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Experimental Performance Evaluation of a Forced Draft Sodium-to-Air Heat Exchanger in a Cross Flow
Hyungmo Kim(김형모),Byeong-Yeon Kim(김병연),Youngil Cho(조영일),Ji-Young Jeong(정지영),Jewhan Lee(이제환) 대한기계학회 2019 대한기계학회 춘추학술대회 Vol.2019 No.11
Heat transfer performance test of a sodium-to-air heat exchanger having M-shape finned-tube banks has been conducted and evaluated to validate computer codes for Prototype Generation IV Sodium-cooled Fast Reactor Development (PGSFR) in our sodium test facility. The PGSFR has decay heat removal system (DHRS) to reject the decay heat of the reactor core to the atmosphere as occasion demands including the failure of normal heat transfer path through steam generators. The active DHRS employs FHX (Forced-draft sodium-to-air heat exchanger) as the final heat sink. To evaluate the FHX performance, we designed and constructed a dedicated separate effect test facility including M-FHX having the same length and height scale with FHX in PGSFR, but the reduced power scale with 1 over 8 by reducing the number of tubes columns (i.e., total 12 tubes in 4 columns) to preserve key thermal-fluidic characteristics of FHX. In this study, we report our experimental evaluation results including uncertainty analyses on heat transfer characteristics of M-FHX.
핀-튜브 군(群)을 가지는 소듐-공기 열교환기 성능실험의 측정 불확실도 평가
김형모(Hyungmo Kim),김병연(Byeongyeon Kim),어재혁(Jaehyuk Eoh),정지영(Ji-Young Jeong) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
A reasonably developed measurement uncertainty analysis approach of a sodium-to-air heat exchanger performance test was conducted for quantified error evaluation. A heat transfer rate of sodium-to-air heat exchanger was calculated temperature and flow rate measured with instruments having some of errors. These error components could affect to the total heat transfer rate obtained the experiment, and it is very essential to determine the quantity of total error in the experiment and measuring system. Total error quantity of our heat transfer rate in the experiment was obtained through the conservative view point and reasonable procedure of measurement uncertainty analysis including the reasonable determination of error components and the error propagation to other parameters for calculation. After the determination of error components, we estimated the bias error and the precision error quantities, separately. As a result, the error quantity in the sodium-side and air-side shows -5.69 %~+3.90 % and ±10.58 %, respectively. The developed methodology for measurement uncertainty analysis can be adapted for other heat exchanger systems, and it can support to estimate error quantities of heat transfer rate in experiments.
Kim, Hyungmo,Kim, Joonwon IOP 2010 JOURNAL OF MICROMECHANICS AND MICROENGINEERING - Vol.20 No.4
<P>This paper presents the results of evaporation experiments using water droplets on aluminum sheets that were either smooth or had surface structures at the micro-scale, at the nano-scale or at both micro- and nano-scales (dual-scale). The smooth surface was a polished aluminum sheet; the surface with micro-scale structures was obtained by sandblasting; the surface with nano-scale structures was obtained using conventional aluminum anodization and the surface with dual-scale structures was prepared using sandblasting and anodization sequentially. The wetting properties and evaporation rates were measured for each surface. The evaporation rates were affected by their static and dynamic wetting properties. Evaporation on the surface with dual-scale structures was fastest and the evaporation rate was analyzed quantitatively.</P>
재조합 Corynebacterium glutamicum으로부터 헴첼 생산에 미치는 프로모터의 효과
양형모 ( Hyungmo Yang ),김필 ( Pil Kim ) 한국미생물생명공학회(구 한국산업미생물학회) 2019 한국미생물·생명공학회지 Vol.47 No.3
We published that bacterial heme was over-produced in a recombinant Corynebacterium glutamicum expressing 5-aminolevulinic acid synthase (hemA<sup>+</sup>) under control of a constitutive promoter (P<sub>180</sub>) and the heme-producing C. glutamicum had commercial potentials; as an iron feed additive for swine and as a preservative for lactic acid bacteria. To enhance the heme production, the hemA<sup>+</sup> gene was expressed under controls of various promoters in the recombinant C. glutamicum. The hemA<sup>+</sup> expression by P<sub>gapA</sub> (a constitutive glycolytic promoter of glyceraldehyde-3-phosphate dehydrogenase) led 75% increase of heme production while the expression by P<sub>H36</sub> (a constitutive, very strong synthetic promoter) resulted in 50% decrease compared with the control (hemA<sup>+</sup> expression by P180 constitutive promoter). The hemA<sup>+</sup> expression by a late log-phase activating P<sub>sod</sub> (an oxidative-stress responding promoter of superoxide dismutase) led 50% greater heme production than the control. The hemA<sup>+</sup> expression led by a heat-shock responding chaperone promoter (P<sub>dnaK</sub>) resulted in 121% increase of heme production at the optimized heat-shock conditions. The promoter strength and induction phase are discussed based on the results for the heme production at an industrial scale.
김형모(Hyungmo Kim),이현석(Hyunsuk Lee),박부민(Poomin Park),양수석(Sooseok Yang) 한국추진공학회 2014 한국추진공학회 학술대회논문집 Vol.2014 No.12
두 개의 액체를 수직 충돌시켜 분무를 형성하는 핀틀 인젝터의 특성을 파악하기 위하여 본 연구에서는 모사 추진제인 물을 이용하여 압력범위 1~5bar에서 슬릿형, 원형, 사각형 등의 다양한 인젝터들에 대하여 모멘텀비에 따른 분무의 형상 및 분무의 발달과정을 쉐도우 기법을 이용하여 관찰하였다. 운동량비로 예측된 분무의 각도와 실제 시험에서 관찰된 각도는 약 10도 이내의 차이를 보이고 있음을 확인하였다. Spray test on pintle injectors which make spray by colliding two stream in right angle was carried out using water as a simulating medium for liquid propellant. Spay shape and development procedure with respect to momentum ratio were observed for pressure range 1~5 bar(g) on circular, rectangular, and slit shape hole injectors by shadow imaging method. The discrepancy between predicted and observed spray angle was about 10 degrees.