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Über dieses Buch

This book comprises state-of-the-art advances in energy, combustion, power, propulsion, environment, focusing on the production and utilization of fossil fuels, alternative fuels and biofuels. It is written by internationally renowned experts who provide the latest fundamental and applied research innovations on cleaner energy production as well as utilization for a wide range of devices extending from micro scale energy conversion to hypersonic propulsion using hydrocarbon fuels. The tailored technical tracks and contributions are portrayed in the respective field to highlight different but complementary views on fuels, combustion, power and propulsion and air toxins with special focus on current and future R&D needs and activities. This book will serve as a useful reference for practicing engineers, research engineers and managers in industry and research labs, academic institutions, graduate students, and final year undergraduate students in mechanical, chemical, aerospace, energy, and environmental engineering.



High-Speed Propulsion


Towards Credible CFD Analysis of High-Speed Propulsion Systems

Computational technologies are beginning to play a major role in the design and development of high-speed propulsion systems. Therefore, it is imperative that the computations conducted are both accurate and representative of the system under consideration. Some of the key issues that must be considered to conduct such credible simulations are discussed in this paper. Concepts such as “verification” and “validation” are introduced and discussed in the context of high-speed propulsion systems. Additional issues that arise when we move from well-established propulsion to newer, advanced propulsion systems are discussed. Specific examples from recent developments in high-speed detonation-based propulsion are used to highlight and clarify some of the important concepts. Outstanding issues that need further research and development are also discussed.
K. Kailasanath

Numerical Study of Spherical and Cylindrical Shock Wave Focusing

A large amount of energy is associated with shock waves. Current work studies the flow parameters upon exposure to cylindrical and spherical shock focusing. Shock wave is allowed to focus by traversing through a confined converging section attached to a shock tube. The shock tube is having 2 m driver and 6 m driven section. Numerical simulations were carried out using commercially available software ANSYS-Fluent. 2-D Planar and 2-D Axisymmetric models were simulated in order to obtain cylindrical and spherical shock wave focusing effect. The shock wave with increased strength is found to accelerate inside the converging section. Moreover, during focusing, spherical shock is observed to have more acceleration in comparison to cylindrical shock. A detailed study of spherical shock focusing with real gas effects was added in the numerical simulations. 47% reduction in the maximum temperature is observed with inclusion of real gas effects.
V. S. Saranyamol, Nanda Soumya Ranjan, Sugarno Mohammed Ibrahim

Renewable Fuels


Renewable Energy Derived from Water Hyacinth Through Hydrothermal Gasification

Renewable energy is one of alternative energy instead of fossil energy such as coal, oil and natural gas which is limited energy, and it is also environmentally friendly. This research is to develop an available biomass and utilize it for commercial benefit, for example, use as fuel for the gasification especially high humidity fuel, such as water hyacinth. The advantage of using water hyacinth is growing very fast and easy to find at water source. Water hyacinth is a plant with very high percentage of moisture which is not suitable for use as fuel in combustion technology. Therefore, hydrothermal gasification is an appropriate technology to produce high-quality gas from wet biomass. Hydrothermal gasification experiments will be carried out in a batch type at temperature ranging from 240 to 320 °C without catalyst. Different biomass to water ratio and reaction time will be used as experimental condition to achieve the best conditions for hydrogen-rich gas production. The composition of producer gas, carbon dioxide (CO2), carbon monoxide (CO), methane (CH4) and hydrogen (H2) will be analyzed by gas chromatograph (GC). The hydrogen-rich producer gas can be used directly as fuel for electricity or heat production or can be used for other fuels production in the future.
Somrat Kerdsuwan, Krongkaew Laohalidanond

