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Qian F, Zhang S, Wang J, Zhu N, Bao X, Yang H, Xu X, Alshahrani WA, Helal MH, Guo Z. Ammonia energy fraction effect on the combustion and reduced NOX emission of ammonia/diesel dual fuel. ENVIRONMENTAL RESEARCH 2024; 261:119530. [PMID: 39004391 DOI: 10.1016/j.envres.2024.119530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 05/08/2024] [Accepted: 06/30/2024] [Indexed: 07/16/2024]
Abstract
With stringent regulations of internal combustion engine on reducing CO2 emission, ammonia has been used as an alternative fuel. Investigating how engine-related performance is affected by partial ammonia replacement of diesel fuel is essential for understanding the combustion. Therefore, in this study, a three-dimensional numerical simulation model is developed for the burning of two fuels of diesel and ammonia based on relevant parameters (i.e., compression ratio, load, ammonia energy fraction, etc.) in a lab-made diesel engine. The consequences of load and compression proportion on combustion and pollutant emissions are investigated for ammonia energy fractions between 50% and 90%. When the ammonia portion rises, the increased ammonia equivalent ratio causes ammonia to move away from the dilute combustion boundary and accelerates the combustion rate of ammonia. An increase in compression ratio significantly increases the specified thermal performance and combustion efficacy. When the compression ratio is 16, as the ammonia energy fractions increases, due to the increase in the proportion of ammonia, that is, the proportion of nitrogen atoms increases, more NOx is generated during the combustion process. When the ammonia substitution rate is 90%, as the compression ratio increases, the cylinder pressure and temperature increase. The combustion efficiency of ammonia increases, generating more NOx and NOx emissions can reach 0.66 mg/m3. At a compression ratio of 18, the NOx emissions can reach 1.59 mg/m3. However, under medium and low load conditions, as the ammonia fraction increases, the total energy of fuel decreases, and the combustion efficiency of ammonia decreases, resulting in a decrease in the heat released during combustion and a decrease in NOx emissions. When the ammonia substitution rate is 90% and the load is 25%, NOx emissions reach 0.1 mg/m3. This research provides theoretical suggestions for the profitable and use ammonia fuel in internal combustion engines in a clean manner.
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Affiliation(s)
- Feng Qian
- School of Automobile and Traffic Engineering, Wuhan University of Science and Technology, Wuhan, Hubei, 430065, China
| | - Shilong Zhang
- School of Automobile and Traffic Engineering, Wuhan University of Science and Technology, Wuhan, Hubei, 430065, China
| | - Jie Wang
- School of Automobile and Traffic Engineering, Wuhan University of Science and Technology, Wuhan, Hubei, 430065, China.
| | - Neng Zhu
- School of Automobile and Traffic Engineering, Wuhan University of Science and Technology, Wuhan, Hubei, 430065, China
| | - Xiong Bao
- School of Automobile and Traffic Engineering, Wuhan University of Science and Technology, Wuhan, Hubei, 430065, China
| | - Hongyun Yang
- Department of Chemical Engineering, Xiangtan University, Xiangtan, Hunan, 411105, China.
| | - Xiaowei Xu
- School of Automobile and Traffic Engineering, Wuhan University of Science and Technology, Wuhan, Hubei, 430065, China
| | - Wafa A Alshahrani
- Department of Chemistry, College of Science, University of Bisha, Bisha, 61922, Saudi Arabia
| | - Mohamed H Helal
- Department of Chemistry, College of Sciences and Arts, Northern Border University, Rafha 91911, Saudi Arabia
| | - Zhanhu Guo
- Department of Chemical Engineering, Xiangtan University, Xiangtan, Hunan, 411105, China
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Liang Y, Lu X. Theoretical Investigation on the H Atom Abstraction Reaction from C1-C4 Alkanes and Alkenes by ṄH 2 Radicals. J Phys Chem A 2024; 128:3396-3407. [PMID: 38634113 DOI: 10.1021/acs.jpca.4c01229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/19/2024]
Abstract
The H atom abstraction reactions from alkanes and alkenes by ṄH2 are decisive in predicting the combustion characteristics of NH3/CxHy binary fuels. Theoretical investigation is carried out on the energy barriers of H atom abstraction reactions from C1-C4 alkanes/alkenes by ṄH2 radicals at the QCISD(T)/CBS//M06-2X/6-311++G(d,p) level of theory. Single-point energies of each species are computed using QCISD(T)/cc-pVDZ, TZ level of theories with basis set corrections from MP2/cc-pVDZ, TZ, and QZ methods. One-dimensional hindered rotor potentials are obtained by the M06-2X/cc-pVTZ method with 10° increment. Rate constants of each channel across temperatures of 298.15-2000 K are calculated by solving the RRKM/Master Equation with conventional transition state theory. For alkanes, rate constants order follows ktertiary> ksecondary> kprimary, while for alkenes the order follows kallylic> kprimary> kvinylic. Among the vinylic carbon sites within the same alkene species, the hydrogen atom sharing the same carbon with the allylic carbon on the C-C double bond is the preferred site for the H atom abstraction reaction. The branching ratio results indicate that the abstraction from tertiary or secondary carbon sites on alkanes and allylic carbon sites on alkenes are dominating during the investigated temperature range but become less important as the temperature increases. The data provided in this work are in good agreement with the literature data, but for the ṄH2+alkenes system, the literature data are scarce and further investigation is needed.
