• Title/Summary/Keyword: Thermal management

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The Trend of System Level Thermal Management Technology Development for Aero-Vehicles (항공기 시스템 레벨 열관리 기술개발 동향)

  • Kim, Youngjin;Son, Changmin
    • Journal of the Korea Institute of Military Science and Technology
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    • v.19 no.1
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    • pp.35-42
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    • 2016
  • Modern aircraft is facing the increase of power demands and thermal challenges. In accordance with the application of more electric technology and advanced mission requirement, aircraft system requires increase of power generation and it cause increase of internal heat generation. Simultaneously, restrictions have significantly been imposed to the thermal management system. Modern aircraft must maintain low radar observability and infra-red signature. In addition, new composite aircraft skins have reduced the amount of heat that can be rejected to the environment. The combination of these characteristics has increased the challenges faced by thermal management. In order to mitigate the thermal challenges, the concept of system level thermal management should be applied and new modeling and simulation tools need to be developed. To develop and utilize system level thermal management technology, three key points are considered. Firstly, the performance changes of subsystems and components must be assessed at an integrated thermal system. It is because that each subsystem and component interacts with other subsystems or components and it can directly effects on overall system performance. Secondly, system level thermal management requirements and solutions must be evaluated early in conceptual design process as vehicle and propulsion system configuration decisions are being made. Finally, new component level thermal management technologies must focus on reducing heat generation and increasing the availability of heat sinks.

Thermal Management Study of PEMFC for Residential Power Generation (가정용 연료전지 시스템의 열관리 해석)

  • Yu, Sang-Seok;Lee, Young-Duk;Ahn, Kook-Young
    • Proceedings of the KSME Conference
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    • 2008.11b
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    • pp.2839-2844
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    • 2008
  • A PEMFC(proton exchange membrane fuel cell) is a good candidate for residential power generation to be cope with the shortage of fossil fuel and green house gas emission. The attractive benefit of the PEMFC is to produce electric power as well as hot water for home usage. Typically, thermal management of vehicular PEMFC is to reject the heat from the PEMFC to the ambient air. Different from that, the thermal management of PEMFC for RPG is to utilize the heat of PEMFC so that the PEMFC can be operated at its optimal efficiency. In this study, dynamic thermal management system is modeled to understand the response of the thermal management system during dynamic operation. The thermal management system of PEMFC for RPGFC is composed of two cooling circuits, one for controling the fuel cell temperature and the other for heating up the water for home usage. Dynamic responses and operating strategies of the PEMFC system are investigated during load changes.

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A Simple Thermal Model of Fuel Thermal Management System in Aircraft Engine

  • Youngjin Kim;Jeonghwan Jeon;Gonghoe Gimm
    • Journal of Aerospace System Engineering
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    • v.17 no.5
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    • pp.11-18
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    • 2023
  • The architecture of the Fuel Thermal Management System (FTMS) in a commercial aircraft engine was built to model and simulate the fuel system. The study shows the thermal interactions between the fuel and engine lubrication oil through the mission profile of a high bypass ratio, two-spool turbofan engine. Fuel temperature was monitored as it flowed through each sub-component of the fuel system during the mission. The heat load in the fuel system strongly depended on the fuel flow rate, and was significantly increased for the periods of cruise and descent with decrease of fuel flow rate, rather than for the periods of take-off. Due to the thermal interaction in the pump housing, the fuel temperature at the outlet of the low-pressure pump was increased (4.0, 9.2, and 30.0) % over the case without thermal interaction for take-off, cruise, and descent, respectively.

A Study on the Actual Conditions of Safety Management in Thermal Oil System (열매체유 시스템의 안전관리 실태에 관한 연구)

  • Lee, Joo Yeob;Lee, Keun Won;Woo, In Sung
    • Journal of the Korean Society of Safety
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    • v.29 no.5
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    • pp.60-66
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    • 2014
  • Depending on the progress of the industrial advances, the use of the thermal oil system in the utility system has been increased, which became an important part in the operation of the plant. However, fire or explosion have occurred due to lack of risk awareness and safety management, more frequently than we know. In this study, by using a questionnaire, actual conditions of safety management in thermal oil system is surveyed and analyzed, it is composed of general, a safety status of the thermal oil system component and the stage of recognition and management in the thermal oil system. These results of this study can be used as basic data to the safety management and the accident prevention of fire or explosion in the workplace.

A Study on Thermal Load Management in a Deep Geological Repository for Efficient Disposal of High Level Radioactive Waste

  • Jongyoul Lee;Heuijoo Choi;Dongkeun Cho
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.20 no.4
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    • pp.469-488
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    • 2022
  • Technology for high-level-waste disposal employing a multibarrier concept using engineered and natural barrier in stable bedrock at 300-1,000 m depth is being commercialized as a safe, long-term isolation method for high-level waste, including spent nuclear fuel. Managing heat generated from waste is important for improving disposal efficiency; thus, research on efficient heat management is required. In this study, thermal management methods to maximize disposal efficiency in terms of the disposal area required were developed. They efficiently use the land in an environment, such as Korea, where the land area is small and the amount of waste is large. The thermal effects of engineered barriers and natural barriers in a high-level waste disposal repository were analyzed. The research status of thermal management for the main bedrocks of the repository, such as crystalline, clay, salt, and other rocks, were reviewed. Based on a characteristics analysis of various heat management approaches, the spent nuclear fuel cooling time, buffer bentonite thermal conductivity, and disposal container size were chosen as efficient heat management methods applicable in Korea. For each method, thermal analyses of the disposal repository were performed. Based on the results, the disposal efficiency was evaluated preliminarily. Necessary future research is suggested.

