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Combustion Stability Study with Low Cetane Number Diesel and Biodiesel with 2-EHN Addition Under LTC Conditions During Cold / Warm Start and Steady State Conditions
ISSN: 0148-7191, e-ISSN: 2688-3627
To be published on September 15, 2020 by SAE International in United States
A single cylinder Diesel engine was used to study combustion stability changes from a cetane number improver (CNI): 2-EHN. The CNI have been added to a low cetane number (CN) Diesel and two biodiesels fuel with 20 % of SME or RME. All fuels have been raised to a CN of 51 with 2-EHN. Those fuels have been compared to a reference Diesel with a CN of 55. Cold and warm start have been recreated by measurement at three conditions: cranking, engine speed increase and idle. Engine temperature have been set to 20°C and 80°C for cold and warm start respectively. 2-EHN effects on combustion stability have been monitored through the IMEP covariance. Under cold start, only the low CN Diesel gets a combustion stability improvement with 2-EHN addition. Moreover, the combustion stability is better than the reference Diesel and the heat release rate show an enhancement of the cold flame. On the contrary, the biodiesel fuels exhibit a higher IMEP covariance. Under warm start, all fuels without 2-EHN show low IMEP covariance. Therefore, the results show less effects of the cetane improver on combustion stability. The low CN diesel doped with 2-EHN heat release show a cold flame improvement and a decrease of the highest maximum heat release. The results with the reference Diesel fuel have the best combustion stability. Lastly, the fuels have been tested for EGR limit for idle, steady state city and extra-urban drives. The results show a higher EGR limit for all fuels except for the biodiesel prepared with SME, which show no gain or degradation of EGR limit.