Porous medium based burner for efficient and clean combustion of ammonia–hydrogen–air systems

Nozari, Hadi; Karaca, Gizem; Tunçer, Onur; Karabeyoğlu, Arif

doi:10.1016/j.ijhydene.2017.03.234

Cited by 64 publications

(13 citation statements)

References 20 publications

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“…Although the NOx levels are still high -up to 600 ppmV -it is clear that the inclusion of catalytic converts can mitigate the problem considerably, thus leading to the production of clean energy if ammonia is recovered via sustainable sources [15][16][17][18]. Further studies on pure ammonia combustion using swirling flows [19] or porous media [20][21] have also revealed the potential of ammonia for power purposes at small scale.…”

Section: Introductionmentioning

confidence: 99%

Preliminary study on lean premixed combustion of ammonia-hydrogen for swirling gas turbine combustors

Valera‐Medina

Pugh

Marsh

et al. 2017

International Journal of Hydrogen Energy

202

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Hydrogen has been considered one of the most promising materials for energy storage during the last decade with considerable research having been undertaken to demonstrate the use of the molecule in power production systems. However, hydrogen presents drawbacks in terms of global commercialisation and deployment since its distribution is only feasible with significant dedicated infrastructure investment including liquefaction or if it is combined with other gases such as methane. The latter will still produce carbon emissions, whilst the former is not economically viable with current technologies. Therefore, an alternative is to use ammonia as a hydrogen storage vector. Ammonia, a molecule that has been used for more than a century, is a well-known material distributed across the world. Moreover, its properties allow its liquefaction at a relatively low pressure under atmospheric temperature compared to hydrogen, serving as a compound that can be used from fertilising to industrial processes. For power generation, ammonia has demonstrated to have a very slow reaction hence flame speeds, thus one option is to dope the fuel with a more reactive molecule such as hydrogen, which conveniently can be obtained from cracking ammonia. Hence, this paper presents the results of a numerical and experimental campaign where a 50:50 (vol%) ammonia-hydrogen blend was used for lean premixed combustion in a generic swirl combustor used in gas turbine studies. The results show that whilst the mixture can produce a good flame velocity similar to methane with the mixture having near equivalent laminar flame speed characteristics, the high diffusivity of hydrogen under these conditions leads to a narrow operational envelope with the potential for boundary layer flashback. High NOx emissions are produced due to the excess production of OH and O radicals. Recommendations for further studies and future developments are also discussed.

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Section: Introductionmentioning

confidence: 99%

Preliminary study on lean premixed combustion of ammonia-hydrogen for swirling gas turbine combustors

Valera‐Medina

Pugh

Marsh

et al. 2017

International Journal of Hydrogen Energy

202

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“…However, the low cost of fossil fuels led to the end of these programs that would be eventually re-activated a few decades later. More recently, a number of different approaches have been followed to use ammonia as a flexible fuel in gas turbines, with most of them finding that emissions are the main concern when burning ammonia directly [6][7][8][9][10]. The work from the Space Propulsion Group (SPG) [6][7] has demonstrated the challenges of the use of ammonia as fuel for propulsion gas turbines, thus leading to the development of new combustion systems based on porous materials that can efficiently burn ammonia blends, although this is achieved only at low power outputs.…”

mentioning

confidence: 99%

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

Valera‐Medina

Guteša²,

Xiao

et al. 2019

International Journal of Hydrogen Energy

205

107

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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%NH3-30%H2 (%vol) blend for utilisation within a gas turbine environment, based on primary combustion diagnostics including combustion stabilityvia 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.

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“…In order to improve the energy conversion efficiency, many works or methods have been studied and tested such as the size of burners [ 9 ], porous media materials [ 10 , 11 ], layer of pores [ 12 , 13 ], and the type of fuel-air consumptions [ 14 ]. Many authors have done novel studies in determining the effectiveness of non-premixed [ 15 , 16 ] and premixed combustions [ 17 , 18 ].…”

Section: Introductionmentioning

confidence: 99%

Entropy Generation and Exergy Analysis of Premixed Fuel-Air Combustion in Micro Porous Media Burner

Ismail

Abdullah

Mazlan

et al. 2020

Entropy

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The performance of porous media micro-burners plays an important role in determining thermal efficiency and improving our daily life. Nowadays, a lot of scholars are actively involved in this research area and ongoing studies are still being carried out due to the burners’ excellent performance. The exergy efficiency and entropy generation of a porous media burner are strongly dependent on the characteristics of the flame and its thermal behavior. In this study, a single-layer and double-layer porous media form were constructed to investigate the effects of various types of porous foam arrangement in a cylindrical burner. The burner was operated using premixed butane-air combustion with an inner diameter of 23 mm and a length of 100 mm. The experiments were carried out in rich fuel conditions with an equivalence ratio, φ ranging from 1.3 to 2.0. The results showed significant improvement in the thermal and exergy efficiency with an increase in the equivalence ratio in a double-layer compared with a single-layer. The peak temperature recorded was 945.21 °C at φ = 1.3 for a porcelain single-layer, and the highest exergy efficiency was 83.47% at φ = 2.0 for an alumina-porcelain double-layer burner. It was also found that the average temperature of the burner wall decreased with an increase in the equivalence ratios for PMB2 and PMB4, whereas the average wall temperature for PMB3 was largely unaffected by the equivalence ratios. The total entropy generation rate reached the highest value at φ = 2.0 for all PMB configurations, and the highest percentage increase for total entropy generation rate was 46.09% for PMB1. The exergy efficiency for all burners was approximately similar with the highest exergy efficiency achieved by PMB4 (17.65%). In addition, the length and location of the flame with thermal distribution was significantly affected by the equivalence ratio between the single-layer and double-layer porous material. Overall, a double-layer porous media burner showed the best performance calculated based on the second law of thermodynamics when compared with other configurations, and it is ideal for domestic application.

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Porous medium based burner for efficient and clean combustion of ammonia–hydrogen–air systems

Cited by 64 publications

References 20 publications

Preliminary study on lean premixed combustion of ammonia-hydrogen for swirling gas turbine combustors

Preliminary study on lean premixed combustion of ammonia-hydrogen for swirling gas turbine combustors

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

Entropy Generation and Exergy Analysis of Premixed Fuel-Air Combustion in Micro Porous Media Burner

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