scholarly journals The effect of channel aspect ratio on flow boiling characteristics within rectangular micro-passages

2021 ◽  
pp. 122201
Author(s):  
Manolia Andredaki ◽  
Konstantinos Vontas ◽  
Anastasios Georgoulas ◽  
Nicolas Miché ◽  
Marco Marengo
Keyword(s):  
Aspect Ratio ◽  
Flow Boiling ◽  
Channel Aspect Ratio

scholarly journals Effect of Channel Aspect Ratio on Flow Boiling Characteristics within Rectangular Micro-passages

2020 ◽  
Author(s):  
Manolia Andredaki ◽  
Konstantinos Vontas ◽  
Anastasios Georgoulas ◽  
Nico Miché ◽  
Marco Marengo
Keyword(s):  
Aspect Ratio ◽  
Flow Boiling ◽  
Channel Aspect Ratio

Confined Bubble and Heat Transfer during Flow Boiling in a High Aspect Ratio Mini-Channel

2011 ◽  
Vol 312-315 ◽  
pp. 548-553 ◽  
Author(s):  
Yuan Wang ◽  
Khellil Sefiane
Keyword(s):  
Heat Transfer ◽  
Aspect Ratio ◽  
Bubble Growth ◽  
Flow Boiling ◽  
Critical Time ◽  
Heat Fluxes ◽  
Equivalent Radius ◽  
Mass Fluxes ◽  
Transfer Mechanisms ◽  
Working Liquid

Single vapour bubble growth and heat transfer mechanism during flow boiling in a rectangular horizontal mini-channel were experimentally investigated. The hydraulic diameter of the channel was 1454 μm, with an aspect ratio (Win/din) of 10. Degassed FC-72 was used as the working liquid. In this paper, bubble equivalent radius was found to increase linearly till a critical time, beyond which the growth turned into exponential. Bubble growth rate increases with increasing heat flux. Heat transfer mechanisms of the bubble growth at different heat fluxes and mass fluxes were discussed. In addition, the relation between thermal and flow conditions with bubble temporal geometry was explored.

Effects of Packing and Aspect Ratio on Mixing and Heterogeneous Catalysis in Microchannels

2007 ◽  
Author(s):  
Robert T. Bailey ◽  
Stephen Ryan ◽  
Frank Jones ◽  
Stephanie Wilson ◽  
James Hiestand
Keyword(s):  
Heterogeneous Catalysis ◽  
Aspect Ratio ◽  
Computational Models ◽  
Chemical Conversion ◽  
Reynolds Numbers ◽  
Mixing Efficiency ◽  
Substantial Impact ◽  
Channel One ◽  
Aqueous Streams ◽  
Channel Aspect Ratio

Many industrial chemical processes involve the mixing of two or more liquids. By reducing chemical reactors to microscale dimensions, engineers seek to take advantage of decreased diffusion lengths, leading to increased effectiveness (e.g., higher purity of product) over larger process components. In this study, computational models developed using the commercial multiphysics code CFD-ACE+ are used to predict flow within microreactor channels. Two aqueous streams enter a channel—one containing a contaminant and the other devoid of the contaminant. Changes in two geometric attributes are investigated with respect to their effect on mixing of the streams: 1) packing feature layout within the channel and 2) channel aspect ratio. Reynolds numbers (Re) for the simulations range between 0.1 and 100. Results indicate that both packing feature position within the channel and channel aspect ratio can have a substantial impact on mixing. Between Re = 0.1 and Re = 1, mixing efficiency generally decreases with increasing Re; however, as the Re is increased from 1 to 100, fluid flow patterns in the channel are altered, and wake regions and streamline changes created by the packing features lead to improved mixing. Examples showing enhanced chemical conversion during heterogeneous catalysis as a result of better mixing are also presented.

scholarly journals Influence of channel aspect ratio on the onset of purely-elastic flow instabilities in three-dimensional planar cross-slots

2016 ◽  
Vol 227 ◽  
pp. 65-79 ◽  
Author(s):  
F.A. Cruz ◽  
R.J. Poole ◽  
A.M. Afonso ◽  
F.T. Pinho ◽  
P.J. Oliveira ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Three Dimensional ◽  
Flow Instabilities ◽  
Channel Aspect Ratio