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Affiliation(s)
- Yueying Liang
- Key Laboratory for Power Machinery and Engineering of M. O. E., Shanghai Jiao Tong University, Shanghai 200240, P. R. China
| | - Xingcai Lu
- Key Laboratory for Power Machinery and Engineering of M. O. E., Shanghai Jiao Tong University, Shanghai 200240, P. R. China
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3
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García-Ruiz P, Salas I, Casanova E, Bilbao R, Alzueta MU. Experimental and Modeling High-Pressure Study of Ammonia-Methane Oxidation in a Flow Reactor. ENERGY & FUELS : AN AMERICAN CHEMICAL SOCIETY JOURNAL 2024; 38:1399-1415. [PMID: 38264622 PMCID: PMC10804275 DOI: 10.1021/acs.energyfuels.3c03959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 12/21/2023] [Accepted: 12/21/2023] [Indexed: 01/25/2024]
Abstract
The present work deals with an experimental and modeling analysis of the oxidation of ammonia-methane mixtures at high pressure (up to 40 bar) in the 550-1250 K temperature range using a quartz tubular reactor and argon as a diluent. The impact of temperature, pressure, oxygen stoichiometry, and CH4/NH3 ratio has been analyzed on the concentrations of NH3, NO2, N2O, NO, N2, HCN, CH4, CO, and CO2 obtained as main products of the ammonia-methane mixture oxidation. The main results obtained indicate that increasing either the pressure, CH4/NH3 ratio, or stoichiometry results in a shift of NH3 and CH4 conversion to lower temperatures. The effect of pressure is particularly significant in the low range of pressures studied. The main products of ammonia oxidation are N2, NO, and N2O while NO2 concentrations are below the detection limit for all of the conditions considered. The N2O formation is favored by increasing the CH4/NH3 ratio and stoichiometry. The experimental results are simulated and interpreted in terms of an updated detailed chemical kinetic mechanism, which, in general, is able to describe well the conversion of both NH3 and CH4 under almost all of the studied conditions. Nevertheless, some discrepancies are found between the experimental results and model calculations.
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Affiliation(s)
- Pedro García-Ruiz
- Department of Chemical and
Environmental Engineering, Aragón Institute of Engineering
Research (I3A), University of Zaragoza, 50018 Zaragoza, Spain
| | - Iris Salas
- Department of Chemical and
Environmental Engineering, Aragón Institute of Engineering
Research (I3A), University of Zaragoza, 50018 Zaragoza, Spain
| | - Eva Casanova
- Department of Chemical and
Environmental Engineering, Aragón Institute of Engineering
Research (I3A), University of Zaragoza, 50018 Zaragoza, Spain
| | - Rafael Bilbao
- Department of Chemical and
Environmental Engineering, Aragón Institute of Engineering
Research (I3A), University of Zaragoza, 50018 Zaragoza, Spain
| | - María U. Alzueta
- Department of Chemical and
Environmental Engineering, Aragón Institute of Engineering
Research (I3A), University of Zaragoza, 50018 Zaragoza, Spain
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4
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Li Y, Jin Z, Wang Z, Tan H, Jia Z, Cui B, Zhou S, Bai F. Evaluation, Reduction, and Validation of a New Skeletal Mechanism for the Cofiring of NH 3 and CH 4. ACS OMEGA 2023; 8:47113-47122. [PMID: 38107915 PMCID: PMC10720029 DOI: 10.1021/acsomega.3c07094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Revised: 11/05/2023] [Accepted: 11/14/2023] [Indexed: 12/19/2023]
Abstract
The evaluation and reduction of kinetic models for the cofiring of NH3 and CH4 can help to guide the application of NH3 and CH4 in industrial equipment. In this work, eight detailed kinetic models on the cofiring of NH3 and CH4 and 15 detailed kinetic models on the NH3 combustion are collected and evaluated based on error function and experiment measurement, and the detailed mechanism of 169 species and 1268 elementary reactions with the best overall performance was determined. By using two mechanism reduction methods of directed relation graph with error propagation (DRGEP) and DRGEP with sensitivity analysis (DRGEPSA), the skeletal mechanism of 45 species and 344 elementary reactions is achieved within the temperatures of 1000-2000 K, pressures of 1-60 atm, and equivalence ratios of 0.5-2.0. The skeletal mechanism is comprehensively validated and achieves good consistency with the detailed mechanism in predicting the laminar burning velocity, species concentration, and ignition delay time. The maximum relative error between the skeletal mechanism and the detailed mechanism is less than 13%.
