Entity

Time filter

Source Type


Hua Z.J.,Northeast Dianli University | Huang N.,North China Electrical Power University | Ju G.,China Sinogy Electrical Engineering Co.
Applied Mechanics and Materials | Year: 2014

Using numerical simulation method, under the adiabatic condition, this paper simulates the of the upstream gas liquid two phase flow in main tube of hydraulic diameter 1 mm T tube. Superficial gas velocity within 0.01~30m/s and fluid velocity within 0.01~5m/s, under simulated by two kinds of gas volume fraction, air-water flow diagram and the flow pattern transition boundary have been got from the simulation. By comparing the simulation results, it shows that under the same environment, small channel volume fraction of gas has important influence on convection type transition boundaries. © (2014) Trans Tech Publications, Switzerland. Source


Huang N.,North China Electrical Power University | Zhou Y.,Northeast Dianli University | Gao J.,China Sinogy Electrical Engineering Co.
Huaxue Fanying Gongcheng Yu Gongyi/Chemical Reaction Engineering and Technology | Year: 2015

The vapor-liquid churn flow in a vertical tube was numerically simulated by volume of fluid (VOF) method to investigate the influence of pressure on gas-liquid churn flow interfacial wave amplitude, stability of interface and period of interfacial wave under high pressure 5.07, 10.1 3 and 17.22 MPa. The model was verified well by the experimental data. The simulation results showed that the interface stability decreased significantly and the period of the interfacial wave was elongated and the gas-liquid churn flow interfacial wave amplitude increased, with the increase of pressure. In addition, the gas-liquid churn flow interfacial wave amplitude decreased with the decrease of liquid velocity or the increase of gas velocity, but such influence became small with the increase of pressure. The liquid upward transport mechanism was different under the different pressures. Based on the characters of two-phase flow, it was considered that the reasons of the phenomenon appeared were from the density difference of gas-liquid. ©, 2015, Zhejiang University. All right reserved. Source


Huang N.,North China Electrical Power University | Zhou Y.-L.,Northeast Dianli University | Gao J.,China Sinogy Electrical Engineering Co.
Gao Xiao Hua Xue Gong Cheng Xue Bao/Journal of Chemical Engineering of Chinese Universities | Year: 2015

A numerical simulation based on the volume of fluid (VOF) method was used to study vapor-liquid flow in a 190 mm vertical tube under high pressure, and the flow pattern maps of the two-phase convection flow were investigated under pressure of 5.07, 10.13 and 17.23 MPa, respectively. The results of flow under high pressure were compared with that of normal pressure. The results show that the flow pattern maps under high pressure in large-diameter vertical pipes are not consistent with the Hewitt and Roberts flow pattern maps. No wispy annular is presented under high pressure in large-diameter vertical pipes, and the bubbly zone and churn zone are enlarged. The slug zone becomes particularly small with little change happened to the annular zone. The simulation results show that the interfacial wave amplitude of the vapor-liquid churn flow decreases with the increase of pressure in large-diameter vertical pipes, and the interface stability is enhanced at the same time. The pipe central area has the highest velocity, which fluctuates at the boundary area and reduces to zero on the pipe wall. Moreover, the disorder degree of the oscillatory velocity field near the pipe wall decreases under high pressure. Mechanisms were analyzed following the simulation results dicussed. © 2015, Editorial Board of "Journal of Chemical Engineering of Chinese Univesities". All right reserved. Source


Gu L.,North China Electrical Power University | Li Y.,North China Electrical Power University | Li L.,China Sinogy Electrical Engineering Co.
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2015

On the base of orthogonal tests of a 600 MW coal firing utility boiler, under three modes of load of 400 MW, 500 MW and 600 MW, coal calorific value identification model, direct combustion optimization model and hybrid combustion optimization model were built based on the artificial neural network. Since the coal calorific value model was used as input variables of boiler combustion and the exhaust gas temperature, carbon content of the fly ash and NOx emission were as output variable, the predictive precision is markedly improved. Date logged test and quantitative analysis show that coal calorific value model with the maximum average relative error up to 3.725% can be used as combustion optimization input variable, and that compared with direct model, the boiler thermal efficiency and NOx emissions predictive precision of hybrid model were increased by 20.73 percentage point and 29.89 percentage point respectively, which illustrate the proposed model is effective and has relatively high accuracy. The model achieves the soft sensor of its furnace temperature, NOx emission, flue gas temperature, carbon content in fly ash and the prediction of boiler thermal efficiency. © 2015 Chin. Soc. for Elec. Eng. Source


Su Y.,China Sinogy Electrical Engineering Co. | Zeng Q.,Nanjing Southeast University | Fu X.,Nanjing Southeast University
Dongli Gongcheng Xuebao/Journal of Chinese Society of Power Engineering | Year: 2014

A finite element model was set up for the shafting of a 1 000 MW unit, based on which verification tests were carried out to study the vibration characteristics of its three-bearing supporting structure. Results show that the supporting characteristics at both ends of the generator have great effects on vibration of the three-bearing supporting structure. Many factors should be considered during field balancing. When determinating the form and axial position of an imbalance, the main-span supporting characteristics should be taken into consideration. In case that the imbalance form is determined directly according to the harmonic component method, repeated dynamic balancing may be ineffective, and even divergent vibration may be caused during vibration treatment. Source

Discover hidden collaborations