Progress toward a low carbon future can be facilitated through the adoption of low carbon or carbon neutral fuels, e.g. second generation bio-fuels. Bio-fuels have different characteristics to conventional fuels some of which can be exploited such as a higher octane rating and charge cooling etc. for improved engine efficiency whereas others must be overcome such as increased NOx and fuel injector deposition.
THE CHALLENGE
To gain further insight into the combustion characteristics of bio-fuels in order to facilitate engine development using robust computational models. These models should predict the combustion characteristics and emissions of bio-fuels. These can enable engineers to carry out virtual engine design optimisations thus reducing development timescales.
THE SOLUTION
The adoption of srm suite and a detailed chemical kinetic fuel model to simulate an engine converted to run on bio-ethanol in a low temperature combustion mode. Specifically by examining the performance of blends of diethyl ether (DEE) and ethanol (EtOH), the characteristics of these fuels can be exploited to extend the operating ranges of the engine while improving the overall engine efficiency and lowering NOx emissions.
THE RESULTS
Insight into the combustion characteristics of bio-fuels
The combustion duration proved highly sensitive to the proportion of DEE in the ethanol blend. Various operating strategies were employed however those blend with reduced concentrations of DEE proved to have longer combustion durations allowing for increased load to be met without engine knock.
Reduced CO2 exhaust emissions
Since the bio-fuels were (or were closer to) carbon neutral when compared to equivalent conventional fuels thus the net CO2 emissions caused by their formation and combustion were reduced. In terms of the engine emissions, the model mimicked the trends observed in the experiments. The emissions were predicted with a great deal of quantitative agreement, enabling engineers to identify which operating regimes resulted in higher emissions.
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