Numerička analiaza izgaranja smjese metan –vodik u cilindru za različita vremena bacanja iskre

In this study, numerical simulations of combustion characteristics using pure methane and 70 % CH4-30 % H2 blends were investigated in a spark ignition engine. The numerical calculations were performed using the finite volume CFD code FLUENT with standard k-ε model using the compression ratio and the engine speed are 10 and 2000 rpm respectively. Excess air ratios were selected as 1, 1.2 and 1.4. The spark timings were started at 45, 30 and 15 degree crank angle (CA) before top dead center (BTDC). The results of the combustion process were investigated as a function of crank angle. The maximum cylinder pressures and temperatures were obtained with 70 % CH4-30 % H2 mixture. It is observed that peak pressure values are decreased when the excess air ratio increased.U ovom se radu numerički simuliraju karakteristike izgaranja čistog metana i smjese 70 % CH4 i 30 % H2 kod motora paljenih sa svjećicom. Numerički proračuni su napravljeni koristeći kontrolni volumen CFD, kod FLUENT, sa standardnim k – ε modelom koristeći kompresijski omjer i brzinu motora 10 i 2000 min-1. Odabrani faktori pretička zraka su 1, 1.2 I 1.4. Vrijeme početka paljenja iskrom odgovaralo je 45, 30 i 15 stupnjeva koljenastog vratila prije gornje mrtve točke. Reultati procesa izgaranja su istraživani u ovisnosti o kutu pretpaljenja. Utvrđeni su maksimalni tlakovi u cilindru za smjesu 70 % CH4 i 30 % H2. Uočeno je da se smanjuju vrijednosti maksimalnog tlaka s povećavanjem faktora pretička zraka

Alternative Fuels for Internal Combustion Engines

Researchers have studied on alternative fuels that can be used with gasoline and diesel fuels. Alternative fuels such as hydrogen, acetylene, natural gas, ethanol and biofuels also uses in internal combustion engines. Hydrogen in the gas phase is about 14 times lighter than the air. Moreover, it is the cleanest fuel in the world. On the other hand because of its high ignition limit (4–75%), low ignition energy, needs special design to use as pure hydrogen in internal combustion engines. It is proved that hydrogen improves the combustion, emissions and performance, when is added as 20% to fuels. Natural gas is generally consisting of methane (85–96%) and it can be used in both petrol and diesel engines. Ethanol can be used as pure fuel or mixed with different fuels in internal combustion engines. In this section, the effects of natural gas, hydrogen, natural gas + hydrogen (HCNG), ethanol, ethanol + gasoline, ethanol + hydrogen, acetylene, acetylene + gasoline mixtures on engine performance and emissions have been examined