• Title/Summary/Keyword: 소결 메쉬

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Comparison of the Heat transport Limitations for Screen Mesh Wick and Sintered Metal Wick Heat Pipes by Theoretical Analysis (이론적 해석에 의한 스크린 메쉬윅과 소결윅 히트파이프의 열수송 한계 비교)

  • Kim Keun-Bae;Kim Yoo
    • Journal of Energy Engineering
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    • v.13 no.4
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    • pp.267-274
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    • 2004
  • Theoretical analysis for predicting the heat transport limitations of screen mesh wick and sintered wick heat pipes was performed. The heat pipe diameter was 8mm and water was used for working fluid. For the 250 mesh, each capillary pressures and heat transport limitations, thermal resistances were analyzed according to the operating temperatures, wick thicknesses and inclination angles, based on the effective capillary radius (r$\_$c/), porosity ($\varepsilon$) and permeability (K). The wick capillary limitation was increased as the operating temperature and the wick thickness were increased, and generally the sintered wick showed higher heat transport limitations than that of the screen wick. The thermal resistance of the screen wick was higher than that of the sintered wick and both thermal resistances were linearly increased as the wick thickness was increased.

A Study on Drag Reduction of Cylindrical Underwater Body Using Sintered Mesh (소결 메쉬를 이용한 원통형 수중운동체 항력 감소 연구)

  • Jung, Chulmin;Paik, Bugeun;Kim, Kyungyoul;Jung, Youngrae
    • Journal of the Korea Institute of Military Science and Technology
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    • v.21 no.2
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    • pp.195-203
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    • 2018
  • Among the techniques of reducing the drag to increase the speed of underwater moving bodies, we studied on the drag reduction method by gas injection. Researches on gas injection method have been paid much attention to reduce the drag of vessels or pipe inner walls. In this study, we used a sintered metal mesh that can uniformly distribute fine bubbles by gas injection method, and applied it to a cylindrical underwater moving body. Using the KRISO medium-sized cavitation tunnel, we measured both the bubble size on the surface of the sintered mesh and the bubble distribution in the boundary layer. Then, drag reduction tests were performed on the cylinder type underwater moving models with cylindrical or round type tail shape. Experiments were carried out based on the presence or absence of tail jet injection. In the experiments, we changed the gas injection amount using the sintered mesh gas injector, and changed flow rate accordingly. As a result of the test, we observed increased bubbles around the body and confirmed the drag reduction as air injection flow rate increased.

Study on Metal Microfilter Coated with Ceramics by Using Plasma Thermal Spray Method (플라즈마 용사를 이용한 복합세라믹 미세필터 연구)

  • Song, In-Gyu;Lee, Young-Min;Shin, Hyun-Myung;Choi, Hae-Woon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.9
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    • pp.1035-1040
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    • 2011
  • This research was performed on a microfilter made of a hybrid material (ceramic + metal) that was coated with ceramics on the metal-filter surface by using the thermal spray method. The ceramic powders used were $Al_2O_3+40TiO_2$ powder with a particle size of $20{\mu}m$ and $Al_2O_3$ (98%+)powder with a particle size of $45{\mu}m$. The metal filters were filter-grade $20{\mu}m$, $30{\mu}m$, and $50{\mu}m$ sintered metal powder filters (SIKA-R 20 IS, 30 IS, 50 IS; Sinter Metals Filters) and filter-grade $75{\mu}m$ sintered mesh filter with five layers. Ceramic-coated filters that were coated using the thermal spray method had a great influence on powder material, particle size, and coating thickness. However, these filters showed a fine performance when used as micro-filters.

Preparation of B4C-Al2O3 Composite Powder by Self-propagation High-temperature Synthesis(SHS) Process under High Pressure (고압 자전 고온반응 합성법에 의한 B4C-Al2O3복합분말 제조)

  • 임경란;강덕일;김창삼
    • Journal of the Korean Ceramic Society
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    • v.40 no.1
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    • pp.18-23
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    • 2003
  • Composite powder of$B_4C-A1_2O_3$was prepared from a mixed powder of$B_2O_3/A1/C$by SHS under argon pressure instead of using a chemical furnace. A mixture of$B_2O_3,$Al and C powder (equivalent amounts to the reaction,$2B_2O_3+4A1+C=B_4C+2A1_2O_3)$was ball milled for 2 h. The mixed powder was placed in a SHS reactor and filled with 10 atm of argon gas and ignited. The inner and outer products were the same by XRD analysis. It was consisted of a composite powder of$B_4C-A1_2O_3$without $AlB_{12}/C_2$which was always produced using a chemical furnace. The composite powder was about$60~100{mu}m$size which was composed of crystalline particles of about 0.3~l${mu}m$size. But when 15 atm of argon was employed, partial sintering took place to give rise hard composite powder of$15~25{mu}m$$B_4C$with $0.1~0.2{mu}m$$A1_2O_3.$

Development of Automatic Nuclear Fuel Rod Character Recognition System Based on Image Processing Technique (영상처리기술을 이용한 핵 연료봉 문자 자동인식시스템 개발)

