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44 results on '"Tang, Songzhen"'

35. Molecular Dynamics Simulation of Low Temperature Corrosion Mechanism of Waste Incinerator.

Author

TANG Songzhen, HAN Kui, and ZHOU Junjie

Abstract

Aiming at the problem of low temperature corrosion on the surface of the heat exchanger in the waste incineration system, the corrosion process of sulfuric acid molecules on the surface of nickel alloy coatings was simulated by molecular dynamics research methods, the corrosion rates of different coatings were explored, and the corrosion process model was established. The results showed that H2SO4 dissociates two hydroxide ions on the surface of nickel metal coating, and the decomposed 0--H ions and 0--S--0 ions were captured by the surface of Ni metal seperatively. 0 in 0--H ions forms bond chains with Ni atoms only. Compared with aluminum oxide, nickel alloy and nickel chromium alloy, nickel chromium alloy had the best inhibition effect on the initial slagging layer, while nickel alloy coating had the worst inhibition effect. The selection of coating materials with strong oxidation resistance could effectively reduce the phenomenon of low temperature corrosion on the surface of the heating surface of the waste incineration system. [ABSTRACT FROM AUTHOR]

Published
2023
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39. Molecular dynamics simulation on CH4 combustion in CO2/O2/N2 atmosphere subjected to electric field.

Author

Zhou, Junjie, Sun, Zhaochen, Tang, Songzhen, and Yu, Yinsheng

Subjects
ELECTRIC fields, MOLECULAR dynamics, COMBUSTION kinetics, COMBUSTION, SELF-propagating high-temperature synthesis, SPECIES diversity
Abstract

In this paper, the CH4 combustion characteristics in CO2/O2/N2 atmosphere subjected to electric field were studied by the molecular dynamics simulation method. Conventional and unique pathways were obtained. The evolution law of reactants and main products and the first reaction time of main intermediates under the influence of different electric field intensities were analysed. Results showed that the addition of external electric fields increased conventional responses and species diversity. The generation of new pathways induced the production of new species, and the further reactions of new species produced other new pathways, thus accelerating the generation of new pathways and species in the electric field. It was noteworthy that, the applied external electric field could advance the reaction start time and reinforce the combustion process, but its effect on the reaction rate was highly nonlinear. The CH4 reaction with CO2 was significantly intensified at E ≥ 105 V/m, while suppressed at E = 104 V/m. Furthermore, electric fields could promote the oxidation degree of CH4, especially at E = 106 V/m. The studies provide theoretical guidance for revealing the mechanism of methane combustion under a high concentration CO2 atmosphere and promoting the efficient capture of CO2. [ABSTRACT FROM AUTHOR]

Published
2023
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44. Coupled optimization of optical and thermal properties for NaCl-Al2O3towards efficient thermal energy storage

Author

Tian, Heqing, Kou, Zhaoyang, Yu, Yinsheng, Tang, Songzhen, and Wu, Xuehong

Abstract

In this paper, a coupled optimization method of optical and thermal performance was explored by us. The microscopic structure of NaCl-Al2O3based composite phase change material (CPCM) was established, the thermal properties were obtained by means of molecular dynamics (MD) simulations combined with experiments. The first principle calculations were also carried out to investigate the optical performance of the CPCM. The results indicated that the addition of nano Al2O3can effectively improve the thermal performance and thermal stability of CPCM, when the mass fraction of Al2O3nanoparticles in CPCM are 2.2 wt% and 7.2 wt%, the mass loss of CPCM samples were 0.14 % and 0.016 % after 100 times cycle, and the thermal conductivity and specific heat capacity can be increased by 15.45 % and 7.63 % at most. In addition, it was found that the optical performance of the CPCM can be also significantly improved. The microscopic coupled optimization mechanism was successfully revealed by the calculation of phonon density of state and band structures, which is desired to be a candidate approach to improve the photo-thermal conversion efficiency of the heat absorber contained in CSP (concentrating solar power) system.

Published
2023
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