Thermochemical Solutions for CO2 Utilization to Fuels and Value-Added Products

Growing energy demands for improved lifestyle and enhanced productivity has caused greater use of energy produced from fossil fuels, which in turn is leading to unsustainability with continuously increasing CO2 into the environment that causes significant impact to climate changes. This chapter provides a review of the CO2 capture techniques, followed by thermochemical pathways for the CO2 utilization for energy, fuels and chemicals production with focus on sustainability and carbon cycle. Thermochemical redox looping techniques are also addressed due to their significantly higher potential compared to their alternatives, along with the considerations on material development for use in redox looping. Recent developments in mixed metal oxides derived from layered double hydroxides provided promising results on sustained redox capability. Furthermore, they offer minimal inhibitive impact of sintering and high CO yield per gram of the material at lower costs, and the process is scalable compared to other methods that use rare earth elements. The challenges and future research directions on the development of oxygen carrier redox materials are provided. CO2–assisted gasification of biomass and solid wastes offers good pathway for CO2 conversion to syngas based on CO2 converted to syngas per gram of feedstock used. The results demonstrated highest throughput and higher efficiency than that known presently. Furthermore, the approach offered good potential for scalability compared to other pathways of CO2 utilization.
K. G. Burra, P. Chandna, Ashwani K. Gupta

Performance and Controlling Regimes Analysis of Methane Steam Reforming on Ru/γ-Al2O3 Cordierite Monoliths

In the frame of methane steam reforming (MSR) process intensification for H2 production, catalysts based on ruthenium (Ru) supported on alumina (Al2O3) on cordierite monolith have been studied in terms of catalytic performance, mass and heat transfer effects. Firstly, we compared the catalytic activity of Ru and Rh supported catalysts. Secondly, we study the effect of catalyst loading by varying the amount of carrier and active metal phase corresponding to 3.20, 6.45 and 12.89 mg cm−2. Then, we evaluated the mass/heat transfer effects and controlling regimes for the best-selected catalyst. Finally, the best-selected catalyst was characterized by means of Brunauer–Emmet–Teller (BET), X-ray diffraction analysis (XRD) and Field-emission scanning electron microscopy (FESEM). The experiments were carried out in the temperature range of 550–850 °C, steam-to-carbon molar ratio (S/C) of 3.0 and different weight hourly space velocity (WHSV = 750, 1500 and 3000 Nl h−1 g cat −1 ). The catalyst with 1.5% Ru on 10% Al (1.5Ru10Al) was found to be the most promising toward the MSR reaction in terms of CH4 conversion and H2 production. This catalyst operates in a mixed regime for all temperature range studied, in which both the kinetic and the intraparticle diffusion co-exist. For the 1.5Ru10Al catalyst, the external thermal effects are important a temperature below 725 °C, while that intraparticle heat effects are absent for all the range of temperature studied. An excellent stability of the 1.5Ru10Al catalyst was observed over 70 h of time on stream (TOS) for MSR process.
Carmen W. Moncada Quintero, Roman Z. Babar, Stefania Specchia

Flames and Reacting Systems


Effect of Natural Gas Blend Enrichment with Hydrogen on Laminar Burning Velocity and Flame Stability

Present study deals with the effect of enrichment with H2 on the laminar burning velocity (LBV) and flame stability of various multicomponent NG–air mixtures. In the present work, constant pressure outwardly propagating spherical flame method is used to experimentally evaluate the LBV and burned gas Markstein length (Lb) of various fuel–air mixtures. The chemical kinetic analysis is performed with the help of CHEMKIN-PRO® simulation software by using various detailed chemical kinetics mechanisms. All the experiments and simulations are performed at an initial pressure and temperature of 0.1 MPa and 300 ± 3 K, respectively. The addition of H2 to NG blends increases the concentration of active radicals (H, O, and OH) in the reaction zone, and hence, enhances the combustion chemistry of the H2-enriched NG blend. The effect is most prominent for the NG6–H2 blend, which has the highest mole fraction of CH4. The addition H2 in the lean fuel–air mixtures reduces their Lewis number and thus may make the flames unstable. However, the NG5–H2 blend, which has the highest mole fraction of C3H8, maintains a positive Lb over a wider range of equivalence ratios (0.7–1.4). The predictions of LBV using GRI-MECH 3.0 is the closest to the experimental results for the blends with 75% H2 in the fuel when compared with those using San Diego and USC-II mechanisms.
A. R. Khan, M. R. Ravi, Anjan Ray

