자연대류와 강제대류에서 펠티에 소자를 이용한 내부터널 구조를 가지는 히트싱크에 관한 연구

이민(Lee, Min),김태완(Kim, Tae-Wan) 한국산학기술학회 2014 한국산학기술학회논문지 Vol.15 No.7

펠티에 소자는 전자부품이나 장비에서 발생하는 열을 냉각하기 위한 방법으로 많이 사용되고, 히트싱크는 이러한 열을 외부로 방출하기 위한 방법으로 많이 사용되고 있다. 본 연구에서는 내부터널의 형상을 가지는 히트싱크에 대한 냉각 및 히팅성능을 자연대류와 강제대류 상태에서 열전달 특성에 대하여 고찰하였다. 또한, 시간에 따른 히트싱크의 열전달 특성 및 온도분포의 변화에 따른 실험을 수행하였고, 자연대류와 강제대류에 따른 히트싱크의 열전달 특성, 온도분포의 변화를 실험을 통해 비교 연구 하였다. 냉각 실험에서 A형상 및 B형상 냉각 핀 히트싱크는 자연대류보다는 강제대류에서 온도가 더 감소하는 것을 알 수가 있었고, 강제대류와 자연대류에서 A, B형상 모두 -15℃까지 떨어지는 것을 알 수 있었다. 전압이 증가 할수록 강제대류와 자연대류 상태에서 A, B형상 냉각 핀 히트싱크 모두 온도가 감소하였다. 히팅실험에서 A형상 및 B형상 냉각 핀 히트싱크는 자연대류보다는 강제대류에서 온도가 더 증가하는 것을 알 수가 있었고, 강제대류와 자연대류에 서 전압이 13V일 때, A형상 냉각 핀 히트싱크는 전압이 150℃, 강제대류에서 B형상 냉각 핀 히트싱크는 145℃까지 증가 하였다. 전압이 증가할수록 강제대류와 자연대류 상태에서 A, B형상 냉각 핀 히트싱크 모두 온도가 증가하였다. The Peltier Module has been used to dissipate the heat from electronic devices and electronic components. In this module, a heat sink is used to release the operating heat into the air outside. This study addressed the heat transfer characteristics for a heat sink with an inner tunnel. Under forced and natural convection conditions, the heat transfer characteristics were different. Therefore, the cooling and heating performances were studied for the heat sink, which has an inner tunnel. The heat transfer conditions were also evaluated by performing an experimental test, which investigated the heat transfer characteristics related to the variance in time and temperature distribution. Experiments on the heat transfer characteristics of the heat sink were conducted based on the forced and natural convection and temperature distribution changes. In the cooling experiment, the A- and B-shaped cooling pin heat sinks decreased the temperature of the forced convection than the temperature of natural convection. In the forced and natural convection, the A- and B-shaped decreased to a minimum of -15°C. Under the forced and natural convection conditions, A- and B-shaped cooling pin heat sinks decreased the temperature when the voltage was increased. In the heating experiment, the A- and B-shaped cooling pin heat sinks increased the temperature of the forced convection than the temperature of natural convection. In forced convection, when the voltage was 15°C, the temperature of the A-shaped cooling pin heat sink increased to 150℃, and the temperature of the B-shaped cooling pin heat sink increased to 145℃. Under forced and natural convection conditions, the A- and B-shaped cooling pin heat sinks showed an increase in temperature with increasing voltage.

A Study on the Convective Cooling Performance of the Secondary Battery in Electric Vehicle

이동렬(Dong-Ryul Lee) Korean Society for Precision Engineering 2018 한국정밀공학회지 Vol.35 No.12

This study is to investigate convection cooling performance of the Secondary Battery of Electric Vehicle without heat sink. Research is focused on the comparative study on cooling between forced convection and natural convection cooling. Selected local locations for various temperature distributions had shown in the flow domain. Final temperature on the cell surface has been compared by forced convection with natural convection. According to the results of velocity and temperature distributions in the fluid domain, Buoyancy appear by density difference in the natural convection. Apparent vortex was detected in the fluid domain for forced convection. According to calculations of convective heat transfer coefficient between cell and atmosphere in the battery pack, average value of more 70-78% heat transfer coefficient increased by forced convection than natural convection. Average temperature value of the cell surface decreased up to 46.50% by forced convection. Due to vortex by air, cooling performance of forced convection is excellent. In addition, cooling on edge of the battery is better than heat source location.

강제 대류가 있는 열소산 구조물의 구조최적설계

윤길호(Gil Ho Yoon),강남철(Namcheol Kang) 한국추진공학회 2009 한국추진공학회지 Vol.13 No.1

In this study, a new topology optimization method is developed to design heat-dissipating structure with forced convection. To cool down electrical devices or mechanical machines, two types of convection models have been widely used: the natural convection model with a large Archimedes number and the forced convection with a small Archimedes number. In these days, lots of engineering application areas such as electrochemical conversion devices (Fuel cell) or rocket propulsion engines adopt the forced convection to dissipate the generated heat. Therefore, to our knowledge, it becomes an important issue to design flow channels inside which the generated heat dissipate. Thus, this paper studies optimal topological designs considering fluid-heat interactions. To consider the effect of the advection in the heat transfer problem, the incompressible Navier-stokes equation is solved. This paper numerically studies the coupling phenomena and presents optimal channel design considering forced convection.

