The First Zeolite with Three-Dimensional Intersecting Straight-Channel System of 12-Membered Rings

2001 ◽  
Vol 123 (22) ◽  
pp. 5370-5371 ◽  
Author(s):  
Zheng Liu ◽  
Tetsu Ohsuna ◽  
Osamu Terasaki ◽  
Miguel A. Camblor ◽  
Maria-Jose Diaz-Cabañas ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Straight Channel ◽  
Channel System

Study on Hydraulic Characteristics and Optimization of Siphon Channel with Two Inlets in Drydock

2014 ◽  
Vol 638-640 ◽  
pp. 1285-1292
Author(s):  
Peng Zhao ◽  
Yu Chuan Bai
Keyword(s):  
Energy Dissipation ◽  
Numerical Model ◽  
Kinetic Energy ◽  
Dissipation Rate ◽  
Three Dimensional ◽  
Flow State ◽  
Hydraulic Characteristics ◽  
Channel System ◽  
Guide Wall ◽  
Low Efficiency

Compared with the siphon channel with one inlet, the siphon channel with two inlets has some problems such as low efficiency of flooding. Combining with the model test of siphon channel with two inlets in a drydock, three-dimensional numerical model was built to study the hydraulic characteristics of siphon channel system. The reliability of numerical model was confirmed by comparing the calculated value and measured value of hump pressure and flooding rate. Results of turbulent kinetic energy and dissipation rate indicate that flow kinetic energy is mainly dissipated by the friction and its impacting the wall behind partition and the effect of energy dissipation pillars are not obvious. By comparing flow state in front of energy dissipation section and flooding rate between design scheme and modified scheme, it is suggested that the guide wall should be dismantled to ameliorate flow state.

Effects of Intersection Angles on Flow and Heat Transfer in Corrugated-Undulated Channels With Sinusoidal Waves

2006 ◽  
Vol 128 (8) ◽  
pp. 819-828 ◽  
Author(s):  
Jixiang Yin ◽  
Guojun Li ◽  
Zhenping Feng
Keyword(s):  
Heat Transfer ◽  
Cross Section ◽  
Three Dimensional ◽  
Computational Domain ◽  
Straight Channel ◽  
Flow Area ◽  
Contact Points ◽  
Flow And Heat Transfer ◽  
Different Characteristics ◽  
Steady Laminar

This paper reported three-dimensional numerical simulations of the steady laminar flow and heat transfer in corrugated-undulated channels with sinusoidal waves, aiming to investigate the effects of intersection angles (θ) between corrugated and undulated plate and Reynolds number (Re) on the flow and heat transfer. The simulations are conducted by using multi-channel computational domain for three different geometries. The code is validated against experimental results and then data for Nusselt number (Nu) and friction factor (f) are presented in a Re range of 100-1500, and intersection angle range of 30-150deg. The simulation confirms the changes of Nuu (averaged over undulated plate) and Nuc (averaged over corrugated plate) with θ representing different characteristics. As θ increases, Nu (Nuu or Nuc) is about 2–16 times higher for the corrugated-undulated configurations CP-UH1 and CP-UP1 and the concomitant f is about 4–100 higher, when compared to a straight channel having square cross section. The minimum of local Nu ( Nuu or Nuc ) is situated at the four contact points where the top plate touches the bottom one, and the high Nu is located upstream of the crest of the conjugate duct. Performance evaluation for the CP-UH1 channel shows that the goodness factors (G) are larger than 1 with the straight channel having a square cross section as a reference, and the 30deg geometry channel has optimal flow area goodness.

scholarly journals Numerical Simulation of Turbulent Heat Transfer and Flow in a Rotating Multiple-Pass Square Channel

1997 ◽  
Author(s):  
Jenn-Jiang Hwang ◽  
Wei-Jyh Wang ◽  
Dong-Yuo Lai
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Constant Heat Flux ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Straight Channel ◽  
Turbulent Fluid Flow ◽  
Square Channel

Three-dimensional turbulent fluid flow and heat transfer characteristics are analyzed numerically for fluids flowing through a rotating periodical two-pass square channel. The two-pass channel is characterized by three parts: (1) a radial-inward straight channel, (2) 180-deg sharp turns, and (3) a radial-outward straight channel. The smooth walls of the two-pass channel are subject to a constant heat flux. A two-equation k-ε turbulence model with modified terms for Coriolis and rotational buoyancy is employed to resolve this elliptic problem. The effects of rotational buoyancy are examined and discussed. It is found that adjacent the 180-deg turn, the rotational buoyancy effect on the local heat transfer is nearly negligible due to the relatively strong entrance effect of 180-deg turns. Downstream the entrance length, the changes in local heat transfer due to the rotational buoyancy in the radially outward flow are more significant than those in the radially inward flow. However, the channel averaged heat transfer is affected slightly by the rotational buoyancy. Whenever the buoyancy effects are sufficiently strong, the flow reversal appears over the leading face of the radial outward flow channel. A comparison of the present numerical results with the available experimental data by taking buoyancy into consideration is also presented.

