• Journal of Fisheries and Marine Sciences Education
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• v.25 no.5
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• pp.1102-1109
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• 2013

An numerical analysis was performed to obtain the design parameters for parallel micro-channels. The parallel micro-channels consist of 10 square channels with a hydraulic diameter of 300 ${\mu}m$ and inlet/outlet manifolds. The channel length is 5mm, 10mm and 40mm respectively. Mass flux was set between 200~600kg/m2s as inlet boundary condition and atmospheric pressure was set as outlet boundary condition. The pressure drop in channels and manifolds were estimated by using the Shah and London correlation and the flow uniformity was represented by the velocity distributions with dimensionless velocity. The results show that the flow uniformity in channels depends on shapes of manifolds, length and mass flux.

• Journal of Fisheries and Marine Sciences Education
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• v.26 no.5
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• pp.1090-1095
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• 2014

The experimental and numerical studies of the single-phase flow pressure drop in parallel micro-channels were performed. The parallel micro-channels consisted of 15 channels with depth 0.2mm, width 0.45mm and length 60mm. The FC-72 was used as the working fluid and the mass fluxes ranged from 62.8 to $1371.6kg/m^2s$. The numerical analysis was performed iterative calculations to solve governing equations and finds the appropriate value. The experimental data was compared with the numerical data, the results showed good agreement with the numerical data.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.5
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• pp.640-651
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• 2000

For the heat and fluid flow analyses of a parallel flow heat exchanger, an improved model considering the effect of flat tube with micro-channels is proposed. The effect of flow distribution on the thermal performance of a heat exchanger is numerically investigated. The flow distribution is examined by varying geometrical parameters, i.e., the position of the separators and the inlet/outlet, and the aspect ratio of micro-channels of the heat exchanger. The flow nonuniformities along the paths of the heat exchanger are proposed and observed to evaluate the thermal performance of the heat exchanger. The optimization using ALM method has been accomplished by minimizing the flow nonuniformity. It is found that the heat transfer rate of the optimized model is increased by 6.0% of that of the reference heat exchanger model, and the pressure drop by 0.4%

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.7
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• pp.821-827
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• 2014

In this study, an experimental study was performed to predict the two-phase frictional pressure drop of FC-72 in parallel micro-channels. The parallel micro-channels consist of 15 channels with depth 0.2 mm, width 0.45 mm and length 60 mm. And tests were performed in the ranges of mass fluxes from 152.2 to $584.2kg/m^2s$ and heat fluxes from 7.5 to $28.3kW/m^2$. The experimental data was compared and analyzed with existing correlations to predict the pressure drop. The existing methods to predict the pressure drop used the homogeneous model and the separated model. In this study, the new correlation was proposed by modified existing correlation using the separated model, and the new correlation predicted consequently with the experimental data within MAE of 9.6%.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.9
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• pp.1032-1038
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• 2014

In this study, an experimental study was performed to understand the boiling heat transfer characteristics of FC-72 in parallel micro-channels. The parallel micro-channels contained channels having a $0.2mm{\times}0.45mm$ [$H{\times}W$] cross section and length of 60 mm. And heat flux was varied from 16.4 to $25.6kW/m^2$ and mass fluxes from 300 to $500kg/m^2s$. The measured heat transfer coefficient was sharply decreased at lower vapor quality and then it was kept approximately constant as the vapor quality is increased. From the experimental results, the boiling heat transfer mechanism of FC-72 was confirmed and the measured heat transfer coefficient was compared and analyzed with the existing correlations to predict the heat transfer coefficient.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1079-1083
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• 2009

In this study, the distribution of $CO_2$ in an evaporator with 10 parallel micro channel aluminum tubes are experimentally investigated. Each tube has 6 circular micro channels with a diameter of 0.8mm. The tubes are heated with electric resistance wires, and the distribution of $CO_2$ into each tube is investigated by measuring the outer wall temperature. The outer wall temperature was found to be higher at the exit part of the top tube. It is thought that the $CO_2$ vapor at the upper part of the header reduces the mass flow rate of $CO_2$ into the top tube.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.12
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• pp.1784-1792
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• 2001

