With the steadily rising volume of road traffic alternative fuels, alternative transmission systems and exhaust gas treatment systems are increasing in inportance.Natural gas transmission systems offer high environmental compatibility, they use natural gas either in liquefied (LNG) or gaseous, compressed (CNG) form. In practice, monovalent or bivalent CNG transmission systems are used. Bivalent vehicles are fitted with a special gas unit and combustion is optimised for either fuel (gas or gasoline). Series-production bivalent vehicles are already offered by BMW, DaimlerChrysler, VOLVO and FIAT. Among the necessary additional equipment is a gas pressure display,sensor technology, high pressure pipes and regulator, gas mixer, CNG storage cylinder and a change over switch. Some monovalent CNG vehicle types are the HONDA Civic GX, the MB Sprinter 314 NGT and the Neoplan N 316 Ü CNG. The structure and operating principle of a CNG transmission system is fully explained: CNG from the storage facility is expanded and drawn into the intake pipe by vacuum, mixing with air via holes in the tube, or the expanded natural gas is fed into the intake pipe by means of injection valves. The exhaust is treated by a catalytic converter with lambda control. Commercial vehicle manufacturers offer lean-mix engines, as well as those with lambda = 1. Comparing emissions from CNG vehicles with conventionally powered vehicles shows that CNG-driven vehicles comply with all the exhaust limit values specified in EURO 3 and in some cases even EURO 4. The power and torque performance of CNG vehicles is 5 % - 10 % less compared to conventional transmission systems. Refilling CNG vehicles is possible either with the slow fill system or the fast fill system used at refilling stations, of which there currently are about 90 in operation in Germany. Economic efficiency can as yet only be achieved by subsidising the additional cost of conversion or purchase, but on the whole natural gas is a mobile energy of the future. Obstacles to further progress lie in the range, insufficient refilling station infrastructure and the economic efficiency.
Natural gas vehicles - a contribution to reduce emissions from road traffic
Erdgas-Fahrzeug - Ein Beitrag zur Emissionsminderung im Straßenverkehr
Dessau Gas Engine Conference, 1 ; 351-367
1999
17 Seiten, 12 Bilder, 2 Tabellen, 4 Quellen
Conference paper
English
Stand der Technik , Vielstoffmotor , Gasmotor , Erdgas , Fahrzeugantrieb , Kraftfahrzeugmotor , Nutzfahrzeug , Systembeschreibung , Gasdruck , Komprimieren , Magermischmotor , Systemvergleich , Emissionsminderung , Kraftstoff-Luft-Gemisch , Wirtschaftlichkeit , Reichweite , Kraftstoffeinspritzung , Automobilindustrie , Brennstoffzuführvorrichtung , Gasversorgung , Flüssigerdgas
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