scholarly journals Three-Dimensional Computation Fluid Dynamics Simulation of CO Methanation Reactor with Immersed Tubes

Energies ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 321
Liyan Sun ◽  
Junjie Lin ◽  
Dali Kong ◽  
Kun Luo ◽  
Jianren Fan

CO methanation is an exothermic process, and heat removal is an essential issue for the methanation reactor. Numerical studies were carried out to investigate the performance of a 3D fluidized bed methanation reactor with immersed cooling tubes. The simulations were carried out in the frame of the Euler–Euler model to analyze the performance of the reactor. The influences of operating temperatures were studied to understand the reaction characteristics. The temperature increases rapidly neared the inlet due to the reactions. The immersed tubes were effective at removing the reaction heat. The chemical equilibrium state was achieved with an operating temperature of 682 K for the case with immersed tubes. Different control mechanisms can be found during the process of increasing and decreasing the temperature. The reaction kinetic is the dominate factor for the cases with lower temperatures, while the chemical equilibrium will play a more important role at high temperature conditions. The configuration with staggered tubes is beneficial for heat removal.

Tri Nguyen ◽  
Elia Merzari

Abstract Buoyancy-driven flows are widespread in diverse engineering applications. Such flows have been studied in great detail theoretically, experimentally, and numerically. However, the fluid-dynamic instabilities and flow reversals of thermosiphon are still actively investigated. The presence of such instabilities limits the effectiveness of such devices for decay heat removal. Traditionally the stability analysis of natural convection loops has been confined to one-dimensional calculations, on the argument that the flow would be mono-dimensional when the ratio between the radius of the loop and the radius of the pipe is much larger than 1. Nevertheless, accurate velocity measurements of the flow in toroidal loops have shown that the flow presents three-dimensional effects. Previous works of the authors have shown that these structures can be seen in thermosiphons. In this paper, we aim to use modern CFD methods to investigate the three-dimensional flow in thermosiphons. This paper focuses on rectangular thermosiphons. In particular, we perform a series of high-fidelity simulations using the spectral element code Nek5000 to investigate the stability behavior of the flow in a rectangular thermosiphon. We compare the results with available existing experimental data from the L2 facility in Genoa. We examine in detail the flow structures generated. Moreover, in the past various authors have demonstrated that the overall behavior of the thermosiphon depends strongly on the boundary conditions (BCs). The simulation campaign was carried out with different BCs to investigate and confirm this effect. In particular, simulations with Dirichlet, Neumann and Robin BCs for heater and sink were performed.

2019 ◽  
Vol 221 ◽  
pp. 01003
Pavel Radchenko ◽  
Stanislav Batuev ◽  
Andrey Radchenko

The paper presents results of applying approach to simulation of contact surfaces fracture under high velocity interaction of solid bodies. The algorithm of erosion -the algorithm of elements removing, of new surface building and of mass distribution after elements fracture at contact boundaries is consider. The results of coordinated experimental and numerical studies of fracture of materials under impact are given. Authors own finite element computer software program EFES, allowing to simulate a three-dimensional setting behavior of complex structures under dynamic loads, has been used for the calculations.

1994 ◽  
Vol 373 ◽  
Roger E. Stoller

AbstractA series of high-energy, up to 20 keV, displacement cascades in iron have been investigated for times up to 200 ps at 100 K using the method of molecular dynamics simulation. Thesimulations were carried out using the MOLDY code and a modified version of the many-bodyinteratomic potential developed by Finnis and Sinclair. The paper focuses on those results obtained at the highest energies, 10 and 20 keV. The results indicate that the fraction of the Frenkel pairs surviving in-cascade recombination remains fairly high in iron and that the fraction of the surviving point defects that cluster is lower than in materials such as copper. In particular, vacancy clustering appears to be inhibited in iron. Some of the interstitial clusters were observed to exhibit an unexpectedly complex, three-dimensional morphology. The observations are discussed in terms of their relevance to microstructural evolution and mechanical property changes in irradiated iron-based alloys.

Robotica ◽  
2010 ◽  
Vol 29 (5) ◽  
pp. 733-743 ◽  
Conghui Liang ◽  
Hao Gu ◽  
Marco Ceccarelli ◽  
Giuseppe Carbone

SUMMARYA mechanical design and dynamics walking simulation of a novel tripod walking robot are presented in this paper. The tripod walking robot consists of three 1-degree-of-freedom (DOF) Chebyshev–Pantograph leg mechanisms with linkage architecture. A balancing mechanism is mounted on the body of the tripod walking robot to adjust its center of gravity (COG) during walking for balancing purpose. A statically stable tripod walking gait is performed by synchronizing the motions of the three leg mechanisms and the balancing mechanism. A three-dimensional model has been elaborated in SolidWorks® engineering software environment for a characterization of a feasible mechanical design. Dynamics simulation has been carried out in the MSC.ADAMS® environment with the aim to characterize and to evaluate the dynamic walking performances of the proposed design with low-cost easy-operation features. Simulation results show that the proposed tripod walking robot with proper input torques, gives limited reaction forces at the linkage joints, and a practical feasible walking ability on a flatten ground.

Guodong Sun ◽  
Xuejing Duan ◽  
Bo Hao ◽  
Afshin Davarpanah

Nitrogen oxides are considered as one of the greenhouse gases. Among the most significant emission sources for this gas is a natural gas-fired power plant. The United Nations General assembly suggested in 1988 that human activities can negatively impact weather patterns, and thus they should be controlled. This control policy can improve the efficiency of final consumers such as power plants, cars, or other energy-intensive industries. In this paper, the existing strategies and explicitly making the dry low nitrogen oxides burner reduce greenhouse gases in power plants are explored. The geometry of the burner has been produced in a three-dimensional form in GAMBIT software, and the results of the simulation have been expressed through FLUENT software. Contours of pressure, temperature, and velocity of the fluid in the furnace are also derived. It is concluded that the dry low nitrogen oxides burners plan has a better result compared with other strategies.

Biochemistry ◽  
1990 ◽  
Vol 29 (45) ◽  
pp. 10317-10322 ◽  
Lennart Nilsson ◽  
Agneta Aahgren-Staalhandske ◽  
Ann Sofie Sjoegren ◽  
Solveig Hahne ◽  
Britt Marie Sjoeberg

2018 ◽  
Vol 32 (34n36) ◽  
pp. 1840083 ◽  
Xuetong Liu ◽  
Jianhua Liu ◽  
Huajiang Ouyang ◽  
Zhenbing Cai ◽  
Jinfang Peng ◽  

The dynamic response of bolted joints subjected to torsional excitation is investigated experimentally and numerically. First, the effects of the initial preload and the angular amplitude on axial force loss of the bolt were studied. Second, the change of hysteresis loops with the increasing number of loading cycles was found under a larger torsional angle. At last, a fine-meshed three-dimensional finite element model was built to simulate the bolted joint under torsional excitation, from which the hysteresis loops were obtained under varying angular amplitudes. The results of numerical analysis are in good agreement with those of experiments.

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