共查询到20条相似文献,搜索用时 9 毫秒
1.
Anas Rao Roopesh Kumar Mehra Hao Duan Fanhua Ma 《International Journal of Hydrogen Energy》2017,42(34):22066-22081
In order to study the nitrous-oxide emissions of HCNG engines a numerical NOx prediction model has been developed and coupled with the most accepted quasi-dimensional combustion model of SI engines. The experiments have been performed at the different hydrogen volumetric percentage (0–40%), ignition timing (22–30oBTDC), A/F ratio (1–1.73) and manifold-absolute pressure (60–137 kPa) at various engine load and speed. In the next phase of study, the simulation has been performed at the different operating conditions and various HCNG blends. The two NOx mechanism: the thermal NOx and prompt NOx mechanism have been used to predict the NOx emission.The presented Model III of NOx prediction is validated by the previous models (Model I by Dawyer et al. and Model II by Kornbluth et al.) and experimental results. The NO packet and three-zone approach are designed and incorporated to Model III, which is based on the temperature duration of NOx formation. The NO curve has been transformed into NO packets through the temperature difference of NOx formation. Whereas, the width of the packet is equal to the ratio of crank angle duration to the total combustion duration. The total combustion duration is divided into three zones (phases). In order to check the accuracy of the model, the percentage error of NOx emission has been evaluated. Three NOx prediction models have been compared, and the model III is the best one. The error range of the model III is within ±15%. 相似文献
2.
Fanhua Ma Shun LiJianbiao Zhao Zhengliang QiJiao Deng Nashay NaeveYituan He Shuli Zhao 《International Journal of Hydrogen Energy》2012
A quasi-dimensional model based on the concepts of fractal geometry has been developed for an SI engine fuelled with natural gas/hydrogen blends. The fundamentals of the thermodynamic model, the fractal combustion model and related equations are introduced. This paper investigates the influence of manifold absolute pressure, equivalence ratio and hydrogen fraction on fractal dimension and improves the fractal dimension expression. Comparisons are conducted between the improved and original models by the prediction outcomes. After the determination of model constants by calibration, the model predictions of cylinder pressure histories and mass fraction burned of an HCNG engine are then compared with experimental data over a wide range of loads, equivalence ratios, engine speeds and hydrogen blending ratios. The pressure profiles show that predictions of the improved model match quite well with the experimental results except for the early combustion stage. The improved model is proved to be more suitable for predicting HCNG engine performance. 相似文献
3.
Kasidet Pichayapat Sukruedee SukchaiSahataya Thongsan Anan Pongtornkulpanich 《International Journal of Hydrogen Energy》2014
Hydrogen and Compressed Natural Gas are great alternatives to the pure fossil fuels. Many researches confirm the advantages of using hydrogen and natural gas blended together for the internal combustion engine in both areas of improving performances and reducing emission levels. In a short to medium range terms, the air pollution throughout the globe could be significantly reduced by using HCNG in the internal combustion engine and in many other applications with the substitution of using HCNG as a main source of fuel or as a secondary source of fuel such as the dual fuel operation system in the diesel vehicle. 相似文献
4.
Fanhua Ma Shun LiJianbiao Zhao Zhengliang QiJiao Deng Nashay NaeveYituan He Shuli Zhao 《International Journal of Hydrogen Energy》2012
This paper investigates the effect of compression ratio and spark timing on the power performance and combustion characteristics of a hydrogen enriched compressed natural gas engine. The experimental data was conducted under variable compression ratios (i.e. 10:1, 11:1 and 12:1) by varying the spark ignition timing. The engine was kept running at a constant speed of 1200 rpm with a constant excess air ratio of 1.6 and a constant manifold absolute pressure of 50 kPa. It has been found from the results that the higher compression ratio, the higher the indicated thermal efficiency. Increase in compression ratio leads to higher brake torque and lower break specific fuel consumption. But the improvements are weakened between higher compression ratios. The peak pressure is higher with higher compression ratio. Faster heat release rates and lesser coefficient of variations of indicated mean effective pressure can also been observed at higher compression ratios. 相似文献
5.
