Gas Sampling Techniques for NOx emissions in Pulse Detonation Combustion

2019 ◽  
Author(s):  
Niclas Hanraths ◽  
Myles D. Bohon ◽  
Christian O. Paschereit ◽  
Neda Djordjevic
Keyword(s):  
Sampling Techniques ◽  
Nox Emissions ◽  
Gas Sampling ◽  
Pulse Detonation ◽  
Detonation Combustion

Numerical Study on NOx Reduction in Pulse Detonation Combustion by Using Steam Injection Decoupled From Detonation Development

2018 ◽  
Author(s):  
Niclas Hanraths ◽  
Fabian Tolkmitt ◽  
Phillip Berndt ◽  
Neda Djordjevic
Keyword(s):  
Initial Conditions ◽  
Numerical Study ◽  
Nox Reduction ◽  
Pollutant Emissions ◽  
Nox Emissions ◽  
Reliable Operation ◽  
Detonation Cell ◽  
Pulse Detonation ◽  
Detonation Combustion ◽  
Reduction Methods

Recently, the focus has been laid on the characteristics of pollutant emissions from pulse detonation combustion. Initial studies indicate possibly high nitrogen oxides (NOx) emissions, so the assessment of potential primary reduction methods is advisable. The present work considers the following reduction methods: lean combustion, nitrogen and steam dilution as well as flue gas recirculation. Since such changes in the combustion mixture reduce its reactivity and thus detonability, they can impair a reliable operation in technical systems. In order to explore the potential and limitations of each of these reduction methods, they are compared for mixtures featuring an identical characteristic detonation cell size at given initial conditions. Furthermore, building upon the use of steam dilution, a modified method to add steam to the combustible mixture is investigated. In order to avoid the strong reduction of mixture detonability by steam addition and ensure a robust detonation formation, steam is injected into the already developed detonation front. It was found that, for sufficiently even steam distribution, NOx reduction comparable to a premixed dilution could be achieved. This approach enables the realization of NOx reduction in pulse detonation combustion also for such conditions, for which premix dilution is not feasible. Therefore, combining the premix dilution with post-shock injection offers a promising strategy to substantially reduce NOx emissions from pulse detonation combustion, while at the same time ensuring its reliable operation.

Numerical Study on the Reduction of NOx Emissions From Pulse Detonation Combustion

2017 ◽  
Vol 140 (4) ◽  
Author(s):  
Neda Djordjevic ◽  
Niclas Hanraths ◽  
Joshua Gray ◽  
Phillip Berndt ◽  
Jonas Moeck
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Emissions Reduction ◽  
Nox Emissions ◽  
Primary Methods ◽  
Detonation Cell ◽  
Pulse Detonation ◽  
Detonation Combustion

A change in the combustion concept of gas turbines from conventional isobaric to constant volume combustion, such as in pulse detonation combustion (PDC), promises a significant increase in gas turbine efficiency. Current research focuses on the realization of reliable PDC operation and its challenging integration into a gas turbine. The topic of pollutant emissions from such systems has so far received very little attention. Few rare studies indicate that the extreme combustion conditions in PDC systems can lead to high emissions of nitrogen oxides (NOx). Therefore, it is essential already at this stage of development to begin working on primary measures for NOx emissions reduction if commercialization is to be feasible. The present study evaluates the potential of different primary methods for reducing NOx emissions produced during PDC of hydrogen. The considered primary methods involve utilization of lean combustion mixtures or its dilution by steam injection or exhaust gas recirculation. The influence of such measures on the detonability of the combustion mixture has been evaluated based on detonation cell sizes modeled with detailed chemistry. For the mixtures and operating conditions featuring promising detonability, NOx formation in the detonation wave has been simulated by solving the one-dimensional (1D) reacting Euler equations. The study enables an insight into the potential and limitations of considered measures for NOx emissions reduction and lays the groundwork for optimized operation of PDC systems.

