Impact of Cycloalkanes on Ignition Propensity Measured As Derived Cetane Number in Multi-Component Surrogate Mixtures
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University of South Carolina Scholar Commons Theses and Dissertations Summer 2019 Impact of Cycloalkanes on Ignition Propensity Measured as Derived Cetane Number in Multi-Component Surrogate Mixtures Dalton Odell Carpenter Follow this and additional works at: https://scholarcommons.sc.edu/etd Part of the Mechanical Engineering Commons Recommended Citation Carpenter, D. O.(2019). Impact of Cycloalkanes on Ignition Propensity Measured as Derived Cetane Number in Multi-Component Surrogate Mixtures. (Master's thesis). Retrieved from https://scholarcommons.sc.edu/etd/5444 This Open Access Thesis is brought to you by Scholar Commons. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of Scholar Commons. For more information, please contact [email protected]. IMPACT OF CYCLOALKANES ON IGNITION PROPENSITY MEASURED AS DERIVED CETANE NUMBER IN MULTI-COMPONENT SURROGATE MIXTURES by Dalton Odell Carpenter Bachelor of Science University of South Carolina, 2016 Submitted in Partial Fulfillment of the Requirements For the Degree of Master of Science in Mechanical Engineering College of Engineering and Computing University of South Carolina 2019 Accepted by: Sang Hee Won, Director of Thesis Tanvir Farouk, Reader Cheryl L. Addy, Vice Provost and Dean of the Graduate School © Copyright by Dalton Odell Carpenter, 2019 All Rights Reserved. ii DEDICATION This work is dedicated to those who have come before, to those who created the foundation on which we are able to stand proud and dream, and to those who are guarding Heaven’s scenes. Here, we hope to see dragons by standing on the shoulders of giants. iii ABSTRACT Cycloalkanes are one type of hydrocarbons present in real jet fuels. The distinct cyclic structure of the cyclo-alkanes impacts the chemical kinetic behavior differently compared to n- and iso-alkanes. At high temperatures, thermal decomposition reactions dominate, producing n-alkyl radicals similar to the oxidation reactions of n-alkanes thus promoting the reactivity. Whereas in low temperatures, the presence of the ring structure essentially suppresses the formation of alkylhydroperoxy radicals (QOOH) from alkylperoxy radicals (RO2), thus exhibiting similar reactivity to iso-alkanes. In previous generations of surrogate fuels, the cyclo-alkane functional group were largely ignored due to low levels of cycloalkanes in traditional jet fuels and their ability to successfully model its characteristics. Cyclo-alkanes have come into renewed interests with their larger presence in alternative jet fuels and the potential of better endothermic performance in high-performance jet fuels (JP-10). Increasing the fraction of cyclo-alkanes in real fuels could create issues in surrogate fuels correctly predicting the chemical functionalities of real fuels with an ever increase fraction of cyclo-alkanes being present. The ignition characteristics of cyclo-alkanes and their mixtures with other molecular classes are investigated by measuring DCN values from an Ignition Quality Tester (IQT). To quantify the role(s) of cyclo-alkane functionality, chemical functional group approach is used by separately defining the CH2 groups in cylco- and n-alkanes and a quantitative structure- property relationship (QSPR) regression model is constructed based on chemical functional group descriptor against the DCN measurement database. A feature sensitivity analyses are iv performed to identify relative significance of cyclo-CH2 functional group in autoignition propensity of multi-component fuels by varying the cyclo-alkane fractions v TABLE OF CONTENTS Dedication .......................................................................................................................... iii Abstract .............................................................................................................................. iv List Of Tables ................................................................................................................... vii List Of Figures ................................................................................................................. viii List Of Abbreviations ......................................................................................................... x Chapter 1: Usage Of Hydrocarbon Combustion For Energy And Transportation ............. 1 Chapter 2: The Need To Investigate Biofuels And Low Temperature Combustion ........ 11 Chapter 3: Surrogate Fuel Formulation And Modeling .................................................... 17 Chapter 4: Experimenatl Methodaology And The IQT .................................................... 23 Chapter 5: Cycloalkanes In Multi-Component Mixtures .................................................. 28 Chapter 6: Analysis Of Cycloalkane Reaction And Low Temp Combustion .................. 44 Chapter 7: Conclusion....................................................................................................... 53 References ......................................................................................................................... 55 vi LIST OF TABLES Table 5.1 DCN of Selected Cyclic Cycloalkenes ..............................................................34 Table 5.2 Coefficients for Scheffe QSPR Equations .........................................................36 vii LIST OF FIGURES Figure 1.1 Word Crude Oil Production................................................................................5 Figure 1.2 Word Energy Consumption ................................................................................6 Figure 1.3 Source of US Energy Consumption ...................................................................7 Figure 1.4 Breakdown of US Energy Production by Source ...............................................8 Figure 1.5 US Transportation Energy Sources ....................................................................9 Figure 1.6 CO2 Global Emissions from Fossil Fuels ........................................................10 Figure 2.1 Global CO2 Emission form Fossil Fuels by Country .......................................15 Figure 2.2 Countries with the Largest Reduction and Increases in CO2 Emissions .........16 Figure 4.1 Schematic of Ignition Quality Tester ...............................................................26 Figure 4.2 IQT Raw Data of Chamber Pressure and Needle Lift Pressure .......................27 Figure 5.1 n-Heptane and Cycloalkane Mixtures by Mole Fraction of n-Heptane ...........35 Figure 5.2 QSPR Database Measured DCN ......................................................................37 Figure 5.3 Normalized Sensitivity Coefficient of Each Chemical Functional Group .......38 Figure 5.4 Normalized Sensitivity Coefficient of MCH and Surrogate 1 .........................39 Figure 5.5 Predicted vs Measured DCN of Cyclic Cycloalkanes ......................................40 Figure 5.6 Mixtures of n-Heptane and Branched Cycloalkane ..........................................41 Figure 5.7 The Difference Between Measured and Predicted Values Cycloalkanes ........42 Figure 5.8 Comparing DCN, 13C NMR .............................................................................43 viii Figure 6.1 Cycloalkanes and n-Alkanes DCN ...................................................................49 Figure 6.2 RON, MON, and DCN of Cyclic Cycloalkanes ...............................................50 Figure 6.3 Ring Strain in Cycloalkanes .............................................................................51 Figure 6.4 Activation Energy and DCN of Cyclic Cycloalkanes ......................................52 ix LIST OF ABBREVIATIONS ASTM ...................................................American Society of Testing and Materials BTU........................................................................................ British Thermal Units DCN ................................................................................... Derived Cetane Number EIA .................................................................... Energy Information Administration HCCI ................................................... Homogeneous Charge Compression Engine H/C Ratio ........................................................................ Hydrogen to Carbon Ratio IQT ........................................................................................ Ignition Quality Tester MON ..................................................................................... Motor Octane Number MW .............................................................................................. Molecular Weight NREL ......................................................... National Renewable Energy Laboratory QSPR.................................................. Quantitative Structure Property Relationship RON ................................................................................. Research Octane Number TSI...................................................................................... Threshold Sooting Index x CHAPTER 1 USAGE OF HYDROCARBON COMBUSTION FOR ENERGY AND TRANSPORTATION For the past century society has been using fossil fuels to generate energy and advanced civilization. Petroleum fuels have become ingrained into our societies’ existence, incorporated into our daily lives by providing the electricity and transportation that keeps the economy running. The use of hydrocarbons over the past 100 years has completely changed the shape of modern society by