Blowoff Characteristics of Laminar Partially Premixed Flames of Palm Methyl Ester/Jet A Blends

The blowoff characteristics of laminar partially premixed flames of prevaporized palm methyl ester (PME) and Jet A blends were studied over a range of equivalence ratios of 0.53–0.83 with and without heated coflow. The injector was designed to produce a uniform inner flow and had an inner diameter of 12.7 mm. The coflow velocity ranged up to 3.5 m/s. The flames were laminar and blue in color (dominated by homogeneous gas-phase reactions). The temperature profiles in all the flames were similar with a peak temperature of 1740 K. The blowoff velocity increased with equivalence ratio for all the flames; the difference in blowoff velocity of pure PME flames and pure Jet A flames was within experimental uncertainty. A Damköhler number (based on the velocity gradient at the jet boundary and chemical reaction timescale estimated from laminar flame velocity) of 2–8 characterized the blowoff velocity. As the coflow velocity was increased, the blowoff velocity was increased, and the differences between the values for the various flames became smaller.
T. Maleta, R. N. Parthasarathy, S. R. Gollahalli

Effect of Composition and Octane Sensitivity of Gasoline Surrogates on PAH Emissions

Primary reference fuels consisting of a mixture of n-heptane and iso-octane have traditionally been used as surrogates to mimic the combustion and emission behavior of gasoline and diesel fuels. However, several recent studies have demonstrated the need to develop more complex surrogates with three or more components in order to better represent the behavior of both conventional and newly emerging fuels, and for a wide range of combustion modes. This is due to the fact that PRF surrogates cannot be used to rate gasoline in terms of RON (research octane number) and octane sensitivity (S) since different PRF surrogates are needed to match the gasoline behavior at different operating conditions. This chapter discusses research dealing with the effects of fuel composition and S on PAHs emissions in laboratory-scale configurations, which include counterflow diffusion and partially premixed flames, and jet-stirred reactor focusing on fuel pyrolysis. Several surrogates with a RON = 70 and S = 0–5.6, and with two, three, and four components containing different amounts of n-heptane, iso-octane, toluene, and ethanol, are considered. For counterflow diffusion flames with binary mixtures (n-heptane/toluene and iso-octane/toluene), results indicate a non-monotonic variation of PAH emission with respect to toluene fraction in the mixture, implying a synergistic effect on PAH emissions at higher toluene content. For the ternary blends investigated, results indicate that RON and S are not true indicators of PAHs emissions. Rather the PAHs emissions are related to the blend composition. On the other hand, for quaternary blends, results indicate a correlation between S and PAH emissions. Thus, an important observation is that the composition of multi-component fuel mixture has a major effect on PAH and soot emissions. In contrast, the effect of S on PAH and soot emissions are not very clear and requires further studies that can explore fuel blends for a wider range of RON and S values.
Krishna C. Kalvakala, Suresh K. Aggarwal

Hybrid RANS/LES Simulation of Methane–LOx Combustion

To have a better understanding of the liquid rocket engine combustion characteristics, numerical simulations of cryogenic combustion need to be carried out. Transcritical combustion involving methane and liquid oxygen propellant mixture is carried out in the 3D domain. Experimental works of Singla et al. in MASCOTTE test chamber are used for comparison with numerical results. Hybrid RANS/LES formulation is employed by carrying out Detached eddy simulations (DES) with a steady diffusion flamelet PDF approach to model the non-premixed combustion regime. Real gas effects are considered using Soave-Redlich-Kwong equations, and a reduced Jones–Linstedt chemkin mechanism is chosen to describe the chemistry. Further, the impact of chamber pressure is also studied by conducting simulations at a higher chamber pressure. The results obtained from the numerical study offer good agreement with experimental findings. The jet flame has thin flame front post injector inlet and gradually broadens downstream. The presence of shear layer and turbulent mixing at near-critical conditions causes large gradients of density and temperature to exist in the flow field while recirculation zones enable flame holding mechanism at Lox tip. At higher chamber pressure, the flame characteristics remain similar but the mixing process is subdued. DES poses certain discrepancies in simulating the rear part of flame, possibly due to the unsuccessful resolution of small, turbulent scales.
Kisalaya Mishra, Malay K. Das, Ashoke De, Kamal K. Kar