Numerical Study on the Reduction of NOx Emissions From Pulse Detonation Combustion

2017 ◽  
Author(s):  
Neda Djordjevic ◽  
Niclas Hanraths ◽  
Joshua Gray ◽  
Phillip Berndt ◽  
Jonas Moeck
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Emissions Reduction ◽  
Nox Emissions ◽  
Primary Methods ◽  
Detonation Cell ◽  
Pulse Detonation ◽  
Detonation Combustion

A change in the combustion concept of gas turbines from conventional isobaric to constant volume combustion (CVC), such as in pulse detonation combustion (PDC), promises a significant increase in gas turbine efficiency. Current research focuses on the realization of reliable PDC operation and its challenging integration into a gas turbine. The topic of pollutant emissions from such systems has so far received very little attention. Few rare studies indicate that the extreme combustion conditions in PDC systems can lead to high emissions of nitrogen oxides (NOx). Therefore, it is essential already at this stage of development to begin working on primary measures for NOx emissions reduction, if commercialization is to be feasible. The present study evaluates the potential of different primary methods for reducing NOx emissions produced during pulsed detonation combustion of hydrogen. The considered primary methods involve utilization of lean combustion mixtures or its dilution by steam injection or exhaust gas recirculation. The influence of such measures on the detonability of the combustion mixture has been evaluated based on detonation cell sizes modelled with detailed chemistry. For the mixtures and operating conditions featuring promising detonability, NOx formation in the detonation wave has been simulated by solving the one-dimensional reacting Euler equations. The study enables an insight into the potential and limitations of considered measures for NOx emissions reduction and lays the groundwork for optimized operation of pulse detonation combustion systems.

Numerical Study on NOx Reduction in Pulse Detonation Combustion by Using Steam Injection Decoupled From Detonation Development

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Niclas Hanraths ◽  
Fabian Tolkmitt ◽  
Phillip Berndt ◽  
Neda Djordjevic
Keyword(s):  
Initial Conditions ◽  
Numerical Study ◽  
Nox Reduction ◽  
Pollutant Emissions ◽  
Nox Emissions ◽  
Reliable Operation ◽  
Detonation Cell ◽  
Pulse Detonation ◽  
Detonation Combustion ◽  
Reduction Methods

Recently, the focus has been laid on the characteristics of pollutant emissions from pulse detonation combustion (PDC). Initial studies indicate possibly high nitrogen oxides (NOx) emissions, so the assessment of potential primary reduction methods is advisable. The present work considers the following reduction methods: lean combustion, nitrogen and steam dilution, as well as flue gas recirculation. Since such changes in the combustion mixture reduce its reactivity and thus detonability, they can impair a reliable operation in technical systems. In order to explore the potential and limitations of each of these reduction methods, they are compared for mixtures featuring an identical characteristic detonation cell size at given initial conditions. Furthermore, building upon the use of steam dilution, a modified method to add steam to the combustible mixture is investigated. In order to avoid the strong reduction of mixture detonability by steam addition and ensure a robust detonation formation, steam is injected into the already developed detonation front. It was found that, for sufficiently even steam distribution, NOx reduction comparable to a premixed dilution could be achieved. This approach enables the realization of NOx reduction in PDC also for such conditions, for which premix dilution is not feasible. Therefore, combining the premix dilution with postshock injection offers a promising strategy to substantially reduce NOx emissions from PDC, while at the same time ensuring its reliable operation.

Lean Operation of a Pulse Detonation Combustor by Fuel Stratification

2020 ◽  
Author(s):  
Fabian E. Habicht ◽  
Fatma C. Yücel ◽  
Niclas Hanraths ◽  
Neda Djordjevic ◽  
Christian Oliver Paschereit
Keyword(s):  
Gas Turbines ◽  
Equivalence Ratio ◽  
Pressure Ratio ◽  
Initial Pressure ◽  
Detonation Initiation ◽  
Nox Emissions ◽  
Shock Focusing ◽  
Pulse Detonation ◽  
Lean Combustion ◽  
Fuel Stratification

Abstract Pressure gain combustion is a promising concept to substantially increase the thermal efficiency of gas turbines. One possible implementation that has been frequently investigated are pulse detonation combustors (PDCs), as they permit stable and reliable operation. At the same time, the need for part-load operation and low NOx emissions requires combustion concepts in the lean regime. However, realizing lean combustion is still very challenging in PDCs since the deflagration to detonation transition (DDT) is very sensitive to the reactant composition. The present work investigates an approach to realize lean combustion in PDC by applying fuel stratification experimentally. The scope is to find the necessary increase of fuel concentration inside the pre-detonation chamber to provide reliable DDT with respect to the overall equivalence ratio. Emission measurements in the exhaust of the PDC allow for a quantification of the NOx emissions as a function of the injected fuel profile. A valveless PDC test rig is used, which contains a shock focusing geometry for detonation initiation and is ignited by a spark plug close to the upstream end wall. The subsequent expansion of the burned gas and interaction of the flame front with turbulence leads to the formation of a leading shock inside the pre-detonation chamber, which is then focused inside a converging-diverging geometry. The successful initiation of a detonation wave by shock focusing is very sensitive to the pressure ratio across the leading shock, which can be influenced by initial pressure, reactant composition and flow velocity. Results reveal that fuel stratification allows for reliable detonation initiation at a global equivalence ratio of ϕglob = 0.65, whereas repeatable successful operation with non-stratified fuel injection is limited to ϕglob ≥ 0.85.

