Estimation of the Optimum Dimensions of a Vertical Channel Model for Natural Air Cooling in Electronic Equipment

2009 ◽  
Author(s):  
Yasushi Nishino ◽  
Masaru Ishizuka ◽  
Shinji Nakagawa
Keyword(s):  
Channel Model ◽  
Vertical Channel ◽  
Velocity Profiles ◽  
Electronic Equipment ◽  
Air Cooling ◽  
Cooling Flow ◽  
Image Velocimetry ◽  
Air Passage ◽  
The Relationship ◽  
Vertical Duct

The cooling capability in compact electronic equipment in natural convective flow fields has been investigated. The relationship between air passage width in the channel and natural cooling capability was obtained. Temperature and velocity measurements were carried out using a channel model of electronic equipment comprising a vertical duct of rectangular section. The channel model had two copper walls and two transparent acrylic walls. The clearance between the copper walls was used as a parameter for the channel model. Velocity profiles of natural cooling flow in the channel were quantitatively measured using particle image velocimetry (PIV). The temperature and velocity results demonstrated that changes in the velocity profiles closely depend on the wall clearances. It is clarified that the clearance from 8 mm to 10 mm is the best size for natural cooling in the channel.

Optimization of Natural Air Cooling in a Vertical Channel of Electronic Equipment

2010 ◽  
Author(s):  
Yasushi Nishino ◽  
Masaru Ishizuka ◽  
Tomoyuki Hatakeyama ◽  
Shinji Nakagawa
Keyword(s):  
Numerical Simulation ◽  
Channel Model ◽  
Vertical Channel ◽  
Electronic Equipment ◽  
Air Cooling ◽  
Measured Temperature ◽  
Model Following ◽  
Image Velocimetry ◽  
Convection Cooling ◽  
Copper Wall

The natural convection cooling capability in a compact item of electronic equipment was investigated quantitatively by experiment and numerical simulation with a simple channel model. The optimization of the channel sizes, especially the clearance between heated walls, was discussed. The channel model, which consists of a vertical duct of rectangular section, was applied as the experimental model of electronic equipment in this study. The channel model consists of two heated copper walls and two transparent acrylic walls. The clearance between the copper walls of the channel was varied from 5 mm to 15 mm. Temperature measurement on the copper wall surfaces and velocity measurement of natural air flow in the channel by using a particle image velocimetry (PIV) were conducted for a few clearances of the channel. Numerical simulation was also carried out, with a model following the experimental setup, for more detailed discussion of various clearances of the channel. The relationship between the clearance and the temperature rise of the walls or velocity profile was investigated. The correlation between the Rayleigh number and the Nusselt number was obtained from measured temperature. The natural cooling capability and the velocity profiles depend on the clearance between the copper walls. When the wall clearances are more than 15 mm, the cooling is not enhanced. On the other hand, in the case that the clearance becomes less than 7 mm, the cooling capability becomes significantly lower. Consequently, it is clarified that the clearance from 8 mm to 10 mm is the best size for natural cooling from the view point of the space and the capability.

Optimization of Natural Air Cooling in a Vertical Channel of Electronic Equipment

2010 ◽  
Author(s):  
Yasushi Nishino ◽  
Masaru Ishizuka ◽  
Tomoyuki Hatakeyama ◽  
Shinji Nakagawa
Keyword(s):  
Numerical Simulation ◽  
Channel Model ◽  
Vertical Channel ◽  
Electronic Equipment ◽  
Air Cooling ◽  
Measured Temperature ◽  
Model Following ◽  
Image Velocimetry ◽  
Convection Cooling ◽  
Copper Wall

