High-Energy-Density Fuels for Advanced Propulsion E-Book

Ji-Jun Zou

• Herausgeber: Wiley-VCH Verlag GmbH & Co. KGaA
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 770

Veröffentlichungsjahr: 2020

Beschreibung

This book comprehensively and systematically demonstrates the theory and practice of designing, synthesizing and improving the performance of fuels. The contents range from polycyoalkane fuels, strained fuels, alky-diamondoid fuels, hypergolic and nanofluid fuels derived from fossil and biomass. All the chapters together clearly describe the important aspects of high-energy-density fuels including molecular design, synthesis route, physiochemical properties, and their application in improving the aerocraft performance. Vivid schematics and illustrations throughout the book enhance the accessibility to the relevant theory and technologies. This book provides the readers with fundamentals on high-energy-density fuels and their potential in advanced aerospace propulsion, and also provides the readers with inspiration for new development of advanced aerospace fuels.

Leseprobe

High‐Energy‐Density Fuels for Advanced Propulsion

Design and Synthesis

Edited by

Ji‐Jun Zou

Xiangwen Zhang

Lun Pan

Editors

Ji‐Jun ZouTianjin UniversitySchool of Chemical Engineering and Technology92 Weijin RoadTianjin 300072China

Xiangwen ZhangTianjin UniversitySchool of Chemical Engineering and Technology92 Weijin RoadTianjin 300072China

Lun PanTianjin UniversitySchool of Chemical Engineering and Technology92 Weijin RoadTianjin 300072China

Cover Image:© Philip Steury /Getty Images

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Print ISBN: 978‐3‐527‐34669‐1ePDF ISBN: 978‐3‐527‐82376‐5ePub ISBN: 978‐3‐527‐82377‐2oBook ISBN: 978‐3‐527‐82378‐9

We would like to dedicate this book to Professor Zhentao Mi, who launched the research on advanced fuel and chemical propellant in Tianjin University as early as in the 1980s. He established a top‐level lab and was the leader of the lab until retiring in 2007. The lab was certificated as Key Laboratory for Advanced Fuel and Chemical Propellant of the Ministry of Education in 2008.

We would also like to dedicate this book to the 125th anniversary of Tianjin University. Tianjin University, founded in 1895 as Peiyang University, is the oldest institution of higher education in the modern history of China. The authors of this book obtained degrees from this university and continue their professional careers in this university.

Preface

Aerospace technology is one key to improve the life quality of human being and extend the capability of exploring space, and high‐energy‐density fuels can specifically boost the performance of aerocrafts. Although most of the high‐energy‐density fuels are hydrocarbons, their molecular structures and compositions are very different from traditional jet fuels and rocket fuels produced directly from petroleum refinery. Therefore such fuels are always synthesized by chemical reactions. The synthesis of high‐energy‐density fuels can be traced back to 1950s, and considerable progress has been achieved especially in the past 20 years. There are many literatures including technical reports and peer‐viewed publications on the synthesis and application of high‐energy‐density fuels. Especially, some reviews have been published by researchers from aerospace industry and focus on the properties of well‐developed fuels, while the synthesis chemistry of fuels, including well‐developed and underdeveloped fuels, have not been treated at a scientific level.

High‐Energy‐Density Fuels for Advanced Propulsion: Design and Synthesis comprehensively and systematically demonstrates the concept, design and synthesis of high‐energy‐density fuels, and its great potential in improving the performance of aerocrafts. The contents range from polycyoalkane fuels, strained fuels, alky‐diamondoid fuels, and hypergolic and nanofluid fuels derived from fossil and biomass, with focus on molecular design, synthesis chemistry, physiochemical properties, and their application. Most of the contents in this book are fresh achievements of the authors' lab, i.e. Key Laboratory for Advanced Fuel and Chemical Propellant of the Ministry of Education, in the past 20 years.

This book will cover the theory and practice of designing, synthesizing, and improving the performance of fuels. We hope it can connect the road from the past, present, and future of fuel chemistry and technology, provide the readers with fundamentals on high‐energy‐density fuels and their potential in advanced aerospace propulsion, and also provide the readers with inspirations for new development of advanced aerospace fuels.

