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RISS 인기검색어
- 검색키워드
- 저자 : Makatar Wae-hayee (검색결과 4 건)
- 무료
- 기관 내 무료
- 유료
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Makatar Wae-hayee,Perapong Tekasakul,Smith Eiamsa-ard,Chayut Nuntadusit 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.7
An effect of cross-flow velocity on flow and heat transfer characteristics of impinging jet in the case of low jet-to-plate distance at H =2D was experimentally and numerically investigated. In the experiments, the air jet from orifice impingement on the wall of wind tunnelwhile a cross-flow was simultaneously induced normal to the jet flow. The jet velocity was fixed while the cross-flow velocity was variedcorresponding to velocity ratios (jet velocity/cross-flow velocity) VR = 3, 5 and 7. The temperature distribution on an impinged surfacewas visualized by using thermochromic liquid crystal sheet (TLCs), and Nusselt number distribution was evaluated by using image processingmethod. The flow pattern on impingement surface was visualized by using oil film technique. The numerical simulation was carriedout for a better understanding of the jet flow in the cross-flow. The results show that Nusselt number peak shifts downstream and theNusselt number peak increases with increasing cross-flow velocity.
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Effects of expansion pipe length on heat transfer enhancement of impinging jet array
Kirttayoth Yeranee,Makatar Wae-hayee,Ibroheng Piya,Yu Rao,Chayut Nuntadusit 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.5
We experimentally and numerically investigated the effect of expansion pipe length on heat transfer enhancement and flow characteristics of impinging jet array with mounting expansion pipe. The inner diameter (d) and the length of each main pipe nozzle was d = 17.2 mm and 200 mm, respectively. Nozzle arrangement was distributed in 5 rows × 5 columns with an in-line configuration. The jet-to-wall distance (H) was fixed at H/d = 8, while the jet-to-jet spacing (S) was varied at S/d = 6 and 8. The expansion pipe length (L) was varied at L/d = 4, 6 and 8, and the inner diameter of the expansion pipe (D) was fixed at D/d = 4. Reynolds number of the jets was kept constant at 30000. The conventional impinging jets were also performed to compare with the case of jets with mounting expansion pipe. The 3-D numerical simulation with v 2 -f turbulence model was applied to simulate the flow characteristics. Results showed that the surrounding air was induced into the expansion pipe, and an entrainment of induced air became greater when expansion pipe was longer. This influenced more markedly on enhancement of Nusselt number at stagnation point for narrow jet-to-jet spacing (S/d = 6).
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Heat transfer characteristics in a channel fitted with zigzag-cut baffles
Chayut Nuntadusit,Ibroheng Piya,Makatar Wae-hayee,Smith Eiamsa-ard 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.6
The heat transfer characteristics were experimentally investigated in a wind channel with different types of cut baffles for heat transferaugmentation. The aim of using zigzag-cut baffles is to create 3D flow structure behind the baffles instead of transverse vortex flow leadingto enhance heat transfer. In this study, 4 types of baffles were examined; conventional baffle (Rectangular cross section with no cut),baffle with rectangular zigzag-cut, baffle with triangle zigzag-cut at 45 degree and at 90 degree. All of the baffles have the same height atH = 15 mm and flow blocking area. In the experiment, the row of seven baffles was attached on the inner surface of wind channel. Theeffects of pitch spacing length were also investigated at baffle pitch distance P/H = 4, 6 and 8 (H: Height of baffle). The experimentswere performed at constant Reynolds number (Re) of 20000. The heat transfer patterns via Thermochromic liquid crystal sheet werevisualized and recorded with a digital camera. The recorded images were then analyzed with image processing technique to obtain thedistribution of Nusselt number. The flow characteristics pass through the baffles were also numerically studied with CFD simulation forunderstanding the heat transfer characteristics. The friction losses were measured to evaluate the thermal performance for each baffle. Itwas found that the baffle with rectangular zigzag-cut gives the best thermal performance due to heat transfer augmentation in upstreamand downstream side of baffle.
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Yan Cao,Hamdi Ayed,Samad Jafarmadar,Mir Ali Asghar Abdollahi,Ahmed Farag,Makatar Wae-hayee,Mehran Hashemian 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.98 No.-
Since the Gas Diffusion Layer (GDL) clearance and the residence time of produced water in gas channelsremarkably affect the proper operation of proton exchange membrane (PEM) Fuel Cells, the watermanagement in this part plays a key role. To this end, the present study aims to introduce novel andoptimized gas channels through geometrical modifications that act efficiently in terms of GDL clearanceand liquid residence time. For this purpose, the VOF (Volume of Fluid) model was employed tonumerically simulate two-phaseflow by means of afinite volume method. Several decisive parametersincluding superficial gas velocity, channel surface wettability, and channel cross-section geometry wereconsidered tofind their effects on the liquid removal behavior. The liquid removal performance wasanalyzed by two-phase pressure drop, area coverage ratio (ACR), and liquid removal time. Results havebeen compared with previous works done on the conventional rectangular channels. Interestingly, it wasfound out that for the analyzed segment of the gasflow channels, the channel with triangle cross-sectionhas superior performance in reducing ACR by 64% for inlet superficial air velocity of 0.5 m=s and 8–24.45%reduction for higher velocities (1, 1.5 and 2.5 m=s). Also, the transition from slugflow tofilmflow alsostable two-phase pressure drop were only seen in this type of channel. The ranking of channels based ontheir residence time merit is as: hexagon > pentagon > rectangular > triangle. Increment of the contactangle of hydrophilic walls causesfluctuations in the two-phase pressure drop and decreases liquid waterresidence time. For triangle channel, surface with a contact angle of 120 and for the hexagon andpentagon channels 85–120 is suggested for the best fuel cell performance.
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