• 제목/요약/키워드: Multi-Heat Sources

검색결과 29건 처리시간 0.019초

고융점 소재의 열 보조 가공에서 레이저 -플라즈마 다중열원의 예열 효과에 대한 연구 (A Study on the Preheating Effect of Multi-Heat Sources using Laser Plasma in the Thermally Assisted Machining of a High-Melting-Point Material)

  • 이춘만;김성규
    • 한국기계가공학회지
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    • 제18권10호
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    • pp.93-98
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    • 2019
  • Recently, with the development of the aerospace and automotive industries, the demand for high-melting-point materials has increased. However, high-melting-point materials are difficult to cut through conventional machining methods. Thermally assisted machining (TAM) is a method for improving the machinability by preheating the materials. A laser, the most commonly used device for TAM, has high efficiency through local preheating but is not sufficient for maintaining a high preheating temperature due to rapid cooling. However, the use of multi-heat sources can supplement the disadvantage of a single heat source. The high preheating temperature can be maintained with a wide and deep heat-affected zone (HAZ) by multi-heat sources. The purpose of this study is to analyze the preheating effects of multi-heat sources using laser plasma. Thermal analysis and preheating experiments were carried out. As a result, the high preheating effect of multi-heat sources compared with a single heat source was verified.

다중열원 보조가공을 위한 평판 시편의 예열 효과에 관한 해석적 연구 (An Analytical Study on the Preheating Effect of Flat Workpiece in Thermally Assisted Machining by Multi Heat Sources)

  • 문성호;이춘만
    • 한국정밀공학회지
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    • 제33권8호
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    • pp.629-634
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    • 2016
  • Laser-assisted machining (LAM) is one of the most effective methods of processing difficult-to-cut materials, such as titanium alloys and various ceramics. However, it is associated with problems such as the inability of the laser heat source to generate an appropriate preheating temperature. To solve the problem, thermally assisted machining with multiple heat sources is proposed. In this study, thermal analysis of multiple heat sources by laser and arc is performed according to power, heat source size, and leading heat source position. Then, the results are analyzed according to each condition. The results of this analysis can be used as a reference to predict preheating temperature in thermally assisted machining with multiple heat sources.

4개 대칭배열 발열 전자소자에서의 확산 열저항 산정 (Evaluation of Spreading Thermal Resistance in Symmetrical Four-Heat Generating Electronic Components)

  • 김윤호;김서영;리광훈
    • 설비공학논문집
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    • 제18권8호
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    • pp.664-671
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    • 2006
  • We propose the correlation to predict the spreading thermal resistance on a plate with symmetrical four heat sources. The correlation transforms four heat sources to a single equivalent heat source and then the spreading thermal resistance can be obtained with the existing equation for a single heat source. When the four heat sources are mounted on a square base plate, the correlation is expressed as a function of the heat source size, the length of base plate, the plate thermal conductivity and the distance between heat sources. Compared to the results of three-dimensional numerical analysis, the spreading thermal resistance by the proposed correlation is in good agreement within 10 percent accuracy.

복합열원 히트펌프 최적 제어를 위한 열원에 따른 히트펌프 성능 및 에너지 소요량 패턴 비교 (Comparison of Heat Pump Performance and Energy Consumption Patterns according to Heat Sources for Optimal Control of Multi-Source Heat Pumps)

  • 고유진;박시훈;민준기
    • 한국지열·수열에너지학회논문집
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    • 제16권4호
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    • pp.31-38
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    • 2020
  • The investment in the technology of using a combined heat source is insufficient, which utilizes the advantages of various heat sources to maximize the potential energy and at the same time increases the performance of the heat pump. In this study, as basic data for the development of a high-efficiency hybrid heat pump system that actively connects and uses various heat sources, simulations were conducted for the heat pumps in two cases where geothermal and hydrothermal heat were applied respectively. In May, COP increased by about 27.3% compared to geothermal heat. In February, the COP percentage decrease of hydrothermal heat compared to geothermal heat is -6.9%. In May, total energy consumption can be reduced by 21.1% when hydrothermal is applied compared to geothermal heat. In February, the total energy consumption increases by 3.4%.

다수의 열원을 가지는 공간에서의 환기 조건에 따른 열환경 해석 (Thermal Environment Analysis of a Room in Accordance with Ventilation Condition with Multi-Heat Sources)

  • 김재중;손영갑;장석원;유동수
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2000년도 추계학술대회논문집B
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    • pp.199-204
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    • 2000
  • This paper reports a thermal environmental analysis of a room in accommodated with multi-heat sources according to ventilation condition. Two case modification have been investigated to obtain the lower temperature distribution in the room. The temperature distribution of the original room were found about $25{\sim}35^{\circ}C$. As a result, the use of, three ventilating fans and two electric fans are useful for room ventilation respectively, and using two electric fan is more recommendable in side of economical efficiency.

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다중열원 열회수형 유동층 열교환기의 전열성능에 대한 실험적 연구 (An Experimental Study on Heat Transfer Performance of Fluidized Bed Heat Exchanger for Heat Recovery from Multi-Heat Sources)

  • 박상일;고창복;이영수
    • 설비공학논문집
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    • 제29권2호
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    • pp.57-62
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    • 2017
  • The heat transfer performance of a multi-heat-source fluidized bed heat exchanger was analyzed. The fluidized bed heat exchanger examined in this study can simultaneously recover the waste heat from gas, water vapor, and hot water. The effects of waste water flow rate, gas flow rate, and cooling water flow rate were examined to find their experimental correlations with the heat transfer coefficient. A computer program using the correlations was developed in this study to predict the thermal performance of the fluidized bed heat exchanger. The calculated heat transfer rates of gas, water vapor, waste water, and cooling water were compared with the measured values. It was found that the error of the calculated values was less than 12%.

