• Title/Summary/Keyword: Turbine efficiency

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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
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    • v.24 no.2
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    • pp.72-78
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    • 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.

Damage Tolerance Analysis Using Surrogate Model (근사모델을 사용한 손상허용해석)

  • Jang, Byung-Wook;Im, Jae-Hyuk;Park, Jung-Sun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.39 no.4
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    • pp.306-313
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    • 2011
  • The damage tolerance analysis is required to guarantee the structural safety and the reliability for aircraft components. The damage tolerance method, which evaluate the life considering the initial crack, considers a fatigue design model of the aircraft main structure. The fatigue crack growth life should be calculated in damage tolerance analysis and the inspection time to define the replacement cycle. In this paper, the damage tolerance analysis is performed for a turbine wheel which has complex geometry. The equation of the stress intensity factor for complex geometry is hard to know, so that they are usually processed by finite element analysis which takes long time. To solve this problem, the stress intensity factors at specified crack are obtained by the FEA and the crack growth life is evaluated using the surrogate model which is generated by the regression analysis of the FEA data. From the results, the efficiency of the crack growth life calculation and the damage tolerance analysis could be increased by taking the surrogate model.

A Study on the high Temperature Properties of the Graded Thermal Barrier Coatings by APS and PAS (APS법으로 제조된 열장벽 피막과 PAS법으로 제조된 열장벽 성형체의 고온 물성에 관한 연구)

  • 강현욱;권현옥;한주철;송요승;홍상희;허성강;김선화
    • Journal of the Korean institute of surface engineering
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    • v.32 no.2
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    • pp.144-156
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    • 1999
  • Thermal Barrier Coating with Functional Gradient Materials (FGM-TBC) can play an important role to protect the parts from harmful environments in high temperatures such as oxidation, corrosion, and wear and to improve the efficiency of aircraft engine by lowering the surface temperature on turbine blade. FGM-TBC can increase the life spans of product and improve the operating properties. Therfore, in this study the evaluations of mechanical and thermal properties of FGM-TBC such as fatigue, oxidation and wear-resistance at high temperatures have been conducted. The samples of both the TBC with 2, 3, 5 layers (YSZ/NiCrAlY) to be produced by Air Plasma Spray method (APS) and the bulk TBC with 6 layers to be produced by Plasma Assisted Sintering method (PAS) were used. Furthermore, residual stress, bond strength, and thermal conductivity were evaluated. The average thickness of the APS was 500$\mu\textrm{m}$ to 600$\mu\textrm{m}$ and the average thickness of the PAS was 3mm. The hardness number of the top layer of APS was 750 Hv to 810Hv and that of PAS was 950 Hv to 1440Hv. The $ZrO_2$ coating layer of APS was composed of tetragonal structure after spraying as the result of XRD analysis. As shown in the results of the high temperature wear test, the 3 layer coating of APS had the best wear resistance at $800^{\circ}C$ and the 5 layer coating of APS had the best wear resistance at $600^{\circ}C$. But, these coatings had the tendency of the low-temperature softening at $300^{\circ}C$. The main mechanism of wear was the adhesive wear and the friction coefficient of coatings was increased as increasing the test temperatures. A s results of thermal conductivity test, the ${\Delta}T$ of the APS coating was increased as number of layer and the range of thermal conductivity of the PAS was $800^{\circ}C$ to $1000^{\circ}C$.

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An Experimental Study on the Effect of Swirler Mass Flowrate and Flare Exit Length on Flow Patterns inside a Model Combustor Chamber (스월러 플레어 출구길이가 모델 챔버내 유동에 미치는 영향에 대한 실험적 연구)

  • Ryu, Gyong Won;Jin, Yu In;Kim, Yeong Ryon;Kim, Hong Jip
    • Journal of the Korean Society of Propulsion Engineers
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    • v.20 no.6
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    • pp.70-75
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    • 2016
  • A swirler is a flame holding device generating recirculation regions in a gas turbine combustor, and the flow pattern due to a swirler has major effects on the flame distributions, combustion efficiency, and characteristics of exhaust gas. An experimental study for a counter-rotating swirler has been conducted to find out effects of the mass flow rate ratio of the inner/outer swirler flow area, the pressure difference between the swirler inlet and outlet, and the flare exit length ratio on the flow patterns in a model combustion chamber by using PIV(Particle Image Velocimetry) technique.

Aerodynamic Design and Performance Prediction of Highly-Loaded 1 Stage Axial Compressor (고부하 1단 축류형 압축기 공력 설계 및 성능 예측)

  • Kang, Young-Seok;Park, Tae-Choon;Yang, Soo-Seok
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2010.11a
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    • pp.101-104
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    • 2010
  • Recently, needs for UAVs and small aircraft and small turbo jet or turbo fan engines for these air-crafts are increasing. Size and weight are the two main restrictions in small air-crafts such as UAV or VLJ propulsion system applications. Therefore, high power density is required in small size and designers come up with unconventional solutions in the design of small aero gas turbine engines. One of the solutions is the usage of highly loaded axial compressors. This paper introduces an aerodynamic design method of a highly loaded axial compressor and its review process. Numerical simulation has been carried out to assess the aerodynamic performance of the compressor.

