Flekiewicz, M., Kubica, G., and Flekiewicz, B., "The Analysis of Energy Conversion Efficiency in SI Engines for Selected Gaseous Fuels," SAE Technical Paper 2014-01-2692, 2014, doi:10.4271/2014-01-2692.
The analysis of the overall performance of the engine powered by selected gaseous fuels has been presented in this paper. Primary objective of the research was to determine the influence of fuel type on efficiency of energy conversion in the tested engine. The scope of the research featured: application low-carbon fuels,use of DME as a renewable fuel in blends with LPG.The use of low-carbon gaseous fuels gives the opportunity to reduce exhaust gases emissions. The basic assumption in the presented research was the use of gaseous fuels, for which the main component is methane. The main problem taken into consideration was excessive duration of the combustion process, which is one of the causes of the engine overall efficiency reduction when running on gaseous fuels. This issue becomes even more important due to the lower heating value of natural gas (methane) when compared to conventional fuels. One of possible solutions is the use of fuel blends, e.g. methane-enriched hydrogen as an activator of the combustion process . Authors have chosen in this case eight methane/hydrogen blends, with various hydrogen shares (by volume): 0% (pure methane), 5%, 10%, 15%, 20%, 30%, 40% and 50%. Another interesting alternative considered by authors was dimethyl ether (DME). Due to its properties, it is recently becoming a more popular fuel. The high cetane number (about 55) allows its easy application for diesel engines propulsion additionally featuring low sooting propensity. Considering that other DME properties are very similar to those of petroleum based hydrocarbon gases, it is possible to effectively use it in the SI engines. One of DME applications presented by authors is a fuel blend based on LPG. The research program provided the use of fuel blends featuring DME mass fraction varying from 0 to 26%. The research project allowed the verification of simulation studies carried on the basis of mathematical model, with the real data from a 4 cylinders 1600cm3 SI engine. This made it possible to conduct a precise analysis of combustion process for all the tested fuels. The relationships between various components of energy balance in the tested engine have also been interpreted.