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Browsing by Author "Boylu, Rahim"

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    Evaluation of Thermal Oxidative Stability of Sustainable Aviation Fuels Using a Novel Thermal Stability Measurement Method
    (University of Alabama Libraries, 2022) Boylu, Rahim; Khandelwal, Bhupendra; University of Alabama Tuscaloosa
    In aviation industry, fuel is used as both propellant and coolant. Because the fuel is used as coolant, it is exposed to thermally stressed. This thermal stress leads to occur thermal oxidative reactions at some temperature levels (150 – 350°C). However, all fuels have different thermal oxidative stability depends on their fuel physical and chemical properties. Thermal oxidative stability can be basically identified as the resistance of autoxidation of fuel. The aim of this study is to develop a new test method and test range of alternative fuels in it, for generation of knowledge in the area of thermal stability of alternative fuels. In order to measure thermal stability of aviation fuels, a novel thermal stability measurement method has been developed in this study. After considering and setting a novel test rig up, experiments have been conducted for some fuels, such as diesel fuel, two Jet A fuels from different manufacturers, Jet Propellant - 5 (JP-5), Jet Propellant - 8 (JP-8) and some sustainable aviation fuels (SAFs), such as HEFA-SPK (Hydro-processed esters and fatty acids)-(Synthetic paraffinic kerosene), Alcohol-to-Jet (ATJ), Biojet and Gevo jet blend fuels. Diesel fuel has been used in this study mostly to analyze if this new measurement method has been working properly. Jet A fuel is also most common used in commercial aviation industry; so, it is a good reference fuel to compare the results of sustainable fuels with. SAFs have a great deal of potential to be used in aviation industry for the future due to their environmentally friendly properties. Unlike other fuels, JP-5 and JP-8 are mostly employed in military aircrafts. Throughout the experimental period, these fuels have been heated to get exposed to thermally stressed, and dissolved oxygen (DO) sensors have been run to analyze oxygen (O2) content inside of each thermally stressed fuel. By measuring the O2 content inside of fuel, fuel break point has been measured. Fuel break point is determined where the thermal oxidative reactions begin. At the end of this study, all results of fuel break points and O2 consumptions of fuels during the thermal oxidative reactions have been compared, and it has found that HEFA-SPK has higher fuel break point than ones of other fuels, while one of Jet A, JP-8, and F-T/ATJ have the lowest one. This study shows that different fuels have different decomposition rate, and trend of fuel break point and oxygen consumption rate of tested fuels has been provided in this study.
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    Experimental Investigation on CO2 Capture Technologies Under Microwave-Based Regeneration Conditions
    (University of Alabama Libraries, 2025) Boylu, Rahim; Amini, Shahriar
    In the United States (US), most (around 74%) human-caused greenhouse gas (GHG) emissions come from burning fossil fuels – coal, natural gas, and petroleum – for energy use. Today, burning fossil fuels accounted for 93% of total anthropogenic CO2 emissions. CO2 sources from other anthropogenic sources and activities were about 6% of total GHG emissions and 7% of total CO2 emissions. Economic growth and weather patterns that affect heating and cooling needs are the main factors that drive the amount of energy consumed. CO2 capture and storage (CCS) is a way of mitigating the contribution of fossil fuel emissions by capturing and subsequently storing the CO2. In 2015, countries agreed to limit warming – caused by such emissions – to below 2 °C and aim for 1.5 °C. According to International Energy Agency, CCS should contribute around 15% of effort in the pursuit of net-zero emissions by 2070. Various methods, such as temperature swing adsorption and pressure swing adsorption, have been used for CO2 regeneration. However, these approaches often struggle with challenges related to energy consumption and capital costs. In contrast, microwave heating-based CO2 capture technology emerges as a potential alternative, offering lower energy consumption and reduced costs.This study explores the necessity of CO2 capture and direct air capture (DAC) technologies, emphasizing their energy demands and heat transfer limitations using zeolite 13X as sorbent. Given these challenges, microwave-based heating emerges as a promising alternative due to its inherent advantages such as rapid and volumetric heating ability, which contributes to achieving homogeneous heat distribution. Experimental investigations were conducted at the Decarbonization Lab at the University of Alabama to evaluate microwave-assisted post-combustion CO2 capture and DAC under either dry or humid conditions. This study presents how the negative impact of humidity on zeolite 13X adsorption performance can be mitigated, ultimately enhancing its effectiveness in humid conditions. Experimental strategies in a fluidized bed reactor demonstrate that humidity effects can be mitigated through microwave-assisted direct air capture. The findings indicate that microwave-based CO2 capture enables lower energy consumption while achieving complete CO2 regeneration, even at low temperatures, positioning it as a viable alternative for sustainable carbon capture.