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Affiliation(s)
- Yuhang Li
- State
Key Laboratory of Multiphase Flow in Power Engineering, Department
of Thermal Engineering, Xi’an Jiaotong
University, Xi’an, Shaanxi Province 710049, China
| | - Zhonghua Jin
- Xi’an
Thermal Power Research Institute Co., Ltd., Xi’an, Shaanxi Province 710054, China
| | - Zhichao Wang
- Xi’an
Thermal Power Research Institute Co., Ltd., Xi’an, Shaanxi Province 710054, China
| | - Houzhang Tan
- MOE
Key Laboratory of Thermo-Fluid Science and Engineering, Department
of Thermal Engineering, Xi’an Jiaotong
University, Xi’an, Shaanxi Province 710049, China
| | - Zixiu Jia
- Xi’an
Thermal Power Research Institute Co., Ltd., Xi’an, Shaanxi Province 710054, China
| | - Baochong Cui
- MOE
Key Laboratory of Thermo-Fluid Science and Engineering, Department
of Thermal Engineering, Xi’an Jiaotong
University, Xi’an, Shaanxi Province 710049, China
| | - Shangkun Zhou
- MOE
Key Laboratory of Thermo-Fluid Science and Engineering, Department
of Thermal Engineering, Xi’an Jiaotong
University, Xi’an, Shaanxi Province 710049, China
| | - Faqi Bai
- Huaneng
Power International, Inc., Beijing 100084, China
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Klippenstein SJ, Mulvihill CR, Glarborg P. Theoretical Kinetics Predictions for Reactions on the NH 2O Potential Energy Surface. J Phys Chem A 2023; 127:8650-8662. [PMID: 37812768 DOI: 10.1021/acs.jpca.3c05181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/11/2023]
Abstract
Recent modeling studies of ammonia oxidation, which are motivated by the prospective role of ammonia as a zero-carbon fuel, have indicated significant discrepancies among the existing literature mechanisms. In this study, high-level theoretical kinetics predictions have been obtained for reactions on the NH2O potential energy surface, including the NH2 + O, HNO + H, and NH + OH reactions. These reactions have previously been highlighted as important reactions in NH3 oxidation with high sensitivity and high uncertainty. The potential energy surface is explored with coupled cluster calculations, including large basis sets and high-level corrections to yield high-accuracy (∼0.2 kcal/mol 2σ uncertainty) estimates of the stationary point energies. Variational transition state theory is used to predict the microcanonical rate constants, which are then incorporated in master equation treatments of the temperature- and pressure-dependent kinetics. For radical-radical channels, the microcanonical rates are obtained from variable reaction coordinate transition state theory implementing directly evaluated multireference electronic energies. The analysis yields predictions for the total rate constants as well as the branching ratios. We find that the NO + H2 channel contributes 10% of the total NH2 + O flux at combustion temperatures, although this channel is not included in modern NH3 oxidation mechanisms. Modeling is used to illustrate the ramifications of these rate predictions on the kinetics of NH3 oxidation and NOx formation. The present results for NH2 + O are important for predicting the chain branching and formation of NO in the oxidation of NH3 and thermal DeNOx.
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Affiliation(s)
- Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Clayton R Mulvihill
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Peter Glarborg
- DTU Chemical Engineering, Technical University of Denmark, 2800 Lyngby, Denmark
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6
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Marshall P, Glarborg P. Probing High-Temperature Amine Chemistry: Is the Reaction NH 3 + NH 2 ⇄ N 2H 3 + H 2 Important? J Phys Chem A 2023; 127:2601-2607. [PMID: 36916833 DOI: 10.1021/acs.jpca.2c08921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Abstract
The reaction NH3 + NH2 ⇄ N2H3 + H2 (R1) has been identified as a key step to explain experimental results for pyrolysis and oxidation of ammonia. However, no direct experimental or theoretical evidence for the reaction has been reported. In the present work, the reaction was studied by ab initio theory and by reinterpretation of experimental data. We could not locate a transition state for R1 occurring as a direct process, but alternative mechanisms yielded an upper bound to k1 of 1.5 × 1013 exp(-58.9 kcal mol-1/RT) cm3 mol-1 s-1 over 1000-2500 K, several orders of magnitude lower than values applied in modeling. Consistent with the theoretical work, re-evaluation of NH3 pyrolysis data supported a very low value of k1. However, this finding opens up a novel unresolved issue. Current kinetic models cannot capture the NH3 oxidation behavior in a number of laminar flow reactor and jet-stirred reactor experiments without adopting an improbably high value for k1. Important oxidation steps might be underestimated or missing from mechanisms.
