The Experts below are selected from a list of 1386 Experts worldwide ranked by ideXlab platform
Yuegui Zhou - One of the best experts on this subject based on the ideXlab platform.
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numerical optimization of the influence of multiple deep Air staged combustion on the nox emission in an opposed firing utility boiler using lean coal
Fuel, 2020Co-Authors: Yongqiang Wang, Yuegui ZhouAbstract:Abstract Multiple deep Air-staged combustion is a promising technology to significantly reduce NOx emission in the opposed firing utility boilers using low-volatile coal. The gas-solid two-phase flow, pulverized coal combustion and NOx emission characteristics of an existing 600 MW coal-fired boiler were numerically simulated to evaluate the influence of Excess Air Coefficient in primary combustion zone (αM), variational Air distribution modes and multiple deep Air-staged combustion on the NOx formation and destruction process in the furnace. The detailed NOx formation and reduction models were proposed to consider the reduction reaction between hydrocarbon and NO under fuel rich conditions and well validated by the experimental results in the laboratory and field tests. The results show that the αM has an important influence on flue gas temperature distribution and forms a reducing atmosphere in the primary combustion zone to significantly reduce NOx concentration. The NOx concentration at the furnace outlet is greatly decreased when the deep Air-staged combustion is adopted with αM of 0.75, and the CO concentration maintains within a lower level. Compared with the balanced Air distribution, the pagoda and inverse pagoda Air distributions are found to be ineffective to enhance NOx reduction performance under deep Air-staged combustion. However, the pagoda Air distribution effectively reduces NOx emission under middle Air-staged combustion condition. The NOx emission is further reduced by adopting the multiple Air-staged combustion due to the higher CO concentration formed in the burnout zone. The results are helpful to the design and operation optimization of the opposed firing utility boilers using lean coal.
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effect of the coal blending ratio on nox formation under multiple deep Air staged combustion
Energy & Fuels, 2020Co-Authors: Yongqiang Wang, Yuegui ZhouAbstract:The Air-staged combustion experiments of lean coal, bituminous coal, and their blends were performed in a one-dimensional coal combustion experimental furnace. The influences of Excess Air Coefficient in the primary combustion zone, multiple Air-staged combustion, and coal blending ratio (CBR) of bituminous coal in coal blends on the burnout ratio and NOₓ emissions were evaluated. The coal blend pyrolysis under both Ar and NO/Ar environments was performed in a fixed bed to investigate the reduction mechanism between pyrolysis products and NO. The results show that, under single Air-staged combustion, the burnout ratio of coal blends is lower than that of linear calculation result when the CBR increases up to 50% and then shows the opposite trend with further increasing CBR. This reflects the competition between the improvement and inhibition effects of bituminous coal combustion on the combustibility of lean coal. The CBR value of the critical point reduces to 25% under multiple Air-staged combustion in comparison to single Air-staged combustion. The emission index of NOₓ of coal blends decreases when the CBR increases up to 50% and then changes a little with further increasing CBR under different Air-staged combustion conditions. The combination of triple Air-staged combustion with the CBR of 50% is optimal to achieve the lower NOₓ emissions. Moreover, the experiments in the fixed bed indicate that CO released from coal blend pyrolysis can effectively reduce NO, which can be used to explain the NOₓ reduction mechanism under coal blending combustion.
Yongqiang Wang - One of the best experts on this subject based on the ideXlab platform.
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numerical optimization of the influence of multiple deep Air staged combustion on the nox emission in an opposed firing utility boiler using lean coal
Fuel, 2020Co-Authors: Yongqiang Wang, Yuegui ZhouAbstract:Abstract Multiple deep Air-staged combustion is a promising technology to significantly reduce NOx emission in the opposed firing utility boilers using low-volatile coal. The gas-solid two-phase flow, pulverized coal combustion and NOx emission characteristics of an existing 600 MW coal-fired boiler were numerically simulated to evaluate the influence of Excess Air Coefficient in primary combustion zone (αM), variational Air distribution modes and multiple deep Air-staged combustion on the NOx formation and destruction process in the furnace. The detailed NOx formation and reduction models were proposed to consider the reduction reaction between hydrocarbon and NO under fuel rich conditions and well validated by the experimental results in the laboratory and field tests. The results show that the αM has an important influence on flue gas temperature distribution and forms a reducing atmosphere in the primary combustion zone to significantly reduce NOx concentration. The NOx concentration at the furnace outlet is greatly decreased when the deep Air-staged combustion is adopted with αM of 0.75, and the CO concentration maintains within a lower level. Compared with the balanced Air distribution, the pagoda and inverse pagoda Air distributions are found to be ineffective to enhance NOx reduction performance under deep Air-staged combustion. However, the pagoda Air distribution effectively reduces NOx emission under middle Air-staged combustion condition. The NOx emission is further reduced by adopting the multiple Air-staged combustion due to the higher CO concentration formed in the burnout zone. The results are helpful to the design and operation optimization of the opposed firing utility boilers using lean coal.