Mu-28: an open-framework fluorogallophosphate with a three-dimensional 12-membered ring channel system

2004 ◽  
Vol 177 (10) ◽  
pp. 3721-3728 ◽  
Author(s):  
Ludovic Josien ◽  
Angélique Simon-Masseron ◽  
Volker Gramlich ◽  
Florence Porcher ◽  
Joël Patarin
Keyword(s):  
Three Dimensional ◽  
Membered Ring ◽  
Channel System ◽  
Open Framework ◽  
Ring Channel

Predicting the Effect of Gas-Flow Channel Spacing on Current Density in PEM Fuel Cells

1999 ◽  
Author(s):  
Hamid Naseri-Neshat ◽  
Sirivatch Shimpalee ◽  
Sandip Dutta ◽  
Woo-kum Lee ◽  
J. W. Van Zee
Keyword(s):  
Fuel Cell ◽  
Cross Sections ◽  
Diffusion Layer ◽  
Current Density ◽  
Gas Flow ◽  
Channel Model ◽  
Three Dimensional ◽  
Pem Fuel Cell ◽  
Flow Channel ◽  
Straight Channel

Abstract The effects of change in diffusion layer width for constant diffusion layer thickness and constant gas-flow channel width are investigated with a straight channel model of a Proton Exchange Membrane (PEM) fuel cell. A three-dimensional 10-cm long straight channel model of the PEM fuel cell is presented. The geometrical model includes diffusion layers on both the anode and cathode sides and the numerical model couples three-dimensional Navier-Stokes flow with electro-chemical reactions occurring in the fuel cell. Contours of the current density, anode water vapor concentration, anode water activity, water molecules per proton flux, and secondary flow velocity vectors at different cross sections are presented for the two diffusion layer widths. For the particular conditions and properties used for this study, the results show a marked difference between the base case (0.16-cm) and the wide (0.72-cm) diffusion layer. The current density is quite uniform at different axial cross sections and cross-flow sections for the 0.16-cm wide diffusion layer. However, for the 0.72-cm wide diffusion layer, the current density decreases more significantly in the axial direction near the edges of the diffusion layer. Numerical predictions of the water transport between cathode and anode across the width of the MEA show the delicate balance of diffusion and electro-osmosis and their effect on the current distribution along channel.

Numerical Study of Droplet Behavior in Straight and L-Shaped Channels

2007 ◽  
Author(s):  
Chang-Wei Kang ◽  
Jinsong Hua ◽  
Jing Lou
Keyword(s):  
Reynolds Number ◽  
Equilibrium Position ◽  
Numerical Study ◽  
Density Ratio ◽  
Three Dimensional ◽  
Initial Position ◽  
Straight Channel ◽  
Front Tracking Method ◽  
Droplet Behavior ◽  
Two Parameters

Numerical simulations using three-dimensional front tracking method are conducted to study the effects of droplet properties on the transient motion, rotation and deformation of a droplet during its transit in straight and L-shaped rectangular channels. The properties under investigation for straight channel are the density ratio, viscosity ratio, Reynolds number, Weber number and droplet initial position. The latter two parameters are chosen for the study of L-shaped channel. The results show that in the straight channel, despite the droplet initial positions, the droplet with the same properties ends up at the same equilibrium position. However, when the Reynolds number increases, the droplet is heavier or less viscous or droplet becomes more deformable, the droplet equilibrium position is much closer to the wall. Also, heavier or less viscous droplet exhibits higher rotational speed, which is believed to enhance oscillatory motion. As for the L-shaped channel, it is found that the droplet deformability can help to avoid the droplet from impacting upon the channel wall.

Three-Dimensional Laminar Flow in a Rotating Multiple-Pass Square Channel With Sharp 180-Deg Turns

1998 ◽  
Vol 120 (3) ◽  
pp. 488-495 ◽  
Author(s):  
Jenn-Jiang Hwang ◽  
Dong-Yuo Lai
Keyword(s):  
Fluid Flow ◽  
Laminar Flow ◽  
Flow Rate ◽  
Stokes Equations ◽  
Rotation Speed ◽  
Three Dimensional ◽  
Elliptic Type ◽  
Straight Channel ◽  
Through Flow ◽  
Sharp Turn

This paper presents a study of three-dimensional laminar flow in a rotating multiplepass channel connected with 180-deg sharp bends. Fluid-flow fields are calculated for the entire domain via the Navier-Stokes equations through a finite-difference scheme. For closure of this elliptic-type problem, periodical fully developed conditions are employed between the entrance and exit of the two-pass module. Experiments for the stationary two-pass channel are conducted to validate the numerical procedure and data. The emphasis of the present prediction is on the rotating and through-flow rate effects on the fluid-flow and friction characteristics in the straight channel as well as in the turn region. It is found that the rotation-induced Coriolis force significantly raises the wall-friction losses in the straight channel. However, the head loss of the sharp turn is decreased with increasing rotation speed, because the flow discrepancy between the inlet and outlet of the sharp turn is less significant for the higher rotation speed. Moreover, overall pressure-drop penalty across the two-pass channel is found to be enhanced by the rotation speed as well as the duct through-flow rate.

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