Yituan He Fanhua Ma Jiao Deng Yiming Shao Xiaochun Jian 《International Journal of Hydrogen Energy》2012
This paper presents an experimental study aimed at idle characteristics of a CNG engine fueled by HCNG with 55% hydrogen blend. The idle speed was reduced from original 800 r/min to 750 r/min and 700 r/min, and the characteristics of combustion & emissions at reduced idle speed were investigated. It is found that, for the HCNG engine, only reducing idle speed cannot reduce fuel consumption at conditions of fixed λ. In order to reduce fuel consumption and keep the COV at rather low levels, the excess air ratio must be increased properly while reducing the engine idle speed. Due to the large valve overlap (30°) of this inlet inject HCNG engine, CH4 emissions are mainly caused by scavenging, which account for the vast majority of THC emissions. The emissions of CO, THC and NOx are reduced with the decrease of ignition advance angle at a fixed λ. 相似文献
6.
Gihun Lim Sungwon Lee Cheolwoong Park Young Choi Changgi Kim 《International Journal of Hydrogen Energy》2013
The wide range of hydrogen's flammable limits enables ultra-lean combustion. A lean burn reduces the combustion temperature, increases thermal efficiency, and reduces knock, which is a serious problem in a spark ignition (SI) engine. The anti-knock improvement from hydrogen addition makes it feasible to increase the compression ratio (CR) and further improve the thermal efficiency. Herein, the effects of the CR on performance and emission characteristics were investigated using an 11-L heavy-duty SI engine fuelled with HCNG30 (CNG 70 vol%, hydrogen 30 vol%) and CNG. These fuels were used to operate an engine with CRs of 10.5 and 11.5. The results showed that thermal efficiency improved with an increased CR, which significantly decreased CO2 emission. On the other hand, the NOx emission was largely increased. Nevertheless, for HCNG30, a CR of 11.5 improved thermal efficiency by 6.5% and decreased NOx emission by over 75%, as compared to a conventional CNG engine. 相似文献
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Hydrogen from renewable energy sources is a clean and sustainable option as a fuel and is seen as a potential alternative to gasoline in the future. However, in the near future the use of hydrogen in internal combustion engines is possible at low fraction in mixture with compressed natural gas (HCNG fuel). 相似文献
9.
稀燃天然气掺氢发动机的热效率与排放特性 总被引:2,自引:0,他引:2
为了分析在天然气中掺入不同体积比的氢气对发动机经济性和排放性的影响,在一台6缸火花点火天然气发动机上开展了体积掺氢比在不同工况下对热效率和排放特性影响的试验研究.结果显示掺氢可以拓宽发动机的稀燃极限,提高燃烧速度,使得最佳转矩点火提前角(MBT)相对推迟;在点火提前角不变的情况下掺氢对热效率没有明显优势,而且会使NOx排放升高.而在MBT时,掺氢可以一定程度上提高发动机的指示热效率,降低未燃CH4和CO的排放,改善NOx与未燃碳氢(主要为CH4)的trade-off关系.掺氢的优势还体现在可以让发动机高效的工作在更稀的情况下,从而有利于降低NOx的排放和传热损失. 相似文献
10.
To analyze and resolve the contradiction of abnormal combustion and improving hydrogen-fueled engine power is the key for promoting the progress of hydrogen-fueled engine research. Optimal control is the most valuable technology for resolving this contradiction. In this paper, the optimal model of hydrogen-fueled engine for multi-variable, multi-objective, multi-constraint under the whole operating conditions was established. The technology was a combination of nonlinear programming theory and optimal calibration algorithm of genetic algorithm. Calibration process can be adjusted dynamically to match with the working conditions of engine by weighted function. It implements the unity of comprehensive performance optimization and individual optimization, and not only simplifies calibration process but also improves calibration speed. Furthermore, a new method that accurately and quickly calibrates MAP under the conditions of multi-variable, multi-goal and multi-constraint is provided to effectively resolve the contradiction of the abnormal combustion and improving hydrogen-fueled engine power. 相似文献
11.
