Measurements of Hydrogen-Enriched Combustion of JP-8 in Open Flame

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Michael Seibert ◽  
Sen Nieh
Keyword(s):  
Flame Structure ◽  
Flame Temperature ◽  
Operational Reliability ◽  
Initial Energy ◽  
Pollutant Emissions ◽  
Gaseous Emissions ◽  
Open Flame ◽  
Point Of Use ◽  
Hydrogen Enrichment ◽  
Secondary Air

Hydrogen enrichment is presented as a control parameter to improve JP-8 combustion. Research in fuel reforming gives an opportunity for hydrogen production at the point of use. Hydrogen-enriched combustion of JP-8 seeks to take advantage of the energy density of JP-8 and the combustibility of hydrogen. At low power output (<2 kWe), technologies such as Stirling engines, thermoelectric, and thermophotovoltaic generators have the potential to compete with diesel engines, but require reliable JP-8 combustion. Experiments were conducted with atomized JP-8 in a 5 kWth open flame, based on a 500 W power source. JP-8 is sprayed through an air-atomizing nozzle. Hydrogen was added to either the atomizing air or to a concentric tube supplying the main combustion air. In these experiments, hydrogen represented up to 26% of the fuel energy contribution (EC). During hydrogen enrichment, JP-8 flow rate was reduced to maintain constant fuel energy input. Temperature is measured vertically and laterally through the flame. Temperature profiles show that combustion shifts toward the nozzle as hydrogen is added. Hydrogen in the secondary air maintains diffusion flame behavior, but earlier in the flame. Hydrogen in the nozzle air creates a premixed pilot flame structure in the center of the flame. This premixed hydrogen and air flame provides initial energy to speed droplet heating and vaporization, producing higher peak temperatures than the other cases studied. Gaseous emissions are measured above the visible flame. Hydrogen enrichment by both methods reduced unburned hydrocarbon emissions by up to 70%. The advantages provided by hydrogen enrichment represent opportunities for reduced size, improved operational reliability and control, and reduced pollutant emissions.

Measurements of Hydrogen Enriched Combustion of Jet Fuel in Open Flame

2016 ◽  
Author(s):  
Michael Seibert ◽  
Sen Nieh
Keyword(s):  
Operational Reliability ◽  
Jet Fuel ◽  
Fuel Combustion ◽  
Mobile Systems ◽  
Pollutant Emissions ◽  
Gaseous Emissions ◽  
Thermo Electric ◽  
Open Flame ◽  
Hydrogen Enrichment ◽  
Photovoltaic Generators

Jet fuel is a common logistics fuel, even for small, mobile systems. At low power output (<2 kWe), technologies such as Stirling engines, thermo electric and thermo-photovoltaic generators have the potential to compete with diesel engines, but require reliable jet fuel combustion. Hydrogen enrichment is presented as a control parameter to improve jet fuel combustion. Research in fuel reforming gives an opportunity for hydrogen production at the point of use. Hydrogen enriched combustion of jet fuel seeks to take advantage of the energy density of jet fuel and the combustibility of hydrogen. Experiments were conducted with atomized jet fuel in a 5 kWth open flame. Jet fuel is sprayed through an air atomizing nozzle. Hydrogen was added to either the atomizing air or to a concentric tube supplying the main combustion air. During hydrogen enrichment, jet fuel flow rate was reduced to maintain constant fuel energy input. Temperature is measured vertically and laterally through the flame. Gaseous emissions are measured above the visible flame. In these experiments, hydrogen represented up to 26% of the fuel energy contribution. Substantial changes to the combustion profile occur with small amounts of hydrogen enrichment. The advantages it provides represent opportunities for reduced size, improved operational reliability and control and reduced pollutant emissions.