Experimental and Numerical Studies on Combustion-Based Small-Scale Power Generators

Experimental and numerical investigations on a microcombustor-based thermoelectric power generator have been performed in the present study. A detailed parametric study on the effect of different heat sources and heat sinks is carried out, and the thermoelectric power characteristics are analysed in detail. The dual combustor is found to be 20% more efficient than the single combustor in thermal characteristics due to the improved flame-to-wall interaction. The water-cooled and air-cooled heat sinks are tested on the dual combustor-based micropower generator, and output power values of 4.5, 2.4 W with conversion efficiencies of 4.6, 2.5% are achieved, respectively, for water- and air-cooled power generators. Furthermore, a self-aspirating microcombustor-based power generator is developed where the system was able to deliver an output power of 0.5 W without any auxiliary power input. Based on the results obtained above, a stand-alone portable 1 W micropower generator is prototyped. Furthermore, a three-dimensional numerical model of thermoelectric power generator is developed. An extensive numerical analysis of the flame dynamics of the combustor by using detailed chemical kinetics and optimizing the performance of the thermoelectric generator simultaneously for the integrated combustor-TEG power generation system is carried out. A maximum output power of 4.35 W with a conversion efficiency of 5.39% is achieved numerically.
B. Aravind, Karan Hiranandani, Sudarshan Kumar

Combustion Systems


Fundamental Combustion Research Challenged to Meet Designers’ Expectations

Authors in recent publications shared their personal “gripe” for the modeling capabilities not reasonably calibrated before the start of their application in gas turbine combustion technology programs conducted since 1973. Concurrently, the supporting fundamental research results did not provide the insight needed for making critical design decisions during the technology and/or product development phase. Therefore, a joint effort was kicked off in 2012 on fundamental research to gauge what it takes to calibrate or validate the models while in parallel support hypothesis-based technology development approach specifically targeted for developing swirl-venturi lean direct injection (SV-LDI) technology. As summarized in this paper, based on this pilot project’s output to date, for a properly formulated applicable fundamental research with limited resources, it takes much longer than what Mongia had wished for since 1973.
Hukam C. Mongia, Kumud Ajmani, Chih-Jen Sung

Mitigation of Thermoacoustic Instability Through Amplitude Death: Model and Experiments

The combustors used in practical devices such as rockets and gas turbine engines are in most cases prone to large amplitude pressure oscillations, known as thermoacoustic instability. Due to such high-amplitude pressure oscillations, the lifetime of the engines reduces, including structural damage and reduction in the performance of the engines. Hence, such oscillations need to be avoided, and therefore, many control techniques, both passive and active, have been implemented in the past to suppress these undesired oscillations. In the present chapter, we discuss an approach based on amplitude death (AD) phenomenon to mitigate thermoacoustic oscillations. AD is a general outcome in coupled oscillators, wherein individual oscillators cease to oscillate when coupled appropriately. We systematically investigate amplitude death (AD) phenomenon in a thermoacoustic system using a mathematical model of coupled prototypical thermoacoustic oscillators, the horizontal Rijke tubes. We particularly examine the effect of time-delay and dissipative couplings on a system of two Rijke tubes when they are symmetrically and asymmetrically coupled. The regions where appropriate combinations of delay time, detuning, and the strengths of time-delay and dissipative coupling lead to AD are identified. The relative ease of attaining AD when both the couplings are applied simultaneously is inferred from the model. In the presence of strong enough coupling, AD is observed even when the oscillators of dissimilar amplitudes are coupled, while a significant reduction in the amplitudes of both the oscillators is observed when the coupling strength is not enough to attain AD. We further focus on the possibility of amplitude death (AD) in a noisy system. In the stochastic case, AD or a complete cessation of oscillation is impossible. However, we observed a considerable amplitude reduction in the coupled limit cycle oscillations. We also substantiate our claim through experiments where two Rijke tubes are coupled through a coupling tube whose length and diameter are varied as coupling parameters. We show that the effectiveness of coupling is sensitive to the dimensions of the coupling tube which can be directly correlated with the time-delay and coupling strength of the system.
Sirshendu Mondal, Nevin Thomas

