SURFACTANT-FREE ALCOHOL-DIESEL-WATER MICROEMULSION FUELS FOR COMPRESSION IGNITION ENGINES
Venue: Date: 8th May 2020 (Friday) Time: 10:30 AM
The examination will be conducted through video conferencing for which the link will be generated by the office of Dean (Academics). Those interested in attending the thesis defense presentation should contact the undersigned to receive the video conference link.
Abstract: Compression ignition (CI) engine is an extensively used diesel-driven internal combustion engine, with a better fuel economy and efficiency as compared to a spark ignition (SI) engine. However, particulate matter (PM) and NOx emissions generated from diesel fuel have serious environmental and health concerns, which led an interest in the diesel alternatives. Most common diesel alternatives developed till date are either uneconomical or require modifications in current engines and infrastructure. For example, hydrotreated vegetable oil requires high temperature and pressure, thus making the process uneconomical. Similarly, ethanol, another renewable alternative, used in dual-fuel mode, requires separate injection system and fuel tank. Microemulsification is a promising technique of developing economical alternative fuels. It does not require any changes in the existing systems and is environmental friendly in terms of simultaneous reduction of PM and NOx emissions. However the high percentage of surfactants used to reduce the interfacial tension between the polar and non-polar phases in the microemulsions renders these fuels uneconomical.
This research was focused on developing surfactant-free water-in-diesel microemulsion fuels, using alcohol as co-surfactant as an economical alternative to diesel for the CI engines. The surfactant-free microemulsions could only be formulated in HLB range of 6.27 to 7.76. The effect of different surfactants and alcohols on water solubilization in alcohol-diesel-water system was also studied. Butanol-diesel-water (BDW) microemulsions with HLB of 7.0 were able to incorporate the maximum percentage of water. Moreover, butanol can be derived from a renewable route, and has properties close to diesel, when compared to other lower alcohols. Hence, BDW microemulsions are more promising as compared to other surfactant-free microemulsions.
The BDW microemulsions with 12.9 to 40.0 % (v/v) butanol, 57.8 to 87.0 % (v/v) diesel, and 0.1 to 2.2 % (v/v) water satisfied the ASTM standard specifications of diesel fuel oil, and were compatible with the existing engine and infrastructure. Further, the microemulsion sample with 19.6 % (v/v) butanol, 80.0 % (v/v) diesel, and 0.4 % (v/v) water had 15.7% reduction in brake specific fuel consumption and 24.7% increase in brake thermal efficiency at load of 3.34 kW with respect to diesel, and the cost was 1.9% lower than that of diesel. Moreover, the microemulsion sample with 35.0 % (v/v) butanol, 64.4 % (v/v) diesel, and 0.6 % (v/v) water had 50.0%, 34.4%, 26.6%, and 49.0% reduction in CO, HC, CO2, and NOx, respectively, and the cost was 3.4% lower than that of diesel. The BDW microemulsions exhibited lower fuel consumption, higher thermal efficiency, and lower emissions of CO, HC, CO2, and NOx when compared to petro-diesel, with upto 3.4% reduction in cost. Hence, BDW microemulsions present optimal, economical and cleaner alternative to diesel.