S.M.V. Sagar Avinash Kumar Agarwal 《International Journal of Hydrogen Energy》2017,42(18):13234-13244
With rapid depletion of petroleum resources, researchers are investigating alternate fuels to meet global transportation energy demand. Gaseous fuels such as compressed natural gas (CNG) and hydrogen are of special interest because of their cleaner combustion characteristics compared to liquid petroleum based fossil fuels. However both these gaseous fuels have some technical issues when they are used as stand-alone alternate fuel in conventional spark ignition (SI) engines. CNG suffers from lower energy density and narrow flammability range whereas backfiring tendency is highly pronounced in hydrogen fueled engines. Hydrogen enriched compressed natural gas (HCNG) mixtures are observed to be good alternative to these individual fuels since these mixtures do not pose the issues experienced by the constituent fuels i.e. CNG and hydrogen. In this study, experiments were conducted in a spark ignited gas engine using various compositions of HCNG mixtures having 0, 10, 20, 30, 50, 70 and 100% (v/v) hydrogen fraction. The performance and combustion characteristics of these test fuels were compared with that of baseline CNG, in order to find an optimum HCNG mixture composition for a single cylinder gas engine. Results obtained showed that 30HCNG mixture delivered superior engine performance compared to other HCNG mixtures and baseline CNG, which is in sharp contrast to 15HCNG being advocated globally. 相似文献
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火花点火发动机准维湍流卷吸燃烧模型的适用性研究(二) 总被引:2,自引:0,他引:2
本文利用作者提出的火花点火发动机准维湍流卷吸燃烧模型,对压缩比为10和12的火球形燃烧室以及压缩比为10的碗形燃烧室变工况进行了计算,将计算得到的示功图、质量燃烧率等与实验值进行了对比对分析。结果表明,合理选取与燃烧室结构相对应的四个经验常数,准维湍流卷吸燃烧模型完全适用于火花点火发动机变工况及不同燃烧室结构工作过程的计算,能够正确反映火花点火发动机结构参数和运转参数对燃烧过程的影响。 相似文献
14.
Experimental study on combustion and emission characteristics of a hydrogen-enriched compressed natural gas engine under idling condition 总被引:1,自引:0,他引:1
Jiao DengFanhua Ma Shun LiYituan He Mingyue WangLong Jiang Shuli Zhao 《International Journal of Hydrogen Energy》2011,36(20):13150-13157
This paper investigates the effect of various hydrogen ratios in HCNG (hydrogen enriched compressed natural gas) fuels on combustion and emission characteristics of a turbocharged spark ignition natural gas engine at idling conditions. The experiments were taken at hydrogen fractions of 0%, 30%, 55% and 75% by volume and were conducted under various operating conditions including different excess air ratio λ and spark timing θig. It is found that under various λ and θig, the addition of hydrogen can significantly reduce CH4 emission and CO emission, although NOx emission increased with the hydrogen addition, it was relatively low at idle conditions compared to other emissions. Meanwhile the addition of hydrogen can significantly reduce COVimep (coefficient of variation of the indicated mean effective pressure), extend the lean burn limit, decrease the combustion duration, achieve higher thermal efficiency and reduce fuel consumption. 相似文献
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There is a growing body of literature as well as increased demonstration of advanced hydrogen-fuelled internal combustion engines. These engines offer the potential of high power output, outperforming gasoline engines; high efficiency, approaching or bettering diesel engines; and very low emissions well within the most strict emission standards. 相似文献
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Fanhua Ma Shangfen DingYu Wang Yefu WangJunjun Wang Shuli Zhao 《International Journal of Hydrogen Energy》2008
Lean burn is widely accepted as an effective approach to simultaneously improve spark-ignition engine's thermal efficiency and decrease exhaust emissions. But although lean burn has a lot of advantages it is also associated with several difficulties including slower flame propagation speed and increased cycle-by-cycle variations. Hydrogen addition is thought to be an ideal approach to tackle these problems. This paper presents an experimental work aimed at investigating the effects of hydrogen addition on the combustion behaviors and cycle-by-cycle variations in a turbocharged lean burn natural gas SI engine. The experiments were conducted over a wide range of hydrogen enhancement levels, equivalence ratios, spark timings, manifold absolute pressures and engine speeds. 相似文献
18.
