Technical Paper
Low-Polluting Gas Fueled Heavy-Duty Vehicles
1991-10-01
912365
There is a strong request for heavy-duty gas engines in the Nordic countries for environmental reasons. Therefore, several research projects are going on. This paper describes two of them: a Finnish Sisu truck and a MAN bus, both operating in the city of Espoo, the hometown of the Technical Research Centre. The truck is equipped with a 7.4 litre Finnish Valmet 612 engine. The development work has included engine tests and tests with a vehicle in laboratory conditions. A 3,3 litre 3-cylinder engine was used for the engine tests. The engine runs on stoichiometric mixture, and has a three-way catalyst based on metal substrate. The engine was run on both methane (compr. ratio 12:1) and propane (compr. ratio 10:1). Emissions were extremely low with both fuels. In the European 13-mode test 0.4 g CO, 0.1 g HC and 0.1 g NOx per kWh were achieved. Peak thermal efficiency was 35 % for both fuels. Maximum mean effective pressure (BMEP) for a naturally aspirated engine is 9 - 9,5 bar.