  • Woong Ki Kim;Yong Bum Lee;Jong Min Lee;Sung IL Chien
    • Nuclear Engineering and Technology
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    • v.25 no.3
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    • pp.424-429
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    • 1993
  • Numeric characters are printed at the end part of nuclear fuel rod containing nuclear pellets. Fuel rods are discriminated and managed systematically by these characters in the process of producing fuel assembly. The characters are also used to examine manufacturing process of fuel rods in the survey of burnup efficiency as well as in inspection of irradiated fuel rod. Therefore automatic character recognition is one of the most important technologies in automatic manufacture of fuel assembly. In this study, character recognition system is developed. In the developed system, mesh feature extracted from each character written in the fuel rod has been compared with reference feature value stored in database, and the character is thus identified. In the result of experiment, 95.83 percent recognition rate is achievable.

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Velocity Considered Sectional Porosity Equivalent Model (VSPE) of Filters for CFD Analysis of Breakaway Devices (수소 브레이크어웨이 디바이스 유동해석을 위한 필터의 구간별 다공성 등가 모델 제시)

  • Son, Seong-Jae;An, Su-Jin;Song, Tae-Hoon;Joe, Choong-Hee;Park, Sang-Hu
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.18 no.8
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    • pp.82-90
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    • 2019
  • We propose an equivalent model of a sintered metal mesh filter calculated by Ergun's equation and polynomial regression for the CFD analysis of breakaway devices at a hydrogen fueling station. CFD analysis of filters that cause high pressure loss is essential because breakaway devices in high-pressure hydrogen conditions require low pressure loss. A differential pressure experiment with a filter was performed in a low-pressure air condition considering similarities. An equivalent model was developed by deriving the resistance value by the polynomial regression using the experimental results. The results of CFD analysis using the equivalent model show that there was almost no error in the operating condition of the breakaway device compared to the experimental results. Through this work, we believe that the proposed equivalent model of a filter can be applied to the analysis of breakaway devices in hydrogen fueling stations. We will study how to optimize the shape and position of the filter in breakaway devices using the developed equivalent model.

Ag Nanoparticle Self-Generation and Agglomeration via Laser-Induced Plasmonic Annealing for Metal Mesh-Based Transparent Wearable Heater (레이저 기반 플라즈모닉 어닐링을 통한 은 나노입자 자가 생성 및 소결 공정과 이를 활용한 메탈메쉬 전극 기반 투명 웨어러블 히터)

  • Hwang, Yun Sik;Nam, Ui Yeon;Kim, Yeon Uk;Woo, Yu Mi;Heo, Jae Chan;Park, Jung Hwan
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.35 no.5
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    • pp.439-444
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    • 2022
  • Laser-induced plasmonic sintering of metal nanoparticles (NPs) is a promising technology to fabricate flexible conducting electrodes, since it provides instantaneous, simple, and scalable manufacturing strategies without requiring costly facilities and complex processes. However, the metal NPs are quite expensive because complicated synthesis procedures are needed to achieve long-term reliability with regard to chemical deterioration and NP aggregation. Herein, we report laser-induced Ag NP self-generation and sequential sintering process based on low-cost Ag organometallic material for demonstrating high-quality microelectrodes. Upon the irradiation of laser with 532 nm wavelength, pre-baked Ag organometallic film coated on a transparent polyimide substrate was transformed into a high-performance Ag conductor (resistivity of 2.2 × 10-4 Ω·cm). To verify the practical usefulness of the technology, we successfully demonstrated a wearable transparent heater by using Ag-mesh transparent electrodes, which exhibited a high transmittance of 80% and low sheet resistance of 7 Ω/square.

Multi-Layered Sintered Porous Transport Layers in Alkaline Water Electrolysis (다층 소결메쉬 확산체를 이용한 알칼라인 수전해 셀)

  • YEOM, SANG HO;YUN, YOUNG HWA;CHOI, SEUNGWOOK;KWON, JIHEE;LEE, SECHAN;LEE, JAE HUN;LEE, CHANGSOO;KIM, MINJOONG;KIM, SANG-KYUNG;UM, SUKKEE;KIM, CHANG-HEE;CHO, WON CHUL;CHO, HYUN-SEOK
    • Transactions of the Korean hydrogen and new energy society
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    • v.32 no.6
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    • pp.442-454
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    • 2021
  • The porous transport layer (PTL) is essential to effectively remove oxygen and hydrogen gas from the electrode surface at high current density operation conditions. In this study, the effect of PTL with different characteristics such as pore size, pore gradient, interfacial coating was investigated by multi-layered sintered mesh. A water electrolysis single cell of active area of the 34.56 cm2 was constructed, and IV performance and impedance analysis were conducted in the range of 0 to 2.0 A/cm2. It was confirmed that the multi-layered sintered mesh PTL, which have an average pore size of 25 to 57 ㎛ and a larger pore gradient, removed bubbles effectively and thus seemed to improve IV performance. Also, it was confirmed that the catalytic metals such as Ni, NiMo coating on the PTL reduced activation overpotential, but increased mass transport overpotential.