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Affiliation(s)
- Paul Marshall
- Department of Chemistry and Center for Advanced Scientific Computing and Modeling, University of North Texas, 1155 Union Circle #305070, Denton, Texas 76203-5017, United States
| | - Peter Glarborg
- DTU Chemical Engineering, Technical University of Denmark, 2800 Lyngby, Denmark
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Zhu D, Ruwe L, Schmitt S, Shu B, Kohse-Höinghaus K, Lucassen A. Interactions in Ammonia and Hydrogen Oxidation Examined in a Flow Reactor and a Shock Tube. J Phys Chem A 2023; 127:2351-2366. [PMID: 36877868 DOI: 10.1021/acs.jpca.2c07784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
Abstract
Ammonia (NH3) is a promising fuel, because it is carbon-free and easier to store and transport than hydrogen (H2). However, an ignition enhancer such as H2 might be needed for technical applications, because of the rather poor ignition properties of NH3. The combustion of pure NH3 and H2 has been explored widely. However, for mixtures of both gases, mostly only global parameters such as ignition delay times or flame speeds were reported. Studies with extensive experimental species profiles are scarce. Therefore, we experimentally investigated the interactions in the oxidation of different NH3/H2 mixtures in the temperature range of 750-1173 K at 0.97 bar in a plug-flow reactor (PFR), as well as in the temperature range of 1615-2358 K with an average pressure of 3.16 bar in a shock tube. In the PFR, temperature-dependent mole fraction profiles of the main species were obtained via electron ionization molecular-beam mass spectrometry (EI-MBMS). Additionally, for the first time, tunable diode laser absorption spectroscopy (TDLAS) with a scanned-wavelength method was adapted to the PFR for the quantification of nitric oxide (NO). In the shock tube, time-resolved NO profiles were also measured by TDLAS using a fixed-wavelength approach. The experimental results both in PFR and shock tube reveal the reactivity enhancement by H2 on ammonia oxidation. The extensive sets of results were compared with predictions by four NH3-related reaction mechanisms. None of the mechanisms can well predict all experimental results, but the Stagni et al. [React. Chem. Eng. 2020, 5, 696-711] and Zhu et al. [Combust. Flame 2022, 246, 115389] mechanisms perform best for the PFR and shock tube conditions, respectively. Exploratory kinetic analysis was conducted to identify the effect of H2 addition on ammonia oxidation and NO formation, as well as sensitive reactions in different temperature regimes. The results presented in this study can provide valuable information for further model development and highlight relevant properties of H2-assisted NH3 combustion.
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Affiliation(s)
- Denghao Zhu
- Department of Physical Chemistry, Physikalisch-Technische Bundesanstalt (PTB), 38116 Braunschweig, Germany
| | - Lena Ruwe
- Department of Fundamentals of Explosion Protection, Physikalisch-Technische Bundesanstalt (PTB), 38116 Braunschweig, Germany
| | - Steffen Schmitt
- Department of Chemistry, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Bo Shu
- Department of Physical Chemistry, Physikalisch-Technische Bundesanstalt (PTB), 38116 Braunschweig, Germany
| | | | - Arnas Lucassen
- Department of Fundamentals of Explosion Protection, Physikalisch-Technische Bundesanstalt (PTB), 38116 Braunschweig, Germany
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He X, Li M, Shu B, Fernandes R, Moshammer K. Exploring the Effect of Different Reactivity Promoters on the Oxidation of Ammonia in a Jet-Stirred Reactor. J Phys Chem A 2023; 127:1923-1940. [PMID: 36800895 DOI: 10.1021/acs.jpca.2c07547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
The low reactivity of ammonia (NH3) is the main barrier to applying neat NH3 as fuel in technical applications, such as internal combustion engines and gas turbines. Introducing combustion promoters as additives in NH3-based fuel can be a feasible solution. In this work, the oxidation of ammonia by adding different reactivity promoters, i.e., hydrogen (H2), methane (CH4), and methanol (CH3OH), was investigated in a jet-stirred reactor (JSR) at temperatures between 700 and 1200 K and at a pressure of 1 bar. The effect of ozone (O3) was also studied, starting from an extremely low temperature (450 K). Species mole fraction profiles as a function of the temperature were measured by molecular-beam mass spectrometry (MBMS). With the help of the promoters, NH3 consumption can be triggered at lower temperatures than in the neat NH3 case. CH3OH has the most prominent effect on enhancing the reactivity, followed by H2 and CH4. Furthermore, two-stage NH3 consumption was observed in NH3/CH3OH blends, whereas no such phenomenon was found by adding H2 or CH4. The mechanism constructed in this work can reasonably reproduce the promoting effect of the additives on NH3 oxidation. The cyanide chemistry is validated by the measurement of HCN and HNCO. The reaction CH2O + NH2 ⇄ HCO + NH3 is responsible for the underestimation of CH2O in NH3/CH4 fuel blends. The discrepancies observed in the modeling of NH3 fuel blends are mainly due to the deviations in the neat NH3 case. The total rate coefficient and the branching ratio of NH2 + HO2 are still controversial. The high branching fraction of the chain-propagating channel NH2 + HO2 ⇄ H2NO + OH improves the model performance under low-pressure JSR conditions for neat NH3 but overestimates the reactivity for NH3 fuel blends. Based on this mechanism, the reaction pathway and rate of production analyses were conducted. The HONO-related reaction routine was found to be activated uniquely by adding CH3OH, which enhances the reactivity most significantly. It was observed from the experiment that adding ozone to the oxidant can effectively initiate NH3 consumption at temperatures below 450 K but unexpectedly inhibit the NH3 consumption at temperatures higher than 900 K. The preliminary mechanism reveals that adding the elementary reactions between NH3-related species and O3 is effective for improving the model performance, but their rate coefficients have to be refined.