CFD 해석을 이용한 한국도로공사 표준 25 [W] LED 모듈의 방열 특성 분석

이세일,허인성,이아람,정민주,유영문,Lee, Se-Il,Her, In-Sung,Lee, A-Ram,Jung, Min-Joo,Yu, Young-Moon 한국전기전자재료학회 2014 전기전자재료학회논문지 Vol.27 No.8

Korea Expressway Corporation established standard of LED lighting fixture in Dec. 2013. To raise compatibility, the standard requires a fixed form and it is applied to street lights and tunnel lights, etc. Because streetlight has different circumstance condition from tunnel light that is down light and exposed to constant wind velocity over height of 8 meters, in case of LED module which has the same shape, characteristic of radiant heat can be different. In this paper, we designed 25 [W] LED Module that is designated by standard of Korea Expressway Corporation and analyzed characteristics of radiant heat about natural convection and forced convection. It is dropped 10.12[$^{\circ}C$] that max temperature is decreased by increasing 20 mm of bended height of heatsink at the condition of natural convection. Radiant heat characteristic of bended height 35 mm became 78.08[$^{\circ}C$] at the condition of natural convection, 55.30[$^{\circ}C$] at the condition of forced convection so that 22.78[$^{\circ}C$] is decreased that is 29.1[%] decrease. Bended height 55mm became 67.96[$^{\circ}C$] at the condition of natural convection, 48.04[$^{\circ}C$] at the condition of forced convection so that 19.92[$^{\circ}C$] is decreased that is 29.3% decrease.

뉴 디자인된 히트싱크의 열 유동 현상 컴퓨터 시뮬레이션

임송철,최종운,강계명,Lim Song Chul,Choi Jong Un,Kang Kae Myung 한국재료학회 2004 한국재료학회지 Vol.14 No.11

For improvement of heat dissipation performance, heat analysis is conducted on the newly designed heat sinks under two convection conditions by using computational fluid dynamics(CFD). Three types of heat sink, plate, wave and top vented wave, are used, and convection conditions are the variations of gravity direction at natural convection and of fan location at forced convection. The results of analysis showed that the heat resistances of top vented wave heat sink were $0.17^{\circ}C$/W(forced convection) and $0.48^{\circ}C$/W(natural convection). In the case of natural convection, gravity direction affected heat flow change, and protection against heat performance was superior in case of z-axis gravity direction. Under the forced convection, all the heat sinks revealed superior thermal characteristics in the fan position of z-axis rather than y-axis. In this study, it was observed that the top vented wave type heat sink showed the best ability of heat radiation comparing with the others.

저온스팀 열처리 방식에 따른 감자의 전처리 특성

최찬익(Chan-Ick Cheigh) 한국식품과학회 2014 한국식품과학회지 Vol.46 No.5

본 연구는 최근 매우 우수한 가열 매체로 인정받고 있는 저온스팀(soft steam) 열처리 공정의 natural convection (NC) 방식과 forced convection-boiler (FC-b) 및 forced convection-fan (FC-f) 방식을 이용하여 처리온도(60, 70, 80℃) 및 시간(0-60분)에 따른 감자의 전처리 특성을 비교 평가하고자 하였다. 스팀처리 방식에 따른 가열실 내부의 온도변화와 감자 내·외부의 온도변화, 감자의 cook value, ascorbic aicd 및 수분의 함량과 중량감소율의 변화를 관찰한 결과, 모든 처리조건에서 FC-b 및 FC-f의 강제대류 방식에 비해 자연대류의 NC 방식이 이들 전처리 특성에 대해 우수한 결과를 나타냄을 확인할 수 있었다. 따라서, 본 연구의 결과들은 감자의 가공 및 전처리를 위해 현재 사용되고 있는 기존의 열처리 공정에 대한 대안으로써 NC 방식 스팀처리의 높은 효율성 및 산업적 적용에 대한 가능성을 제시하고 있다. This study aimed to investigate the effects of various soft steam treatments, namely, forced convection-boiler, forced convection-fan, and natural convection, on the pretreatment characteristics of potatoes. In this study, potatoes were exposed to various cooking conditions, including steaming method, treatment time (0-60 min), and temperature (60, 70, 80℃). Then, changes in temperature, cook value, ascorbic acid content, moisture content, and weight loss in the fresh and steam-treated samples were measured and evaluated. The results clearly showed that natural convective steaming was superior to other treatments in terms of heating characteristics, cook value (FC-b: 46.4±1.7, FC-f: 21.8±1.1, NC: 52.1±1.9 min at 80℃), ascorbic acid content (FC-b: 36.5±2.7, FC-f: 28.5±2.9, NC: 48.2%±2.5% at 80oC), moisture retention (FCb: 74.6±0.8, FC-f: 71.5±0.5, NC: 77.6%±0.4% for 60 min at 80oC), and weight loss (FC-b: 13.9±0.8, FC-f: 15.6±0.6, NC: 10.6%±0.7% for 60 min at 80℃) for thermally processed potatoes.

