http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
블록 크기 및 난류발생기 배치에 따른 수평채널내의 열전달 및 압력강하 특성에 관한 연구
서규원(Kyu-Won Seo),임종한(Jong-Han Lim),윤준규(Jun-Kyu Yoon) 한국산학기술학회 2019 한국산학기술학회논문지 Vol.20 No.4
최근 전자장비의 소형화 및, 고밀도화가 되는 반도체 집적기술의 발달로 인해 칩과 모듈에서 발생되는 내부발열량을 외부로 적절히 방출시키기 위해서 열 제어시스템 적용에 대한 연구의 중요성을 인식하고 있다. 본 연구는 SST k-ω 난류모델을 적용하여 4개의 블록이 부착한 수평채널내에서 열전달 및 압력강하 특성을 고찰하였다. CFD 해석시 적용한 매개변수는 블록 폭, 블록 높이, 열원 및 난류발생기 배치이고, 해석시 기본 경계조건은 채널 입구의 온도 및 유속은 300 K, 3.84 m/s, 열유속은 358 W/㎡으로 하였다. 그 결과로 블록 폭비율(w/h)이 증가할수록 열전달성능이 감소하는 반면에 블록 높이비(h/w)이 증가할수록 열전달특성은 증가하는 경향을 나타내었으며, 열원의 크기배열은 낮은 열유속에서 높은 열유속으로 증가시킬 수록 열원의 영향을 받아 열전달계수는 증가하는 경향을 나타냈고, 난류발생기는 채널 입구에 가까운 블록 1번 위치의 상단에 설치했을 경우가 4개의 가열블록 전체에 가장 영향을 크게 미치게 되고, 압력강하특성을 고려할 때 가장 적절한 위치로 선정할 수 있었다. Recently, as the semiconductor integration technology due to miniaturization and high density of electronic equipment have developed, it is importantly recognized the application of thermal control system in order to release inner heat generated from chips, modules, In this study, we considered the heat transfer and pressure drop characteristics in a horizontal channel with four blocks using k-ω SST turbulence model During CFD (Computational Fluid Dynamics) analysis, the parameters applied block width, block height, heat source and turbulence generator placement etc. As the boundary conditions of analysis, the channel inlet temperature and flow velocity were respectively 300 K and 3.84 m/s, the heat flux was 358 W/㎡. As a result, the heat transfer performance was decreased as the block width ratio (w/h) was increased, while it was increased as the block height ratio (h/w) was increased. In addition, as the arrangement of heat source size was increased to high heat flux from low heat flux, it was influenced by heat source size and the heat transfer coefficient showed a tendency to increase, When the turbulence generator was installed in the upper part of block No. 1 position the closely to the channel entrance, the heat transfer characteristics was greatly influenced on the whole of four heating blocks. and in oder to consider the pressure drop characteristics, we are able to select the most appropriate turbulence generator’s position.
김형주,권길광,서규원,김민철,김형섭,고준석,Kim, Hyung-Joo,Kwon, Kil-Koang,Seo, Kyu-Won,Kim, Min-Chul,Kim, Hyung-Sup,Koh, Joon-Seok 한국섬유공학회 2009 한국섬유공학회지 Vol.46 No.6
In this study, microbial degradation of lignin and pectin in raw hemp was investigated. Using lignin and pectin containing media, various microorganisms were isolated from soil and fecal samples of ruminant. The isolates were identified using the 16s rRNA method. The isolated strains were Klebsiella sp., E. coli, Aspergillus fumigatus, and Burkholderia sp. For the degradation of hemp, a pre-cultured isolate was inoculated (5% v/v) into the medium containing raw hemp (as a sole carbon source: 1% w/v) and nitrogen sources and the mixture was incubate aerobically for 168 hours in a shaking incubator (200 rev $min^{-1}$) at $30^{\circ}C$. The hemp biodegradation activity of the identified microorganism was measured by FT-IR. The FT-IR results showed that the Klebsiella sp. has the highest lignin and pectin degradation activity. These results show that the isolates and the reaction conditions could be applied to the conventional hemp fiber refinery processes.