EXAMINATION OF PHYSICAL PROPERTIES OF FUELS AND MIXTURES WITH ALTERNATIVE FUELS By Anne Lauren Lown A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of Chemical Engineering – Doctor of Philosophy 2015 UNCLASSIFIED: Distribution Statement A. Approved for public release. ABSTRACT EXAMINATION OF PHYSICAL PROPERTIES OF FUELS AND MIXTURES WITH ALTERNATIVE FUELS By Anne Lauren Lown The diversity of alternative fuels is increasing due to new second generation biofuels. By modeling alternative fuels and fuel mixtures, types of fuels can be selected based on their properties, without producing and testing large batches. A number of potential alternative fuels have been tested and modeled to determine their impact when blended with traditional diesel and jet fuels. The properties evaluated include cloud point and pour point temperature, cetane number, distillation curve, and speed of sound. This work represents a novel approach to evaluating the properties of alternative fuels and their mixtures with petroleum fuels. Low temperature properties were evaluated for twelve potential biofuel compounds in mixtures with three diesel fuels and one jet fuel. Functional groups tested included diesters, esters, ketones, and ethers, and alkanes were used for comparison. Alkanes, ethers, esters, and ketones with a low melting point temperature were found to decrease the fuel cloud point temperature. Diesters added to fuels display an upper critical solution temperature, and multiple methods were used to confirm the presence of liquid-liquid immiscibility. These behaviors are independent of chain length and branching, as long as the melting point temperature of the additive is not significantly higher than the cloud point temperature of the fuel. Physical properties were estimated for several potential fuel additive molecules using group contribution methods. Quantum chemical calculations were used for ideal gas heat capacities. UNCLASSIFIED UNCLASSIFIED Fuel surrogates for three petroleum based fuels and six alternative fuels were developed. The cloud point temperature, distillation curve, cetane number, and average molecular weight for different fuel surrogates were simultaneously represented. The proposed surrogates use the experimental mass fractions of paraffins, and the experimental concentrations of mono- and di- aromatics, isoparaffins, and naphthenics. The surrogates represent both low and high temperature properties better than most surrogates in the literature. Three different methods were developed to predict the cetane number of alternative fuels and their mixtures with JP-8, a military jet fuel. The same six alternative fuels were distilled, as well as blended with JP-8, and the cetane numbers measured. The Ghosh and Jaffe model represented the neat fuels with pseudocomponents to predict the cetane numbers of blends. This model worked well for the neat fuels, but the mixture behavior was predicted with incorrect curvature. The second and third methods used near infrared (NIR) and Fourier transform infrared (FTIR) spectroscopy to correlate the cetane number. The correlation provides prediction of the cetane numbers of the blends based on spectral measurements. Both the FTIR and NIR correlations are able to predict mixture cetane numbers within experimental error, but the NIR model was found to be the most reliable of all three methods. Finally, the SAFT-BACK and ESD equations of state were used to model the density and speed of sound for hydrocarbons at elevated pressures. The SAFT-BACK equation was found to be more accurate, and the model was extended to predicting the speed of sound. Mixtures of hydrocarbons were also predicted, but the SAFT-BACK is limited in capability for representing compressed alkanes heavier than octane. UNCLASSIFIED Copyright by ANNE LAUREN LOWN 2015 ACKNOWLEDGEMENTS I would first like to thank my advisor, Dr. Carl Lira, for all of his guidance during my time as his PhD student. He has been a tremendous mentor to me. I would also like to thank my committee, Dr. Dennis Miller, Dr. Andre Lee, and Dr. James Jackson for all of their support and assistance. I want to thank Dr. Lars Peereboom for all his mentoring and training. I also want to thank Ravinder Singh and Jacob Anibal for their assistance with experiments and coding. In addition, I would like to thank my collaborators: James Anderson and Sherry Mueller at Ford Motor Company; Nichole Hubble and Eric Sattler at Tank Automotive Research, Development, and Engineering Center; and Robert Morris, James Edwards, and Linda Shafer at Air Force Research Laboratory. This thesis was also supported through funding from the Defense Logistics Agency (contract numbers SP4701-09-C-0037 and SP4701-11-C-0011), and the United States Army (contract number W56HZV-13-C-0340). Finally, I would like to thank my friends and family for their extensive support and love throughout my time in graduate school. In particular, I would like to thank my husband, without whose support this never would have been possible. v TABLE OF CONTENTS LIST OF TABLES ......................................................................................................................... ix LIST OF FIGURES ..................................................................................................................... xiv CHAPTER 1 ................................................................................................................................... 1 Introduction and Background ......................................................................................................... 1 1.1 Introduction ................................................................................................................... 2 1.2 Background ................................................................................................................... 5 CHAPTER 2 ................................................................................................................................... 7 Cold Flow Properties for Blends of Biofuels with Diesel and Jet Fuels ........................................ 7 2.1 Introduction ................................................................................................................... 8 2.2 Materials and Methods .................................................................................................. 9 2.2.1 Materials ................................................................................................................. 9 2.2.2 Experimental methods .......................................................................................... 13 2.2.2.1 Gas chromatography method .......................................................................... 13 2.2.2.2 Cloud point testing (ASTM D7683) ............................................................... 13 2.2.2.3 Cloud point testing (ASTM D2500) ............................................................... 16 2.2.2.4 Cold filter plugging point (ASTM D6371) ..................................................... 17 2.3 Results and Discussion ............................................................................................... 17 2.3.1 Pure compounds .................................................................................................... 17 2.3.2 Functional group effect on cloud point temperature ............................................. 18 2.3.3 Effect of branching and chain length on cloud point temperature ........................ 22 2.3.4 Dibutyl succinate blends and liquid-liquid phase formation ................................ 24 2.3.4.1 Visual observation .......................................................................................... 24 2.3.4.2 Testing a system with a known liquid-liquid phase separation ...................... 26 2.3.4.3 Comparison of cloud point and cold filter plugging point temperatures ........ 27 2.3.5 Discussion summary ............................................................................................. 28 2.4 Conclusions ................................................................................................................. 29 CHAPTER 3 ................................................................................................................................. 30 Physical Property Prediction Methods for Fuels and Fuel Components ...................................... 30 3.1 Introduction ................................................................................................................. 31 3.2 Property development and extension .......................................................................... 32 3.2.1 Overview ............................................................................................................... 32 3.2.2 Gas phase properties ............................................................................................. 33 3.2.3 Liquid phase properties ......................................................................................... 35 3.3 Summary ..................................................................................................................... 46 CHAPTER 4 ................................................................................................................................. 47 Development of an Adaptable and Widely Applicable Fuel Surrogate ........................................ 47 4.1 Introduction ................................................................................................................