강제대류에 의한 2차 전지의 냉각 효과에 관한 연구

김건형(Gunhyung Kim),정희도(Heedo Jung),박찬우(Chanwoo Park),이동렬(Dongryul Lee) 대한설비공학회 2015 대한설비공학회 학술발표대회논문집 Vol.2015 No.11

Recently, as demand for secondary battery has been increasing, the interest in thermal control which determine the capacity of secondary battery is growing in parallel. Following these trends, the research on thermal management system has gone along actively. In this study, after simplifying the secondary battery with attached heat-sink, the research was conducted for cooling effect on natural convection and forced convection. Also it analyzed the velocity field and temperature field via making second battery lay-out into tetragonal inlet and outlet respectively. Based on them, it is found that in case of natural convection, the temperature increases 22% than the first level and another case of forced convection, the temperature cools down by 39% than at first time. Several results with cooling effect of secondary battery could be obtained from the study.

Natural Convection Between Concentric Spheres in Electromagnetic Fields

Chung-Hyo Jung,Takahiko Tanahashi 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.6

This study performs numerical analyses for two different working fluids. One is an analysis of natural convection us-ing a model with air that is compared with the results of applied experiments. Then, it canpattern of natural convection in concentric spheres. The other is an investigation for the relationship between velocity field, electromagnetic field, and temperature field in a model with molten metal. The subject of the analysis model is the natural convection between two concentric spherical shells. In particular, a process where induced magnetic fields intensify the imposed magnetic field can be called a dynamo process. This study uses a modified B method in order to investigate the role of this induced magnetic field. This method is also compared to a Φ method that only considers magnetic field for the velocity field through applying Coriolis forces.

강제대류-적외선 리플로 솔더링시 전자조립품의 열적반응 분석

손영석,신지영 대한용접접합학회 2003 대한용접·접합학회지 Vol.21 No.6

The thermal response of electronic assemblies during forced convection-infrared reflow soldering is studied. Soldering for attaching electronic components to printed circuit boards is performed in a process oven that is equipped with porous panel heaters, through which air is injected in order to dampen temperature fluctuations in the oven which can be established by thermal buoyancy forces. Forced convection-infrared reflow soldering process with air injection is simulated using a 2-dimensional numerical model. The multimode heat transfer within the reflow oven as well as within the electronic assembly is simulated. Parametric study is also performed to study the effects of various conditions such as conveyor speed, blowing velocity, and electronic assembly emissivity on the thermal response of electronic assemblies. The results of this study can be used in the process oven design and selecting the oven operating conditions to ensure proper solder melting and solidification.

Generation Mechanisms of Convectively Induced Internal Gravity Waves in a Three-Dimensional Framework

최은호,전혜영 한국기상학회 2014 Asia-Pacific Journal of Atmospheric Sciences Vol.50 No.2

The generation mechanisms of convective gravity wavesin the stratosphere are investigated in a three-dimensional frameworkby conducting numerical simulations of four ideal storms underdifferent environmental conditions: one un-sheared and three constantlow-level sheared basic-state winds with the depth of the shearlayer of 6 km and the surface wind speeds (Us) of 8, 18, and 28 m s−1,using the Advanced Regional Prediction System (ARPS) model. Thestorms simulated under the un-sheared (Us = 0 m s−1), weakly sheared(Us = 8 and 18ms−1), and strongly sheared (Us = 28ms−1) basicstatewinds are classified into single-cell, multicell, and supercellstorms, respectively. For each storm, the wave perturbations in acontrol simulation, including nonlinearity and microphysical processes,are compared with those in quasi-linear dry simulations forced bydiabatic forcing and nonlinear forcing that are obtained from thecontrol simulation. The gravity waves generated by the two forcingterms in the quasi-linear dry simulations are out of phase with eachother for all of the storms. The gravity waves in the control simulationare represented by a linear sum of the wave perturbationsgenerated by the nonlinear forcing and diabatic forcing. This result isconsistent with the results of previous studies in a two-dimensionalframework. This implies that both forcing mechanisms are importantfor generating the convective gravity waves in the three-dimensionalframework as well. The characteristics of the three-dimensionalgravity waves in the stratosphere were determined by the spectral combinationof the forcing terms and the wave-filtering and resonancefactor that is determined from the basic-state wind and stability aswell as the vertical structure of the forcing.