Results Obtained by Methanol Fuelling Diesel Engine 2001-01-3748
The control of diesel engine exhaust emissions (NOx and smoke) can be achieved using methanol as a single fuel or together with classic diesel fuel. The low value of methanol Cetane Number (CN≤5) makes autoignition difficult. This paper presents the experimental results obtained by providing two different methods of diesel fuel and methanol engine supplying. The first method consists in the methanol admission through a carburettor combined with the classic diesel fuel injection (diesel-carburettor D-C), and the second one refers to the separate fuels injection (double injection DMI). The experimental research related to the first fuelling method was carried out on two types of DI engines: the D 115 (multi-sprays) type and the D 2156 MTN 8 type (injected on the wall) The main goal is to analyse the exhaust emissions when the engine operates following the D-C method using the maximum possible methanol percentage substituting diesel fuel. Considering these, the power obtained for certain operating regimes is higher than that obtained for classic diesel engine D. From the exhaust emissions measurements resulted that the NOx levels can be significantly reduced for all the engine loads. Regarding the smoke, reduced levels were achieved only at high engine loads (>50%) although it is known that these smoke reduced levels are provided at low engine loads for D. The smoke level could mark a limitation for the methanol used quantity inside the engine's cylinder.
In order to increase even more the substitute methanol percentage, analysis were made on D 2156 MTN 8 engine type applying the second described fuelling method DMI. A model was issued for simulating the processes that develop inside the engine's cylinder, presenting the heat release characteristics typical for the methanol combustion.