Hydrojet engine with pulse detonation combustion of liquid-fuel

2017 ◽  
Vol 475 (1) ◽  
pp. 129-133 ◽  
Author(s):  
S. M. Frolov ◽  
V. S. Aksenov ◽  
I. A. Sadykov ◽  
K. A. Avdeev ◽  
I. O. Shamshin
Keyword(s):  
Liquid Fuel ◽  
Pulse Detonation ◽  
Detonation Combustion

Application of Pulse Detonation Combustion to Turbofan Engines

2002 ◽  
Vol 125 (1) ◽  
pp. 270-283 ◽  
Author(s):  
M. A. Mawid ◽  
T. W. Park ◽  
B. Sekar ◽  
C. Arana
Keyword(s):  
Cfd Analysis ◽  
Turbofan Engine ◽  
Turbofan Engines ◽  
Pulse Detonation ◽  
Detonation Combustion ◽  
Partial Filling ◽  
Significant Performance ◽  
Specific Thrust ◽  
Performance Gains ◽  
Engine Concept

The potential performance gain of utilizing pulse detonation combustion in the bypass duct of a turbofan engine for possible elimination of the traditional afterburner was investigated in this study. A pulse detonation turbofan engine concept without an afterburner was studied and its performance was assessed. The thrust, specific fuel consumption (SFC), and specific thrust of a conventional turbofan with an afterburner and the new pulse detonation turbofan engine concept were calculated and compared. The pulse detonation device performance in the bypass duct was obtained by using multidimensional CFD analysis. The results showed that significant performance gains can be obtained by using the pulse detonation turbofan engine concept as compared to the conventional afterburning turbofan engine. In particular, it was demonstrated that for a pulse detonation bypass duct operating at a frequency of 100 Hz and higher, the thrust and specific thrust of a pulse-detonation turbofan engine can nearly be twice as much as those of the conventional afterburning turbofan engine. SFC was also shown to be reduced. The effects of fuel-air mixture equivalence ratio and partial filling on performance were also predicted. However, the interaction between pulse detonation combustion in the bypass duct and the engine fan, for potential fan stall, and engine nozzle have not been investigated in this study.

scholarly journals Unsteady Effects on NOx Measurements in Pulse Detonation Combustion

2021 ◽  
Author(s):  
Niclas Hanraths ◽  
Myles D. Bohon ◽  
Christian Oliver Paschereit ◽  
Neda Djordjevic
Keyword(s):  
Sampling Technique ◽  
Extraction Process ◽  
Operating Conditions ◽  
Exhaust Gas ◽  
One Dimensional ◽  
Pulse Detonation ◽  
Detonation Combustion ◽  
Unsteady Effects ◽  
Sample Time ◽  
Probe Geometry

AbstractEmission measurements from unsteady combustion systems such as Pulse Detonation Combustion (PDC) are challenging due to the inherently large variations in pressure, temperature, composition, and flow velocity of the exhaust gas. Comparison of experimental data is additionally complicated by differences in operating conditions and gas sampling setup between different facilities. Qualitative considerations with regard to the sampling process from PDC, based on one-dimensional simulations, indicate a systematic influence of the sampling setup and extraction process on the resulting concentration measurements. Therefore, operating frequency, sample time, fill time, as well as PDC outlet and probe geometry were varied experimentally in order to assess the degree to which each of these parameters impact the resulting measured $${\rm NO}_{\rm x}$$ NO x in order to better inform researchers of these effects when making measurements. It was shown that measured $${\rm NO}_{\rm x}$$ NO x emissions can vary significantly depending on the choice of these parameters and therefore care must be exercised in order to reduce the influence of the sampling technique when aiming for comparable results.

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