This book is directed primarily to fuel chemistry and technology and aerospace propulsion technology and aims to be a definitive reference book for researchers, engineers, and students majoring in chemical science and engineering, mechanical engineering, and aerospace engineering.

4 December 2019

Ji‐Jun Zou

Xiangwen Zhang

Lun Pan

Tianjin, China

About the Editors

Dr. Ji‐Jun Zou is a chair professor at School of Chemical Engineering and Technology, Tianjin University, and head of Department of Chemical Technology. He received PhD degrees from School of Chemical Engineering and Technology, Tianjin University, in 2005. He was a visiting scholar at the University of California, Riverside, from 2014 to 2015. He has been devoted to synthesis and application of advanced aerospace fuels for about 15 years. He has authored more than 130 papers and was granted with more than 20 patents. He received several awards including Technological Leading Scholar of Ten Thousand Talent Project, Changjiang Young Scholar, National Science Fund for Excellent Young Scholars, and National Excellent Doctoral Dissertation. He is an associate editor of RSC Advances and editor member of Chinese Journal of Energetic Materials.

Dr. Xiangwen Zhang is a professor at School of Chemical Engineering and Technology, Tianjin University, and the director of Key Laboratory of Advanced Fuel and Chemical Propellant of the Ministry of Education. He received his academic degrees from Tianjin University and became a full professor in 2006. He has been devoted to the investigation and development of fuel chemistry including fuel processing technology and reaction engineering for more than 20 years. He has authored/coauthored more than 300 papers and 30 patents.

Dr. Lun Pan is an associate professor at School of Chemical Engineering and Technology, Tianjin University. He received his BS and PhD degrees from the School of Chemical Engineering and Technology, Tianjin University, in 2009 and 2014, respectively. He was a visiting scholar at Georgia Institute of Technology from 2016 to 2017. His research interests mainly focus on the synthesis of high‐performance hydrocarbon liquid fuels and the rational design and synthesis of functional catalysts. He has published more than 50 papers and 5 patents. He has been devoted to the investigation and development of fuel chemistry for more than 10 years. He is currently an editor member of Shandong Chemical Industry.

Acknowledgments

Over the years, many students and colleagues have contributed to the development of the concepts, design, synthesis, and application of high‐energy density fuels included in this book. Professor Li Wang, Professor Qingfa Wang, and Professor Guozhu Liu provide the kind support and cooperation in the research work. This book covers many thesis research works of our graduate students, including Dr. Zhongqiang Xiong, Dr. Enhui Xing, Dr. Lei Wang, Dr. Hong Han, Dr. Jing Kong, Dr. Jiajia Song, Dr. Qiang Deng, Dr. Genkuo Nie, Dr. Xiu‐Tian‐Feng E, Kai Jiang, Qian Miao, Bin Zhu, Mingyue Zhang, Yi Liu, Di Cao, Na Chang, Yu Zhang, Yan Xu, TingTing Ma, Fang Wang, Peijuan Han, and Zhen Li. Especially, several people made contributions to the writing of this book by checking and polishing the chapters including PhD candidates Yutong Wang, Minhua Ai, Jisheng Xu, Ying Chen, and Shangcong Sun and MS candidates Xuewei Lang and Xiaoting Xu.

The work included in this book is partially supported by National Natural Science Foundation of China (20906069, 21222607, U1462119, 21978200, 21676193, 51661145026, 21506156, 21476168), Ministry of Education of China (6141A02033522, 6141A02022507), and the Tianjin Municipal Natural Science Foundation (15CZDJ37300, 16JCQNJC05200).

1Introduction

Ji‐Jun Zou

Tianjin University, Key Laboratory of Advanced Fuel and Chemical Propellant of the Ministry of Education, Key Laboratory for Green Chemical Technology of the Ministry of Education, Department of Chemical Technology, School of Chemical Engineering and Technology, 92 Weijin Road, Tianjin, 300072, China

The aerospace technology has undergone tremendous development since the first flight by Wright Brothers in 1903, which has significantly improved the life quality of human being and extended the capability of space explosion. Nowadays the aerospace vehicles mainly include commercial/military airplanes, missiles, rockets, spaceships, and satellites, which equipped with turbine, turbofan, ramjet, or rocket engines. Most of them apply liquid fuels majorly including hydrocarbon‐based and hydrazine‐based fuels. Hydrocarbons are the sole liquid fuel of airplanes, most missiles, and some rockets, meanwhile hydrazine and its derivatives are solely used for rockets for space exploration. Hydrocarbons have obvious advantages of safety and nontoxicity compared with hydrazine; thus many rockets using hydrocarbons have been used.