LES of Hydrogen Enriched Methane/Air Combustion in the SGT-800 Burner at Real Engine Conditions

2018 ◽  
Author(s):  
Daniel Moëll ◽  
Daniel Lörstad ◽  
Xue-Song Bai
Keyword(s):  
High Pressure ◽  
Mixture Fraction ◽  
Flame Structure ◽  
Flame Temperature ◽  
Flow Simulation ◽  
Sudden Expansion ◽  
Inlet Temperature ◽  
Complex Flow ◽  
Control Variables ◽  
Hydrogen Enrichment

DLE (Dry Low Emission) techniques are widely used today to reduce the harmful NOx emissions associated with high combustion temperatures. In many DLE systems the fuel and air are pre-mixed which effectively keep the flame temperature as low as possible, ideally equal to the turbine inlet temperature. By using pre-mixing stability issues such as flash back and combustion driven dynamics may occur. Operating the engine with hydrogen diluted natural gas will decrease the flash back limits of the system due to the high diffusivity and highly reactive nature of hydrogen. In this study the stability effects of hydrogen diluted into methane in the Siemens SGT-800 combustor is studied. The SGT-800 combustor is an annular combustor where the flame is stabilized using a swirl burner combined with a sudden expansion combustor. The expansion gives rise to a vortex break down where the flame stabilizes in the local low speed zones. Here a single burner sector is studied using the flow solver Siemens PLM software STAR-CCM+. The turbulence is simulated through the use of LES (Large Eddy Simulation) where the largest energy carrying flow scales are resolved and only the smaller scales are modelled. The chemistry is coupled to the turbulent flow simulation by the use of FGM (Flamelet Generated Manifolds) which are integrated using presumed probability density functions. The FGM approach assumes that the local flame structure is laminar and that all species across a flame can be related to a set of control variables. The control variables in this case are the heat loss, the mixture fraction and its variance and a reaction progress variable. In this paper two effects are studied, first the transition from an atmospheric flame to a pressurized flame and second the effect of hydrogen enrichment. The flame shape and position are mainly affected by the transition from atmospheric to high pressure, where the power density increases by almost a factor of 20. The flame is moving further upstream closer to the burner in all pressurized cases. The hydrogen enrichment plays a strong role in how the combustion driven dynamics is coupling with the acoustics of the rig. The high pressure pure methane case show a strong pressure peak whereas the hydrogen enriched case dampens that peak and distributes the energy to other frequencies. This work shows that high fidelity CFD is capable of capturing complex flow and flame interactions such as thermoacoustic instabilities in industrial scale systems.

The Development of a Monitoring and Control System for Pulverised Coal Flames Using Neural Networks

2003 ◽  
Author(s):  
O. H. Tan ◽  
S. J. Wilcox ◽  
J. Ward ◽  
M. Lewitt
Keyword(s):  
Control System ◽  
Low Cost ◽  
Air Flow ◽  
Combustion Process ◽  
Combustion Noise ◽  
Pollutant Emissions ◽  
Furnace Chamber ◽  
Gaseous Emissions ◽  
Monitoring And Control ◽  
Secondary Air

This paper presents the results obtained from a series of experiments that have been conducted on a 150kW pf burner rig based at Casella CRE Ltd. in the United Kingdom. These experiments systematically varied the burner swirl number and the secondary air flow rate over a significant range for two different coals so that both satisfactory and ‘poor’ combustion conditions were obtained. The infra-red emissions from the flame and the combustion noise generated in the furnace chamber were measured with appropriate sensors as were the fuel and air flow rates and pollutant emissions. The signals from the sensors were analysed using signal processing techniques to yield a number of features. These in turn were employed to train a neural network to accurately estimate the gaseous emissions from the rig, such as NOx and CO. In a separate set of experiments, where the combustion process was placed in a poor condition, the sensors were coupled with the neural models and incorporated into an intelligent control system, which was able to alter the excess air level to improve the process. In this fashion simultaneous low Nox and CO levels were achieved with both coal types. This method thus uses a combination of relatively low cost sensors and artificial intelligence techniques to control the combustion of the pulverised fuel burner. It is envisaged as particularly attractive for multiple burner installations that are fed from a common manifold, where individual burner performance is not known.

Dual Fuel Concept for an Innovative Co-Axial Burner, Thermal Characteristics and Combustion Performance

2014 ◽  
Author(s):  
Joseph Soliman ◽  
Ahmed Emara ◽  
Adel Hussien
Keyword(s):  
Fuel Injection ◽  
Flame Structure ◽  
Flame Temperature ◽  
Thermal Characteristics ◽  
Axial Direction ◽  
Gaseous Fuel ◽  
Pollutant Emissions ◽  
Dual Fuel ◽  
Inclination Angles ◽  
The Way

