Ma S.,Shanghai Marine Diesel Engine Research Institute |
Meng F.,Shanghai Maritime University
IEEE Access | Year: 2017
In recent years, selective catalytic reduction (SCR) system has been used in modern ship or vehicle diesel engines to reduce emissions. SCR technique is a key enabler for NOx reduction, which is critical for the performance and fuel economy of both ship and vehicle diesel engines, since a more advanced timing of the diesel injection is used. The ammonia (NH3) is generated from reaction mechanism of SCR system by using the liquid urea as the reluctant. Therefore, a precise urea dosing system is crucial, and its flow control is very challenging as the traditional approach is still in the open-loop fashion or little urea requirement quantity. To address this challenge, a new urea dosing sub-system of SCR is proposed, which realizes flow feedback with a flow sensor and different control method. The proposed system is novel as it embeds all the control elements in the flow rate regulation, which successfully solves the precise control of the urea dosing system with nonlinear dynamics. In this paper, we first present the working principle of the new urea dosing system. Then, the mechanical system design is shown and the system dynamic model is built. To this end, the proposed system control mechanism is fabricated and validated in a testing fixture. The new urea dosing system performance is finally presented through a series of simulation and experimental results. © 2013 IEEE.
Kuang L.,Tianjin University of Technology |
Huang P.,Shanghai Marine Diesel Engine Research Institute |
Sun H.,Shandong Chemical Technician Institute |
Jiang H.,Tianjin University of Technology |
Zhang M.,Tianjin University of Technology
Journal of Rare Earths | Year: 2013
The nano-crystalline Cu-Ce-Zr-O composite oxides were successfully prepared by the supercritical anti-solvent (SAS) process. The physicochemical properties and catalytic performances were investigated by X-ray diffraction (XRD), Raman spectroscopy, H2 temperature-programmed reduction (H 2-TPR), oxygen storage capacity (OSC) measurement and catalytic activity evaluation. It was found that Cu2+ ions incorporated into CeO2-ZrO2 lattice to form Cu-Ce-Zr-O solid solution associated with the formation of oxygen vacancies. The Cu-Ce-Zr-O catalysts prepared via the SAS process with the Cu content 2.63 mol.% showed the highest OSC index of 636.9 μmol/g. Compared with the samples prepared by impregnation method, Cu doping using SAS process could improve the dispersion of Cu 2+ in the composite oxide, enhance the interaction between Cu 2+ and CeO2-ZrO2, improve the reducibility of catalyst, and thus improve the OSC performance and increase the catalytic activity for CO oxidation at low temperature. © 2013 The Chinese Society of Rare Earths.
Yi L.,Shanghai JiaoTong University |
Hu G.,Shanghai JiaoTong University |
Huang H.,Shanghai Marine Diesel Engine Research Institute
Powder Technology | Year: 2014
Trimanganese tetroxide (Mn3O4) nanosheets can evolve into various morphologies in supercritical N,N-dimethylformamide (SC-DMF), including particulate materials, triangle, rhombus, cube, and other regular polyhedrons. The obtained polyhedrons have sizes from hundred nanometers to several micrometers (1-3μm), along with a growing course. The phases are changed from Mn3O4 to MnO, as the processing time increases. The growth of manganese oxides in SC-DMF has a rate of 28.7-61.5nm·min-1. The phenomena of accelerated growth for manganese oxides in supercritical fluid are discovered. The growth kinetics of manganese oxides is performed by the classical Lifshitz-Slyozov-Wagner (LSW) model. A mass transfer (MT) model of growth kinetics applicable to supercritical fluid surrounding is proposed. Solubility and diffusion, as main factors, are included in the proposed model. The theoretical model and the fitting curve are in accordance with experimental results. The growth of manganese oxides in SC-DMF satisfies the first-order kinetics, obeying the exponential law. © 2014 .
Zhou W.J.,Xi'an Jiaotong University |
Luan H.B.,Shanghai Marine Diesel Engine Research Institute |
He Y.L.,Xi'an Jiaotong University |
Sun J.,CAS Institute of Engineering Thermophysics |
Tao W.Q.,Xi'an Jiaotong University
Microfluidics and Nanofluidics | Year: 2014
This paper presents an investigation of the non-periodic boundary condition (NPBC) which is often used in multiscale atomistic-continuum simulations. The relationship between the boundary force exerted by the imaginary atoms outside the atomistic domain and the fluid state parameters including density and temperature at the boundary is studied. A fitting formula of the boundary force as a function of the fluid state has been proposed based on the relationship. The accuracy of the fitting formula is verified by the equilibrium molecular dynamics (MD) simulations. Poiseuille flow with viscous dissipation and unsteady heat transfer between two walls is then simulated using the proposed fitting formula. The elimination of density oscillation near the boundary of atomistic region and good agreement of velocity and temperature evolutions with time from pure MD and the multiscale simulations adopting NPBC further confirm the correctness of our fitting formula. © 2013 Springer-Verlag Berlin Heidelberg.
