Load characteristics of a spark-ignited ethanol engine with DME enrichment

• We tested the performance of an SI ethanol engine with DME enrichment at 1400 rpm.
• DME blending helps increase the indicated thermal efficiency for SI ethanol engines.
• DME addition could reduce HC emissions of the SI ethanol engine.
• DME addition is an effective way for improving the performance of SI ethanol engines.

Alternative fuels have become the new energy for future life. Compared with others, Dimethyl ether (DME) is regarded as one of the most promising choices for future internal combustion (IC) engines. Due to some negative properties of ethanol, spark-ignited (SI) ethanol engines always encounter some barriers such as the high fuel consumption, low power output, and difficulty in cold start. In order to deal with the above problems, the SI ethanol engine is enriched with DME aiming at improving the overall performance.Under the engine speed of 1400 rpm, three DME volume fractions of 0–2% and various intake manifold absolute pressures from 43.4 kPa to 81.0 kPa, the influence of DME addition on the performance of SI engines at the stoichiometric air/fuel ratio were experimentally investigated in this paper. The intake and exhaust manifolds were modified to ensure the injection of ethanol and DME as well as collect the exhaust emissions.The results indicate that, DME addition avails increasing the engine indicated thermal efficiency by about 15%. And DME addition benefits reducing the combustion duration due to the elevated flame speed of mixtures, especially at mid-to-high loads. Besides, the DME blending is also capable of reducing HC emissions under the test conditions. The HC emissions of the DME/ethanol engine are decreased by 35%, compared with those of the original ethanol fueled engine. Thus, under the tested operating conditions, DME enhancement can be used to enhance the fuel economy and reduce parts of the exhaust emissions for SI ethanol engines.