The demand for industrial burners and gas turbine engines with reduced emission levels, stable combustion conditions and low specific fuel consumption is the goal at the past two decades. A significant challenge is to develop a practical dual fuel corresponded with these requirements in the way to produce an efficient combustion and to comply with environmental concerns and government regulations. The investigated burner consists of eight gaseous jets arranged in two consecutively interacted equal lotus bundles in the axial direction downstream of the flow. These eight jets can be easily moved and directed to penetrate the combustion reaction zone at different axial positions with four inclination angles at the burner axis (θ= 0°, 30°, 45°, and 60°). This axial motion is easily performed by adjusting few screws mounted on the burner end in the way to facilitate the jet interaction inside the surrounded combustion air. The present work aims to demonstrate the flame structure, inflame temperature, and stack emissions at different liquid fuel ratio, gaseous fuel injection locations and jet inclination angles. It is noticed that, the two different fuels at different interaction locations have an influence on the pollutant emissions and temperature as well as the combustion efficiency. In addition, increasing the gaseous fuel reduces the flame size and increases the flame temperature.

scholarly journals Design Optimization of Centrifugal Microfluidic “Lab-on-a-Disc” Systems towards Fluidic Larger-Scale Integration

2021 ◽  
Vol 11 (13) ◽  
pp. 5839
Author(s):  
Jens Ducrée
Keyword(s):  
Design Optimization ◽  
Retention Rate ◽  
Point Of Care ◽  
Operational Reliability ◽  
Band Width ◽  
Disc Space ◽  
Laboratory Unit ◽  
Digital Twin ◽  
Point Of Use ◽  
Scale Integration

Enhancing the degree of functional multiplexing while assuring operational reliability and manufacturability at competitive costs are crucial ingredients for enabling comprehensive sample-to-answer automation, e.g., for use in common, decentralized “Point-of-Care” or “Point-of-Use” scenarios. This paper demonstrates a model-based “digital twin” approach, which efficiently supports the algorithmic design optimization of exemplary centrifugo-pneumatic (CP) dissolvable-film (DF) siphon valves toward larger-scale integration (LSI) of well-established “Lab-on-a-Disc” (LoaD) systems. Obviously, the spatial footprint of the valves and their upstream laboratory unit operations (LUOs) have to fit, at a given radial position prescribed by its occurrence in the assay protocol, into the locally accessible disc space. At the same time, the retention rate of a rotationally actuated CP-DF siphon valve and, most challengingly, its band width related to unavoidable tolerances of experimental input parameters need to slot into a defined interval of the practically allowed frequency envelope. To accomplish particular design goals, a set of parametrized metrics is defined, which are to be met within their practical boundaries while (numerically) minimizing the band width in the frequency domain. While each LSI scenario needs to be addressed individually on the basis of the digital twin, a suite of qualitative design rules and instructive showcases structures are presented.

Thermoacoustic Stability Analysis of a Full-Annular Lean Combustor for Heavy-Duty Applications

2021 ◽  
Author(s):  
Daniele Pampaloni ◽  
Antonio Andreini ◽  
Alessandro Marini ◽  
Giovanni Riccio ◽  
Gianni Ceccherini
Keyword(s):  
Stability Analysis ◽  
Gas Turbine ◽  
Flame Temperature ◽  
Numerical Procedure ◽  
Pollutant Emissions ◽  
Computational Time ◽  
Heavy Duty ◽  
Operational Parameters ◽  
3D Fem ◽  
Wide Range

Abstract Thermoacoustic characterization of gas turbine combustion systems is of primary importance for successful development of gas turbine technology, to meet the stringent targets on pollutant emissions. In this context, it becomes more and more necessary to develop reliable tools to be used in the industrial design process. The dynamics of a lean-premixed full-annular combustor for heavy-duty applications has been numerically studied in this work. The well-established CFD-SI method has been used to investigate the flame response varying operational parameters such as the flame temperature (global equivalence ratio) and the fuel split between premixed and pilot fuel injections: such a wide range experimental characterization represents an opportunity to validate the employed numerical methods and to give a deeper insight into the flame dynamics. URANS simulations have been performed, due to their affordable computational costs from the industrial perspective, after validating their accuracy through the comparison against LES results. Furthermore, an approach where the pilot and the premixed flame responses are analyzed separately is proposed, exploiting the independence of their evolution. The calculated FTFs have been implemented in a 3D FEM model of the chamber, in order to perform linear stability analysis and to validate the numerical approach. A boundary condition for rotational periodicity based on Bloch-Wave theory has been implemented into the Helmholtz solver and validated against full-annular chamber simulations, allowing a significant reduction in computational time. The reliability of the numerical procedure has been assessed through the comparison against full-annular experimental results.

