Semester of Graduation
Master of Science in Mechanical Engineering (MSME)
Conventional fuel testing machines like CFR engines require large quantities of fuel. The current study seeks to overcome this limitation by introducing an alternative method using a microscale combustion reactor which consumes relatively small amounts of fuel (100-250 ml). For this reason, Primary Reference Fuels (PRF’s: volumetric mixtures of n-heptane and iso-octane) which are simple surrogates of gasoline are selected to test using micro reactor. The primary goal is to determine the effectiveness of using the micro reactor setup to differentiate fuels of different octane number. Experiments with stoichiometric PRF/air mixtures are performed inside a cylindrical quartz tube of 1mm internal diameter. The fuel-air mixture velocity is varied from 5 to 80 cm/s, and three distinct combustion regimes are observed: weak flames, flames with repetitive extinction and ignition (FREI), and normal flames. In experiments, the extent of CH* chemiluminescence is captured by a monochrome machine vision camera at each set point velocity. In initial tests, wall temperature profiles are measured by a translating thermocouple setup. The experimental setup is subsequently changed to thin filament pyrometry (TFP) to allow for temperature profiles at elevated pressures. Post processing involves the extraction of flame locations to obtain ignition and extinction points. Flame temperatures are extracted from the flame locations using wall temperature profile. Different PRF blends are compared and a larger temperature difference between n-heptane and other PRFs is seen but no clear differentiation is observed from RON 50-100 at 1 atm. However, PRFs tend to show larger differences in ignition and extinction temperatures at higher pressures. To check the feasibility of the micro reactor for newly developed fuels, four fuel samples of different hydrocarbon chains with the same RON are tested in the last part of the work and results show responsiveness to octane sensitivity.
Naralasetti, Veerendra, "Micro Combustion of Primary Reference Fuels in Narrow Heated Channels" (2018). LSU Master's Theses. 4786.