Data-driven prediction of laminar burning velocity for ternary ammonia/hydrogen/methane/air premixed flames

Zero-carbon fuels such as hydrogen and ammonia play a pivotal role in the energy transition by offering cleaner alternatives to natural gas (methane), especially in industrial combustion systems. Binary and ternary blends of these fuels offer a transitionary, low-carbon solution in the near future. Laminar burning velocity (LBV), as a fundamental combustion property, is significantly different for ammonia, hydrogen, and methane. Although the LBV of binary blends of these fuels is well-studied, ternary blends have not been...

Applicability of the Peclet number approach to blow-off and flashback limits of common steelworks process gases

The ever-increasing importance of energy efficiency has given rise to numerous areas of concern for operators and developers of combustion plants; as the need to utilise fuel gases of increasingly poor quality and variability is essential for sustainability, while emission standards continuing to become more stringent. Swirl combustors are ubiquitous in industry owing to their great stability range which occurs due to the formation of a CRZ, which through the recycling of heat and active chemical species to the root of the flame enhances stability over a wide range of operating conditions. Alternative fuels containing hydrogen offer the possibility of reduced greenhouse gas emissions; however flashback is of special concern with hydrogen enriched fuels, owing to the very high flame speed of hydrogen. Many by-products of process and waste industries can include a high proportion of hydrogen, for example Coke Oven Gas. Alternatively, many by-product process gases can contain a high proportion of non-combustible species such as nitrogen and carbon dioxide which can substantially reduce their flame speed and as a consequence increase the possibility of the flame extinguishing through blow-off. This paper examines the blow-off and flashback potential of common steelworks process gases (including one which contains hydrogen) in a compact, premixed swirl burner in swirl number regimes representative of those found in practical systems. Methane is used as a base fuel for comparison. All results are obtained at atmospheric pressure without air preheat. The Peclet number modelling approach incorporating a flame quenching parameter was applied to the results obtained for each of the fuel gases. Using this model, the quench factor value was seen to be dependent on burner configuration as well as fuel composition. It was found that the stable burner operating conditions significantly change from fuel to fuel; with the operating points at which flashback occurs with Coke Oven Gas producing blow-off with weaker process gases such as Blast Furnace Gas and Basic Oxygen Steelmaking gas

Experimental and theoretical investigation of the effect of rotating circular cylinder speed on the lift and drag forces

Flow past a circular cylinder is a problem for understanding flow around bluff bodies. This flow has been studied both experimentally and numerically of laminar infinite flow of viscous incompressible fluid around a rotating circular cylinder at Reynolds number 80,120,160 and dimensionless rotation rate, α , (ratio of cylinder surface speed to the free stream velocity) varying from 0 to 6 has been carried out. Navier–Stokes and continuity equations were solved numerically by using finite volume technique is conducted with ANSYS CFX 15 package program. High Speed Photography and LDV, present new experimental results for correlation purposes, captured the flow profile. Rotation can be used as a drag reduction technique. Comparison with previous studies showed good agreement

Influence of environmental factors on the sport performance of the horse, in an objective selection test (Show Jumping)

Ponencia publicada en ITEA, vol.104Desde el año 2004 el MAPyA organiza en España Pruebas de Selección de Caballos Jóvenes (PSCJ), para diferentes disciplinas, entre las que se encuentra el Salto de Obstáculos. Participan animales jóvenes (4 a 6 años). Con la información acumulada en estos 3 años (4.441 participaciones de 87 caballos participantes) hemos analizado los factores externos que condicionan los resultados obtenidos por los animales en este tipo de pruebas. Para ello se ha utilizado un modelo padre mediante el Proc MIXED del SAS, incluyendo como variables dependientes las penalizaciones finales y el ranking transformado. Se han analizado 14 factores, relacionados con el propio animal (edad, sexo…), el lugar de celebración del concurso y las condiciones de la pista, las condiciones climatológicas, el día de la prueba, el nivel de entrenamiento y el nivel de cansancio/estrés del animal antes de la competición. El jinete y el padre se han incluido como factores aleatorios en el modelo y el orden de salida, como covariable. Aunque la mayoría de los factores y combinaciones de factores han sido estadísticamente significativos, han explicado una muy baja varianza (entre 0,07% y 1,78%) con excepción de la edad (2,40%), padre (9,25%) y jinete (8,28%).Since 2004, the Ministry of Agriculture, Fisheries and Food of Spain organize the Young Horses Performance Selection Tests, for different disciplines, like Show Jumping. Only young animals participate in these events (4 to 6 years old). With the data collected during 3 years (4.441 participations from 87 different horses), we have analyzed the environmental factors that influence the performance results of the animal in these type of tests. A Proc MIXED model from SAS was used, including final penalizations and transformed ranking as dependent variables. 14 factors, related to the animal (age, sex…), the competition location and the racetrack conditions, the climatologic conditions, the training level and the stress level of the animal, were analyzed before the competition. The rider and the father were included in the model as random factors, and the participation order as the covariate. Although most of the factors and their combinations were significant, they explained a very low variance (from 0.07% to 1.78%), excluding the age (2.40%), the father effect (9.25%) and the rider (8.28%)

Premixed ammonia/hydrogen swirl combustion under rich fuel conditions for gas turbines operation

