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Zheng D.,Tsinghua University | Zhang Y.-P.,National Energy Conservation Center | Zhong B.-J.,Tsinghua University
Wuli Huaxue Xuebao/ Acta Physico - Chimica Sinica

A chemical kinetic model consisting of 103 species and 395 elementary reactions has been developed. This kinetic model well describes the formation of polycyclic aromatic hydrocarbons (PAHs) for multi-component gasoline surrogate fuels. Model validation results showed that the predicted PAHs and aromatic precursors using this chemical mechanism were consistent with the experimental results in the premixed flame of ethylene, toluene, n-heptane, and the opposed flow flame of n-heptane. The mechanism is not yet applicable to multidimensional computational fluid dynamics simulations for PAH formation of gasoline combustion. However, compared with the existing kinetic model, the present kinetic model contains fewer species and reactions, so it is closer to the aim of a model for practical applications. © Editorial office of Acta Physico-Chimica Sinica. Source

Dong X.-Q.,CAS Technical Institute of Physics and Chemistry | Dong X.-Q.,University of Chinese Academy of Sciences | Gong M.-Q.,CAS Technical Institute of Physics and Chemistry | Zhang Y.,National Energy Conservation Center | And 3 more authors.
Kung Cheng Je Wu Li Hsueh Pao/Journal of Engineering Thermophysics

A method was presented to predict the binary homogeneous azeotropes. In this method, the UNIFAC model was used to calculate the binary interaction parameters of the WS mixing rule, and then the PR equation of state was used to obtain the pressure of the mixture. Newton's method was used to compute the root which makes the first derivative of the pressure with respect to the composition equal to zero. The root is the azeotropic composition for the azeotropic mixture. The type of the azeotropes can also be determined. This method was verified by the experimental data, and good agreement was obtained. Source

Jin L.-J.,Tongji University | Yan S.-J.,Tongji University | Liu Y.,National Energy Conservation Center
Xitong Fangzhen Xuebao / Journal of System Simulation

A research on vibration damper recognition based on Haar-like features and cascade AdaBoost classifier is proposed to solve the problem of only detecting a single vibration damper. At first, the extended Haar-like features are extracted by integral image, then a small set of critical features are chosen to compose complex classifier in the process of training AdaBoost, finally the complex classifiers were combined in a cascade method for vibration damper recognition. Experimental results demonstrate that the proposed method has better performance in recognizing vibration damper from complex background. Source

Zhang C.,Tongji University | Zhang C.,Harvard University | Anadon L.D.,Harvard University | Mo H.,National Energy Conservation Center | And 2 more authors.
Environmental Science and Technology

The energy sector is increasingly facing water scarcity constraints in many regions around the globe, especially in China, where the unprecedented large-scale construction of coal-fired thermal power plants is taking place in its extremely arid northwest regions. As a response to water scarcity, air-cooled coal power plants have experienced dramatic diffusion in China since the middle 2000s. By the end of 2012, air-cooled coal-fired thermal power plants in China amounted to 112 GW, making up 14% of China's thermal power generation capacity. But the water conservation benefit of air-cooled units is achieved at the cost of lower thermal efficiency and consequently higher carbon emission intensity. We estimate that in 2012 the deployment of air-cooled units contributed an additional 24.3-31.9 million tonnes of CO2 emissions (equivalent to 0.7-1.0% of the total CO2 emissions by China's electric power sector), while saving 832-942 million m3 of consumptive water use (about 60% of the total annual water use of Beijing) when compared to a scenario with water-cooled plants. Additional CO2 emissions from air-cooled plants largely offset the CO2 emissions reduction benefits from Chinese policies of retiring small and outdated coal plants. This water-carbon trade-off is poised to become even more significant by 2020, as air-cooled units are expected to grow by a factor of 2-260 GW, accounting for 22% of China's total coal-fired power generation capacity. © 2014 American Chemical Society. Source

Zhu X.F.,Central South University | Zhu X.F.,Changsha University of Science and Technology | Wei X.Y.,National Energy Conservation Center | Huang X.,National Energy Conservation Center | Zhang Y.P.,National Energy Conservation Center
Applied Mechanics and Materials

Experimental studies were conducted on unidirectional and multidirectional freezing of artificial soils in a rectangular cavity. The ice lenses were observed through transparent plexiglass plate. Temperature gradients in soil specimen were obtained during freezing process. The experimental results indicated that the temperature gradient may change the shape of ice lenses. The amount of frost heave of multidirectional freezing was less than unidirectional freezing, so multidirectional freezing mode is helpful to restrain vertical frost heave. © (2013) Trans Tech Publications, Switzerland. Source

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