Seang-Wock LeeAuthor VitaeWoongchul ChoiAuthor Vitae Yong-Seok ChoAuthor Vitae 《International Journal of Hydrogen Energy》2012,37(1):682-690
In an effort to reduce the dependency on crude oil based fuels and to decrease pollutant emissions, hydrogen-CNG (HCNG) attracted a considerable attention with its low HC/CO2 emission and fast burn rate. In this study, a constant volume chamber with a single spark plug and a dual spark plug configuration was designed to obtain fundamental combustion characteristics of HCNG and to evaluate possible advantages of the dual spark plug over the single spark plug ignition setup. Various mixtures of hydrogen and CNG were systematically experimented to evaluate effects of hydrogen fraction to lean burn limit, combustion pressure, rate of heat release and emission characteristics for both configurations. With the current experimental results, it was clearly demonstrated that an appropriate mixture of HCNG along with a suitable spark plug configuration, could become a promising candidate to replace the crude oil based IC engine fuels to alleviate the dependency on the depleting petroleum resource and to meet the stricter emission regulation. 相似文献
19.
The micro-genetic algorithm (μGA) as a highly effective optimization method, is applied to calibrate to a newly developed reduced chemical kinetic model (40 species and 62 reactions) for the homogeneous charge compression ignition (HCCI) combustion of n-heptane to improve its autoignition predictions for different engine operating conditions. The seven kinetic parameters of the calibrated model are determined using a combination of the Micro-Genetic Algorithm and the SENKIN program of CHEMKIN chemical kinetics software package. Simulation results show that the autoignition predictions of the calibrated model agree better with those of the detailed chemical kinetic model (544 species and 2 446 reactions) than the original model over the range of equivalence ratios from 0.1–1.3 and temperature from 300–3 000 K. The results of this study have demonstrated that the μGA is an effective tool to facilitate the calibration of a large number of kinetic parameters in a reduced kinetic model. __________ Translated from Journal of Combustion Science and Technology, 2006, 12(4): 373–377 [译自: 燃烧科学与技术] 相似文献
20.
Marco Gambini Tommaso Stilo Michela Vellini Roberto Montanari 《International Journal of Hydrogen Energy》2017,42(25):16195-16202
Metal hydrides have become more and more significant both as hydrogen storage devices and as basic elements in energy conversion systems. Magnesium hydride (MgH2) shows very interesting characteristics – i.e. high enthalpy of reaction and hydrogen gravimetric density – making it capable of being employed in the field of energy production. So there is interest in investigating the behaviour of this kind of hydride, placed in an energy system. In order to examine MgH2 in depth, its main kinetic parameters must be found and this can be accomplished by means of the calibration of a model previously realised by author Marco Gambini in his 1989–1994 works.In the light of this, an assessment of the activation energies (Ea = 72,200 kJ/kmol, Ed = 89,000 kJ/kmol) and kinetic constants (k0a = 15,000 s?1, k0d = 198,500 s?1) in both absorption and desorption phase of magnesium hydride has been provided. Thanks to these values, the behaviour of MgH2 can be modelled, making the performance of a magnesium hydride-based energy system estimable. 相似文献