Emission Characteristics and Flame Stability in HEFA Fueled Gas Turbine Combustors

Combustion rig tests of an RQL (rich burn quick quench lean burn) gas turbine combustor and of a single concentric lean-burn combustor were performed using kerosene (Jet A1), 100% hydro-treated ester and fatty acid (HEFA) alternative jet fuel and their blends. The results showed a clear tendency of suppression of non-volatile PM (nvPM) emission with an increase in the blending ratio of HEFA. Combustion test results were examined with the help of basic atmospheric and high-temperature and high-pressure testing. Blowout conditions and flame oscillations are also discussed.
H. Fujiwara, P. Salman, S. Ando, H. Ishikawa, S. Nakaya, M. Tsue, K. Okai

Aerothermal Technologies for Low Emissions Combustors

Developments in aeroengine gas turbine combustors have been driven primarily by the pollutant emissions targets set by initiatives such as Flightpath 2050. Technologies to meet these goals are underpinned by research which must increasingly adopt a multidisciplinary/systems approach, accounting for integration/performance matching of combustion system and compressor/turbine turbomachinery. Low emissions lean burn combustors with an increased fraction of compressor efflux through the fuel injector introduce new challenges. Increased size and multi-passage geometries lead to increased complexity of flame-stabilising swirl flow aerodynamics and decreased availability of cooling air. Combustion-induced thermo-acoustics makes all aspects of the combustor acoustic environment important. Illustrations are provided of research into combustor aerothermal technologies being developed to address these problems. For example, the use of a bespoke-design atmospheric isothermal 3D annular test rig allows cost-effective experimental studies of compressor/turbomachinery interactions and arrangements for cooled cooling air architecture. URANS CFD to predict injector acoustic response and LES CFD for high injector aerodynamics and effusion cooling are assessed/validated against representative experimental data.
M. Brend, J. F. Carrotte, J. J. McGuirk

Cluster Analysis of Turbulent Premixed Combustion Using On-the-fly Flame Particle Tracking

The recently developed flame particle tracking (FPT) technique [18] has provided critical insights into turbulence–flame interactions from the viewpoint of an observer co-moving with the flame. So far, FPT was implemented and used as a post-processing tool which required saving the Eulerian fields of fluid velocity and other scalars, obtained from the direct numerical simulations (DNS), onto external storage media. The field data were stored at equal time intervals which were usually smaller than the Kolmogorov time scale to accurately track the trajectories of the flame particles. The FPT, therefore, became extremely demanding on the storage space requirements, especially with increase in the domain size and/or the turbulence Reynolds number. Thus, there is a considerable advantage in terms of data storage, without compromising the accuracy of particle tracking, by implementing the algorithm to track flame particles within the DNS solver. We refer to this implementation as “on-the-fly” FPT as the particle tracking is performed concomitantly with the DNS. In this paper, we report the details of the first implementation of on-the-fly FPT in an open-source reacting flow DNS solver—the Pencil Code. The results from on-the-fly FPT are validated by analyzing the time series of the scalar property which by definition is required to be conserved along the trajectories of the flame particles. Subsequently, we use on-the-fly FPT to investigate the dynamics of flame annihilation. As the flame surfaces interact with turbulence, the flame particles defined on them preferentially drift and cluster in the trailing, concave regions of the surface before annihilation. Analyzing such clustering phenomenon elucidates mechanisms like kinematic restoration and flame island formation that leads to the local flame annihilation events.
Madwaraj Hatwar, Ashwin S. Nayak, Himanshu L. Dave, Utkarsh Aggarwal, Swetaprovo Chaudhuri

