Fluid Flow and Heat Transfer Simulations of the Cooling-Water Channel in a Tera-Hertz Radiation Detector

2012 ◽  
Author(s):  
Usama Tohid ◽  
Arturo Pacheco-Vega ◽  
Rodion Tikhoplav ◽  
Marcos Ruelas
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Laser Irradiation ◽  
Stokes Equations ◽  
Cooling System ◽  
Rectangular Channel ◽  
Operating Conditions ◽  
Channel Height ◽  
Flow And Heat Transfer ◽  
Direct Laser

Detailed numerical simulations have been carried out to find the velocity and temperature fields of a rectangular channel with large aspect-ratio. The channel under analysis is aimed to cool a thermo-chromic liquid crystal material (TLC) that is able to capture laser irradiation in the terahertz range. The overall objective of the cooling system is to maintain a nearly-homogeneous temperature of the TLC layer that is not exposed to the direct laser irradiation. The fluid flow and heat transfer simulations are carried out on the basis of three-dimensional versions of the Navier-Stokes equations, along with the energy equation, for an incompressible flow, to determine values of velocity, pressure and temperature inside the channel under different operating conditions. These values are then used to find, from a specific set, the value of the channel height that allows for the most uniform temperature distribution within the expected operating conditions. Results from this analysis indicate that, for all the inlet velocities considered, there is a common value of the channel height, that represents the optimum.

Thermal Convection and Stress Analysis of the Cooling System for a Terahertz Radiation Detector

2015 ◽  
Author(s):  
Angela Wu ◽  
Arturo Pacheco-Vega ◽  
Jeanette Cobian
Keyword(s):  
Fluid Flow ◽  
Laser Irradiation ◽  
Cooling System ◽  
Rectangular Channel ◽  
Radiation Detector ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Temperature Fields ◽  
Stress Strain ◽  
Direct Laser

Detailed three-dimensional numerical simulations have been carried out to find the velocity and temperature fields, in combination with shear and normal stresses, of the fluid flow inside a rectangular channel with large aspect-ratio. The channel under analysis is aimed to cool a thermochromic liquid crystal material (TLC) that is able to capture laser irradiation in the terahertz range. The TLC is manufactured on an extremely-thin substrate. The overall objective of the cooling system is to maintain a nearly-homogeneous temperature of the TLC-domain that is not exposed to the direct laser irradiation, while minimizing the deformation in the TLC caused by the fluid-solid interaction. The fluid flow, stress-strain and heat transfer simulations are carried out on the basis of three-dimensional Navier-Stokes and energy equations for an incompressible flow, coupled with the stress-strain equation for the TLC-layer, to determine values of velocity, pressure and temperature for the fluid inside the channel and the stresses and deformation of the TLC layer, under different operating conditions. These values are then used to find, from a specific set, the value of the channel gap that enables a nearly-uniform temperature distribution in the fluid and the least amount of deformation in the solid layer, within the expected operating conditions. Results from this analysis indicate that, for all the inlet velocities considered, there is a common value of the channel gap, that represents the optimum for the cooling system.

Fluid flow and heat transfer of natural convection accompanied with reverse flow in a vertical rectangular channel.

2004 ◽  
Vol 2004 (0) ◽  
pp. 89-90
Author(s):  
Satoshi ANMA ◽  
Isao ISHIHARA ◽  
Ryosuke MATSUMOTO ◽  
Tomomasa UEMURA ◽  
Yasuhumi YAMAMOTO
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Natural Convection ◽  
Reverse Flow ◽  
Rectangular Channel ◽  
Flow And Heat Transfer

Developing Fluid Flow and Heat Transfer in a Semi-Porous Square Channel

2003 ◽  
Author(s):  
Tien-Chien Jen ◽  
Tuan-Zhou Yan ◽  
S. H. Chan
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Fluid Flow ◽  
Stokes Equations ◽  
Temperature Fields ◽  
Porous Channel ◽  
Navier Stokes ◽  
Axial Position ◽  
Navier Stokes Equations ◽  
Flow And Heat Transfer

A three-dimensional computational model is developed to analyze fluid flow in a semi-porous channel. In order to understand the developing fluid flow and heat transfer process inside the semi-porous channels, the conventional Navier-Stokes equations for gas channel, and volume-averaged Navier-Stokes equations for porous media layer are adopted individually in this study. Conservation of mass, momentum and energy equations are solved numerically in a coupled gas and porous media domain in a channel using the vorticity-velocity method with power law scheme. Detailed development of axial velocity, secondary flow and temperature fields at various axial positions in the entrance region are presented. The friction factor and Nusselt number are presented as a function of axial position, and the effects of the size of porous media inside semi-porous channel are also analyzed in the present study.

A Numerical Simulation on the Fluid Flow and Heat Transfer Around a Vehicle in a Paint Drying Process

2013 ◽  
Author(s):  
Jongrak Choi ◽  
Nahmkeon Hur ◽  
Hee-Soo Kim
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Fluid Flow ◽  
Moving Boundary ◽  
Numerical Results ◽  
Operating Conditions ◽  
Drying Process ◽  
Automotive Manufacturing ◽  
Flow And Heat Transfer ◽  
Paint Drying

In the automotive manufacturing process, the paint drying process is very important to improve the appearance of the vehicle. In the present study, the fluid flow and heat transfer around a vehicle were numerically investigated for the purpose of predicting the drying performance of the paint drying process. In order to simulate the operating conditions of the paint drying process, the following techniques were used: relative moving boundary conditions, multiple reference frames, and conjugated heat transfer. The present numerical method was verified by comparing the numerical results of the temperature at several monitoring points on a vehicle, while using the experimental data. To evaluate the drying performance quantitatively, the absorbed heat energy that is closely related to the drying of paint was obtained from the numerical simulation. It was found that the drying performance is greatly affected by operating conditions such as the temperature and flow rate of blowing air. To improve the drying performance, the operating conditions of the paint drying process were optimized using the numerical results of various operating conditions.