Energy storage is one of the highest priority challenges in transitioning to a low-carbon economy. Fluctuating, intermittent primary renewable sources such as wind and solar require low-carbon storage options to enable effective load matching, ensuring security of supply. Chemical storage is one such option, with low or zero carbon fuels such as hydrogen, alcohols and ammonia having been proposed. Ammonia provides zero-carbon hydrogen storage whilst offering liquefaction at relatively low pressures and atmospheric temperatures, enabling ease of transportation in a pre-existing infrastructure. Ammonia can also be used directly as a fuel in power plants such as gas turbines to avoid complete conversion back to hydrogen. It is a relatively unreactive fuel, and so it is of interest to explore the potential utilisation of ammonia/hydrogen mixtures. Hence, the goal of this paper is to provide a first assessment of the suitability of a chosen 70%NH330%H2 (%vol) blend for utilisation within a gas turbine environment, based on primary combustion diagnostics including combustion stability – via OH chemiluminescence - and emissions (NOx and NH3). An established optical generic swirl-burner enabled studies of the influence of equivalence ratio (φ > 1), ambient temperature (<484 ± 10 K) and bypass air, with a focus on NOx reduction, one of the main challenges for ammonia combustion. A numerical GT cycle model is developed alongside the experimental investigation. The results demonstrate that the blend has considerable potential as a fuel substitute with reasonable combustion stability and significant reduction of emissions for the cases without bypass air, due to increased chemical reactivity of unburned ammonia. However, emissions are still above those recommended for gas turbine cycles, with a theoretical cycle that still produces low efficiencies compared to DLN methane, highlighting the requirement for new injection techniques to reduce NOx/unburned NH3 in the flue gases whilst ensuring increased power outputs

On nanosecond plasma-assisted ammonia combustion: Effects of pulse and mixture properties

In this study, the effects of nanosecond plasma discharges on the combustion characteristics of ammonia are investigated over a wide range of mixture properties and plasma settings. The results reveal that the impacts of the plasma on ammonia combustion change non-monotonically by altering the reduced electric field value. Within the studied range of the reduced electric field, i.e., 100–700 Td, it is shown that plasma is most effective in the medium range, e.g., 250–400 Td. At lower values, the main fraction of the plasma energy is consumed to excite the diluent to higher vibrational levels. At very high reduced electric field values, a substantial portion of the plasma energy is transferred into the ionization reactions of the diluent, which compromises the effective excitations of fuel and oxidizer species. In terms of the pulse energy density, results indicate that an increase in the range of 0–20 mJ/cm3, at a given reduced electric field, decreases the ignition delay time by five orders of magnitude, and increases the laminar flame speed up to an order of magnitude, depending on the mixture composition. The results show that the plasma discharge produces more radicals, electronically excited and charged species when He is used as the diluent in the oxidizer instead of N2, since NH3 and O2 ionization reactions are strengthened in NH3/O2/He. Moreover, plasma discharge is highly effective in assisting the combustion of preheated lean mixtures. The present study also indicates that ammonia flame thickness is minimum at a critical pulse energy density in the range of 12–14 mJ/cm3. Further increases in the pulse energy density can manipulate the inner structure of the flame, altering the pre-heat zone of the flame to include some levels of chemical reactions toward the flameless mode of combustion

Using eye temperature and heart rate for stress assessment in young horses competing in jumping competitions and its possible influence on sport performance

The aims of this study were, first, to evaluate eye temperature (ET) with infrared thermography and heart rate (HR) to measure stress in horses during show jumping competitions and their relationship with competition results, and second, to evaluate the influence of different extrinsic and intrinsic factors of the horse on the stress measurements analysed. One hundred and seventy-three Spanish Sport Horses were analysed for ET and HR, and these measurements were taken 3 h before the competition, just after and 3 h after it. Two interval measurements were also assessed for each parameter. Positive significant correlations were found between ET and HR, measured before (r=0.23), just after competition (r= 0.28) and for the later interval (r= 0.26), whereas negative correlations with competition results were found only for ET when measured just after competing (r=− 0.25). Two intrinsic factors (genetic line and age) and no extrinsic factors showed significant differences for ET, whereas one intrinsic factor (age) and two extrinsic factors (journey duration and number of training hours) showed significant differences for HR. The marginal means showed significantly higher ET values for the Anglo-Arab genetic line and for 5-year-old animals. HR values were significantly higher for 4-year-old animals, for horses which had travelled 4 to 6 h and for horses that had 3 to 6 h of daily training. This study suggests that, although ET and HR seemed to share a similar physiological basis, the factors that most influenced each parameter were different. Finally, ET seems to be a suitable tool for assessing stress during show jumping competitions in horses

Modelos para la valoración genética de la disciplina de concurso completo de equitación a partir del control de rendimientos en las pruebas de selección de caballos jóvenes

Una de las principales fuentes de información funcional para la valoración genética precoz de los animales para las distintas disciplinas ecuestres son las Pruebas de Selección de Caballos Jóvenes (PSCJ), reguladas por el MAPyA, que se están celebrando en nuestro país desde el año 2004. Las PSCJ son muy importantes en la selección de los équidos deb ido a las altas correlaciones genéticas que se han encontrado entre las variables analizadas en animales jóvenes y los resultados obtenidos posteriormente en las competiciones, lo cual implica una buena predicción del rendimiento en el animal adulto (Wallin et al. , 2003). El concurso completo de equitación (CCE), conocido internacionalmente como “Eventing”, es una disciplina ecuestre que combina distintas pruebas (doma, salto y cross), exigiendo al animal un elevado grado de diversas aptitudes. Las principales razas de caballos participantes en España en CCE son, el Caballo de Deporte Español (CDE), el caballo de raza Anglo-árabe (A-á) y el Pura Raza árabe (PRá) El objetivo de este estudio ha sido establecer los modelos genéticos idóneos para la estimación de los valores de mejora y obtener estimas de heredabilidad de los caracteres de la disciplina de CC