The primary role of liquid fuels is to provide energy source for propulsion, so the energy density of fuels is critically important because to a large degree it can determine the flight distance and payload of vehicles. Of course, fuels with high‐energy density are always desirable because they can provide sufficient energy to enhance the flight performance. With the same fuel tank, the utilization of high‐energy density fuels can extend the flight distance, increase the payload, or increase the cruise endurance. Otherwise, the volume of fuel tank can be reduced when using high‐energy density fuels; thus the more space is accessible for loading or the overall volume of vehicles can be greatly reduced. This is especially important for volume‐limited vehicles like battle planes, unmanned aerial vehicles, tactical missiles, spaceships, and satellites, for which the space for fuels is strictly restricted.

Traditional liquid fuels produced from petroleum refinery industry, like widely used jet kerosene and rocket kerosene, possess relatively low energy density (<34 MJ/l). And high‐energy density fuels generally have energy density higher than 36 MJ/l, which is a result of density multiplied by mass energy. To get high‐energy density fuels, synthesis chemistry is the first choice, for which two ways can be used. One is to synthesize polycyclic and diamondoid hydrocarbons with contact cyclic structure to afford high density (called high‐density fuels); however its mass energy is not increased or even slightly decreased due to the lowered H content. The other is to synthesize strained cyclic hydrocarbons, which not only provide high density but also increase the mass energy attributed to the additional trained energy in the molecules, and thus is more effective to increase the energy density. Actually, the synthesis chemistry of high‐energy density fuels has been rapidly developed. However, it is difficult to further increase the energy density of hydrocarbons, so many new approaches have been explored, like the addition of energetic nanoparticles in hydrocarbons to get nanofluid and gelled fuels. Also, as response to the sustainable development, producing high‐energy density fuels from renewable source like biomass has become a hot topic, which is different from the synthesis of common biojet fuels and requires more sophisticated synthesis. Moreover, the applications of high‐energy density fuels have been extended from traditional vehicles to many advanced vehicles that often work under adverse circumstances. In this case how to realize the energy of fuels to maximum degree is a big challenge; for this purpose it is necessary to enhance the ignition and combustion of fuels. It is also worth noting that the reason for the wide use of toxic hydrazine derivates in rocket engines as fuel of bicomponent propellant is the excellent hypergolicity of hydrazine, which can ensure the reliability and avoid the use of complex ignition device. To replace toxic hydrazine derivates, it is necessary to develop safe and green hypergolic fuels. And energetic ionic liquids have been proved as a good choice, although its energy density is not so high.

Besides the high‐energy density, advanced fuels must satisfy several specifications for application, such as low‐temperature fluidity, thermal oxidative stability, combustion characteristics, compatibility with materials, and volatility. The structure and composition of fuel must be finely controlled, which depends on the synthesis technology that may include several aspects of synthesis chemistry such as design of fuel molecules, design of synthesis route, understanding of reaction mechanism, design and fabrication of catalyst, integration and scale‐up of reaction, etc.

