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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.
김형모(Hyungmo Kim),이강엽(Kangyeop Lee),박부민(Poomin Park),황오식(Ohsik Hwang),양수석(Sooseok Yang),고영성(Youngsung Ko) 한국연소학회 2011 KOSCOSYMPOSIUM논문집 Vol.- No.43
Understanding flame structure and NOx formation characteristics of dual lean premixed combustor is critically important in combustor design and NOx emission performance data analysis, but is poorly understood. this problem is addressed via the study of NOx formation in actual gas turbine combustors operating on dual lean premixed natural gas/air. OH-chemiluminescence (308㎚ band filtered) methodology, direct flame temperature measurement by C-type thermocouple and two dimensional NOx measurement by gas analyzer was adopted for investigating flame structure and NOx formation characteristics. The parameters, pilot fuel mass fraction (fPF)and pilot air mass fraction(fPA),were developed to analyze the relations of each burner. These experiments focus on the effects of pilot fuel mass fraction(0~0.7), overall equivalence ratio(0.4~0.6), inlet temperature(573~653K) and residence time(0.43~5.22㎳). The results show that flames in each burner form and progress in the separated area; pilot flame forms in the pilot burner and has strong sharp edge, main flame forms from downstream of main fuel/air mixture jet due to relatively lower reaction rate than pilot flame and spreads out to fill the whole combustor chamber, even outer recirculation zone (ORZ). This experimental data clearly shows that the amount of NOx formed in a lean, homogeneous combustion system depends on the post-combustion temperature and is rarely affected by residence time.
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.
김형모(Hyungmo Kim),최영호(Youngho Choi),김동식(Dongsik Kim),박부민(Poomin Park) 한국항공우주연구원 2007 항공우주기술 Vol.6 No.1
On the stage of combustor development process, many aerodynamic and combustion characteristics are found out not by only ideal design concept but by only useful tests which are top confidentiality of technically advanced engine development companies, RR and GE, etc. In this study, test techniques of one of that company are analysed and described about some unique tests for test low emission combustors.