Environmental and performance impacts of 2-ethylhexyl nitrate and ethanol in diesel blends: A comprehensive study

Abstract

This study investigates the performance and emissions of a compression ignition engine fueled with blends of ethanol and petroleum diesel with 2-EHN (2 ethylhexyl nitrate) as a cetane improver. Three blends, named E20 (20% ethanol with 80% diesel), E20A (20% ethanol, 0.1% 2-EHN, and 79.9% petroleum diesel), E20B (20% ethanol, 0.2% 2-EHN, and 79.8% petroleum diesel), and petroleum diesel were analyzed for their brake thermal efficiency (BTHE), specific fuel consumption, net heat release rate, indicated thermal efficiency, and emissions of carbon monoxide (CO), CO2, hydrocarbon (HC), and NOx. The experiments were conducted at variable loading conditions and at compression ratio of 16.5. Results showed that at no load conditions, petroleum diesel exhibited higher indicated power (IP) compared to E20, E20A, and E20B. However, at full load conditions, blend E20B showed higher IP compared to petroleum diesel, E20, and E20A. The blend E20B at a compression ratio of 16.5 showed the highest BTHE of 27%, compared to petroleum diesel (25%) under full load conditions, making it a better performing fuel. However, at higher loads and compression ratio of 16.5, the blends E20A and E20B exhibited emissions of CO, HC, CO2, and NOx that were significantly higher than diesel and E20 at all load conditions. Specifically, at full load conditions and compression ratio of 16.5, the emissions for each fuel were as follows: CO emission for E20, E20A, and E20B was around 0.01%, much less than petroleum diesel (0.1%); HC emission for E20 (15 ppm), E20A (17 ppm), E20B (10 ppm) was much higher than petroleum diesel (2.5 ppm); CO2 emission for E20, E20A, and E20B was about 13% less than petroleum diesel (15%); and NOx emission for E20, E20A, and E20B was around 150 ppm, comparable with petroleum diesel (140 ppm). These results imply that further improvements are required in using ethanol blended alternate fuel in diesel engines with 2-EHN (cetane improver) to reduce emissions with improved performance.