scholarly journals Characteristics of a Non-Premixed Rotating Detonation Combustor Using Natural Gas-Hydrogen Blend at Elevated Air-Preheat Temperature and Backpressure

2018 ◽  
Author(s):  
Arnab Roy ◽  
Donald Ferguson ◽  
Todd Sidwell ◽  
Peter Strakey
Keyword(s):  
Experimental Study ◽  
Natural Gas ◽  
Detonation Wave ◽  
Inlet Temperature ◽  
Operational Mode ◽  
Atmospheric Conditions ◽  
Theoretical Understanding ◽  
Air Inlet ◽  
Continuous Detonation ◽  
Rotating Detonation

Operational characteristics of an air breathing Rotating Detonation Combustor (RDC) fueled by natural gas-hydrogen blends are discussed in this paper. Experiments were performed on a 152 mm diameter uncooled RDC with a combustor to inlet area ratio of 0.2 at elevated inlet temperature and combustor pressure while varying the fuel split between natural gas and hydrogen over a range of equivalence ratios. Experimental data from short-duration (∼6sec) tests are presented with an emphasis on identifying detonability limits and exploring detonation stability with the addition of natural gas. Although the nominal combustor used in this experiment was not specifically designed for natural gas-air mixtures, significant advances in understanding conditions necessary for sustaining a stable, continuous detonation wave in a natural gas-hydrogen blended fuel were achieved. Data from the experimental study suggests that at elevated combustor pressures (2–3bar), only a small amount of natural gas added to the hydrogen is needed to alter the detonation wave operational mode. Additional observations indicate that an increase in air inlet temperature (up to 204°C) at atmospheric conditions significantly affects RDC performance by increasing deflagration losses through an increase in the number of combustion (detonation/Deflagration) regions present in the combustor. At higher backpressure levels the RDC exhibited the ability to achieve stable detonation with increasing concentrations of natural gas (with natural gas / hydrogen-air blend). However, losses tend to increase at intermediate air preheat levels (∼120°C). It was observed that combustor pressure had a first order influence on RDC stability in the presence of natural gas. Combining the results from this limited experimental study with our theoretical understanding of detonation wave fundamentals provides a pathway for developing an advanced combustor capable of replacing conventional constant pressure combustors typical of most power generation processes with one that produces a pressure gain.

scholarly journals Numerical Analysis of Detonability Assessment in a Natural Gas-Air Fueled Rotating Detonation Engine

2019 ◽  
Author(s):  
Pankaj Saha ◽  
Peter Strakey ◽  
Donald Ferguson ◽  
Arnab Roy
Keyword(s):  
Natural Gas ◽  
Detonation Wave ◽  
Hydrogen Fuel ◽  
Air Breathing ◽  
Wave Characteristics ◽  
Fuel Blends ◽  
Rotating Detonation Engine ◽  
Continuous Detonation ◽  
Detonation Engine ◽  
Rotating Detonation

Abstract Rotating Detonation Engines (RDE) offer an alternative combustion strategy to replace conventional constant pressure combustion with a process that could produce a pressure gain without the use of a mechanical compressor. Recent numerical and experimental publications that consider air as the oxidizer have primarily focused on the ability of these annular combustors to sustain a stable continuous detonation wave when fueled by hydrogen. However, for this to be a viable consideration for the land-based power generation it is necessary to explore the ability to detonate natural gas and air within the confines of the annular geometry of an RDE. Previous studies on confined detonations have expressed the importance of permitting detonation cells to fully form within the combustor in order to achieve stability. This poses a challenge for natural gas–air fueled processes as their detonation cell size can be quite large even at moderate pressures. Despite the practical importance, only a few studies are available on natural gas detonations for air-breathing RDE applications. Moreover, the extreme thermodynamic condition (high temperature inside the combustor) allows limited accessibility inside the combustor for detailed experimental instrumentations, providing mostly single-point data. Recent experimental studies at the National Energy Technology Laboratory (NETL) have reported detonation failure at higher methane concentration in an air-breathing RDE fueled by natural gas-hydrogen fuel blends. This encourages to perform a detailed numerical investigation on the wave characteristics of detonation in a natural gas-air fueled RDE to understand the various aspects of instability associated with the natural gas-air detonation. This study is a numerical consideration of a methane-air fueled RDE with varying operating conditions to ascertain the ability to achieve a stable, continuous detonation wave. The simulations have been performed in a 2D unwrapped RDE geometry using the open-source CFD library “OpenFOAM” employing an unsteady pressure-based compressible reactive flow solver with a k–ε turbulence model in a structured rectangular grid system. Both reduced and detailed chemical kinetic models have been used to assess the effect of the chemistry on the detonation wave characteristics and the underlying flow features. A systematic grid sensitivity study has been conducted with various grid sizes to quantify the weakly stable overdriven detonation on a coarse mesh and oscillating features at fine mesh resolutions. The main focus of the current study is to investigate the effects of operating injection pressure on detonation wave characteristics of an air-breathing Rotating Detonation Engine (RDE) fueled with natural gas-hydrogen fuel blends. Wave speeds, peak pressures and temperatures, and dominant frequencies have been computed from the time histories. The flow structures were then visualized using 2D contours of temperature and species concentration.