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effect of the coal blending ratio on nox formation under multiple deep Air staged combustion
Energy & Fuels, 2020Co-Authors: Yongqiang Wang, Yuegui ZhouAbstract:The Air-staged combustion experiments of lean coal, bituminous coal, and their blends were performed in a one-dimensional coal combustion experimental furnace. The influences of Excess Air Coefficient in the primary combustion zone, multiple Air-staged combustion, and coal blending ratio (CBR) of bituminous coal in coal blends on the burnout ratio and NOₓ emissions were evaluated. The coal blend pyrolysis under both Ar and NO/Ar environments was performed in a fixed bed to investigate the reduction mechanism between pyrolysis products and NO. The results show that, under single Air-staged combustion, the burnout ratio of coal blends is lower than that of linear calculation result when the CBR increases up to 50% and then shows the opposite trend with further increasing CBR. This reflects the competition between the improvement and inhibition effects of bituminous coal combustion on the combustibility of lean coal. The CBR value of the critical point reduces to 25% under multiple Air-staged combustion in comparison to single Air-staged combustion. The emission index of NOₓ of coal blends decreases when the CBR increases up to 50% and then changes a little with further increasing CBR under different Air-staged combustion conditions. The combination of triple Air-staged combustion with the CBR of 50% is optimal to achieve the lower NOₓ emissions. Moreover, the experiments in the fixed bed indicate that CO released from coal blend pyrolysis can effectively reduce NO, which can be used to explain the NOₓ reduction mechanism under coal blending combustion.
Bilal Aydogan - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation of tetrahydrofuran combustion in homogeneous charge compression ignition hcci engine effects of Excess Air Coefficient engine speed and inlet Air temperature
Journal of The Energy Institute, 2020Co-Authors: Bilal AydoganAbstract:Abstract In this study, the effects of tetrahydrofuran (THF) which is nontoxic and generated from renewable environmentally friendly lignocelluloses, and n-heptane/THF blends on combustion, performance and emission characteristics were investigated at various lambda, engine speed and inlet Air temperatures. Wide ranges of lambda value and engine speed were investigated and the results were presented in comparison to n-heptane as reference fuel. The combustion parameters such as cylinder pressure, heat release rate, in-cylinder gas temperature, CA10, CA50, thermal efficiency, ringing intensity, maximum pressure rise rate and imep, the performance parameters such as brake torque, power output, specific fuel consumption and HC and CO emissions were determined. Operating range of the HCCI engine was also determined. The results showed that, increasing the lambda value decreased both the in-cylinder pressure and the heat release rate for all test fuels. The addition of tetrahydrofuran led to retard combustion phasing. Thermal efficiency increased about 54% for F60N40 compared to n-heptane at 60 °C inlet Air temperature, 1200 rpm engine speed and λ = 2.2. The results also showed that HC and CO emissions increased with the increase of tetrahydrofuran. Furthermore, tetrahydrofuran caused to expand HCCI operating range towards to knocking and misfiring boundaries.
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the comparison of combustion engine performance and emission characteristics of ethanol methanol fusel oil butanol isopropanol and naphtha with n heptane blends on hcci engine
Fuel, 2020Co-Authors: Alper Calam, Bilal Aydogan, Serdar HalisAbstract:Abstract Recently, there has been increased emphasis on the homogenous charge compression ignition (HCCI) engine which offers higher thermal efficiency and ultra-low NOx and soot emissions. The central thesis of this paper is that the effects of different alternative fuels with different physical and chemical properties on combustion, performance and emissions in a HCCI engine. Ethanol (E25), methanol (M25), fusel oil (F25), butanol (B25), isopropanol (IP25) and naphtha (N25) were used alternative fuels blended with n-heptane 25% by volume. The experiments were performed at 333 K intake Air temperature (IAT) and with various Excess Air Coefficient in a single cylinder SI-HCCI test engine. The parameters such as in-cylinder pressure, heat release rate (HRR), start of combustion (SOC), combustion duration, CA50, indicated thermal efficiency (ITE), COVIMEP, maximum pressure rise rate (MPRR), HC and CO emissions were investigated. In addition, operating range of the fuels were also defined. The results showed that N25 has the largest operating range among all the test fuels. The maximum indicated mean effective pressure (IMEP) value was obtained for E25 as 5.71 bar at 800 rpm engine speed and λ = 1.3. Knocking tendency were determined for all test fuels but it decreased with increasing lambda value. The highest HC and CO emissions were obtained for F25 due to the water content of the fuel. On the contrary, the lowest HC and CO emissions were obtained for N25.
