Date of Graduation

2014

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

Gregory J Thompson

Committee Co-Chair

Hailin Li

Committee Member

Andrew Nix

Abstract

In recent years the U.S. Navy has developed several energy goals to displace foreign petroleum-derived fuels. One of these goals involves replacing existing fuels with alternative hydrotreated biofuels. Hydrotreated biofuels are a second generation renewable diesel fuel and generally have similar fuel properties and characteristics as petroleum-derived fuels. The U.S Navy is currently investigating several alternative biofuels including HRJ5, HRD76, DSH76, and HDCD76. To ensure these fuels perform similarly to or better than petroleum fuels, the U.S. developed a fuel specification program. Part of this program involves preliminary evaluations of the alternative biofuels in a laboratory environment to identify negative combustion characteristics and allow a down-select of fuels before they are evaluated in the field such as on-board Navy vessels. The overall objective of this study is to identify any negative combustion characteristics of refinery-based hydrotreated renewable diesel fuels targeted for Navy use. To fulfill this objective, the biofuels were compared in neat and blended ratios against existing U.S. Navy Fuels JP-5 and F-76. Additionally, the engine performance and fuel consumption of the biofuels were evaluated as well as the regulated gaseous and particulate matter exhaust emissions to provide additional assessment information.;To evaluate the performance of these refinery-based hydrotreated biofuels each was tested in the following ratios: Neat HRJ5, 50/50 JP5/HRJ5, Neat HRD76, 50/50 F76/HRD76, Neat DSH76, 50/50 F76/DSH76, 80/20 F76/DSH76, and 80/20 F76/HDCD76. The fuels were investigated on a 1992 DDC Series 60 engine equipped with a sensor for in-cylinder pressure measurement and combustion process analysis. The engine was test on a 15 mode steady state and a transient idle to full power step test (for JP-5 fuels only). The biofuels, depending on the blend ratios and base fuel, showed reductions in heat release rate and maximum in-cylinder pressure and temperature. The biofuels also demonstrated retarded injection timing, shorter ignition delay, shorter premix combustion, and longer diffusion combustion. The only biofuel that did not follow these trends was 80/20 F76/HDCD76. These result suggested significant effect of fuel properties, such as cetane number, aromatic content, density, and heating value, on combustion parameters.;The biofuels also showed favorable emission results. Brake specific emissions of NOx, HC, CO, CO2, and PM were measured to determine the effect of different fuels, and hence fuel properties, on exhaust emissions. Significant reductions in NOx, CO2, and PM were achieved, while only slight reductions in HC and CO were achieved with operation of the biofuels. Reductions in emissions were attributed to the lower fuel density, lower aromatic content, and higher cetane number of the biofuels. The 80/20 F76/HDCD76 blend higher emissions values due to its higher fuel density, aromatic content, and lower cetane number compared to the F76.

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