• Title/Summary/Keyword: forced air cooling

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Study on Numerical Analysis for Ram-Air flow of Cooling Duct on the Propulsion System (추진시스템 냉각유로의 주행풍 유동에 대한 수치해석적 연구)

  • Ryoo, Seong-Ryoul;Jo, Jung-Rae;Jo, Tae-Sik;Kim, Chul-Ju
    • Proceedings of the KSR Conference
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    • 2009.05b
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    • pp.507-513
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    • 2009
  • The cooling technology of power conversion semiconductors in the propulsion system for the HEMU(High Electrical Multi Unit) are applied in water cooling method and phase change method such as the immersed type and the heat pipe type. Both of cooling systems need a condenser and a fan through forced wind to emit that is radiated heat from electric power conversion semiconductor(IGBT) stack effectively, now in the case of Japanese Fastec 360S, is using ram-air that is flowed in establishing cooling passage to propulsion system for cooling of condenser. In this research, it is that achieved the computing numerical analysis using ADINA of commertial program to examine flow characteristics and pressure distribution of ram-air for a condenser in cooling passage.

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Energy Consumption and Thermal Comfort Assessment of Conventional Forced-air System According to AHU Discharge Air Temperature (AHU 토출온도에 따른 일반 공조시스템의 에너지 소비량 및 실내 온열환경 분석)

  • Kim, Min Ji;Yeon, Sang Hun;Lee, Kwang Ho
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.30 no.2
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    • pp.51-57
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    • 2018
  • Recently, global warming has been a serious issue on the worldwide, and the importance of energy conservation is increasing. In most buildings, energy consumption increases due to cooling, heating, and ventilation. Because of these issues, researches have been carried out to reduce building energy. However, in most conventional forced-air system, the guidelines for the Air Handling Unit (AHU) discharge air temperature are not fully established. The purpose of this study is to assess the impact of AHU discharge air temperature, which is one of the important control variables, on the overall energy consumption and thermal comfort characteristics by modeling conventional forced-air system using EnergyPlus. In addition, recommendations for energy reduction in conventional AHU is provided.

Heatsink Design of High Power Converter (대용량 컨버터의 방열판 설계)

  • Kim, Chan-Gi
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.48 no.4
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    • pp.194-202
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    • 1999
  • Various ways of designing heat sink are available for commercial high power converters and among them, the method of air cooling is the most popular and practical method than any other ones. In this paper, a practical method of cooling high power converter, which includes a method of reducing noise and vibration caused by the fan and a method of estimating the gap and contact resistances existing between the thyristor and heat sink, is presented. Finally, the heat transfer analysis and implementation methods of heat sink for high power converter is presented.

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Design of a Heat Dissipation System for the 400kW IGBT Inverter (400kW급 IGBT 인버터용 방열 시스템 설계)

  • 이진우
    • The Transactions of the Korean Institute of Power Electronics
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    • v.9 no.4
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    • pp.350-355
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    • 2004
  • This paper deals with the design of a heat dissipation system, which consists of a heat source of power semiconductor devices, a heat sink ;md a fan for the forced air cooling. It suggests the method of appropriately dividing the whole heat transfer system into analytical subsystems and also presents the correspondent analytic or experimental design equations for the subsystems. The experimental results on the designed heat dissipation system for the 400kW IGBT inverter show less than 10[%] error with respect to the design temperature and therefore verify the validity of the proposed analytical design method in the steady state.

Heat Transfer Characteristics Around a Surface-Mounted Module Cooled by Piezoelectric Fan (압전세라믹 냉각홴에 의한 강제 공랭 모듈 주위의 열전달특성)

  • Park, Sang-Hee;Park, Gyu-Jin;Choi, Seong-Dae
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.7
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    • pp.780-788
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    • 2004
  • This paper reports the fluid flow and heat transfer around a module cooled by forced air flow generated by a piezoelectric(PZT) cooling fan. The fluids are locally accelerated by a flexible PZT fan which deflects inside a fluid transport system of comparatively simple structure mounted on a PCB in a parallel-plate channel(450${\times}$80${\times}$700㎣). Input voltages of 20-100V and a resonance frequency of 23㎐ were used to vibrate the cooling fan. Input power to the module was 4W. The fluid flow around the module was visualized by using PIV system. The temperature distributions around a heated module were visualized by using liquid crystal film(LCF). The cooling effect using a PZT fan was independent of the vent area ratios at the channel inlet and was similar to the forced convection cooling. We found that the flow type was Y-shape and the cooling effect was increased by the wake generated by a piezoelectric cooling fan.

Study for Effective Cooling of Ni-MH Battery Module Using Forced Air Flow (공기 유동에 따른 Ni-MH 배터리 모듈의 효과적인 냉각에 관한 연구)

  • Ahn, Chi-Yeong;Kim, Tae-Sin;Kim, Jun-Bom
    • Journal of the Korean Electrochemical Society
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    • v.14 no.4
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    • pp.253-260
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    • 2011
  • In this study, computational simulation was performed for thermal management of modules consisting of 10 batteries. Simplified structure and equivalent thermal resistance network was applied to maintain the thermal properties. Verification test of the mesh were in progress to ensure the reliability of 2.6 mm in the narrow gap between the battery, resulting in at least three divided mesh between the shape of the grid was required. Type of air from rear of the module, type of air from top of the module and type of air from bottom of the module were applied and effective cooling methods are discussed based on the location of fan and air intake of the modules. Maximum temperature and temperature differences of modules that directly affect the performance of the module were compared, and also behavior of the fluid was confirmed by comparing the air flow. The best maximum temperature is shown type of air from bottom of the module to $40.27^{\circ}C$ and type of air from top of the module shows smallest temperature difference $0.73^{\circ}C$.