Fatih Sahin - One of the best experts on this subject based on the ideXlab platform.
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effects of engine parameters on ionization current and modeling of Excess Air Coefficient by artificial neural network
Applied Thermal Engineering, 2015Co-Authors: Fatih SahinAbstract:Abstract This study investigates the effects of engine speed, load, ignition timing and Excess Air Coefficient on the ionization current and presents an artificial neural network model to predict the in-cylinder Air-fuel ratio by using data of the ionization current. A secondary spark plug was used as an ionization current sensor. Experimental studies were conducted on a spark-ignition engine at variable speed, load, ignition timing, and Excess Air Coefficient. The effects of these parameters on the ionization current were investigated individually. For modeling of the Excess Air Coefficient, an artificial neural network model was developed with the experimental results. The network was trained with Levenberg-Marquardt and Scaled Conjugate Gradient training algorithms. Performance of the network was measured by comparing the predictions with the remaining experimental results. The Excess Air Coefficient can be predicted with the network with a Coefficient of determination of 0.99508. This study shows, the ionization current signal can be used to predict the in-cylinder Excess Air Coefficient as a feasible alternative to the production Air-fuel ratio sensors.
Banglin Deng - One of the best experts on this subject based on the ideXlab platform.
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influences of Excess Air Coefficient on combustion and emission performance of diesel pilot ignition natural gas engine by coupling computational fluid dynamics with reduced chemical kinetic model
Energy Conversion and Management, 2019Co-Authors: Jun Shu, Jingping Liu, Shuqian Wang, Yanshan Yin, Banglin Deng, Sid BeckerAbstract:Abstract In the presented study, the influence of lean-burn on combustion and emission performance of diesel pilot ignition natural gas engine was investigated by using the method of computational fluid dynamics coupling with the reduced chemical kinetic model. Based on bench tested results, the computational fluid dynamics model was validated in four typical conditions, and then it was used for the simulation at different Excess Air Coefficient. Due to the visibility of computational fluid dynamics results, the combustion medium process and emissions medium products were obtained, which then were used to explain the influence mechanism of Excess Air Coefficient. The simulated results show that, under 50% load, the maximum cylinder pressure becomes larger and the start of combustion is advanced when the Excess Air Coefficient increases from 1.0 to 1.5, and the maximum advance of the start of combustion reaches 9.5 °CA. Nevertheless, under 100% load, the start of combustion is advanced first and then retarded. Meanwhile, the higher the Excess Air Coefficient is, the earlier the heat release rate shoots up. When the Excess Air Coefficient increases from 1.2, the 10–50%, 50–90% and 10–90% combustion duration become longer. The nitrogen oxide emission increases as the Excess Air Coefficient rises from 1.0 to 1.1 but decreases if it continues to increase. The unburned methane emission decreases first and then increases with the increase of the Excess Air Coefficient. Nevertheless, at 1500 rpm and full load, the unburned methane emission shoots up as the Excess Air Coefficient changes from 1.3 to 1.5 and the maximum difference of unburned methane emission reaches 3233 ppm.
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the Excess Air Coefficient effect on the performances for a motorcycle twin spark gasoline engine a wide condition range study
Applied Thermal Engineering, 2019Co-Authors: Banglin Deng, Jianqin Fu, Zhengxin Xu, Yangyang Chen, Songyu Hu, Renhua Feng, Lili ZhouAbstract:Abstract The performance of motorcycles has a great influence on energy and environment due to the huge quantity. In this work we mainly explore the impact of Air/fuel composition (λ) on engine torque, ECR (energy consumption rate), emissions and knocking of a twin-spark single cylinder motorcycle engine by experiment. The results illuminated that, the engine torque is smaller with the increase of λ. For example, at 60% engine load and 3000 rpm the engine torque decreases by 20.5% when the λ increased from 0.85 to 1.2. ECR becomes smaller as the λ increases, this phenomenon indicated that the thermal-work conversion is more efficient at lean operation. The CO and HC emissions decrease with the increase of λ. For instance, at 60% engine load, when λ increases from 0.85 to 1.2, while the CO decreases by 1294.73%. As expected, NO emission increases with the increase of λ, but further extension of λ does not deteriorate NO too much while gets lots benefits in CO emissions. In addition, the engine knocking is effectively inhibited for different λs under dual spark operation. Besides, the combustion process is also analyzed to explain the engine phenomenal performances.