Starting Characteristics of a Micro Gas Turbine Engine at Different Loading Conditions

Gas turbines offer a more efficient alternative for power generation using fuel derived from waste. They have lower emissions, higher power-to-weight ratio, a smaller footprint, lower emissions, higher reliability and can be used with a wide range of fuels. These qualities make them a lucrative alternative to other conventional power generation methods, especially for distributed power (electricity) generation and supply system applications. In practice, the electrical load profile varies with time, causing the gas turbine to operate at loading conditions other its design point, or better known as off-design conditions. Operation of a gas turbine engine at off-design conditions requires in-depth analysis, especially during starting and load variations when connected to the grid, where transients may lead to instability issues if not regulated appropriately. This analysis is required to design necessary control schedules and put in place corrective actions in case of an instability. In the current work, a micro gas turbine (turbojet) engine is tested at two different loading conditions. The engine is instrumented with pressure, temperature and speed sensors at different locations in the engine. The load on the engine is increased by reducing the nozzle exit area. The objective of the current work is to study both the steady-state and transient operation of the engine, comparing its performance with the baseline engine. Under the first loading condition, the engine running line on the compressor map shifted toward the surge line. Also, the turbine pressure ratio decreased and the turbine entry temperature increased. At the second loading condition, the engine failed to start. At this loading condition, the turbine inlet temperature exceeded safe limits before the engine reached the required speed for a successful start. This failed start is attributed to the reduction in turbine pressure ratio. Under this loading condition, the turbine pressure ratio was not enough to accelerate the rotor speed to the desired speed. The control system continued increasing the fuel flow to facilitate the rotor speed to reach the desired starting speed. This resulted in high fuel flow rates resulting in a very high turbine inlet temperature.
T. Chandra Sekar, Ramraj H. Sundararaj, Rajat Arora, Abhijit Kushari

Transport Processes in Energy Systems


Transported PDF Modeling of Jet-in-Hot-Coflow Flames

A probability density function (PDF)-based combustion modeling approach for RANS simulation of a jet issuing into a hot and diluted coflow is performed. A tabulated chemistry-based model, i.e., flamelet-generated manifold (FGM), is adopted in the PDF method. The manifolds are constructed using igniting counterflow diffusion flamelets with different coflow compositions. To handle the inhomogeneity of the coflow and the entrainment of the ambient air, a second mixture fraction is defined to quantify the mixing of a representative coflow composition with the ambient air. The chemistry is then parameterized as a function of two mixture fractions and a reaction progress variable. To assess the modeling approach, Adelaide JHC flames, namely HM1, HM2, and HM3, having different oxygen concentrations in the hot coflow, 3%, 6%, and 9% O2, respectively, have been simulated for Reynolds number (Re) = 10,000. Profiles of mean mixture fraction and major species are accurately captured by the model along with the mean temperature. The mean temperature profiles are also captured nicely, while the sensitivity of progress variable (PV) on the predictions is highlighted.
Ashoke De, Gerasimos Sarras, Dirk Roekaerts

CFD Simulation of Soot Dynamics in the Exhaust System of an Engine to Meet Particulate Standards of 2020 and Beyond