Experimental study on propagation mode of H 2 /Air continuously rotating detonation wave

2015 ◽  
Vol 40 (4) ◽  
pp. 1980-1993 ◽  
Author(s):  
Wei Lin ◽  
Jin Zhou ◽  
Shijie Liu ◽  
Zhiyong Lin ◽  
Fengchen Zhuang
Keyword(s):  
Experimental Study ◽  
Detonation Wave ◽  
Propagation Mode ◽  
Rotating Detonation

scholarly journals Investigating Instabilities in a Rotating Detonation Combustor Operating With Natural Gas–Hydrogen Fuel Blend—Effect of Air Preheat and Annulus Width

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Arnab Roy ◽  
Clinton R. Bedick ◽  
Donald H. Ferguson ◽  
Todd Sidwell ◽  
Peter A. Strakey
Keyword(s):  
Natural Gas ◽  
Detonation Wave ◽  
Air Temperature ◽  
Detonation Waves ◽  
Operating Pressure ◽  
Hydrogen Fuel ◽  
Fuel Blend ◽  
Operational Envelope ◽  
Rotating Detonation ◽  
Gap Width

Abstract Propagation characteristics of a detonation wave in an air-breathing rotating detonation combustor (RDC) using natural gas (NG)–hydrogen fuel blends is presented in this paper. Short-duration (∼up to 6 s) experiments were performed on a 152.4 mm OD uncooled RDC with two different annulus gap widths (5.08 mm and 7.62 mm) over a range of equivalence ratios (0.6–1.0) at varying inlet air temperatures (∼65–204 °C) and NG content (up to 15%) with precombustion operating pressure slightly above ambient. It was observed that the RDC, with an annulus gap width of 5.08 mm, was inherently unstable when NG was added to the hydrogen fuel while operating at precombustion pressures near ambient and at an inlet air temperature of 65 °C. Increasing the annulus gap width to 7.62 mm improved the stability of the detonation wave at similar temperatures and pressure permitting operation with as much as 5% NG by volume. While observed speeds of the detonation waves were still below theoretical values, an increase in inlet air temperature reduced the variability in wave speed. The frequency analysis thus explored in this study is an effort to quantify detonation instability in an RDC under varying operational envelope. The data presented are relevant toward developing strategies to sustain a stable detonation wave in an RDC using NG for land-based power generation.

scholarly journals Comparison and Analysis of kW-Class SOFC-CHP Systems with Different Fuels

2020 ◽  
Author(s):  
Jianzhong Zhu ◽  
Hao Meng ◽  
Minfang Han
Keyword(s):  
Natural Gas ◽  
Combined Heat And Power ◽  
Inlet Temperature ◽  
Electrical Efficiency ◽  
Air Inlet ◽  
Operational Costs ◽  
System Energy ◽  
Comparison And Analysis ◽  
Semi Empirical ◽  
Stack Model

Abstract SOFC is an ideal device for developing distributed combined heat and power (CHP) systems. In this paper, kW-class SOFC system models based on semi-empirical SOFC stack model were established to optimize the systems with the aim of maximizing the system electrical efficiency. Four types of SOFC-CHP systems using different fuel including natural gas (NG), hydrogen, methanol, syngas were compared, and the relationships between key parameters and system energy effciency were analyzed. Simlulation results show that decreasing the air inlet temperature (AIT) and increasing stack temperature will promote electrical effciency most significantly. In addition, the operational costs of four different systems were also compared, and among which the methanol-fueled system was the lowest.