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Affiliation(s)
- Xiaoyu He
- Department of Physical Chemistry, Physikalisch-Technische Bundesanstalt, 38116 Braunschweig, Germany
| | - Mengdi Li
- Department of Physical Chemistry, Physikalisch-Technische Bundesanstalt, 38116 Braunschweig, Germany
| | - Bo Shu
- Department of Physical Chemistry, Physikalisch-Technische Bundesanstalt, 38116 Braunschweig, Germany
| | - Ravi Fernandes
- Department of Physical Chemistry, Physikalisch-Technische Bundesanstalt, 38116 Braunschweig, Germany
| | - Kai Moshammer
- Department of Physical Chemistry, Physikalisch-Technische Bundesanstalt, 38116 Braunschweig, Germany
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Wang Y, Liu J, Wang L, Fu Z, Weng P. Non-premixed combustion and NOX emission characteristics in a micro gas turbine swirl combustor fueled by methane and ammonia at various heat loads. Heliyon 2023; 9:e14521. [PMID: 37009334 PMCID: PMC10060175 DOI: 10.1016/j.heliyon.2023.e14521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Revised: 10/21/2022] [Accepted: 03/10/2023] [Indexed: 03/17/2023] Open
Abstract
In comparison to methane (CH4), ammonia (NH3) is considered a potential carbon-free alternative fuel that can reduce greenhouse gas emissions. But a principal concern is the generation of elevated nitrogen oxide (NOX) emissions from NH3 flame. In this study, the detailed reaction mechanisms and thermodynamic data of CH4 oxidation and NH3 oxidation were performed using the steady and unsteady flamelet models. After validation of the turbulence model, the combustion and NOX emission characteristics of CH4/air and NH3/air non-premixed flames in a micro gas turbine swirl combustor under a series of identical heat loads were numerically investigated and compared. The present results show that the high-temperature zone of the NH3/air flame migrates more rapidly toward the outlet of the combustion chamber than that of the CH4/air flame as the heat load increases. The average NO, N2O, and NO2 emission concentrations at all heat loads from NH3/air flame are respectively 6.12, 161.05 (given the very low N2O emission concentration from CH4/air flame), and 2.89 times higher than those from CH4/air flame. There are correlation trends between some parameters (e.g. characteristic temperature and OH emissions) with the variation of the heat load, and the relevant parameters can be tracked to predict the emission trends after changing the heat load.
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Fujioka K, Kaiser RI, Sun R. Unsupervised Reaction Pathways Search for the Oxidation of Hypergolic Ionic Liquids: 1-Ethyl-3-methylimidazolium Cyanoborohydride (EMIM +/CBH -) as a Case Study. J Phys Chem A 2023; 127:913-923. [PMID: 36574603 DOI: 10.1021/acs.jpca.2c07624] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Hypergolic ionic liquids have come under increased study for having several desirable properties as a fuel source. One particular ionic liquid, 1-ethyl-3-methylimidazolium/cyanoborohydride (EMIM+/CBH-), and oxidant, nitric acid (HNO3), has been reported to be hypergolic experimentally, but its mechanism is not well-understood at a mechanistic level. In this computational study, the reaction is first probed with ab initio molecular dynamics simulations to confirm that anion-oxidant interactions likely are the first step in the mechanism. Second, the potential energy surface of the anion-oxidant system is studied with an in-depth search over possible isomerizations, and a network of possible intermediates are found. The critical point search is unsupervised and thus has the potential of identifying structures that deviate from chemical intuition. Molecular graphs are employed for analyzing 3000+ intermediates found, and nudged elastic band calculations are employed to identify transition states between them. Finally, the reactivity of the system is discussed through examination of minimal energy paths connecting the reactant to various common products from hypergolic ionic liquid oxidation. Eight products are reported for this system: NO, N2O, NO2, HNO, HONO, HNO2, HCN, and H2O. All reaction paths leading to these exothermic products have overall reaction barriers of 6-7 kcal/mol.
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Affiliation(s)
- Kazuumi Fujioka
- Department of Chemistry, The University of Hawai'i at Manoa, Honolulu, Hawaii96822, United States
| | - Ralf I Kaiser
- Department of Chemistry, The University of Hawai'i at Manoa, Honolulu, Hawaii96822, United States
| | - Rui Sun
- Department of Chemistry, The University of Hawai'i at Manoa, Honolulu, Hawaii96822, United States
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11
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Effect of Ammonia Addition on the Ignition Delay Mechanism of Methyl Decanoate. JOURNAL OF MARINE SCIENCE AND ENGINEERING 2022. [DOI: 10.3390/jmse10070922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In this study, the effect of mixing a small amount of ammonia on the ignition delay time of methyl decanoate under different conditions was studied from the perspective of the combustion mechanism. The effect of adding ammonia on the ignition delay time of methyl decanoate at different pressures and temperatures was studied by means of simulation calculations and numerical comparison. Integrating the detailed mechanism and reaction path of methyl decanoate, the sensitivity of the ignition delay time was investigated. Analyses of the ignition delay time and rate of production were conducted to explore the transformation and influence of ammonia on the oxidation/decomposition process of the main elementary reaction during the ignition of methyl decanoate. The research illustrated that the ignition delay time of methyl decanoate increased with the number of moles of mixed ammonia at a certain temperature range, and in the negative temperature coefficient region, the effect of ammonia on the ignition delay time was the greatest. In addition, the susceptibility and yield analysis of methyl decanoate showed that the addition of ammonia had a weakening effect on the elementary reactions that originally promoted and inhibited methyl decanoate, and its consumption and production rates were reduced.
