The Experts below are selected from a list of 7704 Experts worldwide ranked by ideXlab platform
Changjian Wang - One of the best experts on this subject based on the ideXlab platform.
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Experimental study of premixed hydrogen-air flame quenching in a channel with the Perforated Plate
Fuel, 2020Co-Authors: Yang Wan, Changjian Wang, Xinjiao LuoAbstract:Abstract The effect of the Perforated Plate on the premixed hydrogen-air flame quenching was experimentally investigated with various Perforated Plate lengths and initial pressures in a channel. The Perforated Plate has the same cross-sectional area and five lengths in the range of 20 mm, 40 mm, 60 mm, 80 mm and 100 mm. High-speed Schlieren photography was used to track the flame evolution, and correspondingly the flame front speed was calculated. Two piezoelectric pressure sensors were mounted upstream and downstream of the Perforated Plate to detect the local pressure. The results show that three kinds of flame phenomena were observed: “Pass”, “Quench” and “Near limit”. The “Pass” mode is characterized by successful flame propagation, and involving laminar flame, jet flame, and turbulent flame. Three pressure peaks can be observed on the pressure curve of the sensor in the upstream region. The first peak pressure is equal to two times the initial pressure. The flame tip speed in the downstream region decreases with the increase of the Perforated Plate length, and two pressure peaks were observed. In the “Quench” model, the flame does not successfully pass through the Perforated Plate. Furthermore, there are only two pressure peaks on the pressure curve in the upstream region and one in the downstream region. With the increase in the Perforated Plate length, the critical initial pressure for flame quenching also increases.
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Geometric influence of Perforated Plate on premixed hydrogen-air flame propagation
International Journal of Hydrogen Energy, 2018Co-Authors: Quan Li, Xing Wang, Zhi Zhang, Shouxiang Lu, Changjian WangAbstract:Abstract Geometrical influence of the Perforated Plate on flame propagation in hydrogen-air mixtures with various equivalence ratios and initial pressures was experimentally investigated in a channel with the length of 1 m and the cross-section of 7 cm × 7 cm. The Perforated Plate has the same cross section and three thicknesses of 40 mm, 80 mm and 120 mm. High-speed schlieren photography was employed to capture the flame shape evolution and derive the flame tip velocity. High-speed piezoelectric pressure transducers were flush-mounted upstream and downstream of the Perforated Plate to measure the pressure transient. It was found that, with the Perforated Plate in the path of flame, flame undergoes either “go”, or “quench” propagation mode. The limit between these two was dependent on the geometrical size of the Perforated Plate and the initial conditions of mixtures. Both velocity and pressure were effectively attenuated with the increase in the Perforated Plate length. Moreover, for “go” propagation mode, the flame process through the Perforated Plate was characterized by three obvious stages: laminar flame stage, jet flame stage and turbulent flame stage. Whereas, only laminar flame stage was observed in the “quench” mode.
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experimental study of flame propagation across a Perforated Plate
International Journal of Hydrogen Energy, 2018Co-Authors: Xuxu Sun, Xing Wang, Zhi Zhang, Sen Han, Changjian WangAbstract:Abstract Flame propagation across a single Perforated Plate was experimentally studied in a square cross-section channel. Experiments were performed in premixed hydrogen-air mixture with different equivalence ratios and initial pressures, aiming at identifying the parametric influence. High-speed schlieren photography and pressure records were used to capture the flame front and obtain the pressure build-up. Four stages for the flame front crossing the Perforated Plate were obtained, namely, laminar flame, jet flame, turbulent flame and secondary flame front. Following ignition, a laminar flame was obtained, which was nearly not affected by the confinement. This laminar flame was squeezed to pass through the Perforated Plate, producing the jet flame with a step change on velocity. Turbulent flame was generated by merging the jets, which facilitated the acceleration of the flame front. Secondary flame front induced by Rayleigh-Taylor instability was clearly observed in the process of the turbulent front moving forward. Both velocity and pressure are enhanced in this stage. Parametric studies suggested that the secondary flame front is more obvious in the stoichiometric mixture with higher initial pressure, and characterized by a faster propagation velocity and a bigger pressure rise.
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The effect of a Perforated Plate on the propagation of laminar hydrogen flames in a channel – A numerical study
International Journal of Hydrogen Energy, 2014Co-Authors: Changjian WangAbstract:Abstract Laminar hydrogen flame propagation in a channel with a Perforated Plate is investigated using 2D reactive Navies-Stokes simulations. The effect of the Perforated Plate on flame propagation is treated with a porous media model. A one step chemistry model is used for the combustion of the stoichiometric H 2 –air mixture. Numerical simulations show that the Perforated Plate has considerable effect on the flame propagation in the region downstream from the Perforated Plate and marginal effect on the upstream region. It is found to squeeze the flame front and result in a ring of unburned gas pocket around the flame neck. The resulting abrupt change in flow directions leads to the formation of some vortices. Downstream of the Perforated Plate, a wrinkled “M”-shape flame is observed with “W” shape flame speed evolution, which lastly turns back to a convex curved flame front. Parametric studies have also been carried out on the inertial resistance factor, porosity, Perforated Plate length and its location to investigate their effects on flame evolution. Overall, for parameter range studied, the Perforated Plate has an effect of reducing the flame speed downstream of it.