scholarly journals Investigating Instabilities in a Rotating Detonation Combustor Operating With Natural Gas-Hydrogen Fuel Blend: Effect of Air Preheat and Annulus Width

2019 ◽  
Author(s):  
Arnab Roy ◽  
Clinton Bedick ◽  
Donald Ferguson ◽  
Todd Sidwell ◽  
Peter Strakey
Keyword(s):  
Natural Gas ◽  
Detonation Wave ◽  
Air Temperature ◽  
Gas Content ◽  
Detonation Waves ◽  
Operating Pressure ◽  
Hydrogen Fuel ◽  
Fuel Blend ◽  
Rotating Detonation ◽  
Gap Width

Abstract Propagation characteristics of a detonation wave in an air-breathing Rotating Detonation Combustor (RDC) using natural gas-hydrogen fuel blends is presented in this paper. Short duration (∼up to 6s) experiments were performed on a 152.4mm OD uncooled RDC with two different annulus gap widths (5.08mm and 7.62mm) over a range of equivalence ratios (0.6–1.0) at varying inlet air temperatures (∼65°C-204°C) and natural gas content (up to 15%) with pre-combustion operating pressure slightly above ambient. It was observed that the RDC, with an annulus gap width of 5.08mm, was inherently unstable when natural gas (NG) was added to the hydrogen fuel while operating at pre-combustion pressures near ambient and at an inlet air temperature of 65°C. Increasing the annulus gap width to 7.62mm improved the stability of the detonation wave at similar temperatures and pressure permitting operation with as much as 5% NG by volume. While observed speeds of the detonation waves were still below theoretical values, an increase in inlet air temperature reduced the variability in wave speed. The frequency analysis thus explored in this study is an effort to quantify detonation instability in an RDC under varying operational envelope. The data presented is relevant towards developing strategies to sustain a stable detonation wave in an RDC using natural gas for land based power generation.

scholarly journals Experimental Investigation of a Piloted, Natural Gas-Air Rotating Detonation Wave Combustor

2018 ◽  
Author(s):  
Ian V. Walters ◽  
Chris Journell ◽  
Aaron Lemcherfi ◽  
Rohan Gejji ◽  
Stephen D. Heister ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Natural Gas ◽  
Detonation Wave ◽  
Rotating Detonation

Computational and Experimental Investigation of Emissions in a Highly Humidified Premixed Flame

2003 ◽  
Author(s):  
Fredrik Hermann ◽  
Jens Klingmann ◽  
Rolf Gabrielsson
Keyword(s):  
Air Temperature ◽  
Combustion Efficiency ◽  
Reaction Scheme ◽  
Operating Conditions ◽  
Aerodynamic Load ◽  
Inlet Temperature ◽  
Atmospheric Conditions ◽  
Air Inlet ◽  
Stirred Reactor ◽  
Maximum Humidity

Emission formation and flame stability were investigated, both experimentally and computationally, for premixed combustion with varying amounts of water vapor in the mixture. Emission measurements were made in a gas turbine combustor at atmospheric conditions, using Danish Natural Gas (NG) as fuel. The emissions were mapped as a function of humidity, inlet air temperature, equivalence ratio and aerodynamic load. Operating conditions were chosen to match what can be expected from e.g. an EvGT cycle for power generation. The inlet air temperature was slightly lower than the inlet temperatures that would be found in a recuperated cycle. The degree of humidity was varied from 0w% to 33w% of the airflow in the experiment, while the air inlet temperature was varied from 500K to 800K. Computations were made using a single Perfectly Stirred Reactor (PSR) model and a reaction scheme with 821 reactions and 69 species. It was found that the NOx emissions were strongly reduced by the addition of water. Most of this decrease vanishes in practical combustion since richer combustion is required to keep CO emissions (combustion efficiency) at a tolerable level. The maximum humidity was found to be dependent on inlet air temperature and aerodynamic load. In this experiment, the maximum humidity achieved was 33%.

Experimental study of a hydrogen-air rotating detonation engine with variable air-inlet slot

2018 ◽  
Vol 43 (24) ◽  
pp. 11253-11262 ◽  
Author(s):  
Shengbing Zhou ◽  
Hu Ma ◽  
Shuai Li ◽  
Changsheng Zhou ◽  
Daokun Liu
Keyword(s):  
Experimental Study ◽  
Air Inlet ◽  
Rotating Detonation Engine ◽  
Detonation Engine ◽  
Rotating Detonation
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