Originally posted by Scania N113CRB luver:
U mean the Volvo DH10A/B/C isn't fuel efficient? As far as i know, methane forms most of Natural Gas ( in this case CNG), up to 75%.
Ai.....I still dont know how the CNG engines operates. Could anyone here enlighten me?
Sorry, I made a slight mistake in my original post. I meant that the
GH10A/B/C require catalytic converters to meet Euro 2/3/4. Diesel engines also require catalytic converters for Euro 1 or stricter requirements.
Regarding CNG engines, here's a brief description on how they work.
1. Natural gas fuel is stored at high pressure (up to 200 bar) in cylinders usually mounted on the roof of a bus.
2. Gas is delivered to the engine bay from the cylinders via a high pressure gas line.
3. Prior to entering the intake stream, the gas is filtered for impurities and then depressurized to a set working pressure, typically anywhere from zero pressure to 10 bar. This is done in one or more pressure regulators, heated with coolant from the radiator. The pressure regulator(s) may have one or more stages.
4. The gas is then mixed with incoming air. This can be done at a gas mixer (elementry carburettor) or via gas injectors.
5. Airflow is controlled by a butterfly valve in the intake stream and in case of a turbocharged engine, a wastegate in the exhauast stream.
6. When the air/fuel mixture reaches the engine, it is ignited by spark plugs that are connected to the engine's ignition control system.
Regards,
Dave