• Title/Summary/Keyword: Heat exchanger

Search Result 2,436, Processing Time 0.03 seconds

Research of High Efficiency Integrated Reforming System Using Separated Reforming System (분리형 개질기를 이용한 고효율 일체형 개질기 개발에 관한 연구)

  • PARK, SANG-HYOUN;KIM, CHUL-MIN;SON, SUNG-HYO;JANG, SE-JIN;KIM, JAE-DONG;BANG, WAN-KEUN;LEE, SANG-YONG
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.29 no.1
    • /
    • pp.11-18
    • /
    • 2018
  • A high efficiency integrated reforming system for improving the efficiency of the 5 kW PEMFC system used as the back up power of building was studied. The separated reforming system consisted of three parts - A steam reformer with two stage concentric circular shape, a heat exchanger type steam generator and a CO shift reactor. Temperature and steam carbon ratio (SCR) were control variables during operation. The operating conditions were optimized based on the thermal efficiency of the steam reformer as reformate gas composition changes at different temperature. In experiments, water was fully vaporized in the steam generator up to SCR 3.5 and the maximum thermal efficiency was achieved at the operating temperature around $700^{\circ}C$ in the steam reforming reactor. With the results of the separated reforming system research, we improved the shape of high efficiency integrated reformer. The performance evaluation of the integrated reformer was based on optimized operating conditions in SCR 3.5. As a result, the developed integrated reforming system maintained an efficiency of 76% and constant performance over 3,000 hours.

Seismic Response Amplification Factors of Nuclear Power Plants for Seismic Performance Evaluation of Structures and Equipment due to High-frequency Earthquakes (구조물 및 기기의 내진성능 평가를 위한 고주파수 지진에 의한 원자력발전소의 지진응답 증폭계수)

  • Eem, Seung-Hyun;Choi, In-Kil;Jeon, Bub-Gyu;Kwag, Shinyoung
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.24 no.3
    • /
    • pp.123-128
    • /
    • 2020
  • Analysis of the 2016 Gyeongju earthquake and the 2017 Pohang earthquake showed the characteristics of a typical high-frequency earthquake with many high-frequency components, short time strong motion duration, and large peak ground acceleration relative to the magnitude of the earthquake. Domestic nuclear power plants were designed and evaluated based on NRC's Regulatory Guide 1.60 design response spectrum, which had a great deal of energy in the low-frequency range. Therefore, nuclear power plants should carry out seismic verification and seismic performance evaluation of systems, structures, and components by reflecting the domestic characteristics of earthquakes. In this study, high-frequency amplification factors that can be used for seismic verification and seismic performance evaluation of nuclear power plant systems, structures, and equipment were analyzed. In order to analyze the high-frequency amplification factor, five sets of seismic time history were generated, which were matched with the uniform hazard response spectrum to reflect the characteristics of domestic earthquake motion. The nuclear power plant was subjected to seismic analysis for the construction of the Korean standard nuclear power plant, OPR1000, which is a reactor building, an auxiliary building assembly, a component cooling water heat exchanger building, and an essential service water building. Based on the results of the seismic analysis, a high-frequency amplification factor was derived upon the calculation of the floor response spectrum of the important locations of nuclear power plants. The high-frequency amplification factor can be effectively used for the seismic verification and seismic performance evaluation of electric equipment which are sensitive to high-frequency earthquakes.

Development of Eddy Current Test Probe for Profilometry Inspection of Tube (원형튜브 단면형상검사용 와전류탐촉자 개발)

  • Lee, H.J.;Nam, M.W.;Lee, C.H.
    • Journal of the Korean Society for Nondestructive Testing
    • /
    • v.17 no.4
    • /
    • pp.262-269
    • /
    • 1997
  • An eddy current probe ($8{\times}1$ multiple-element, surface scan) was successfully designed and fabricated at the KEPRI using the impedance equivalent circuit theory. The probe is intended for the detection of circumferential deformations (cross-section view) of the heat exchanger tubing that can occur due to corrosion, erosion, and denting. Optimum design parameters providing the highest sensitivity and signal-to-noise ratio, such as the coil dimensions, electrical characteristics, and test frequencies, were determined based on initial laboratory experiments conducted on the test specimen (SS304 tubing: OD : 9.68mm, wall-thickness : 0.47mm) containing artificial flaws (e.g., dents and corroded surface on tube OD) using the available Zetec-made probe. Using this parameters, a new probe was made and tested on an unknown specimen. The result indicated that the new probe is capable of detecting the circumferential deformation with the error of ${\pm}0.2%$ (0.022mm) of the tube O.D.

