Investigation of low temperature combustion of diethyl ether added ethanol/biodiesel fuels under different injection strategies in a diesel engine

The effects of alternative fuels like biodiesel, ethanol, and diethyl ether in a diesel engine on combustion and pollutant emissions were investigated experimentally in this thesis using different injection strategies and low temperature combustion conditions. A single cylinder diesel engine was used in the experiments. While biodiesel was injected directly into the engine using a high-pressure fuel injection system, ethanol or ethanol with diethyl ether was injected via port and direct injection. The direct injection method also allowed for the testing of various injection timing. The engine was run at 25%, 50%, and 75% engine loads with a constant engine speed of 2400 rpm during the tests. Experiments were carried out in these conditions by using the port injection strategy to prepare biodiesel (BD100%), biodiesel-ethanol (BDE), and biodiesel-ethanol-diethyl ether (BDE 10%DEE-BDE 30%DEE) mixtures with different energy contents. The secondary fuel's total energy content was kept constant at 30%. The same operations were then carried out in the same order using the direct injection strategy. Following that, using the direct injection strategy, the injection start time (-340 crank angle), which had been kept constant in previous experiments, was changed, and ethanol or 20% diethyl ether added ethanol injection was provided with crankshaft angles of -260, -180, and -100. According to the findings, the fuels added to biodiesel increased CO emissions at 25% and 50% engine load, but decreased them at 75% engine load, regardless of injection strategy (port or direct) or premixed ratio. For low-temperature combustion conditions, significant reductions in HC emissions were obtained by increasing engine load and increasing the ratio of diethyl ether added to ethanol at all engine loads, regardless of injection strategy and premixed ratio. Although NO emissions were lower at 25% and 50% engine loads when compared to biodiesel, there was an increase at 75% engine load. For all engine loads and fuel ratios, smoke opacity decreased when compared to biodiesel. As the injection timing approached top dead center, CO and HC emissions generally decreased. The obtained results were considered promising for the development of low-temperature combustion concepts. Keywords: Alternative fuels, Low-temperature combustion, Biodiesel, Ethanol, Diethyl ether