Experimental Investigation of Turbulence Structure in a Three-Nozzle Combustor

2007 ◽  
Author(s):  
Benjamin Boehm ◽  
Andreas Dreizler ◽  
Markus Gnirss ◽  
Cameron Tropea ◽  
Jens Findeisen ◽  
...  
Keyword(s):  
Flow Field ◽  
Turbulent Flow ◽  
Air Entrainment ◽  
Pollutant Emissions ◽  
Laser Doppler Velocimeter ◽  
Velocity Signal ◽  
Size And Shape ◽  
Recirculation Zones ◽  
Turbulent Flow Field ◽  
Secondary Air

Proper mixing of fuel, primary and secondary air is a major issue to optimize engine performance in terms of efficiency and pollutant emissions. The underlying turbulent flow field determines these mixing processes. Most experimental and numerical investigations are performed in single nozzle combustors for reasons of optical accessibility and simplicity. The focus of the present study is to compare the variation of the non-reacting turbulent flow field for the case of single-nozzle and three-nozzle operation. In addition, the influence of secondary air entrainment is investigated. The flow configuration is based on commercial geometries. Using a two component laser Doppler velocimeter (LDV) the mean and fluctuating velocities of all three components, as well as two Reynolds-stress components were measured. The autocorrelation function and spectral distributions of the fluctuating velocity signal clearly revealed coherent fluid motions. These observations, together with high speed-flow visualisations indicate a precessing vortex core (PVC). An additional lower frequency for all three nozzles in operation revealed a pulsation of the recirculation zones. A major result of this investigation is that the size and shape of the internal recirculation zones were significantly influenced by operation of adjacent nozzles. Furthermore the generation of PVCs were augmented in the three-nozzle configuration. The additional secondary air entrainment interacts with the primary flow, changing the size and shape of the recirculation zone and affecting the low frequency pulsation.

scholarly journals Influence of Eddy-Generation Mechanism on the Characteristic of On-Source Fire Whirl

2019 ◽  
Vol 9 (19) ◽  
pp. 3989 ◽  
Author(s):  
Cheng Wang ◽  
Anthony Chun Yin Yuen ◽  
Qing Nian Chan ◽  
Timothy Bo Yuan Chen ◽  
Qian Chen ◽  
...  
Keyword(s):  
Flame Structure ◽  
Flame Temperature ◽  
Combustion Process ◽  
Flame Height ◽  
Reacting Flow ◽  
Detailed Chemistry ◽  
Eddy Generation ◽  
Fire Whirl ◽  
Generation Mechanisms ◽  
The Impact

This paper numerically examines the characterisation of fire whirl formulated under various entrainment conditions in an enclosed configuration. The numerical framework, integrating large eddy simulation and detailed chemistry, is constructed to assess the whirling flame behaviours. The proposed model constraints the convoluted coupling effects, e.g., the interrelation between combustion, flow dynamics and radiative feedback, thus focuses on assessing the impact on flame structure and flow behaviour solely attribute to the eddy-generation mechanisms. The baseline model is validated well against the experimental data. The data of the comparison case, with the introduction of additional flow channelling slit, is subsequently generated for comparison. The result suggests that, with the intensified circulation, the generated fire whirl increased by 9.42 % in peak flame temperature, 84.38 % in visible flame height, 6.81 % in axial velocity, and 46.14 % in velocity dominant region. The fire whirl core radius of the comparison case was well constrained within all monitored heights, whereas that of the baseline tended to disperse at 0.5   m height-above-burner. This study demonstrates that amplified eddy generation via the additional flow channelling slit enhances the mixing of all reactant species and intensifies the combustion process, resulting in an elongated and converging whirling core of the reacting flow.

scholarly journals Co-Combustion of Waste Tires and Plastic-Rubber Wastes with Biomass Technical and Environmental Analysis

