Co-Optimization of Fuels and Engines (Co-Optima) initiative of the U.S Department of Energy (DOE) started research on biofuel and biodiesel to replace the gasoline (petrol) and diesel for over the road internal combustion engines. From an initial list of thousands of fuels, selected bio-fuels and biodiesels were investigated for further combustion studies following the implementation of screening, which consisted of biodegrading, toxicity, flash point, research octane number, motor octane numbers, cetane number, and economic effect, etc. Experimental measurements of laminar burning velocity (LBV) are key parameters to understand fuel performance and applicability in engines. Furthermore, knowledge of LBV is required to understand turbulent combustion and validate the chemical mechanism. This study includes the LBV measurements of seven biofuels and three biodiesels using a constant volume method. LBVs of different biofuel/Synthetic air mixtures were measured at 428 K and 1 atm. Ethanol is one of the selected biofuels, which is a very well-known biofuel. The effect of pressure and temperature on the LBV of ethanol was studied at different initial pressure (1 atm, 2 atm, and 10 atm) and different initial temperature (300 K, 428 K, and 453 K). Flame instability was observed during a combustion event at high-pressure experiments using ethanol. To delay the occurrence of a cellular structure during combustion, a mixture of helium (He) and nitrogen (N2) in synthetic air was employed as a diluent. He increases the Lewis number greater than 1. LBVs of biodiesels were measured at 453 K and 1 atm with synthetic air. The buffer gas method was applied to measure fuel's partial pressure because of low vapor pressure and high boiling point of biodiesels. To check the condensation of biodiesel fuel in the system, a laser absorption technique was used. Regardless of the fuels tested, the maximum laminar burning velocity occurred at an equivalence ratio of approximately 1.1. For future work, the LBV measurement of blended fuel and different initial temperatures and initial pressure is recommended based on the current study.


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Graduation Date





Vasu Sumathi, Subith


Doctor of Philosophy (Ph.D.)


College of Engineering and Computer Science


Mechanical and Aerospace Engineering

Degree Program

Mechanical Engineering




CFE0008342; DP0023779





Release Date

December 2021

Length of Campus-only Access

1 year

Access Status

Doctoral Dissertation (Open Access)