This book will cover the theory and practice of designing, synthesizing, and improving the performance of fuels and connect the road from the past, current, and future of fuel chemistry and technology. In the following Chapters 2–9, we will comprehensively and systematically demonstrate the concept, design, and synthesis of high‐energy density fuels and its potential in improving the performance of aerospace vehicles. The contents range from polycyoalkane fuels, strained fuels, alky‐diamondoid fuels, and hypergolic and nanofluid fuels derived from fossil and biomass (Figure 1.1), including molecular design, synthesis route, physiochemical properties, and their application. Chapter 2 will summarize the development history and basics of aerospace fuels including traditional fuels and high‐energy density fuels. Chapter 3 will present the design and synthesis of high‐density polycyoalkane fuels, with the catalyst and reaction optimization as focus. Chapter 4 will introduce the synthesis of high‐density diamondoid fuels and focus on two control synthesis routes. Chapter 5 will introduce the design and synthesis of high‐energy strained fuels, in which the synthesis will extend from liquid to solid strained hydrocarbons. Chapter 6 will summarize the design and synthesis of high‐density fuels from biomass derivates, including the typical reaction route, catalysts, and mechanism. Chapter 7 will show synthesis of energetic nanofluid fuels and the gelling technology to stabilize them. Chapter 8 will present the design and synthesis of green hypergolic liquid fuels and show it potential to replace toxic hydrazine. Chapter 9 will focus on how to improve the combustion properties of high‐energy density fuels.

Figure 1.1 The synthesis and upgrade of high‐energy‐density fuels including fossil, biomass, nanofluid, and ionic liquid‐based fuels for aerospace propulsion.

Source: Zhang et al. (2018). Reproduced with permission of Elsevier.

Reference

Zhang, X.W., Pan, L., Wang, L. et al. (2018). Review on synthesis and properties of high‐energy‐density liquid fuels: hydrocarbons, nanofluids and energetic ionic liquids.

Chemical Engineering Science

180 (28): 95–125.

2Development History and Basics of Aerospace Fuels

Xiangwen Zhang and Tinghao Jia

Tianjin University, Key Laboratory of Advanced Fuel and Chemical Propellant of the Ministry of Education, Key Laboratory for Green Chemical Technology of the Ministry of Education, Department of Chemical Technology, School of Chemical Engineering and Technology, 92 Weijin Road, Tianjin, 300072, China

2.1 Introduction

Hydrocarbon fuels are widely used in aerospace propulsion platforms since Wright brothers used gasoline to achieve their first flight in 1903 (Edwards 2007, p. 13). The invention of the gas turbine engine or “turbojet” was regarded as the milestone event in aviation industry. However, for nearly a decade after the first flight of the turbojet, attempts to define a suitable fuel specification were less than successful. From late 1930s, the successful application of gas turbine engines in aviation industry prompted the development of more and more rigorous jet fuel specifications (Maurice et al. 2001, p. 747). As engine performance and therefore aircraft operational capabilities developed, jet fuel production and specification progressed to meet the flight requirements while maintaining a balance between availability and cost. Special fuels (such as high‐density fuels and high‐thermal‐oxidative‐stability fuels) have been developed to meet the requirement of unique operation, especially the high‐speed and long‐duration flights. For example, experience gained in fuel development efforts for flights leads to consideration of fuels for high‐speed flights, such as supersonic and hypersonic flights. Moreover, fuel density, more specifically, the energy density of fuel is the main criteria used in selecting liquid hydrocarbons for certain flight regimes of long‐duration applications (Zhang et al. 2018, p. 95).

Variation in fuel properties and performance owing to differences in chemical composition can be significant (Yue et al. 2016, p. 1216). However, the composition of kerosene fuels is not fixed through specifications (Billingsley et al. 2010, p. 6824). The relationships between fuel compositions, physical and chemical properties, and performance in realistic operating conditions are imperative to be established; however, this task definitely is time consuming. Ideally, several models will be incorporated in the optimization of fuel composition to meet requirements for future systems in the areas of alternative fuels certification, hypersonic vehicles, and liquid rocket propulsion systems.

The requirement of aviation transportation to environment and supply safety is being a key factor in jet fuel field (Chiong et al. 2018, p. 640; Wang et al. 2019, p. 31). To reduce greenhouse gas (GHG) emission and ensure abundant fuel supply, the shift from conventional petroleum resources to coal or biomass fuels is very necessary. A promising technological route for addressing this challenge is the chemical conversion of coal, shale oil, natural gas, or plants, which ultimately can result in the upgrade of low‐value feedstock to high‐value fuels.

In this chapter, development history of conventional (petroleum‐derived) jet fuels and non‐petroleum jet fuels is reviewed, with special focus on more recent developments of specialized high‐density fuels and high‐thermal‐oxidative‐stability fuels. Furthermore, the basic requirements of jet fuels are introduced as well as the relationship between fuel composition and performance. Finally, we briefly discuss the main challenges of future high‐performance jet fuels that comprise various factors.