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The Effect of Temperature on SCC of Heat Exchanger Tube for LNG Vessel (LNG선박 열교환기 세관의 SCC에 미치는 용액의 온도의 영향)

  • Jeong Hae Kyoo;Lim Uh Joh
    • Journal of the Korean Institute of Gas
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    • v.8 no.1 s.22
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    • pp.1-6
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    • 2004
  • In general, inlet temperature of cooling sea water for steam turbine condenser is about $25^{\circ}C$ and outlet temperature is about $60^{\circ}C$. For oil cooler, outlet temperature is about $40^{\circ}C$. Therefore corrosion heavily depends on the temperature of the coolant of a heat exchanger system. It is necessary to set the temperature of the cooling water to have maximum heat transfer efficiency. This paper was studied on the effect of temperature on SCC of Al-brass which is used as a tube material of vessel heat exchanger in $3.5\%$ NaCl + $0.1\%\;NH_4OH$ solution under flow by constant displacement tester. Based on the test results, the behavior of polarization characteristic, stress corrosion crack popagation and dezincification characteristic of Al-brass was investigated.

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A Study on Protection of Generator Asynchronization by Impedance Relaying (임피던스 계전기를 이용한 발전기 비동기 투입 보호 연구)

  • Lee, Jong-Hweon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.11
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    • pp.2000-2006
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    • 2011
  • Asynchronous phenomenon occurs on the synchronous generators under power system when a generator's amplitude of electromagnetic force, phase angle, frequency and waveform etc become different from those of other synchronous generators which can follow instantly varying speed of turbine. Because the amplitude of electromagnetic force, phase frequency and waveform differ from those of other generators with which are to be put into parallel operation due to the change of excitation condition for load sharing and the sharing load change, if reactive current in the internal circuit circulates among generators, the efficiency varies and the stator winding of generators are overheated by resistance loss. Where calculation method of protection settings and Logic for Protection of Generator Asynchronization will be recommended, A distance relay scheme is commonly used for backup protection. This scheme, called a step distance protection, is comprised of 3 steps for graded zones having different operating time. As for the conventional step distance protection scheme, Zone 2 can exceed the ordinary coverage excessively in case of a transformer protection relay especially. In this case, there can be overlapped protection area from a backup protection relay and, therefore, malfunctions can occur when any fault occurs in the overlapped protection area. Distance relays and overcurrent relays are used for backup protection generally, and both relays have normally this problem, the maloperation, caused by a fault in the overlapped protection area. Corresponding to an IEEE standard, this problem can be solved with the modification of the operating time. On the other hand, in Korea, zones are modified to cope with this problem in some specific conditions. These two methods may not be obvious to handle this problem correctly because these methods, modifying the common rules, can cause another coordination problem. To overcome asynchronizing protection this paper describes an improved backup protection coordination scheme using a new Logic that will be suggested.

Trend on the Recycling Technologies for the used Tungsten Carbide(WC) by the Patent and Paper Analysis (특허(特許)와 논문(論文)으로 본 텅스텐카바이드(WC) 재활용(再活用) 기술(技術) 동향(動向))

  • Jeong, Jin-Ki;Lee, Jae-Chun;Park, Sang-Woo;Kang, Kyung-Seok
    • Resources Recycling
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    • v.21 no.1
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    • pp.82-92
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    • 2012
  • There are several kinds of tungsten carbide(WC) such as light bulbs, metal cutting tools, drill bits, mining tools, military ordinance, high speed tool steels, chemicals/catalysts, wear resistance parts, jet engine turbine blades, etc.. These days it has been widely studied for the recycling technologies of the used tungsten carbide(WC) from view points of economy and efficiency. In this paper, open/registered patents of US, JP, EP, and KR and SCI Journal related to recycling technologies of the used Tungsten Carbide(WC) between 1969-2011 were reviewed. Patents and papers were collected using key-words searching and filtered by filtering criteria. The trends of the patents and papers was analyzed by the years, countries, companies, and technologies.

Control of 30kW Grid-Connected PCS for Wave Power Generation (파력발전용 30kW 계통연계형 PCS 제어)

  • Kim, Wan-Seok;Kim, Jae-Hyuck
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.3
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    • pp.470-475
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    • 2019
  • This paper deals with a 30kW grid-connected PCS (Power Conversion System) for an Oscillating Water Column (OWC) wave-power generation system. Wave power generation in marine energy is suitable for Korea with the characteristics of a peninsula with three sides facing the sea. In the case of coastal disasters, wave generators can act as a breakwater to reduce damage, and can be integrated with other marine power generation systems to increase efficiency. Wave power generation systems are classified into various types, such as oscillating bodies, OWC, and overtopping according to the operation principle, and they can also be classified into two types according to the installation method: a fixed structure and floating structure. This paper proposes a 30kW grid-connected PCS topology and model for OWC wave power generation that is structurally stable with a turbine and generator that are relatively easy to maintain, and then provide a control method required for grid connection, including DC link voltage control. Simulation verification was performed to verify the proposed PCS.

LNG-Vessels Hybrid Engine Seawater Desalination Complex System (LNG 선박 하이브리드 엔진 및 해수 담수화 복합 시스템)

  • Lim, Jae Jun;Lee, Dong-Heon;Byun, Gi-Sik;Kim, Gwan-Hyung
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2016.10a
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    • pp.663-664
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    • 2016
  • Temperature difference power generation using sea water is a method repeatedly closed liquefaction and gasification by using the ammonia (refrigerant) of the deep sea water and surface water with a temperature difference between turning the turbine. The larger the temperature difference between the nature of the temperature characteristic energy generation development, the better. This is the story that the surface waters of the deep-water temperature difference is large. But the winter is not large temperature difference between surface water and deep water has lowered energy efficiency. And desalination technologies accounted for 97% of the earth, but we can not eat the technology to convert sea water into fresh water, fresh water produced by the desalination technology that is available for various industries such as irrigation, drinking water in the vessel.In this paper, LNG transport vessels, based on the LNG transport ship to the temperature difference power generation using cold energy of thermal energy and LNG marine diesel engines, which use the existing order to improve the temperature of the surface waters of the season that is the current problem we propose that a complex development of desalination and desalination of seawater freezing research into hybrid research and utilizing the cold energy of the engine.

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