Wybrane problemy stosowania gazu ziemnego do zasilania silników o zapłonie samoczynnym

W artykule omówiono niektóre problemy związane z zasilaniem silników o zapłonie samoczynnym gazem ziemnym sprężonym. Przedstawiono analizę opłacalności zasilania gazowego w silnikach autobusowych oraz wyniki badań stanowiskowych. Wnioski oparto na badaniach silnika 1CA90 zasilanego dwupaliwowo. Wykazały one, że w silniku o zapłonie samoczynnym możliwe jest zmniejszenie emisji tlenków azotu o około 35/45% oraz ponad 4-krotne zmniejszenie silnika. Ważną korzyścią ze stosowania gazu ziemnego jest ponadto zmniejszenie emisji CO2 w granicach 10/25%. System dwupaliwowy charakteryzuje się wysoką sprawnością silnika, porównywalną do sprawności silnika zasilanego olejem napędowym i znacznie wyższą od sprawności silników gazowych o zapłonie iskrowym.

Forecasts for the nearest years anticipate significant increase of natural gas consumption in European Union states. Such situation is caused by pro-ecological capabilities of the gas, good deal of resources and common availability. It seams that at the present moment compressed natural gas shall find the main implementation. The present paper shows testing results of a single cylinder; direct injected dual fuel engine fed on compressed natural gas. In course of performed experiments it has been found that the engine operating in range of engine revolutions of 2000-2750 rpm at maximal load has reached higher thermal efficiencies comparing with engine fed traditionally.Usage of natural gas enables to significantly reduce NO[x], CO[2] emissions and smokiness of exhaust gases. Reduction of NO[x] emissions at maximal engine load has amounted to 35-45% with respect to emissions from an engine fed traditionally.Even bigger differences were observed at partial loads where reduction of NO[x] emissions was nearly threefold. The biggest differences in smokiness of exhaust gases were present at maximal load of dual fuel engine, where more than fourfold reduction of the smokiness has been observed. Dual fuel engines, however, have shown increased emissions of CO and non-burnt THC hydrocarbons. Growth of CO and THC emis.sions was nearly twice at maximal engine load and had increased at partial load. The reason of increased emissions of CO and THC is worsening of conditions of gas oxidation at partial load and increasing range of flame extinction near cylinder walls.