2.2 General Properties and Requirements of Aerospace Fuels

The composition of aerospace fuels is determined by specifications that are primarily based upon operational requirements. As shown in Figure 2.1, the specifications regulate several basic characteristics: volatility, fluidity, composition, combustion, corrosion, stability, and contamination levels (e.g. sulfur content; Yang et al. 2019, p. 916). These properties influence important operational considerations such as range potential, operability, system maintenance requirements, and safety. Moreover, cost and availability are always paramount importance in the selection of jet fuels. Actually, the final jet fuel must be the compromise of abovementioned properties.

Figure 2.1 Several basic characteristics of typical jet fuels.

Source: Yang et al. (2019). Reproduced with permission of Elsevier.

2.2.1 Density

Density can determine the loaded fuel weight and further the fly range of aircraft, which can be also used for flow calculations, tank gauging, fuel metering devices, and structural design of fuel tanks. Normally, fuel density is largely determined by the nature of the crude oil from where they are derived. Figure 2.2 illustrates the typical density of jet fuel as a function of cycloalkanes content (Elmalik et al. 2013, p. 1856). Obviously, the density exhibits strong linear trends with the cycloalkane content. As expected, the density of the n‐alkanes would be the lowest of the three compositional groups among aromatics, cycloalkanes, and linear alkanes. According to ASTM D1655, the density of aviation turbine fuels is specified to 0.775–0.840 g/cm3 at 15 °C. Since civil aircraft is a weight‐limited vehicle, a high premium is assigned to hydrocarbon fuels with a maximum gravimetric heat content or hydrogen‐to‐carbon ratio. Alkanes have high mass heat of combustion (about 45 MJ/kg) owing to its relatively high H/C atomic ratio. Therefore, Jet A or Jet A‐1 (jet fuel for civilian) with density about 0.78–0.82 g/cm3 usually comprises approximately 40–60% of alkanes (Shi et al. 2017, p. 395).

On the contrary, the military aircrafts are usually volume‐limited vehicles. The density of alkanes is relatively low; therefore the volumetric net heat of combustion (NHOC) of alkane usually is too low to meet the requirement of military aircrafts (see Figure 2.3). Cycloalkane possesses higher density and usually features high energy density (HED) comparing with alkane (e.g. 0.66 g/cm3 at 20 °C for n‐hexane vs. 0.78 g/cm3 at 20 °C for cyclohexane; Zhang et al. 2018, p. 95). With this consideration, cycloalkane fuels can increase vehicle range and/or payload of volume‐limited vehicles. High‐density fuels usually refer to the fuels with density higher than 0.85 g/cm3 at 20 °C, and accordingly, the fuel characterized with volumetric NHOC higher than 36.0 MJ/l is regarded as HED fuel (Chung et al. 1999, p. 641). Figure 2.4 traces the chronological development of HED fuels, and up to now, some of them, such as exo‐tetrahydrodicyclopentadiene (THDCPD), have been used in civil and military aircrafts successfully.

Figure 2.2 Density as a function of cycloalkane content.

Source: Elmalik et al. (2013). Reproduced with permission of American Chemical Society.

Figure 2.3 Correlation between density and volumetric heating value.

Source: Chung et al. (1999). Reproduced with permission of American Chemical Society.

2.2.2 Low‐Temperature Fluidity

The low‐temperature fluidity, which is one of the most important characteristics of jet fuels, can be characterized by freezing point and kinematic viscosity. The temperature of fuel tank is extremely low at high altitudes (usually at −55 °C when aircraft operated at 8 km); thus the freezing point and kinematic viscosity of jet fuels must be sufficiently low to ensure proper fuel fluidity in turbine engine systems.

2.2.2.1 Viscosity

The decrease in the temperature of fuels in the fuel tank during long‐duration flight produces a number of effects, which can influence flight performance. Viscosity is directly used in calculating pressure drop when designing fuel systems. The increase of fuel viscosity necessitates more pumping energy for pump system. The viscosity directly controls the atomization in nozzle (Yang et al. 2019