Solar Vehicles Design for Urban Use: Case Adapted to Cuitláhuac Veracruz

AbstractSolar energy has now proved, surprisingly, an excellent alternative energy. Particularly Mexico and Veracruz area lies within the world's sunbelt sun being an invaluable source of energy that has not been exploited in all its aspects.The main objective of this paper is to show the efficiency of a prototype electric car for urban use powered by a photovoltaic system. This car must have a minimum of 4hours autonomy with a speed of 70km / h and be able to carry four persons weighing not more than 800kg. During the first stage is the design of a sedan car with a direct current electric motor, the design is very important for mechanical components are light as it is vital to save energy.The next study explains the calculations about braking force between the tire and the road and validates the forces applied to the vehicle steering system.This paper is proposed by the Technological University Center in Veracruz and Industrial Maintenance Area, through this project seeks to raise awareness of the benefits and advantages in the use of renewable energy sources to boost vehicles

Analysis of gas turbine compressor fouling and washing on line

This work presents a model of the fouling mechanism and the evaluation of compressor washing on line. The results of this research were obtained from experimental and computational models. The experimental model analyzed the localization of the particle deposition on the blade surface and the change of the surface roughness condition. The design of the test rig was based on the cascade blade arrangement and blade aerodynamics. The results of the experiment demonstrated that fouling occurred on both surfaces of the blade. This mechanism mainly affected the leading edge region of the blade. The increment of the surface roughness on this region was 1.0 μm. This result was used to create the CFD model (FLUENT). According to the results of the CFD, fouling reduced the thickness of the boundary layer region and increased the drag force of the blade. The model of fouling was created based on the experiment and CFD results and was used to calculate the engine performance in the simulation code (TURBOMATCH). The engine performance results demonstrated that in five days fouling can affect the overall efficiency by 3.5%. The evaluation of the compressor washing on line was based on the experimental tests and simulation of the engine performance. This system demonstrated that it could recover 99% of the original blade surface. In addition, this system was evaluated in a study case of a Power Plant, where it proved itself to be a techno-economic way to recover the power of the engine due to fouling. The model of the fouling mechanism presented in this work was validated by experimental tests, CFD models and information from real engines. However, for further applications of the model, it would be necessary to consider the specific conditions of fouling in each new environment.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Fuel rich ammonia-hydrogen injection for humidified gas turbines

The use of new fuels and operating strategies for gas turbine technologies plays a relevant component for carbon emissions reduction and the use of sustainable energy sources. Among non-carbon fuels, hydrogen-based fuels have been proposed as one of the main strategies for decarbonisation of the power sector. Ammonia is a good representative of these fuels as it is carbon-free and the second largest chemical commodity, having been produced worldwide for more than a century from various energy resources, i.e. fossil fuels, biomass or other renewable sources. However, the use of ammonia as a fuel in industrial gas turbines brings some practical challenges directly linked to the final efficiency of these systems, especially when the latter are compared to current Dry Low Nitrogen Oxides technologies. Thus, this work covers a series of analytical, numerical and experimental studies performed to determine the efficiency of using ammonia/hydrogen blends in combination with humidified methodologies to deliver competitive systems for the use of ammonia-hydrogen power generation. The study was conducted using CHEMKIN-PRO reaction networks employing novel reaction chemical kinetics, in combination with bespoke analytical codes to determine efficiencies of systems previously calibrated experimentally. Finally, experimental trials using steam injection were carried out to determine potential of these blends. The novel results demonstrate that the use of humidified ammonia-hydrogen injection provides similar efficiencies to both Dry Low Nitrogen Oxides and humidified methane-based technologies ∼30%, with flames that are stable and low polluting under swirling conditions, thus opening the opportunity for further progression on the topic

Numerical predictions of a swirl combustor using complex chemistry fueled with ammonia/hydrogen blends

Ammonia, a chemical that contains high hydrogen quantities, has been presented as a candidate for the production of clean power generation and aerospace propulsion. Although ammonia can deliver more hydrogen per unit volume than liquid hydrogen itself, the use of ammonia in combustion systems comes with the detrimental production of nitrogen oxides, which are emissions that have up to 300 times the greenhouse potential of carbon dioxide. This factor, combined with the lower energy density of ammonia, makes new studies crucial to enable the use of the molecule through methods that reduce emissions whilst ensuring that enough power is produced to support high-energy intensive applications. Thus, this paper presents a numerical study based on the use of novel reaction models employed to characterize ammonia combustion systems. The models are used to obtain Reynolds Averaged Navier-Stokes (RANS) simulations via Star-CCM+ with complex chemistry of a 70%–30% (mol) ammonia–hydrogen blend that is currently under investigations elsewhere. A fixed equivalence ratio (1.2), medium swirl (0.8), and confined conditions are employed to determine the flame and species propagation at various operating atmospheres and temperature inlet values. The study is then expanded to high inlet temperatures, high pressures, and high flowrates at different confinement boundary conditions. The results denote how the production of NOx emissions remains stable and under 400 ppm, whilst higher concentrations of both hydrogen and unreacted ammonia are found in the flue gases under high power conditions. The reduction of heat losses (thus higher temperature boundary conditions) has a crucial impact on further destruction of ammonia post-flame, with a raise in hydrogen, water, and nitrogen through the system, thus presenting an opportunity of combustion efficiency improvement of this blend by reducing heat losses. Final discussions are presented as a method to raise power whilst employing ammonia for gas turbine systems

