Doctor of Philosophy (PhD)
Department of Mechanical & Industrial Engineering
Conventional test methods for characterizing the combustion behavior of fuels have been devel- oped for many years and can be implemented for numerous conditions. Although these methods are beneficial for many applications, there are still drawbacks that make it necessary to develop new methods, which suit particular applications. Currently, conventional fuel testing (e.g. Co- operative Fuel Research-CFR) engines are being widely used for characterizing the combustion behavior of fuels. Drawbacks of CFRs include: (1) the large quantity of fuel is required to de- termine the properties of fuel, (2) large space occupied by the device, and (3) high maintenance cost. CFR engines consume liters of fuel for the test procedure. The high consumption rate makes CFR inappropriate for fuels that are produced in the laboratory in small quantities (e.g. new bio- fuels). Production of new fuels is usually very costly and conventional test methods impose a high cost. Due to the mentioned reasons, finding an alternative method, which consumes less quantity of fuel (i.e. μ-liter) is desirable. Besides, the CFR engine has many moving parts that cause the maintenance cost to surge. However, micro-combustors have none of the mentioned drawbacks of the CFR engine. Due to the small size of the combustion chamber, the required quantity of the fuel is drastically decreased and reduces the occupied space by the device. Besides, it has almost no moving part, which leads maintenance costs to decrease. Studies on micro-combustion as an alternative method to characterize the fuel’s combustion characteristics started in the late 2000’s. The current study uses micro-combustion to investigate the effects of pressure and dilution on the combustion behavior of both gaseous (Ethane) and liquid fuels (Primary reference fuel- PRF). Three different types of flames have been observed in the current study: (1) Weak flames are type of flame that is observed at the lowest range of velocity. It is by nature dimmer than other types of flames. (2) Flames with repetitive extinction and ignition (FREI) which are formed at medium range velocities, and (3) stable (strong or normal) flames are seen at the highest velocity range. Measurements are focused on extinction and ignition locations of the flame. To determine temperatures at those locations, a thin filament pyrometry (TFP) technique is applied to estimate the temperature along the micro-channel. A thin SiC filament with 76µm diameter is mounted adjacent to the micro-channel wall. By determining the temperature along the micro-channel and correlating the position of flame edges, the extinction and ignition temperatures are calculated. It is found that by increasing the dilution, the extinction temperature increases. It is observed that increasing the pressure causes both extinction and ignition temperatures to decrease at the same dilution level.
Roohani Isfahani, Seyed Navid, "Investigation of Combustion Characteristics in an Externally Heated Micro-Channel" (2021). LSU Doctoral Dissertations. 5650.
Schoegl, Ingmar M.
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