Josua P Meyer - One of the best experts on this subject based on the ideXlab platform.
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multi objective and thermodynamic optimisation of a parabolic trough receiver with Perforated Plate inserts
Applied Thermal Engineering, 2015Co-Authors: Aggrey Mwesigye, Tunde Belloochende, Josua P MeyerAbstract:Abstract In this paper, multi-objective and thermodynamic optimisation procedures are used to investigate the performance of a parabolic trough receiver with Perforated Plate inserts. Three dimensionless Perforated Plate geometrical parameters considered in the optimisation include the dimensionless orientation angle, the dimensionless Plate diameter and the Plate spacing per unit meter. The Reynolds number varies in the range 1.02 × 10 4 ≤ Re ≤ 1.36 × 10 6 depending on the fluid temperature. The multi-objective optimisation was realised through the combined use of computational fluid dynamics, design of experiments, response surface methodology and the Non-dominated Sorted Genetic Algorithm-II. For thermodynamic optimisation, the entropy generation minimisation method was used to determine configurations with minimum entropy generation rates.
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heat transfer and thermodynamic performance of a parabolic trough receiver with centrally placed Perforated Plate inserts
Applied Energy, 2014Co-Authors: Aggrey Mwesigye, Tunde Belloochende, Josua P MeyerAbstract:In this paper, a numerical investigation of thermal and thermodynamic performance of a receiver for a parabolic trough solar collector with Perforated Plate inserts is presented. The analysis was carried out for different Perforated Plate geometrical parameters including dimensionless Plate orientation angle, the dimensionless Plate spacing, and the dimensionless Plate diameter. The Reynolds number varies in the range 1.02 � 10 4 6 Re 6 7.38 � 10 5 depending on the heat transfer fluid temperature. The fluid temperatures used are 400 K, 500 K, 600 K and 650 K. The porosity of the Plate was fixed at 0.65. The study shows that, for a given value of insert orientation, insert spacing and insert size, there is a range of Reynolds numbers for which the thermal performance of the receiver improves with the use of Perforated Plate inserts. In this range, the modified thermal efficiency increases between 1.2% and 8%. The thermodynamic performance of the receiver due to inclusion of Perforated Plate inserts is shown to improve for flow rates lower than 0.01205 m 3 /s. Receiver temperature gradients are shown to reduce with the use of inserts. Correlations for Nusselt number and friction factor were also derived and presented.
Xinjiao Luo - One of the best experts on this subject based on the ideXlab platform.
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Experimental study of premixed hydrogen-air flame quenching in a channel with the Perforated Plate
Fuel, 2020Co-Authors: Yang Wan, Changjian Wang, Xinjiao LuoAbstract:Abstract The effect of the Perforated Plate on the premixed hydrogen-air flame quenching was experimentally investigated with various Perforated Plate lengths and initial pressures in a channel. The Perforated Plate has the same cross-sectional area and five lengths in the range of 20 mm, 40 mm, 60 mm, 80 mm and 100 mm. High-speed Schlieren photography was used to track the flame evolution, and correspondingly the flame front speed was calculated. Two piezoelectric pressure sensors were mounted upstream and downstream of the Perforated Plate to detect the local pressure. The results show that three kinds of flame phenomena were observed: “Pass”, “Quench” and “Near limit”. The “Pass” mode is characterized by successful flame propagation, and involving laminar flame, jet flame, and turbulent flame. Three pressure peaks can be observed on the pressure curve of the sensor in the upstream region. The first peak pressure is equal to two times the initial pressure. The flame tip speed in the downstream region decreases with the increase of the Perforated Plate length, and two pressure peaks were observed. In the “Quench” model, the flame does not successfully pass through the Perforated Plate. Furthermore, there are only two pressure peaks on the pressure curve in the upstream region and one in the downstream region. With the increase in the Perforated Plate length, the critical initial pressure for flame quenching also increases.
Zhi Zhang - One of the best experts on this subject based on the ideXlab platform.