Heat Transfer and Fluid Flow Characteristic of One Side Heated Vertical Rectangular Channel That Inserted Thin Metallic Wire

2020 ◽  
Author(s):  
Gota Suga ◽  
Tetsuaki Takeda
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
High Temperature ◽  
Natural Convection ◽  
Cooling System ◽  
Copper Wire ◽  
Rectangular Channel ◽  
Flow Characteristics ◽  
Experimental Apparatus ◽  
High Temperature Reactor

Abstract A Very High Temperature Reactor (VHTR) is one of the next generation nuclear systems. From a view point of safety characteristics, a passive cooling system should be designed as the best way of a reactor vessel cooling system (VCS) in the VHTR. Therefore, the gas cooling system with natural circulation is considered as a candidate for the VCS of the VHTR. Japan Atomic Energy Agency (JAEA) is advancing the technology development of the VHTR and is now pursuing design and development of commercial systems such as the 300MWe gas turbine high temperature reactor GTHTR300C (Gas Turbine High Temperature Reactor 300 for Cogeneration). In the VCS of the GTHTR300C, many rectangular flow channels are formed around the reactor pressure vessel (RPV), and a cooling panel utilizing natural convection of air has been proposed. In order to apply the proposed panel to the VCS of the GTHTR300C, it is necessary to clarify the heat transfer and flow characteristics of the proposed channel in the cooling panel. Thus, we carried out an experiment to investigate heat transfer and fluid flow characteristics by natural convection in a vertical rectangular channel heated on one side. Experiments were also carried out to investigate the heat transfer and fluid flow characteristics by natural convection when a porous material with high porosity is inserted into the channel. An experimental apparatus is a vertical rectangular flow channel with a square cross section in which one surface is heated by a rubber heater. Dimensions of the experimental apparatus is 600 mm in height and 50 mm on one side of the square cross section. Air was used as a working fluid and fine copper wire (diameter: 0.5 mm) was used as a porous material. The temperature of the wall surface and gas in the channel were measured by K type thermocouples. We measured the outlet flow rate by hot-wire anemometer which is an omnidirectional spherical probe of diameter 2.5mm. The experiment has been carried out under the condition that a copper wire with a scourer model and a cubic lattice model were inserting into the channel.

Fluid Flow Inside a Rectangular Duct With Two Opposite Walls Roughened by Deepened Scales

2009 ◽  
Author(s):  
T. M. Liou ◽  
S. W. Chang ◽  
J. S. Chen ◽  
C. Y. Chan
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Flow Visualization ◽  
Laser Sheet ◽  
Rectangular Channel ◽  
Laminar Flows ◽  
Maximum Depth ◽  
Channel Height ◽  
Mean Velocity ◽  
Cross Sectional

Laser-Doppler velocimetry (LDV) measurements supplemented by numerical simulation and flow visualization were performed to study flow characteristics and explain the reported heat transfer features in a rectangular channel with two opposite walls roughened by deepened scales. The study is lacking in the published literature. Ratios of scale print diameter to channel height, scale maximum depth to channel height and scale pitch to scale maximum depth were 1.0, −0.1, and 10 respectively. The scale-roughened section had a cross-sectional width to height ratio of 8. All measurements were undertaken at a fixed Reynolds number, based on hydraulic diameter and cross-sectional bulk mean velocity, of 10000 with air flows directed forward and downward. Results are documented in terms of distributions of mean velocity components, mean velocity vector field, fluctuation components, and turbulent kinetic energy. The distances attaining periodic fully developed flow condition are identified. Both LDV measurements and laser-sheet flow visualization unravel the presence of near-wall secondary vortex arrays in the cross-sectional planes. The fluid flow results are subsequently used to explain previously published heat transfer trends. The dominant flow dynamic factors are recognized to provide the logic for the differences in heat transfer enhancements attained by the forward and downward channel flows over the scaled walls. A comparison of the computed sizes of cavity trapped vortex illustrates the reported difference in heat transfer augmented by the scale and dimple roughened surfaces as well as by the turbulent and laminar flows.

Numerical Computation of Fluid Flow and Heat Transfer in Microchannels

2005 ◽  
Author(s):  
Ningli Liu ◽  
Rene Chevray ◽  
Gerald A. Domoto ◽  
Elias Panides
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Energy Equation ◽  
Stokes Equations ◽  
Numerical Approach ◽  
Time Dependent ◽  
Navier Stokes ◽  
Temperature Profiles ◽  
Navier Stokes Equations ◽  
Flow And Heat Transfer

A finite difference numerical approach for solving slightly compressible, time-dependent, viscous laminar flow is presented in this study. Simplified system of Navier-Stokes equations and energy equation are employed in the study in order to perform more efficient numerical calculations. Fluid flow and heat transfer phenomena in two dimensional microchannels are illustrated numerically in this paper. This numerical approach provides a complete numerical simulation of the development of the fluid flow and the temperature profiles through multi-dimensional microchannels.

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