NOx Reduction in Diesel-Hydrogen Engines Using Different Strategies of Ammonia Injection

Galdo, María Isabel Lamas; Rodríguez, Cristian

doi:10.3390/en12071255

Cited by 21 publications

(11 citation statements)

References 40 publications

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“…Combustion of gases that contain hydrogen [5,6] occupies a significant role for clean and efficient energy supply. Hydrogen allows a useful way of storing the surplus power generated by photovoltaics and wind [7].…”

Section: Introductionmentioning

confidence: 99%

Comparison of Combustion Models for Lifted Hydrogen Flames within RANS Framework

Benim

Pfeiffelmann

2019

Energies

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Within the framework of a Reynolds averaged numerical simulation (RANS) methodology for modeling turbulence, a comparative numerical study of turbulent lifted H 2 /N 2 flames is presented. Three different turbulent combustion models, namely, the eddy dissipation model (EDM), the eddy dissipation concept (EDC), and the composition probability density function (PDF) transport model, are considered in the analysis. A wide range of global and detailed combustion reaction mechanisms are investigated. As turbulence model, the Standard k-ε model is used, which delivered a comparatively good accuracy within an initial validation study, performed for a non-reacting H 2 /N 2 jet. The predictions for the lifted H 2 /N 2 flame are compared with the published measurements of other authors, and the relative performance of the turbulent combustion models and combustion reaction mechanisms are assessed. The flame lift-off height is taken as the measure of prediction quality. The results show that the latter depends remarkably on the reaction mechanism and the turbulent combustion model applied. It is observed that a substantially better prediction quality for the whole range of experimentally observed lift-off heights is provided by the PDF model, when applied in combination with a detailed reaction mechanism dedicated for hydrogen combustion.

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Section: Introductionmentioning

confidence: 99%

Comparison of Combustion Models for Lifted Hydrogen Flames within RANS Framework

Benim

Pfeiffelmann

2019

Energies

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“…A value of −18º CA ATDC leads to important NO x reduction with a noticeable SFC penalty. Basically, the NO x reduction achieved with a high pre-injection rate or by a late pre-injection rate is reached through a reduction in the combustion temperature, since the high combustion temperatures reached in the combustion chamber are responsible for most NO x emitted to the atmosphere [41,42]. On the other hand, the entropy method provides case 25 as the most appropriate injection pattern, with a −22º CA ATDC pre-injection starting instant, 25% pre-injection rate, and 5º CA pre-injection duration.…”

Section: Standard Deviation Weighting Methodsmentioning

confidence: 99%

Optimization of a Multiple Injection System in a Marine Diesel Engine through a Multiple-Criteria Decision-Making Approach

Galdo

Castro-Santos

Rodríguez³

2020

JMSE

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In this work, a numerical model was developed to analyze the performance and emissions of a marine diesel engine, the Wärtsilä 6L 46. This model was validated using experimental measurements and was employed to analyze several pre-injection parameters such as pre-injection rate, duration, and starting instant. The modification of these parameters may lead to opposite effects on consumption and/or emissions of nitrogen oxides (NOx), carbon monoxide (CO), and hydrocarbons (HC). According to this, the main goal of the present work is to employ a multiple-criteria decision-making (MCDM) approach to characterize the most appropriate injection pattern. Since determining the criteria weights significantly influences the overall result of a MCDM problem, a subjective weighting method was compared with four objective weighting methods: entropy, CRITIC (CRiteria Importance Through Intercriteria Correlation), variance, and standard deviation. The results showed the importance of subjectivism over objectivism in MCDM analyses. The CRITIC, variance, and standard deviation methods assigned more importance to NOx emissions and provided similar results. Nevertheless, the entropy method assigned more importance to consumption and provided a different injection pattern.

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“…In CFD, it is common to employ the so called extended Zeldovich mechanism [48,49], based on 3 reactions and 7 species. Nevertheless, previous works [44,50] compared several kinetic schemes using experimental results and concluded that the model of Yang et al provides satisfactorily accurate results.…”

Section: Nox Formation Kinetic Schemementioning

confidence: 99%

Numerical Analysis of NOx Reduction Using Ammonia Injection and Comparison with Water Injection

Galdo

Castro-Santos

Vidal³

2020

JMSE

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This work analyzes NO x reduction in a marine diesel engine using ammonia injection directly into the cylinder and compares this procedure with water injection. A numerical model based on the so-called inert species method was applied. It was verified that ammonia injection can provide almost 80% NO x reduction for the conditions analyzed. Furthermore, it was found that the effectiveness of the chemical effect using ammonia is extremely dependent on the injection timing. The optimum NO x reduction was obtained when ammonia is injected during the expansion stroke, while the optimum injection timing using water is near top dead center. Chemical, thermal, and dilution effects of both ammonia and water injection were compared. The chemical effect was dominant in the case of ammonia injection. On the other hand, water injection reduces NO x through dilution and, more significantly, through a thermal effect.that the main factors that influence NO x formation are the temperatures reached in the combustion process and the amount of time in which the combustion gases remain at high temperatures [5][6][7]. Based on this, primary measures focus on addressing these factors and reducing the concentrations of oxygen and nitrogen [8,9]. Well-known primary measures are exhaust gas recirculation (EGR), Miller timing, common rail, modification of injection and other parameters of the engine, and water addition. Water can be introduced as a fuel-water emulsion injected via the fuel valve, through separate nozzles or by humidifying the scavenge air. Despite the extensive research on primary measures along the recent years, a procedure to reduce NO x without decreasing emission of other pollutants and/or consumption has not effectively been developed. In this regard, secondary measures reduce NO x from the flue gas through downstream cleaning techniques. Many applications have been undertaken to reduce NO x by selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR). The disadvantages of SCR are its price, poor durability of catalysts, and deposition of particulate on the catalyst. These disadvantages are not present in SNCR, but this procedure is limited to a narrow temperature range with optimal temperatures that are much higher than those characteristic of flue gas from diesel engines [10]. This limitation constitutes a drawback for practical applications in exhaust gases from diesel engines. As SCR reducing agents, ammonia (NH 3 ), urea, and cyanuric acid have been extensively employed. SNCR using ammonia, urea, and cyanuric acid are known as DeNO x [11,12], NO x OUT [13,14], and RAPRENO [15-17], respectively. Between these, this work focuses on NO x reduction using ammonia. The NO x reduction capabilities of ammonia were discovered in the seventies by Lyon [18], who found that ammonia selectively reduces NO x without a catalyst over the temperature range of 1100-1400 K. Typical exhaust gas temperatures from marine engines, around 300-450 • C [19], remain considerably lower than this optimal temperature ra...

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NOx Reduction in Diesel-Hydrogen Engines Using Different Strategies of Ammonia Injection

Cited by 21 publications

References 40 publications

Comparison of Combustion Models for Lifted Hydrogen Flames within RANS Framework

Comparison of Combustion Models for Lifted Hydrogen Flames within RANS Framework

Optimization of a Multiple Injection System in a Marine Diesel Engine through a Multiple-Criteria Decision-Making Approach

Numerical Analysis of NOx Reduction Using Ammonia Injection and Comparison with Water Injection

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