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Geometric influence of Perforated Plate on premixed hydrogen-air flame propagation
International Journal of Hydrogen Energy, 2018Co-Authors: Quan Li, Xing Wang, Zhi Zhang, Shouxiang Lu, Changjian WangAbstract:Abstract Geometrical influence of the Perforated Plate on flame propagation in hydrogen-air mixtures with various equivalence ratios and initial pressures was experimentally investigated in a channel with the length of 1 m and the cross-section of 7 cm × 7 cm. The Perforated Plate has the same cross section and three thicknesses of 40 mm, 80 mm and 120 mm. High-speed schlieren photography was employed to capture the flame shape evolution and derive the flame tip velocity. High-speed piezoelectric pressure transducers were flush-mounted upstream and downstream of the Perforated Plate to measure the pressure transient. It was found that, with the Perforated Plate in the path of flame, flame undergoes either “go”, or “quench” propagation mode. The limit between these two was dependent on the geometrical size of the Perforated Plate and the initial conditions of mixtures. Both velocity and pressure were effectively attenuated with the increase in the Perforated Plate length. Moreover, for “go” propagation mode, the flame process through the Perforated Plate was characterized by three obvious stages: laminar flame stage, jet flame stage and turbulent flame stage. Whereas, only laminar flame stage was observed in the “quench” mode.
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experimental study of flame propagation across a Perforated Plate
International Journal of Hydrogen Energy, 2018Co-Authors: Xuxu Sun, Xing Wang, Zhi Zhang, Sen Han, Changjian WangAbstract:Abstract Flame propagation across a single Perforated Plate was experimentally studied in a square cross-section channel. Experiments were performed in premixed hydrogen-air mixture with different equivalence ratios and initial pressures, aiming at identifying the parametric influence. High-speed schlieren photography and pressure records were used to capture the flame front and obtain the pressure build-up. Four stages for the flame front crossing the Perforated Plate were obtained, namely, laminar flame, jet flame, turbulent flame and secondary flame front. Following ignition, a laminar flame was obtained, which was nearly not affected by the confinement. This laminar flame was squeezed to pass through the Perforated Plate, producing the jet flame with a step change on velocity. Turbulent flame was generated by merging the jets, which facilitated the acceleration of the flame front. Secondary flame front induced by Rayleigh-Taylor instability was clearly observed in the process of the turbulent front moving forward. Both velocity and pressure are enhanced in this stage. Parametric studies suggested that the secondary flame front is more obvious in the stoichiometric mixture with higher initial pressure, and characterized by a faster propagation velocity and a bigger pressure rise.
Xing Wang - One of the best experts on this subject based on the ideXlab platform.
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Geometric influence of Perforated Plate on premixed hydrogen-air flame propagation
International Journal of Hydrogen Energy, 2018Co-Authors: Quan Li, Xing Wang, Zhi Zhang, Shouxiang Lu, Changjian WangAbstract:Abstract Geometrical influence of the Perforated Plate on flame propagation in hydrogen-air mixtures with various equivalence ratios and initial pressures was experimentally investigated in a channel with the length of 1 m and the cross-section of 7 cm × 7 cm. The Perforated Plate has the same cross section and three thicknesses of 40 mm, 80 mm and 120 mm. High-speed schlieren photography was employed to capture the flame shape evolution and derive the flame tip velocity. High-speed piezoelectric pressure transducers were flush-mounted upstream and downstream of the Perforated Plate to measure the pressure transient. It was found that, with the Perforated Plate in the path of flame, flame undergoes either “go”, or “quench” propagation mode. The limit between these two was dependent on the geometrical size of the Perforated Plate and the initial conditions of mixtures. Both velocity and pressure were effectively attenuated with the increase in the Perforated Plate length. Moreover, for “go” propagation mode, the flame process through the Perforated Plate was characterized by three obvious stages: laminar flame stage, jet flame stage and turbulent flame stage. Whereas, only laminar flame stage was observed in the “quench” mode.
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experimental study of flame propagation across a Perforated Plate
International Journal of Hydrogen Energy, 2018Co-Authors: Xuxu Sun, Xing Wang, Zhi Zhang, Sen Han, Changjian WangAbstract:Abstract Flame propagation across a single Perforated Plate was experimentally studied in a square cross-section channel. Experiments were performed in premixed hydrogen-air mixture with different equivalence ratios and initial pressures, aiming at identifying the parametric influence. High-speed schlieren photography and pressure records were used to capture the flame front and obtain the pressure build-up. Four stages for the flame front crossing the Perforated Plate were obtained, namely, laminar flame, jet flame, turbulent flame and secondary flame front. Following ignition, a laminar flame was obtained, which was nearly not affected by the confinement. This laminar flame was squeezed to pass through the Perforated Plate, producing the jet flame with a step change on velocity. Turbulent flame was generated by merging the jets, which facilitated the acceleration of the flame front. Secondary flame front induced by Rayleigh-Taylor instability was clearly observed in the process of the turbulent front moving forward. Both velocity and pressure are enhanced in this stage. Parametric studies suggested that the secondary flame front is more obvious in the stoichiometric mixture with higher initial pressure, and characterized by a faster propagation velocity and a bigger pressure rise.