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Abstract
This study develops system-level models of ammonia-fuelled powertrains that reflect the characteristics of four oceangoing vessels to evaluate the efficacy of ammonia as an alternative fuel in the marine environment. Relying on thermodynamics, heat transfer, and chemical engineering, the models adequately capture the behaviour of internal combustion engines, gas turbines, fuel processing equipment, and exhaust aftertreatment components. The performance of each vessel is evaluated by comparing its maximum range and cargo capacity to a conventional vessel. Results indicate that per unit output power, ammonia-fuelled internal combustion engines are more efficient, require less catalytic material, and have lower auxiliary power requirements than ammonia gas turbines. Most merchant vessels are strong candidates for ammonia fuelling if the operators can overcome capacity losses between 4% and 9%, assuming that the updated vessels retain the same range as a conventional vessel. The study also establishes that naval vessels are less likely to adopt ammonia powertrains without significant redesigns. Ammonia as an alternative fuel in the marine sector is a compelling option if the detailed component design continues to show that the concept is practically feasible. The present data and models can help in such feasibility studies for a range of vessels and propulsion technologies.
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13
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Methane/Ammonia Radical Formation during High Temperature Reactions in Swirl Burners. ENERGIES 2021. [DOI: 10.3390/en14206624] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Recent studies have demonstrated that ammonia is an emerging energy vector for the distribution of hydrogen from stranded sources. However, there are still many unknown parameters that need to be understood before ammonia can be a substantial substitute in fuelling current power generation systems. Therefore, current attempts have mainly utilised ammonia as a substitute for natural gas (mainly composed of methane) to mitigate the carbon footprint of the latter. Co-firing of ammonia/methane is likely to occur in the transition of replacing carbonaceous fuels with zero-carbo options. Hence, a better understanding of the combustion performance, flame features, and radical formation of ammonia/methane blends is required to address the challenges that these fuel combinations will bring. This study involves an experimental approach in combination with numerical modelling to elucidate the changes in radical formation across ammonia/methane flames at various concentrations. Radicals such as OH*, CH*, NH*, and NH2* are characterised via chemiluminescence whilst OH, CH, NH, and NH2 are described via RANS κ-ω SST complex chemistry modelling. The results show a clear progression of radicals across flames, with higher ammonia fraction blends showing flames with more retreated shape distribution of CH* and NH* radicals in combination with more spread distribution of OH*. Simultaneously, equivalence ratio is a key parameter in defining the flame features, especially for production of NH2*. Since NH2* distribution is dependent on the equivalence ratio, CFD modelling was conducted at a constant equivalence ratio to enable the comparison between different blends. The results denote the good qualitative resemblance between models and chemiluminescence experiments, whilst it was recognised that for ammonia/methane blends the combined use of OH, CH, and NH2 radicals is essential for defining the heat release rate of these flames.
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Benés M, Pozo G, Abián M, Millera Á, Bilbao R, Alzueta MU. Experimental Study of the Pyrolysis of NH 3 under Flow Reactor Conditions. ENERGY & FUELS : AN AMERICAN CHEMICAL SOCIETY JOURNAL 2021; 35:7193-7200. [PMID: 35673549 PMCID: PMC9165062 DOI: 10.1021/acs.energyfuels.0c03387] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 01/12/2021] [Indexed: 06/15/2023]
Abstract
The possibility of using ammonia (NH3), as a fuel and as an energy carrier with low pollutant emissions, can contribute to the transition to a low-carbon economy. To use ammonia as fuel, knowledge about the NH3 conversion is desired. In particular, the conversion of ammonia under pyrolysis conditions could be determinant in the description of its combustion mechanism. In this work, pyrolysis experiments of ammonia have been performed in both a quartz tubular flow reactor (900-1500 K) and a non-porous alumina tubular flow reactor (900-1800 K) using Ar or N2 as bath gas. An experimental study of the influence of the reactor material (quartz or alumina), the bulk gas (N2 or Ar), the ammonia inlet concentration (1000 and 10 000 ppm), and the gas residence time [2060/T (K)-8239/T (K) s] on the pyrolysis process has been performed. After the reaction, the resulting compounds (NH3, H2, and N2) are analyzed in a gas chromatograph/thermal conductivity detector chromatograph and an infrared continuous analyzer. Results show that H2 and N2 are the main products of the thermal decomposition of ammonia. Under the conditions of the present work, differences between working in a quartz or non-porous alumina reactor are not significant under pyrolysis conditions for temperatures lower than 1400 K. Neither the bath gas nor the ammonia inlet concentration influence the ammonia conversion values. For a given temperature and under all conditions studied, conversion of ammonia increases with an increasing gas residence time, which results into a narrower temperature window for NH3 conversion.