2020 ◽  
Vol 12 (3) ◽  
pp. 1036 ◽  
Author(s):  
Luís Carmo-Calado ◽  
Manuel Jesús Hermoso-Orzáez ◽  
Roberta Mota-Panizio ◽  
Bruno Guilherme-Garcia ◽  
Paulo Brito
Keyword(s):  
Energy Recovery ◽  
Calorific Value ◽  
Thermal Conversion ◽  
Pollutant Emissions ◽  
Limiting Factors ◽  
Gaseous Emissions ◽  
Waste Tires ◽  
Feeding Difficulties ◽  
Stable Conditions ◽  
Combustion Tests

The present work studies the possibility of energy recovery by thermal conversion of combustible residual materials, namely tires and rubber-plastic, plastic waste from outdoor luminaires. The waste has great potential for energy recovery (HHV: 38.6 MJ/kg for tires and 31.6 MJ/kg for plastic). Considering the thermal conversion difficulties of these residues, four co-combustion tests with mixtures of tires/plastics + pelletized Miscanthus, and an additional test with 100% Miscanthus were performed. The temperature was increased to the maximum allowed by the equipment, about 500 °C. The water temperature at the boiler outlet and the water flow were controlled (60 °C and 11 L/min). Different mixtures of residues (0–60% tires/plastics) were tested and compared in terms of power and gaseous emissions. Results indicate that energy production increased with the increase of tire residue in the mixture, reaching a maximum of 157 kW for 40% of miscanthus and 60% of tires. However, the automatic feeding difficulties of the boiler also increased, requiring constant operator intervention. As for plastic and rubber waste, fuel consumption generally decreased with increasing percentages of these materials in the blend, with temperatures ranging from 383 °C to 411 °C. Power also decreased by including such wastes (66–100 kW) due to feeding difficulties and cinder-fusing problems related to ash melting. From the study, it can be concluded that co-combustion is a suitable technology for the recovery of waste tires, but operational problems arise with high levels of residues in the mixture. Increasing pollutant emissions and the need for pre-treatments are other limiting factors. In this sense, the thermal gasification process was tested with the same residues and the same percentages of mixtures used in the co-combustion tests. The gasification tests were performed in a downdraft reactor at temperatures above 800 °C. Each test started with 100% acacia chip for reference (like the previous miscanthus), and then with mixtures of 0–60% of tires and blends of plastics and rubbers. Results obtained for the two residues demonstrated the viability of the technology, however, with mixtures higher than 40% it was very difficult to develop a process under stable conditions. The optimum condition for producing a synthesis gas with a substantial heating value occurred with mixtures of 20% of polymeric wastes, which resulted in gases with a calorific value of 3.64 MJ/Nm3 for tires and 3.09 MJ/Nm3 for plastics and rubbers.

Theoretical Assessment of Convective and Radiative Heat Losses in a One-Dimensional Multiregion Premixed Flame With Counter-Flow Design Crossing Through Biofuel Particles

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Mehdi Bidabadi ◽  
Saman Hosseinzadeh ◽  
Sadegh Sadeghi ◽  
Mostafa Setareh
Keyword(s):  
Temperature Profile ◽  
Radiative Heat ◽  
Flame Structure ◽  
Flame Temperature ◽  
Heat Losses ◽  
Flame Velocity ◽  
Mass Fractions ◽  
Interface Matching ◽  
Energy Balances ◽  
Stagnation Plane

Due to perspective of biomass usage as a viable source of energy, this paper suggests a potential theoretical approach for studying multiregion nonadiabatic premixed flames with counterflow design crossing through the mixture of air (oxidizer) and lycopodium particles (biofuel). In this research, convective and radiative heat losses are analytically described. Due to the properties of lycopodium, roles of drying and vaporization are included so that the flame structure is created from preheating, drying, vaporization, reaction, and postflame regions. To follow temperature profile and mass fraction of the biofuel in solid and gaseous phases, dimensionalized and nondimensionalized forms of mass and energy balances are expressed. To ensure the continuity and calculate the positions of drying, vaporization, and flame fronts, interface matching conditions are derived employing matlab and mathematica software. For validation purpose, results for temperature profile is compared with those provided in a previous research study and an appropriate is observed under the same conditions. Finally, changes in flame velocity, flame temperature, solid and gaseous fuel mass fractions, and particle size with position measured from the position of stagnation plane, strain rate, and heat transfer coefficient in the presence/absence of losses are evaluated.

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