This study presents a computational model for the detailed prediction of particulate matter size distribution in thermal precipitators systems by coupling CFD with population balance models (ACRi, 2016 [1]; Ni et al. in Fuel 228:215–225, 2018 [23]; Rajagopal et al. in Energy for propulsion. Springer, Singapore, pp. 345–364, 2018 [31]; Rodrigues et al. in Combust Flame 190:477–499, 2018 [32]). Detailed size distributions of particulate matter are very helpful in the design of after-treatment devices for removing soot from vehicle exhaust systems and enabling vehicles to meet emission norms of 2020 and beyond (Di Natale et al. in Fuel Process Technol 175:76–89, 2018 [22]). An existing and well-validated, reacting flow, Navier-Stokes solver (ACRi, 2016 [1]) is enhanced with numerical schemes to solve the population balance equations using the sectional method (Rajagopal et al. in Energy for propulsion. Springer, Singapore, pp. 345–364, 2018 [31]). This numerical scheme takes account of particle aggregation through the Fuchs kernel for transition regime, and deposition processes, including gravitational settling, thermophoresis, and inertial deposition. The numerical models for each of the aerosol processes were validated with analytical or numerical solutions. The combined particulate flow model was validated against results from open literature for deposition of sodium chloride and sodium fluorescein particles in a rectangular duct, and deposition of soot particles in a plate precipitator under conditions relevant to diesel engine exhaust systems. The validated soot tool would find application in gas turbine combustor as well with appropriate combustion models.
P. S. Rajagopal, Ashish Magar, Janki Shinde, Madhukar M. Rao, Akshai K. Runchal

Polydisperse Spray Modeling Using Eulerian Method

Sprays play a significant role in many engineering applications such as liquid fuel injectors, industrial spray coaters, water sprinklers and agricultural sprayers. In most of the numerical study, Eulerian and Lagrangian formulations have been used for the gas and liquid phases, respectively. However, modeling of droplets using Lagrangian approach is computationally expensive for complex configuration. An Eulerian–Eulerian approach, also referred to as multi-fluid method in the literature, is developed in recent time to reduce the computation cost. This chapter presents a brief review of the recent studies on spray modeling using Eulerian multi-fluid method. Initially, one-dimensional transport of polydisperse evaporating water spray in a spatially varying velocity and temperature field is reported. A comprehensive analysis on droplet clustering pattern in an oscillating flow field is presented. Then, transport of polydisperse evaporating liquid spray in crossflow configuration using multi-fluid method is reported.
Sourav Sarkar, Joydeep Munshi, Achintya Mukhopadhyay, Swarnendu Sen

Sustainable Energy Technologies


Future Aviation Biofuel, Efficiency and Climate Change

Petroleum fuels are often used as a source of energy for aviation transport and the key issue with this is that it is not sustainable. The aviation industry is a major contributor to greenhouse gas emissions throughout the world, and altogether produces approximately 2% of all anthropogenic CO2 emissions. According to predictions, air traffic is set to double over the next two decades, which will undoubtedly increase fuel requirement, and in turn, increase CO2 emissions. What’s more, the cost of fossil fuel fluctuate ever more as the days go on. For this reason, implementing and industrializing innovative types of fuel from renewable sources are crucial, with biomass being a key source of interest. Many industrial commitments and collaborations have been created as a means of identifying alternative manners of creating bio-aviation fuels. Moreover, this jet fuel has to be in accordance with ASTM international specifications and must be a complete replacement for petroleum jet fuel. The present research will assess and analyse the current technologies being use to produce renewable jet fuels, and these are classified as alcohols-to-jet, oil-to-jet, syngas-to-jet and sugar-to-jet methods. The key issues associated with every technology pathway outlined, such as issues pertaining to the theoretical process design, process economics and life-cycle evaluation of greenhouse gas emissions will be explored. Despite the feedstock price, availability and energy efficiency of the process serving as key obstacles in producing renewable energy, jet fuel created through biomass may be able to serve as an alternative source to traditional jet fuel in order to address commercial and military demand.
G. Abdulkareem-Alsultan, N. Asikin-Mijan, Y. H. Taufiq-Yap

A Review of Modern Hydrogen Combustor Injection Technologies for the Aerospace Sector