The natural convection cooling capability in a compact item of electronic equipment was investigated quantitatively by experiment and numerical simulation with a simple channel model. The optimization of the channel sizes, especially the clearance between heated walls, was discussed. The channel model, which consists of a vertical duct of rectangular section, was applied as the experimental model of electronic equipment in this study. The channel model consists of two heated copper walls and two transparent acrylic walls. The clearance between the copper walls of the channel was varied from 5 mm to 15 mm. Temperature measurement on the copper wall surfaces and velocity measurement of natural air flow in the channel by using a particle image velocimetry (PIV) were conducted for a few clearances of the channel. Numerical simulation was also carried out, with a model following the experimental setup, for more detailed discussion of various clearances of the channel. The relationship between the clearance and the temperature rise of the walls or velocity profile was investigated. The correlation between the Rayleigh number and the Nusselt number was obtained from measured temperature. The natural cooling capability and the velocity profiles depend on the clearance between the copper walls. When the wall clearances are more than 15 mm, the cooling is not enhanced. On the other hand, in the case that the clearance becomes less than 7 mm, the cooling capability becomes significantly lower. Consequently, it is clarified that the clearance from 8 mm to 10 mm is the best size for natural cooling from the view point of the space and the capability.

Effects of Clearance Between Heating Walls on Natural Cooling in a Channel Model of Electronic Equipment

2007 ◽  
Author(s):  
Yasushi Nishino ◽  
Ryoji Imai ◽  
Shinji Nakagawa ◽  
Masaru Ishizuka
Keyword(s):  
Temperature Rise ◽  
Printed Circuit Boards ◽  
Channel Model ◽  
Maximum Velocity ◽  
Vertical Channel ◽  
Cooling Capacity ◽  
Electronic Equipment ◽  
Heated Wall ◽  
Parallel Plates ◽  
The Relationship

Making electronic products smaller in size requires air passages in the products to be narrow. For effective thermal management with natural convection, the relationship between cooling performance and a space for the air passages must be clarified. In this study, the natural cooling capacity and flow field in relatively small electronic equipment have been investigated. A channel model was used as an experimental model of electronic equipments. The channel model has two vertical copper walls modeling the printed circuit boards and two transparent walls modeling the casing walls. The walls constitute a vertical channel with the height of 120mm, the depth of 56mm, and the variable width. The width of the channel is called “a wall clearance” here and it is varied from 5mm to 15mm. The copper walls were heated using electric heaters. Temperatures in the model were measured with thermo-couples. In addition, velocity distributions in the channel were quantitatively measured using a particle image velocimetry (PIV). The natural cooling capacity was obtained as functions of the wall clearance and heating power. Temperature rise of the heated wall showed small differences with the clearances of 10 mm and 15mm. However, when the clearance was decreased to 5mm, temperature rise increased. The relationship between Nusselt number and Rayleigh number obtained in this study agrees with those obtained for the parallel plates without side walls. The results of the velocity measurement revealed that the velocity showed a 33% decrease when the wall clearance decreased from 10mm to 5mm. On the other hand, the maximum velocity in the channel showed a 10% increase when the clearance decreased from 15mm to 10mm. The changes in the velocity profiles depending on the heating conditions are clarified.

J0103-5-3 Study on the enhancement of natural air cooling capability in the vertical channel model of electronic equipment

2009 ◽  
Vol 2009.6 (0) ◽  
pp. 83-84
Author(s):  
Yasushi NISHINO ◽  
Masaru ISHIZUKA ◽  
Shinji NAKAGAWA ◽  
Tomoyuki HATAKEYAMA
Keyword(s):  
Channel Model ◽  
Vertical Channel ◽  
Electronic Equipment ◽  
Air Cooling

1918 Natural Convection Air Cooling in a Vertical Channel of Electronic Equipment

2007 ◽  
Vol 2007.7 (0) ◽  
pp. 203-204
Author(s):  
Yasushi NISHINO ◽  
Ryoji IMAI ◽  
Shinji NAKAGAWA ◽  
Masaru ISHIZUKA
Keyword(s):  
Natural Convection ◽  
Vertical Channel ◽  
Electronic Equipment ◽  
Air Cooling

Experimental Analysis of Natural Convection and Flow Visualization in an Asymmetrically Heated Open Vertical Channel

2019 ◽  
Vol 11 (5) ◽  
Author(s):  
Yassine Cherif ◽  
Emilio Sassine ◽  
Laurent Zalewski ◽  
Kaies Souidi ◽  
Stephane Lassue
Keyword(s):  
Natural Convection ◽  
Rayleigh Number ◽  
Aspect Ratio ◽  
Thermal Flux ◽  
Vertical Channel ◽  
Velocity Profiles ◽  
Heated Wall ◽  
Image Velocimetry ◽  
Channel Aspect Ratio ◽  
Thermal Phenomena