High momentum flow region and central recirculation zone interaction in swirling flows

‘Fuel-flexible’ gas turbines will be required over the next 20 years at least. However, this contrasts with recent experiences of global operators who report increasing emissions and difficult combustion dynamics with even moderate variations in the fuel supply. Swirl stabilized combustion, being the most widely spread technology to control combustion in gas turbines, will be a technology needed for dynamic stabilization of the flow field. However, the features of the recirculation zone are highly complex, three dimensional and time dependent, depending on a variety of parameters. A high momentum flow region inherent to swirling flows has attracted the attention of several groups interested in blowoff and stretch flame phenomena. Therefore, this study focuses on experimental results obtained to characterise the relation between the central recirculation zone and the high momentum flow region under moderate swirl levels using a well-studied tangential swirl burner for power generation applications. As to be expected the recirculation zone and the high momentum flow region rotate together about the central axis. Moreover, the interaction between them produces high, intense local velocities. This region of High Momentum (shearing flow) also presents a complex geometry that seems to be based on the geometrical features of the burner, different to previous findings on the burner where the system was thought to have a unique shearing flow region. The high three dimensional interaction of these structure is confirmed at the point where the precessing vortex core losses its strength

High momentum flow region and central recirculation zone interaction in swirling flows

‘Fuel-flexible’ gas turbines will be required over the next 20 years at least. However, this contrasts with recent experiences of global operators who report increasing emissions and difficult combustion dynamics with even moderate variations in the fuel supply. Swirl stabilized combustion, being the most widely spread technology to control combustion in gas turbines, will be a technology needed for dynamic stabilization of the flow field. However, the features of the recirculation zone are highly complex, three dimensional and time dependent, depending on a variety of parameters. A high momentum flow region inherent to swirling flows has attracted the attention of several groups interested in blowoff and stretch flame phenomena. Therefore, this study focuses on experimental results obtained to characterise the relation between the central recirculation zone and the high momentum flow region under moderate swirl levels using a well-studied tangential swirl burner for power generation applications. As to be expected the recirculation zone and the high momentum flow region rotate together about the central axis. Moreover, the interaction between them produces high, intense local velocities. This region of High Momentum (shearing flow) also presents a complex geometry that seems to be based on the geometrical features of the burner, different to previous findings on the burner where the system was thought to have a unique shearing flow region. The high three dimensional interaction of these structure is confirmed at the point where the precessing vortex core losses its strength

Flashback avoidance in swirling flow burners

Lean premixed combustion using swirling flows is widely used in gas tur - bines and combustion. Although flashback is not generally a problem with natural gas combustion, there are some reports of flashback damage with existing gas turbines, whilst hydrogen enriched fuel blends cause concerns in this area. Thus, this paper describes a practical approach to study and avoid flashback in a pilot scale 100 kW tangential swirl burner. The flash - back phenomenon is studied experimentally via the derivation of flashback limits for a variety of different geometrical conditions. A high speed camera is used to visualize the process and distinguish new patterns of avoidance. The use of a central fuel injector is shown to give substantial benefits in terms of flashback resistance. Conclusions are drawn as to mitigation technologi