Yang J.,Xi'an Jiaotong University |
Bu S.,Xi'an Jiaotong University |
Dong Q.,Shanghai Marine Diesel Engine Research Institute |
Wu J.,Xi'an Jiaotong University |
Wang Q.,Xi'an Jiaotong University
Experimental Thermal and Fluid Science | Year: 2015
In the present study, the electrochemical technique is used to test flow transitions in random packed beds with five low tube to particle diameter ratios (N=dt/dp), including N=2.6, 5.3, 8.1, 9.9 and 12.5. The microelectrodes are placed at the tube wall and inner particle surfaces to test the local flow at the pore level, with particle Reynolds number (Re) ranging from 20 to 2200. The critical Reynolds numbers corresponding to the end of laminar flow and onset of turbulent flow are obtained according to Fluctuating Rate (FR) of current signals. The results of tube wall probes and inner probes are compared in detail to analyze the influences of the tube to particle diameter ratio N on flow transitions. It is found that, the critical Reynolds numbers corresponding to the end of laminar flow regime of packed beds with different tube to particle diameter ratios are at about 110 for packed beds with N=5.3, 8.1, 9.9 and 12.5. Meanwhile, as the tube to particle diameter ratio N increases, the onset of turbulence would take place earlier for inner probes in different packed beds. Furthermore, the critical Reynolds numbers corresponding to both the end of laminar flow and onset of turbulent flow in the packed bed with N=9.9 are quite close to those in the packed bed with N=12.5, which would indicate that, when N≥9.9, the wall effects on flow transitions in the packed beds would be unremarkable. © 2015 Elsevier Inc.
Lu H.,China University of Mining and Technology |
He Y.,Shanghai Marine Diesel Engine Research Institute |
Zhang Y.,Northeastern University China
Advances in Mechanical Engineering | Year: 2014
There are usually several potential failure modes in mechanical components. The conventional model for the system analysis is built under the condition that all failure modes are independent of each other. However, in engineering practice, failure modes are mostly dependent due to the fact that the elements involved in each failure mode are closely interrelated. System reliability analysis and evaluation simply conducted under independent assumption often result in excessive errors or even wrong conclusion. A novel method to evaluate system reliability of mechanical components with multiple failure modes based on moment method are proposed here. Firstly, the moment-based reliability and reliability sensitivity analysis method is proposed with independent assumption. Secondly, the proposed method is deduced by taking the correlation between failure modes into account and the correlation model is established with the copula function, which is proved to be a useful tool to model nonlinear correlation with marginal distributions. The robust design is performed as a biobjection optimization process based on the reliability sensitivity. The numerical examples show that the applied procedure is able to efficiently consider various failure modes of mechanical components in probabilistic assessment and reliability-based optimization. © 2014 Hao Lu et al.
Lu X.,Harbin Engineering University |
Li Q.,Shanghai Marine Diesel Engine Research Institute |
Zhang W.,Harbin Engineering University |
Guo Y.,Harbin Engineering University |
And 2 more authors.
Applied Thermal Engineering | Year: 2013
In this paper, an inverse heat transfer method is employed to conduct thermal numerical analysis on a 4-ring articulated piston of marine diesel engine. The secondary motion of piston and piston ring, and the lubrication oil film has been considered in estimating the coefficient of heat transfer values. Specially manufactured metal plugs were installed in the head of an articulated piston and the piston skirt to measure the temperature distribution of them. A Series of thermal couples were used for cylinder temperature measurement. The boundary condition for numerical simulation is verified with experiment result and applied to predict the temperature distribution of a new piston design which had small change of piston head profile and one less ring scheme. Reasonable agreement was obtained between prediction and experiment for the new design. Experiment result showed increase of temperature in low-temperature area and decrease of maximum value in high-temperature area. The thermal load of the top ring for new piston was lower than old one. The new design had some potential of intensifying improvement from the view point of piston thermal load. © 2012 Elsevier Ltd. All rights reserved.
Li C.-K.,Shanghai Marine Diesel Engine Research Institute
Petrochemical Equipment | Year: 2013
Experimentations of air staging combustion have been carried out to investigate the influence rule of NOx emissions by changing the locations of staging air entered furnace, the air coefficients of primary air, the location and angle of waste water injection on acrylonitrile waste water incinerator test apparatus.
Zhong Z.-J.,Shanghai Marine Diesel Engine Research Institute
Xiandai Huagong/Modern Chemical Industry | Year: 2012
In order to satisfy the anti-explosion and anti-polymerization requirement of process screw compressor for butadiene plant, the special design was made, which used two stages of dry compressors, improved shaft seals and modified the process design. In addition, it should pay much attention to the temperature control. The commissioning test results indicate that the unit can meet the process requirement. Moreover, the anti-explosion and anti-polymerization problems are solved well.
Yang Y.,Shanghai Marine Diesel Engine Research Institute
Xiandai Huagong/Modern Chemical Industry | Year: 2011
The first screw compressor for styrene off-gas is developed in China to meet the requirement of off-gas compressor during the styrene production process. The cause and hazard of the polymerization of styrene are analyzed. Various measures in preventing the polymerization of styrene are proposed. The new processes are provided. This screw compressor has been applied to many styrene units in China. The operation time is above 4 years. More importantly, the accidents of polymerization of styrene in the off-gas screw compressor have never happened.