Papers by Author: Yang Yan Zheng

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Authors: Qun Hui Lu, Yang Yan Zheng, Biao Yuan
Abstract: Through finite volume method, this study establishes a steady state flow and heat transfer model of a single phase flow flowing vertically upward in annular space. The model sets the inner cylinder of the annular space as a heating body with fixed heat generation rate. Flow and heat transfer boundary layers are set between the flow and the inner cylinder wall, in order to give more accurate description of momentum and heat coupling and transfer processes between the fluid and the solid near the wall. Compared with the constant physical property model, the variable physical property model, in which the fluid density, heat transfer coefficient, and viscosity change along with the temperature, has relatively lower heat transfer capacity and a little bit lower interface shear stress between the fluid and the solid heat transfer surfaces. Through the comparison between Re and Ri of the constant physical property model and the variable physical properties model, it can be concluded that the physical property changes of the fluid have gradually lower impact on flow and heat transfer processes along with the acceleration of the forced circulation of the fluid.
Authors: Biao Yuan, Y.Z. Wang, X. Ma, Yang Yan Zheng, Shan Tung Tu
Abstract: Zirconium tube is widely used in heat exchanger equipments in petrochemical process for significant corrosion resistance. The connection joint of tube-tubesheet is the weakest parts in a heat exchanger. The experiment and numerical analysis of different materials (zirconium tubes, titanium tubes and 16MnR tubesheets, 316L tubesheet) joints were performed in this paper. The expansion joints specimens were prepared at the pressure ranging from 28MPa to 38MPa. And pulling out test was performed from 20°C to 300°C. The finite element model of tube-tubesheet joint was established. The effect of expansion pressure, temperature and groove on the pulling out strength of joints was analyzed. Both the experiments and the finite element analysis show that the pull-out strength increases with the increasing expansion pressures. Working temperature also has a great effect on the connection strength of tube-to-tubesheet joints, especially for the zirconium and 316L joints, which have the most significant difference of thermal expansion coefficient between tube and tubesheet. The residual contacting pressure on the contact surface between tubes and the tubesheet is not uniformly distributed and two tightness bands are found near the surfaces of the tubesheet or at the two brinks of the groove on the tubesheet hole. Compared with the ungrooved joint, the residual contacting pressure on the tightness bands for the grooved joint is much higher, indicating a grooved joint has better tightness.
Authors: Jiang Lu, Yi Ning Wang, Yang Yan Zheng, Ji Chun Li
Abstract: In this paper a process framework was constructed for the inspection and assessment of urban gas pipeline. Take a certain gas pipeline network as an example, work directory for complete inspection was established as well as models for risk assessment. Feasible and effective rectification measures could be taken according to the relative importance of the results of the inspection and assessment. Some work in this paper could be adopted for the inspection and assessment of urban gas pipeline.
Authors: Wen Zhong Cai, Shan Tung Tu, Yang Yan Zheng, Jian Ming Gong
Abstract: A new methodology of computer simulation is proposed to perform finite element (FE) calculations of uniaxial tensile deformation on the three-dimensional (3D) complex microstructures, through its application to the microstructure of aluminum matrix containing randomly distributed and oriented SiC particles of highly variable and angular geometry. Compared with the simplified microstructure model, the complex microstructure model shows significant differences in terms of micromechanical fields and macroscopic uniaxial deformation. The results reveal that a quantitative and convenient reconstruction of microstructure of particulate composites is crucial for both the prediction and design of material properties.
Authors: Yi Ning Wang, Qun Hui Lu, Yang Yan Zheng, Biao Yuan
Abstract: In this article, simulation analysis has been performed for the flow and heat transfer performance of spiral flow double-pipe heat exchanger using finite volume method, respectively for the relationship between Nu and the average shear force on inner pipe outer wall at different turbulent flow Re with different radial offset of inlet and outlet pipes and different spacing of inlet and outlet pipes. The results show that, as compared with an ordinary double-pipe heat exchanger, in a spiral flow double-pipe heat exchanger, both inner pipe convective heat exchange coefficient and inner pipe wall surface shear force are lower, with the magnitude of reduction related to a number of factors such as radial offset of inlet and outlet pipes and Re. The study in this article has provided theoretical basis for further engineering application of spiral flow double-pipe heat exchangers.
Authors: Yang Yan Zheng, Yi Ning Wang, Qun Hui Lu, Biao Yuan
Abstract: This paper establishes a model of turbolator with arc notches at its edges to simulation the heat transfer and flowing characteristics of hetat exchanger. Results show that notched turbolator apparently enhanced the heat transfer and changes form of flowing inside tube apparently.
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