다수의 열원을 가진 채널의 경사각이 전자장비의 열적 안정성에 미치는 영향 (The effect of Inclined angle of Channel with multi heat source on Thermal Stability of Electronic Equipment)

  • 방창훈;김정수;예용택
    • 한국안전학회지
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    • 제16권3호
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    • pp.12-18
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    • 2001
  • The objective of the present work is to examine the effect of inclined angle of channel with multi heat source on thermal stability of electronic equipment. The heat sources are mounted on both sides of channel walls by two kinds of configuration such as the zig-zag md symmetric on. Conductive heat transfer was estimated by using of thermocouples and heat flux sensor. Thus, convective heat transfer and mean Nusselt number could be obtained. With increased inclined angle, the convective heat transfer coefficient was decreased. When inclined angle was smaller than 30 degree, The average Nusselt number of Big-zag configuration was larger than that of symmetric. Furthermore, when protruding ration was 0.082, the temperature was strongly affected by inclined angle. whereas, when protruding ration was 0.25, the temperature was strongly affected by heat source configuration.

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위상잠금 적외선 현미경 관찰법을 이용한 다층구조 칩의 내부결함 위치 분석 (Internal Defect Position Analysis of a Multi-Layer Chip Using Lock-in Infrared Microscopy)

  • 김선진;이계승;허환;이학선;배현철;최광성;김기석;김건희
    • 비파괴검사학회지
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    • 제35권3호
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    • pp.200-205
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    • 2015
  • 현대의 컴팩트 반도체 소자들은 정확한 품질검사를 위해 비파괴, 고분해능의 검사 장비가 요구되고 있다. 검사 장비 중 고분해능 적외선 대물렌즈와 적외선 센서로 구성된 초정밀 열영상 현미경은 반도체 내부의 결함에서 발생되는 국소적 열원의 위치와 깊이 정보를 얻는데 유용하게 활용되고 있다. 본 연구에서는 위 상잠금기법이 적용된 적외선열영상 현미경을 이용하여 다층구조로 된 반도체 소자 내부 열원의 위치와 깊이 정보에 대해 분석하였다. 시편은 내부에 3개의 열원을 포함한 TSV(through silicon via technology) 기반 4단 적층구조로서 측정 표면으로부터 열원의 깊이는 $240{\mu}m$이다. 본 실험에서는 위상잠금기법을 통해 시편 내부열원의 위치와 깊이를 정확히 찾을 수 있는 초점면 위치, 노출시간 그리고 위상잠금주파수 등 최적의 조건을 찾고 그 조건에서 적외선 대물렌즈와 시편의 거리 변화에 따른 위상 변이와 깊이 정보에 대한 영향을 알아보았다. 이와 같은 반도체 내부결함에 의한 열원의 위치와 깊이 분석에 대한 연구는 품질검사용 열영상 분석장비 개발에 큰 도움을 줄 것으로 예상한다.

빌딩 마이크로그리드가 포함된 새로운 빌딩에너지 시스템 구축방향에 관한 연구 (The Novel Configuration for Building Energy System Including Build ins Microgrid)

  • 홍원표
    • 한국조명전기설비학회:학술대회논문집
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    • 한국조명전기설비학회 2008년도 추계학술대회 논문집
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    • pp.235-240
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    • 2008
  • The recent development of efficient thermal prime movers for distributed generation id changing the focus of the production of electricity from large centralized power plants to local generation units scattered over the territory. The scientific communality is addressing the analysis and planning of the distributed energy resources(der) with wide spread approaches, taking into account technical, environmental, economical and social issues. The coupling of cogeneration system to absorption/electric chillers or heat pumps as well as the interactions with renewable sources, allow for setting up multi-generation systems for building cooling heating and power(BCHP) systems of different energy vectors such as electricity, heat(at different enthalpy levels), cooling power, hydrogen, various chemical substances and so forth. Adoption of the composite multi-generation systems may lead to significant benefits in term of higher efficiency, reduced $CO_2$ emissions and enhanced economy. This paper outlines the main aspects of the BCHP system framework, illistrating its characteristics and summarizing the relevant distributed multi-generation structures.

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Development of scaling approach based on experimental and CFD data for thermal stratification and mixing induced by steam injection through spargers

  • Xicheng Wang;Dmitry Grishchenko;Pavel Kudinov
    • Nuclear Engineering and Technology
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    • 제56권3호
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    • pp.1052-1065
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    • 2024
  • Advanced Pressurized Water Reactors (APWRs) and Boiling Water Reactors (BWRs) employ a suppression pool as a heat sink to prevent containment overpressure. Steam can be discharged into the pool through multi-hole spargers or blowdown pipes in both normal and accident conditions. Direct Contact Condensation (DCC) creates sources of momentum and heat. The competition between these two sources determines the development of thermal stratification or mixing of the pool. Thermal stratification is of safety concern as it reduces the cooling capability compared to a completely mixed pool condition. In this work we develop a scaling approach to prediction of the thermal stratification in a water pool induced by steam injection through spargers. Experimental data obtained from large-scale pool tests conducted in the PPOOLEX and PANDA facilities, as well as simulation results obtained using validated codes are used to develop the scaling. Two injection orientations, namely radial injection through multi-hole Sparger Head (SH) and vertical injection through Load Reduction Ring (LRR), are considered. We show that the erosion rate of the cold layer can be estimated using the Richardson number. In this work, scaling laws are proposed to estimate both the (i) transient erosion velocity and (ii) the stable position of the thermocline. These scaling laws are then implemented into a 1D model to simulate the thermal behavior of the pool during steam injection through the sparger.