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15
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Pelucchi M, Arunthanayothin S, Song Y, Herbinet O, Stagni A, Carstensen HH, Faravelli T, Battin-Leclerc F. Pyrolysis and Combustion Chemistry of Pyrrole, a Reference Component for Bio-oil Surrogates: Jet-Stirred Reactor Experiments and Kinetic Modeling. ENERGY & FUELS : AN AMERICAN CHEMICAL SOCIETY JOURNAL 2021; 35:7265-7284. [PMID: 34083872 PMCID: PMC8161689 DOI: 10.1021/acs.energyfuels.0c03874] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 02/18/2021] [Indexed: 06/12/2023]
Abstract
Fast-pyrolysis bio-oils (FPBOs) obtained from lignocellulosic biomass are gaining attention as sustainable fuels for various applications, including the transport sector and power production. A significant fraction of bio-oils is constituted by nitrogen-containing compounds (N fuels) that should be considered when developing surrogate models for FPBOs. Moreover, the content of N fuels in FPBOs is expected to strongly contribute to the production of nitrogen oxides (NO x ) directly from fuel-bound nitrogen (fuel NO x ), in addition to the thermal NO x formation pathways typical of high-temperature combustion conditions. This work investigates the pyrolysis and combustion chemistry of pyrrole (C4H5N), a candidate reference fuel component for FPBO surrogate models. Speciation measurements in an atmospheric pressure jet-stirred reactor have been performed for both pyrolysis and oxidation conditions. Pyrolysis experiments have been performed for 1% pyrrole/helium mixtures over the temperature range T = 925-1200 K. Oxidation experiments were carried out for 1% pyrrole/oxygen/helium mixtures at three equivalence ratios (φ = 0.5, 1.0, and 2.0) over the temperature range T = 700-1200 K. These new data significantly extend the number of experimental targets for kinetic model validation available at present for pyrrole combustion. After a thorough revision of previous theoretical and kinetic modeling studies, a preliminary kinetic model is developed and validated by means of comparison to new experimental data and those previously reported in the literature. The rate of production and sensitivity analyses highlight important pathways deserving further investigations for a better understanding of pyrrole and, more in general, N fuel combustion chemistry. A critical discussion on experimental challenges to be faced when dealing with pyrrole is also reported, encouraging further experimental investigation with advanced diagnostics.
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Affiliation(s)
- Matteo Pelucchi
- CRECK
Modeling Lab, Department of Chemistry Materials and Chemical Engineering, Politecnico di Milano, 20133 Milano, Italy
| | - Suphaporn Arunthanayothin
- Laboratoire
Réactions et Génie des Procédés, CNRS,
Université de Lorraine, ENSIC, 54001 Nancy Cedex, France
| | - Yu Song
- Laboratoire
Réactions et Génie des Procédés, CNRS,
Université de Lorraine, ENSIC, 54001 Nancy Cedex, France
- University
Orléans, INSA-CVL, PRISME, EA 4229, 45072 Orléans, France
| | - Olivier Herbinet
- Laboratoire
Réactions et Génie des Procédés, CNRS,
Université de Lorraine, ENSIC, 54001 Nancy Cedex, France
| | - Alessandro Stagni
- CRECK
Modeling Lab, Department of Chemistry Materials and Chemical Engineering, Politecnico di Milano, 20133 Milano, Italy
| | - Hans-Heinrich Carstensen
- Fundación
Agencia Aragonesa para la Investigación y Desarrollo (ARAID), 50018 Zaragoza, Spain
- Department
of Chemical and Environmental Engineering, Engineering and Architecture
School, University of Saragoza, 50018 Zaragoza, Spain
| | - Tiziano Faravelli
- CRECK
Modeling Lab, Department of Chemistry Materials and Chemical Engineering, Politecnico di Milano, 20133 Milano, Italy
| | - Frédérique Battin-Leclerc
- Laboratoire
Réactions et Génie des Procédés, CNRS,
Université de Lorraine, ENSIC, 54001 Nancy Cedex, France
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16
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Glarborg P, Hashemi H, Cheskis S, Jasper AW. On the Rate Constant for NH 2+HO 2 and Third-Body Collision Efficiencies for NH 2+H(+M) and NH 2+NH 2(+M). J Phys Chem A 2021; 125:1505-1516. [PMID: 33560846 DOI: 10.1021/acs.jpca.0c11011] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In low-temperature flash photolysis of NH3/O2/N2 mixtures, the NH2 consumption rate and the product distribution is controlled by the reactions NH2 + HO2 → products (R1), NH2 + H (+M) → NH3 (+M) (R2), and NH2 + NH2 (+M) → N2H4 (+M) (R3). In the present work, published flash photolysis experiments by, among others, Cheskis and co-workers, are re-interpreted using recent direct measurements of NH2 + H (+N2) and NH2 + NH2 (+N2) from Altinay and Macdonald. To facilitate analysis of the FP data, relative third-body collision efficiencies compared to N2 for R2 and R3 were calculated for O2 and NH3 as well as for other selected molecules. Results were in good agreement with the limited experimental data. Based on reported NH2 decay rates in flash photolysis of NH3/O2/N2, a rate constant for NH2 + HO2 → NH3 + O2 (R1a) of k1a = 1.5(±0.5) × 1014 cm3 mol-1 s-1 at 295 K was derived. This value is higher than earlier determinations based on the FP results but in good agreement with recent theoretical work. Kinetic modeling of reported N2O yields indicates that NH2 + HO2 → H2NO + O (R1c) is competing with R1a, but perturbation experiments with addition of CH4 indicate that it is not a dominating channel. Measured HNO profiles indicate that this component is formed directly by NH2 + HO2 → HNO + H2O (R1b), but theoretical work indicates that R1b is only a minor channel. Based on this analysis, we estimate k1c = 2.5 × 1013 cm3 mol-1 s-1 and k1b = 2.5 × 1012 cm3 mol-1 s-1 at 295 K, with significant uncertainty margins.
