary gas analysers are recognized. Further investigations should clarify whether the method is applicable to further tractors and other tractor works.