  • PDF

Development of Automatic Measurement and Control Method based on Single Chip Microcomputer for Tackjoo Fermentation (Single Chip Microcomputer를 이용한 탁주발효(濁酒醱酵)의 자동계측(自動計測)과 제어방법(制御方法)의 개발(開發))

  • Kim, Kyung-Man;Chun, Jae-Kun
    • Korean Journal of Food Science and Technology
    • /
    • v.25 no.4
    • /
    • pp.391-394
    • /
    • 1993
  • For the automation of Tackjoo fermentation, a sensor measurable gas production during brewing and a controller were built. The performance tests were carried out at 10 litter Tackjoo fermentor, The sensor was consisted of a transparent acryl cell for bubble formation and photo-interrupter for the detection of bubbles of 0.018ml size. The fermentation controller was fabricated with a single chip microcomputer (MC68705R3) and provided with both the monitoring module of temperature measurement and the valve controling device for the cooling water circulation in coil type heat exchanger. The operation programs were developed and systemized in ROM. With this computer system, the gas production amount and rate were acquired during the Tackjoo fermentation. The fermentation curve based on the gas production rate showed a good agreement with that of alcohol concentration. The maximum rate of gas production was found after 24 hr at $30^{\circ}C$. The correlation equation between the gas production and alcohol concentration was established and used as the control algorithm of the fermentation.

  • PDF

Construction of a High-Altitude Ignition Test Facility for a Small Gas-turbine Combustor (소형 가스터빈 연소기 고공환경 점화 시험 설비 구축 및 검증 실험)

  • Kim, Tae-Woan;Lee, Yang-Suk;Kim, Ki-Woo;Kim, Bo-Yean;Ko, Young-Sung;Kim, Sun-Jin;Kim, Hyung-Mo;Jung, Yong-Wun
    • Journal of the Korean Society of Propulsion Engineers
    • /
    • v.14 no.3
    • /
    • pp.61-68
    • /
    • 2010
  • A small high altitude test facility has been developed to investigate ignition performance of a small gas-turbine combustor under high altitude conditions. Supersonic diffusers and a heat exchanger were used to perform a low pressure and a low temperature condition, respectively. Experimental results showed that the low pressure environment could be controlled by upstream pressure of primary nozzle flow and low temperature environment by mixture ratio of cooled air and ambient air. Ignition performance tests were performed to verify the performance of the facility under simulated high altitude conditions. Conclusively, it was proven that the test facility could be used for ignition performance test of a small gas-turbine combustor under high altitude condition of approximately 6,100m.

반도체 및 Optic Industries 클린룸 배기가스의 오염제어 및 청정화기술

  • 황유성
    • Air Cleaning Technology
    • /
    • v.17 no.4 s.67
    • /
    • pp.39-57
    • /
    • 2004
  • 첨단산업으로 불리는 반도체, LCD, PDP, 유기EL(OLED) 등의 생산 공정은 고도의 청정상태를 요구하며, 때문에 이들의 생산공정 중 대부분이 클린룸 내에서 이루어진다. 클린룸 내에서의 주요공정은 크게 박막형성(Layering), 노광(Photo Lithography), 식각(Etching) 등 3가지 공정으로 나눌 수 있으며, 반도체 제조공정의 경우 특별히 도핑(Doping) 공정이 추가된다. 오염물질을 함유하는 클린룸 배기는 일반적으로 산, 알칼리, Toxic(PFCs, Flammable), VOC 등으로 분류하며, 각각의 배기는 각 배기특성에 맞는 오염제어 장치를 통해, 정화된 후, 대기로 방출된다. 산, 알칼리 배기는 일반적으로 최종 단계에서 중앙집중식 습식스크러버에 의해 흡수, 중화 처리되며, VOC의 경우 농축기(Concentrator) & 축열식 열 산화장치(RTO) 설비에 의해 연소 처리된다. 하지만 CVD공정으로부터의 배기가 주를 이루는 Toxic배기의 경우, 다량의 PFCs(과불소화합물) 가스를 함유하고 있는 이유로, 대부분 클린룸 내부에 P.O.U(Point of use) 처리장치가 설치되며, P.O.U에 의해 1차 처리된 후 최종적으로 중앙집중식 습식스크러버를 거쳐 대기로 방출된다. 알칼리배기의 주성분으로는 암모니아($NH_3$), HMDS (Hexa Methyl DiSilazane), TMAH (Tetra Methyl Ammonium Hydroxide), LGL, CD 등이며 흡수액에 황산(Sulfuric Acid)용액을 공급, 중화처리하고 있다. 탄소성분을 먹이로 하는 미생물의 번식에 의한 막힘 문제를 제외하고는 큰 문제가 없다. 하지만 Toxic배기 및 산배기의 경우 처리효율이, 가스흡수 이론에 의한 계산결과와 비교할 때, 매우 저조하게 나타나는 효율부족 현상을 겪고 있으며, 이는 잔여 PFCs 가스성분 및 반응에어로졸, 응축에어로졸 등의 영향으로 추정하고 있다. 최근 Toxic 배기의 경우, P.O.U 설비를 Burn & Wet type으로 변경하여, 배기 중 PFCs 및 반응에 에어로졸($SiO_2$)의 농도를 원천적으로 감소시키는 노력이 진행 중이다. 산배기의 경우, 산결로 현상에 의한, 응축에어로졸이 문제가 되고 있으나 내식열교환기(Anti-Corrosive Heat Exchanger), 하전액적스크러버 시스템(Charged Droplets Scrubber System), Wet ESP(Wet Electrostatic Procipitator) 등의 도입을 통해 문제해결을 위한 노력을 경주하고 있다.