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Affiliation(s)
- Peter Glarborg
- DTU Chemical Engineering, Technical University of Denmark, 2800 Lyngby, Denmark
| | - Hamid Hashemi
- DTU Chemical Engineering, Technical University of Denmark, 2800 Lyngby, Denmark
| | - Sergey Cheskis
- School of Chemistry, Tel Aviv University, Ramat Aviv, IL-69978 Tel Aviv, Israel
| | - Ahren W Jasper
- Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S Cass Ave., Argonne, Illinois 60439 United States
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17
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Cai T, Zhao D, Li X, Shi B, Li J. Mitigating NO x emissions from an ammonia-fueled micro-power system with a perforated plate implemented. JOURNAL OF HAZARDOUS MATERIALS 2021; 401:123848. [PMID: 33113747 DOI: 10.1016/j.jhazmat.2020.123848] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 07/14/2020] [Accepted: 08/24/2020] [Indexed: 06/11/2023]
Abstract
In this work, three-dimensional numerical simulations with a simplified reaction mechanism are conducted to investigate the effect of implementing a perforated plate in an ammonia-fueled micro-power systems on the NOx emission behavior. Detailed analyses on 1) the perforated plate hole dimensionless width w, dimensionless location l as well as the material property are performed. Results show that with an optimized perforated plate implemented, the NO emission is reduced by up to 73.3 % compared to those in the absence of perforated plates. The decrease is mainly due to the formation of a recirculation zone with a low flame temperature. Increasing w is shown to play a positive role in minimizing the NO generation, while l leads to a reverse trend resulting from the size variation of the recirculation zone. In contrast, the plate material has a negligible effect on NOx emissions. It is also shown that the pressure loss Ploss is varied non-monotonically with l, but monotonically with w and the NH3 volumetric flow rate. Furthermore, the conjugate heat transfer between the plate and combustion products has a certain impact on Ploss. The present work shed lights on reducing NOx emissions by implementing a well-designed perforated plate for practical micro-power systems.
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Affiliation(s)
- Tao Cai
- Department of Mechanical Engineering, College of Engineering, University of Canterbury, Private Bag 4800, Christchurch, 8140, New Zealand
| | - Dan Zhao
- Department of Mechanical Engineering, College of Engineering, University of Canterbury, Private Bag 4800, Christchurch, 8140, New Zealand.
| | - Xinyan Li
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing, 100083, China
| | - Baolu Shi
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing, 100083, China
| | - Junwei Li
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing, 100083, China
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Kawka L, Juhász G, Papp M, Nagy T, Zsély IG, Turányi T. Comparison of detailed reaction mechanisms for homogeneous ammonia combustion. Z PHYS CHEM 2020. [DOI: 10.1515/zpch-2020-1649] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Ammonia is a potential fuel for the storage of thermal energy. Experimental data were collected for homogeneous ammonia combustion: ignition delay times measured in shock tubes (247 data points in 28 datasets from four publications) and species concentration measurements from flow reactors (194/22/4). The measurements cover wide ranges of temperature T, pressure p, equivalence ratio φ and dilution. The experimental data were encoded in ReSpecTh Kinetics Data Format version 2.2 XML files. The standard deviations of the experimental datasets used were determined based on the experimental errors reported in the publications and also on error estimations obtained using program MinimalSplineFit. Simulations were carried out with eight recently published mechanisms at the conditions of these experiments using the Optima++ framework code, and the FlameMaster and OpenSmoke++ solver packages. The performance of the mechanisms was compared using a sum-of-square error function to quantify the agreement between the simulations and the experimental data. Ignition delay times were well reproduced by five mechanisms, the best ones were Glarborg-2018 and Shrestha-2018. None of the mechanisms were able to reproduce well the profiles of NO, N2O and NH3 concentrations measured in flow reactors.
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Affiliation(s)
- L. Kawka
- Institute of Chemistry, ELTE Eötvös Loránd University , Budapest , Hungary
| | - G. Juhász
- Institute of Chemistry, ELTE Eötvös Loránd University , Budapest , Hungary
| | - M. Papp
- Institute of Chemistry, ELTE Eötvös Loránd University , Budapest , Hungary
| | - T. Nagy
- IMEC, RCNS, Eötvös Loránd Research Network , Budapest , Hungary
| | - I. Gy. Zsély
- Institute of Chemistry, ELTE Eötvös Loránd University , Budapest , Hungary
| | - T. Turányi
- Institute of Chemistry, ELTE Eötvös Loránd University , Budapest , Hungary
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