Combustion features of CH4/NH3/H2 ternary blends

The use of so-called “green” hydrogen for decarbonisation of the energy and propulsion sectors has attracted considerable attention over the last couple of decades. Although advancements are achieved, hydrogen still presents some constraints when used directly in power systems such as gas turbines. Therefore, another vector such as ammonia can serve as a chemical to transport and distribute green hydrogen whilst its use in gas turbines can limit combustion reactivity compared to hydrogen for better operability. However, pure ammonia on its own shows slow, complex reaction kinetics which requires its doping by more reactive molecules, thus ensuring greater flame stability. It is expected that in forthcoming years, ammonia will replace natural gas (with ∼90% methane in volume) in power and heat production units, thus making the co-firing of ammonia/methane a clear path towards replacement of CH4 as fossil fuel. Hydrogen can be obtained from the pre-cracking of ammonia, thus denoting a clear path towards decarbonisation by the use of ammonia/hydrogen blends. Therefore, ammonia/methane/hydrogen might be co-fired at some stage in current combustion units, hence requiring a more intrinsic analysis of the stability, emissions and flame features that these ternary blends produce. In return, this will ensure that transition from natural gas to renewable energy generated e-fuels such as so-called “green” hydrogen and ammonia is accomplished with minor detrimentals towards equipment and processes. For this reason, this work presents the analysis of combustion properties of ammonia/methane/hydrogen blends at different concentrations. A generic tangential swirl burner was employed at constant power and various equivalence ratios. Emissions, OH∗/NH∗/NH2∗/CH∗ chemiluminescence, operability maps and spectral signatures were obtained and are discussed. The extinction behaviour has also been investigated for strained laminar premixed flames. Overall, the change from fossils to e-fuels is led by the shift in reactivity of radicals such as OH, CH, CN and NH2, with an increase of emissions under low and high ammonia content. Simultaneously, hydrogen addition improves operability when injected up to 30% (vol), an amount at which the hydrogen starts governing the reactivity of the blends. Extinction strain rates confirm phenomena found in the experiments, with high ammonia blends showing large discrepancies between values at different hydrogen contents. Finally, a 20/55/25% (vol) methane/ammonia/hydrogen blend seems to be the most promising at high equivalence ratios (1.2), with no apparent flashback, low emissions and moderate formation of NH2/OH radicals for good operability

Methane/ammonia radical formation during high temperature reactions in swirl burners

Recent studies have demonstrated that ammonia is an emerging energy vector for the distribution of hydrogen from stranded sources. However, there are still many unknown parameters that need to be understood before ammonia can be a substantial substitute in fuelling current power generation systems. Therefore, current attempts have mainly utilised ammonia as a substitute for natural gas (mainly composed of methane) to mitigate the carbon footprint of the latter. Co-firing of ammonia/methane is likely to occur in the transition of replacing carbonaceous fuels with zero-carbo options. Hence, a better understanding of the combustion performance, flame features, and radical formation of ammonia/methane blends is required to address the challenges that these fuel combinations will bring. This study involves an experimental approach in combination with numerical modelling to elucidate the changes in radical formation across ammonia/methane flames at various concentrations. Radicals such as OH*, CH*, NH*, and NH2* are characterised via chemiluminescence whilst OH, CH, NH, and NH2 are described via RANS κ-ω SST complex chemistry modelling. The results show a clear progression of radicals across flames, with higher ammonia fraction blends showing flames with more retreated shape distribution of CH* and NH* radicals in combination with more spread distribution of OH*. Simultaneously, equivalence ratio is a key parameter in defining the flame features, especially for production of NH2*. Since NH2* distribution is dependent on the equivalence ratio, CFD modelling was conducted at a constant equivalence ratio to enable the comparison between different blends. The results denote the good qualitative resemblance between models and chemiluminescence experiments, whilst it was recognised that for ammonia/methane blends the combined use of OH, CH, and NH2 radicals is essential for defining the heat release rate of these flames

Ammonia combustion in furnaces: A review

Ammonia is a formidable chemical that has been investigated over 150 years for its use in the chemical processing field. The potential of the molecule to be used in farming applications has enabled a demographic explosion whilst its implementation in refrigeration technologies ensure continuous operation of cooling systems at high efficiencies. Other areas have also benefited from ammonia, whilst the use of the molecule in fuelling applications was scarce until the 2010s. A combination of factors that include climate change and energy dependency have reignited the interest of using ammonia as an energy vector that can potentially support applications that range from small devices to large power applications, thus supporting the transition to a net zero economy. Therefore, ammonia appears as a tangible option towards the reduction of emissions that can support a truly carbon-free energy transition in the coming years. As the recognition of the molecule increases, research areas based on combustion processes have also expanded towards the utilization of ammonia. The research around the topic has considerably augmented not only in the academic community, but also across governmental institutions and industrial consortia willing to demonstrate the potential of such a chemical. Therefore, this review approaches the latest findings and state-of-the-art research on the use of ammonia as a combustion fuel for furnaces. Different to other reviews, the present work attempts to gather the latest fundamental research, the most critical technologies evaluating ammonia for system operation, and novel approaches that suggest various breakthrough concepts that will ensure the reliable, cleaner consumption of the molecule as furnace fuel. Further, the present manuscript includes the latest research from all corners of the world, in an attempt to summarise the extensive work that dozens of groups are currently conducting. Finally, future trends and requirements are also addressed, providing guidance to those interested in doing research and development in ammonia-fuelling systems