  • PDF

Evaluation of Fatigue Life on Alloy 617 Base Metal and Alloy 617/Alloy 617 Weld Joints under Low Cycle Fatigue Loading (저사이클피로 하중하의 Alloy 617 모재와 용접부재에 대한 피로 수명 평가)

  • Dewa, Rando Tungga;Kim, Seon-Jin;Kim, Woo-Gon;Kim, Min-Hwan
    • Journal of Power System Engineering
    • /
    • v.18 no.5
    • /
    • pp.122-128
    • /
    • 2014
  • Generally, the mechanical components and structures are joined by many welding techniques, and therefore the welded joints are inevitable in the construction of structures. The Alloy 617 was initially developed for high temperature applications above $800^{\circ}C$. It is often considered for use in aircraft and gas turbines, chemical manufacturing components, and power generation structures. Especially, the Alloy 617 is the primary candidate for construction of intermediate heat exchanger (IHX) on a very high temperature reactor (VHTR) system. In the present paper, the low cycle fatigue (LCF) life of Alloy 617 base metal (BM) and the gas tungsten arc welded (GTAWed) weld joints (WJ) are evaluated by using the previous experimental results under strain controlled LCF tests. The LCF tests have been performed at room temperature with total strain ranges of 0.6, 0.9, 1.2 and 1.5%. The LCF lives for the BM and WJ have been evaluated from the Coffin-Manson and strain energy based life methods. For both the BM and WJ, the LCF lives predicted by both Coffin-Manson and strain energy based life methods was found to well coincide with the experimental data.

Development of Remote Field Eddy Current Pipeline Inspection System (원격장 와전류 배관 탐상 시스템 개발)

  • Jeong, Jin-Oh;Yi, Jae-Kyung;Kim, Hyoung-Jean
    • Journal of the Korean Society for Nondestructive Testing
    • /
    • v.21 no.5
    • /
    • pp.556-560
    • /
    • 2001
  • Remote field eddy current testing (RFECT) with through-wall transmission characteristic is being applied to pipes ranging from small tubes of heat exchanger to natural gas supply pipelines. Cast iron pipes with nominal diameter of 100mm are used primarily as the waterline pipes. The leakage of water occurs due to defects in the pipes caused by vibration of automobiles and corrosion. But, the use of direct inspection methods such as insertion of inspection equipment inside the pipelines has been limited due to its lack of economical efficiency. Economical development of inspection equipments is possible since RFECT method can be easily employed for system integration and quantitative evaluation of both inside and outside defects. In this study, the development of underground pipeline inspection system was tarried out by using RFECT method in consideration of the characteristics of waterline network. This paper specifically describes the design and production of RFECT pipeline inspection pig using centralizer mechanism, development of remote field eddy current signal acquisition and processing software, and review of RFECT system operation procedures.

  • PDF

Required Pressurant Mass for Cryogenic Propellant Tank with Pressurant Temperature Variation (가압가스 온도에 따른 극저온 추진제탱크 가압가스 요구량)

  • Kwon, Oh-Sung;Kim, Byung-Hun;Cho, In-Hyun;Ko, Young-Sung
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.38 no.12
    • /
    • pp.1202-1208
    • /
    • 2010
  • The prediction of the required pressurant mass for maintaining the pressure of propellant tanks during propellant feeding is an important issue in designing pressurization system. The temperature of pressurant fed into propellant tank is the critical factor in the required pressurant mass and is one of the most crucial design parameters in the development of pressurization system including designing the weight of pressurant tanks and the size of heat exchanger. Hence a series of propellant drainage tests by pressurizing propellant stored in a cryogenic propellant tank have been performed with measuring the temperature distribution inside ullage and the required pressurant mass according to the temperature condition of pressurant. Results shows that the required pressurant mass decreases as the temperature of pressurant increases. However, the rate of the actual pressurant mass to the ideal required pressurant mass increases.

Experimental Study of a Recuperator with Offset Strip Fins (오프셋 스트립 휜을 가지는 리큐퍼레이터에 대한 실험적 연구)

  • Kim, Taehoon;Do, Kyu Hyung;Han, Yong-Shik;Choi, Byung-Il;Kim, Myungbae
    • Journal of Energy Engineering
    • /
    • v.24 no.2
    • /
    • pp.72-78
    • /
    • 2015
  • In the present study, a recuperator to improve the thermal efficiency of a micro gas turbine is considered. The counter flow plate-fin heat exchanger with offset strip fins is chosen as the type of the recuperator. From the optimization study as varying design parameters of the recuperator determined from the ideal cycle analysis, the internal structure of the recuperator is determined. The recuperator is made from stainless steel 304. In order to evaluate performance of the recuperator, experimental investigation is performed. The effects of inlet temperature of hot-side of the recuperator on the thermal performance of the recuperator are investigated. As a result, effectiveness of the recuperator obtained from the experiments is well consistent with that obtained from the correlations.