An experimental device was designed to perform the thermal and dynamic study of natural convection airflow in an open vertical channel. The two side walls of the vertical channel are made of Plexiglas allowing the visualization of the flow via the particle image velocimetry (PIV) method. For the two other vertical walls, one is heated at a constant temperature, and the other is insulated with a 9-cm thick polystyrene insulation. The dynamic characterization of convection is carried out by nonintrusive measurements (PIV), and thermal phenomena are analyzed using nonintrusive heat flux instrumentation (simultaneous temperature and velocity measurements have been carried out across the channel at different elevations). Moreover, this study deals with the influence of the Rayleigh number on the measured vertical velocity profiles as well as the thermal flux densities recorded along the heated wall. To do this, different values of the modified Rayleigh numbers were considered in the interval with the channel aspect ratio of A = 5 and A = 12.5. The obtained Nusselt number values have been compared successfully with those of the literature. The impacts of the Rayleigh number and the aspect ratio on the velocity profiles and the convective and radiative heat transfer have been examined.

Numerical Simulation on Velocity Profiles of Mill Bearing Lubrication

2010 ◽  
Vol 145 ◽  
pp. 282-286
Author(s):  
Qing Xue Huang ◽  
Jian Mei Wang ◽  
Yu Gui Li ◽  
Li Feng Ma ◽  
Chun Jiang Zhao
Keyword(s):  
Cross Section ◽  
Velocity Profiles ◽  
Flow State ◽  
Oil Film ◽  
Velocity Gradients ◽  
Oil Flow ◽  
The Mathematical Model ◽  
The Relationship ◽  
General Velocity ◽  
Oil Film Pressure

No 460 oil-film bearing oil as the dedicated lubricant is regarded as the incompressible Newtonian fluid. To comprehensively analyze the real oil flow state, the mathematical model on velocity profiles, together with its dimensionless equations, is established, and the calculating program is developed to simulate the 3D velocity profiles and velocity gradients at different oil flow layers. The relationship between velocity profiles and the oil film pressure is discussed, and the velocity tendency is consistent with the general velocity profile of wedge cross section. The conclusions are beneficial to the further study on lubricating performances of heavy contact components and to prolong their service lives.

Experimental investigation on the momentumless wake using trailing edge blowing

2008 ◽  
Vol 222 (8) ◽  
pp. 1477-1486 ◽  
Author(s):  
Y Wu ◽  
X Zhu ◽  
Z Du
Keyword(s):  
Three Dimensional ◽  
Velocity Profiles ◽  
Axial Fan ◽  
Trailing Edge ◽  
Mean Velocity ◽  
Piv Measurement ◽  
Image Velocimetry ◽  
Velocity Spectra ◽  
Momentumless Wake ◽  
Wake Characteristics

A developed plate stator model with and without trailing edge blowing (TEB) is studied using experimental methods. Wake characteristics of flow over the stator in the three-dimensional wake regimes are studied using hot-wire anemometry (HWA) and particle image velocimetry (PIV) techniques. First, the mean velocity profiles have been measured in the wake of the stator using HWA. Four wake characteristics have been obtained through momentum thickness judgments: pure wake, weak wake, momentumless wake, and jet. These velocity profiles show some differences in momentum deficit for the four cases. Then, the velocity spectra of the pure wake and momentumless wake obtained through the HWA measurements showed that TEB can eliminate the shedding vortex of the stator. Characteristic length scales based on the wake turbulent intensity profiles showed that the momentumless wake can reduce the wake width and depth. PIV measurement is carried out to measure the flow field of the four wakes. Finally, the application of TEB approaching momentumless wake status is used on an industrial ventilation low-pressure axial fan to assess noise reduction. The results show that TEB can make the outlet of the stator uniform, reduce velocity fluctuation, destroy the vorticity structure downstream of the stator, and reduce interaction noise level of the stator and rotor.

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