The effect of channel aspect ratio on air entrapment during imbibition in soil-on-a-chip micromodels with 2D and 2.5D pore structures

Lab on a Chip ◽  
2021 ◽  
Author(s):  
Chia-Wen Tsao ◽  
Qun-Zhan Huang ◽  
Chang-Ye You ◽  
Markus Hilpert ◽  
Shao-Yiu Hsu ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Adhesive Bonding ◽  
Film Flow ◽  
Ct Images ◽  
Cnc Machining ◽  
Air Entrapment ◽  
Dry Adhesive ◽  
X Ray ◽  
Piston Displacement ◽  
Channel Aspect Ratio

“Soil-on-a-chip” micromodels designed with X-ray CT images were fabricated by tabletop CNC machining and dry adhesive bonding. The competition between film flow and piston displacement causes the air entrapment differences in 2D and 2.5D micromodels.

Thermohydrodynamic Performance Evaluation of Recharging, Interrupted and Simple Microchannels: A Comparative Study

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Sangram Kumar Samal ◽  
Manoj Kumar Moharana
Keyword(s):  
Heat Transfer ◽  
Aspect Ratio ◽  
Three Dimensional ◽  
High Heat ◽  
Heat Sinks ◽  
High Heat Flux ◽  
Transverse Wall ◽  
Performance Factor ◽  
Channel Aspect Ratio ◽  
Small Channels

Abstract In this study, a three-dimensional numerical investigation on the thermohydrodynamic performance of a recently proposed recharging microchannel (RMC) is carried out. In this design, a straight microchannel is split into more than one smaller length channels (having individual inlet and outlet) placed end to end. This design enhances overall heat transfer and maintains temperature uniformity across the substrate length. The comparison of fluid flow and heat transfer performance of RMC, interrupted microchannel (IMC) and straight microchannel (SMC) with the same hydraulic diameter and substrate length are presented to explore the effect of geometrical configuration on heat transfer enhancement. The parametric variations include the number of channels (n), transverse wall length (Ltw), channel aspect ratio (α), and flow Reynolds number. The results reveal that recharging microchannel shows better thermal performance compared to simple and interrupted microchannel with a maximum performance factor of 1.80. The results also indicate that the performance factor of RMC increases with an increase in the number of small channels, transverse wall length, and channel aspect ratio. The outcome of this study indicates the possible use of recharging microchannel heat sinks for high heat flux removal applications such as electronic cooling.

scholarly journals Fluid Flow and Entropy Generation Analysis of Al2O3–Water Nanofluid in Microchannel Plate Fin Heat Sinks

Entropy ◽  
2019 ◽  
Vol 21 (8) ◽  
pp. 739 ◽  
Author(s):  
Hao Ma ◽  
Zhipeng Duan ◽  
Liangbin Su ◽  
Xiaoru Ning ◽  
Jiao Bai ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Aspect Ratio ◽  
Entropy Generation ◽  
Volume Fraction ◽  
Microchannel Plate ◽  
Heat Sinks ◽  
Entropy Generation Rate ◽  
Nanoparticle Volume Fraction ◽  
Channel Aspect Ratio

The flow in channels of microdevices is usually in the developing regime. Three-dimensional laminar flow characteristics of a nanofluid in microchannel plate fin heat sinks are investigated numerically in this paper. Deionized water and Al2O3–water nanofluid are employed as the cooling fluid in our work. The effects of the Reynolds number (100 < Re < 1000), channel aspect ratio (0 < ε < 1), and nanoparticle volume fraction (0.5% < Φ < 5%) on pressure drop and entropy generation in microchannel plate fin heat sinks are examined in detail. Herein, the general expression of the entropy generation rate considering entrance effects is developed. The results revealed that the frictional entropy generation and pressure drop increase as nanoparticle volume fraction and Reynolds number increase, while decrease as the channel aspect ratio increases. When the nanoparticle volume fraction increases from 0 to 3% at Re = 500, the pressure drop of microchannel plate fin heat sinks with ε = 0.5 increases by 9%. It is demonstrated that the effect of the entrance region is crucial for evaluating the performance of microchannel plate fin heat sinks. The study may shed some light on the design and optimization of microchannel heat sinks.

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