A Study on the Characteristics of Heating and Cooling Loads of Standard Chicken Houses in South Korea (국내 표준계사의 냉난방부하 특성 연구)

  • Kwon, Young-Cheol
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.35 no.10
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    • pp.235-243
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    • 2019
  • In South Korea, millions of poultry have died due to repeated heat waves every year. The purpose of this study is to analyze the characteristics of heating and cooling loads of chicken houses in Korea and to present an effective insulation and ventilation measures to minimize the damage of poultry due to summer heat wave and to save energy in chicken houses in winter. The heating and cooling loads of standard chicken house were calculated. As a result of the calculation of maximum heating load based on the minimum ventilation rate in winter, the outdoor air temperature requiring heating was $6{\sim}7^{\circ}C$ to keep the indoor air temperature of chicken houses as $24^{\circ}C$. The peak cooling load of chicken houses was mostly taken by the heat generated by chickens and the heat gain due to ventilation. The heat gain through building envelopes was as small as neglectable. Most of chicken houses is usually cooled by gigantic forced ventilation in summer in Korea. When the chicken houses are cooled by electric cooling machine such as cooler or air conditioner, it is more effective to keep minimum ventilation rate to reduce the maximum cooling load. To lower the temperature of supplying water to cooling pad, it is recommended to use the underground water below 10 meters from the ground if there is abundant underground water.

Design and investigation of a shape memory alloy actuated gripper

  • Krishna Chaitanya, S.;Dhanalakshmi, K.
    • Smart Structures and Systems
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    • v.14 no.4
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    • pp.541-558
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    • 2014
  • This paper proposes a new design of shape memory alloy (SMA) wire actuated gripper for open mode operation. SMA can generate smooth muscle movements during actuation which make them potentially good contenders in designing grippers. The principle of the shape memory alloy gripper is to convert the linear displacement of the SMA wire actuator into the angular displacement of the gripping jaw. Steady state analysis is performed to design the wire diameter of the bias spring for a known SMA wire. The gripper is designed to open about an angle of $22.5^{\circ}$ when actuated using pulsating electric current from a constant current source. The safe operating power range of the gripper is determined and verified theoretically. Experimental evaluation for the uncontrolled gripper showed a rotation of $19.97^{\circ}$. Forced cooling techniques were employed to speed up the cooling process. The gripper is simple and robust in design (single movable jaw), easy to fabricate, low cost, and exhibits wide handling capabilities like longer object handling time and handling wide sizes of objects with minimum utilization of power since power is required only to grasp and release operations.

Initial cooling conditions that extend the shelf-life of fresh oak mushrooms (Lentinula edodes) after harvest (신선 표고의 수확 후 유통수명 연장을 위한 예냉조건 구명)

  • Choi, Ji Weon;Lee, Ji Hyun;Kim, Chang-Kug;Park, Me Hea;Choi, Hyun jin;Lim, Sooyeon;Eum, Hyang Lan;Chang, Min-Sun;Hong, Yoon Pyo
    • Journal of Mushroom
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    • v.20 no.3
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    • pp.138-146
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    • 2022
  • To optimize initial cooling conditions, forced-air cooling was applied to freshly harvested oak mushrooms at 2 levels (0℃ for 30 minutes, at 0℃ for 1 hour) followed by room cooling at 3 levels (-3℃ for 1 day, 0℃ for 1 day, 3℃ for 1 day). After initial cooling, the oak mushrooms were packaged with PVC film, then held in a storage room at 1℃ for 6 weeks. Quality characteristics and percentage marketability were then investigated. As a control, Mushrooms were placed in storage with no initial cooling. The quality factors impacting marketability of fresh oak mushrooms were color change and appearance of decay. Off-odor did not occur or developed only slightly, so it did not affect oak mushroom quality within 6 weeks of low temperature storage. In all treatment groups, the shelf life in which 100% marketability was maintained was up to 3 weeks. At week 5, percent marketability of the 3 treatment groups 1 hour room cooling treatment at 0℃, 1 hour forced air cooling, and control was 100%. 80% In the group that underwent 30 min forced air cooling retained 80% marketability, and the group exposed to 1 day in room cooling at -3℃ retained 86.7% marketability. At week 6 of 1℃ storage, the marketability ratio was 80% in the 1 day room cooling at 0℃ group, 66.7% in the 1 day room cooling at 3℃ group, 46.7% in the 1 hour forced air cooling group, and 33% or less in all other treatment groups. Therefore, the most suitable initial cooling parameter to extend shelf-life of oak mushrooms is 1 day of in room cooling at 0℃ immediately after harvest.

제너 다이오드를 이용한 공기 유속계측 장치개발

  • 김영재;김희식;조흥근
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.11a
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    • pp.496-500
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    • 1996
  • An air flow measurement device is proposed. The thermal characteristic of a semiconductor element is adopted as a cooling parameter of thermal convection rate. The difference between forced convection and natural convection of two Zener diodes results enough difference in temperature. Experiment at various air flow conditions shows the measuring capability of the air flow in a duct. This measuring device has some merits, such as a reliability n hard field condition, simple circuit for signal processing, small volume of the element, less air flow resistance, independance of various ai temperature. The experimental result shows that it is an exact and usefull air flow measurement device.

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