With hydrocarbon fuel reserves depleting across the planet, humankind will soon have to change energy sources. This affects the aerospace sector significantly. Hydrogen may offer a solution to the energy crisis our species will soon face. The aerospace sector can harness hydrogen for use with gas turbines. The present work reviews various existing hydrogen injector technologies that can be used with gas turbines, whether land-based for power generation or airborne for keeping aircraft aloft. Main performance points evaluated include temperature distribution, agreement between numerical and experimental results, and NOx emissions. Technologies reviewed include premixed systems, rotating detonation engines, rich-lean injectors, diffusive-mixing-based systems, and micromix injectors. Initial findings show that Dry-Low-NOx systems emit the least amount of nitrogen oxides, at a low of 1.7 ppmv. With further development, it is possible that micromix technology will be able to improve on its current emissions performance and be implemented in several gas turbine applications, thereby helping with more widespread implementation of hydrogen into the aerospace sector.
Pierre F. Ghali, Huanrong Lei, Bhupendra Khandelwal

Aerodynamic Behavior of Rear-Tubercle Horizontal Axis Wind Turbine Blade

This chapter presents the study of wind energy performance using different wind turbine blades. The text contains three different sections of the study. The first of which involves the design of three airfoil-based turbine blades designed and tested in the wind tunnel laboratory. The airfoils were verified independently to investigate the lift and drag forces developed by varying wind velocities through a wind tunnel. The second section of the study is the redesign and improvement of a support structure used to mount each blade being tested in the wind tunnel. An ideal structure will produce no forces or moments that may affect results obtained from the turbine blade. The final portion of the chapter is an improvement of the wind turbine column developed for the extensive testing. This testing was done by putting a strain gauge on the column to test compression and tension during oscillation. If testing shows that the support bar decreases vibration enough, the design was accepted and implemented. Additional improvement to the wind turbine column was the addition of Plexiglas/polycarbonate to supporting the new motor, along with an improved turbine blade hub. This improvement holds the wind turbine in place and increases efficiency that would typically have been lost due to excess movement. The designed hub allows the wind turbine mast to attach to the motor securely. The important discoveries through the improvement of wind turbine blades are discussed toward the end of this chapter.
Ryoichi S. Amano

Methanol-Based Economy: A Way Forward to Hydrogen

The energy is the driver in the economic development of any country. It is expected that the developing countries like India will account for 25% rise in global energy demand by 2040 due to an increase in the per capita income and rapid industrialization. The non-uniform distribution of oil reserves across the world is forcing the movement of crude petroleum, which results in an impact on the environment as well as exchequer of developing countries. The perturbations in the crude oil price, sanctions on Iran and climate change due to the use of petroleum-based fuels are some of the concern for developing countries. Methanol economy can play a breakthrough role in improving the worldwide global energy scenario. It is a single carbon compound and can be produced from a wide variety of fossil fuels and biomass products. Since coal and natural gas are non-renewable, the researchers are working with other resources for producing methanol. The syngas produced from the gasification of biomass can be converted into methanol. Moreover, another interesting method for the production of methanol is capturing of carbon dioxide from industries and power plants into the water by an electrochemical process and converting it into methanol. The electricity for the process can be obtained from renewable energy sources such as wind, solar, hydro, geothermal, etc. This method solves the twin problems of carbon emissions from industries and the use of fossil fuels. The properties of methanol are conducive for use in gasoline engines since it has high octane number and flame speed. Also, as it burns better, the overall engine exhaust emissions are lower. Methanol can also be used as cooking fuel in rural areas which are still dependent upon the wood. Fuel cells can be made to run on methanol wherein the methanol is reformed on-board for production of hydrogen and carbon dioxide. The developing countries can switch to methanol economy, wherein methanol can solve their requirement of fuel for the transportation sector, for domestic cooking and lastly as a raw material for various chemicals production.
Naveen Kumar, Mukul Tomar, Ankit Sonthalia, Sidharth, Parvesh Kumar, Harveer S. Pali, Dushyant Mishra
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