Numerical analysis on a parallel flow heat exchanger(PFHE) is performed using 2 dimensional turbulent porous modeling. This modeling can consider three-dimensional configuration of passage (flat tube with micro-channels), and the stability and accuracy of numerical results are improved. The geometrical parameters(e.g., the position of separators, inlet/outlet, and porosity of passages of a PFHE) are varied in order to examine the flow and thermal characteristics and flow distribution of the single phase multiple passages system. The flow non-uniformities along the paths of the PFHE are observed to evaluate the thermal performance of the heat exchanger. The location of inlet affects the heat transfer, and the location of outlet affects the pressure drop. The porosity with the optimum thermal performance is around 0.53.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.6
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• pp.774-782
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• 2004

This article presents a numerical and experimental investigation for the single-phase forced laminar convective heat transfer through arrays of micro-channels in micro heat exchangers to be used for cooling power-intensive semiconductor packages, especially the stacked multi-chip modules. In the numerical analysis, a parametric study was carried out for the parameters affecting the efficiency of heat transfer in the flow of coolants through parallel rectangular micro-channels. In the experimental study, the cooling performance of the micro heat exchanger was tested on prototypes of stacked multi-chip modules with difference channel dimensions. The simulation results and the experiment data were acceptably accordant within a wide range of design variations, suggesting the numerical procedure as a useful method for designing the cooling mechanism in stacked multi-chip packages and similar electronic applications.

• Design & Manufacturing
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• v.16 no.3
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• pp.58-65
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• 2022

Micro-fluidic chip has been fabricated by lithography process on silicon or glass wafer, casting using PDMS, injection molding of thermoplastics or 3D printing, etc. Among these processes, 3D printing can fabricate micro-fluidic chip directly from the design without master or template for fluidic channel fabricated previously. Due to this direct printing, 3D printing provides very fast and economical method for prototyping micro-fluidic chip comparing to conventional fabrication process such as lithography, PDMS casting or injection molding. Although 3D printing is now used more extensively due to this fast and cheap process done automatically by single printing machine, there are some issues on accuracy or surface characteristics, etc. The accuracy of the shape and size of the micro-channel is limited by the resolution of the printing and printing direction or layering direction in case of SLM type of 3D printing using UV curable resin. In this study, the printing direction and thickness of each printing layer are investigated to see the effect on the size, shape and surface of the micro-channel. A set of micro-channels with different size was designed and arrayed orthogonal. Micro-fluidic chips are 3D printed in different directions to the micro-channel, orthogonal, parallel, or skewed. The shape of the cross-section of the micro-channel and the surface of the micro-channel are photographed using optical microscopy. From a series of experiments, an optimal printing direction and process conditions are investigated for 3D printing of micro-fluidic chip.

• Journal of the Korean Electrochemical Society
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• v.10 no.4
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• pp.245-251
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• 2007

The performance of fuel cell is enhanced with increasing reaction surface. Narrow flow channels in flow plate cause increased pumping power. Therefore it is very important to consider the pressure drops in the flow channel of fuel cell. Previous research for pressure drop for micro channel of fuel cell was focused on effects of various configuration of flow channel without electrochemical reaction. It is very important to know pressure loss of micro flow channel with electrochemical reaction because fluid density in micro channel is changed due to chemical reaction. In this paper, it is investigated that the pressure drops in micro channel of various geometries at anode and cathode with electrochemical reaction and compared them to friction coefficient (fRe), velocity, pressure losses for corresponding non reacting flow channel. The results show that friction factors for cold flow channel could be used for parallel and bended flow channel for flow channel design of fuel cell. In the other hand, pressure drop for serpentine flow channel is the lowest among flow channels due to bypass flow across gas diffusion layer under reacting flow condition although its pressure drop is highest for cold flow condition.