Using Natural Graphite Heat Spreaders to Increase CCFL LCD Operating Temperatures

  • Norley, Julian;Shives, Gary D.;Reis, Brad;Schober, John
    • 한국정보디스플레이학회:학술대회논문집
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    • 2007.08a
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    • pp.273-276
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    • 2007
  • A natural graphite heat spreader increased the upper operating temperature limit of a CCFL backlit LCD television. A 0-80W heat source was used to simulate additional electronics. Without the heat spreader, internal circuitry shut-down at ${\sim}30;$ no shut-down occurred above 80W with a heat spreader. Additionally, brightness, temperature uniformity, and operating ranges were improved, verified by environmental chamber performance testing at various ambient conditions.

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Performance Characteristics of the Thermal Management System for Passenger Hydrogen Fuel Cell Vehicle (수소연료전지 자동차의 열관리시스템 성능특성에 관한 연구)

  • Lee, Ho-Seong;Won, Jong-Phil;Cho, Chung-Won;Lee, Moo-Yeon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.3
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    • pp.986-993
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    • 2012
  • The objective of this study is to investigate performance characteristics of the thermal management system for passenger hydrogen fuel cell vehicle under various operating conditions. The thermal management systems comprised of a stack cooling system, an electric device cooling system and an air conditioning system for a passenger room were tested with driving conditions. As a result, in highway driving mode, the cooling performance of the stack cooling system with air conditioning on condition was 28.8 % lower than that of the air conditioning off condition. And cooling load of the electric cooling system in the city driving mode was 65.6% higher than that of the highway driving mode.

Experimental Study on the Mutual Influence of Thermal Management System for Hydrogen Fuel Cell Vehicle (수소연료전지 자동차 열관리 시스템의 상호 영향도 분석을 위한 실험적 연구)

  • Lee, Moo-Yeon;Won, Jong-Phil;Cho, Choong-Won;Lee, Ho-Seong
    • Transactions of the Korean hydrogen and new energy society
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    • v.22 no.6
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    • pp.852-858
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    • 2011
  • This paper is aiming to estimate the mutual influence of the stack cooling performances with the operation modes of the thermal management system for the hydrogen fuel cell vehicles. The heat capacity of the thermal management system was measured by varying the operating modes such as stack cooling heat exchanger only (Mode 1), stack cooling and electric devices cooling heat exchangers (Mode 2), and stack cooling and electric devices cooling heat exchangers with an operation of the condenser (Mode 3).As the results, Performance of the thermal management system (TMS) at Mode 3 decreased up to 34.0%, compared with the result of the Mode 1. In addition, in order to optimize the performance of TMS, the entropy change of stack cooling heat exchanger using irreversibility analysis technique was analyzed with the relationship between entropy generation and entering air velocity of the thermal management system.

Comparative Legal Study of Workplace Thermal Environment Management Legislation (작업장 온열환경 관리 법제의 비교법적 고찰)

  • Saemi Shin;Hea Min Lee;Nosung Ki;Sang-Hoon Byeon;SunghoKim
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.33 no.4
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    • pp.485-501
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    • 2023
  • Objectives: The Ministry of Employment and Labor has revised the articles regarding management of the thermal environment in the workplace. Currently, two types of regulations exist together with indoor workplaces as the scope of application. It appears that the time has come to discuss regulations. In this study, we aim to identify the feasibility of and problems with the current system through a comparative legal review of workplace thermal environment management laws from around the world. We suggest directions for improving South Korea's workplace thermal environment management laws. Methods: For the several selected countries, we analyzed the classification and content of obligations stipulated for the thermal environment, the presence or absence of specific measures for thermal environment management, legal status and content, and the scope of application of thermal environment provisions and measures. The investigated content was classified according to Zweigelt-Kotz's legal theory. Results: In some countries, employers' obligations for regulating the thermal environment are broadly divided into two types: results and actions. The scope of application of provisions and measures on the thermal environment was extensive, with most of the selected countries targeting general workplaces. Conclusions: In the case of South Korea, restricting and classifying target workplaces and imposing separate obligations to manage a workplace thermal environment goes against global practices, and stipulating legal orders and separate action obligations in guidelines does not conform to the characteristics of South Korea's legal system, meaning that improvement is needed.

Characterization of a Thermal Interface Material with Heat Spreader (전자부품의 방열방향에 따른 접촉열전도 특성)

  • Kim, Jung-Kyun;Nakayama, Wataru;Lee, Sun-Kyu
    • Journal of the Korean Society for Precision Engineering
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    • v.27 no.1
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    • pp.91-98
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    • 2010
  • The increasing of power and processing speed and miniaturization of central processor unit (CPU) used in electronics equipment requires better performing thermal management systems. A typical thermal management package consists of thermal interfaces, heat dissipaters, and external cooling systems. There have been a number of experimental techniques and procedures for estimating thermal conductivity of thin, compressible thermal interface material (TIM). The TIM performance is affected by many factors and thus TIM should be evaluated under specified application conditions. In compact packaging of electronic equipment the chip is interfaced with a thin heat spreader. As the package is made thinner, the coupling between heat flow through TIM and that in the heat spreader becomes stronger. Thus, a TIM characterization system for considering the heat spreader effect is proposed and demonstrated in detail in this paper. The TIM test apparatus developed based on ASTM D-5470 standard for thermal interface resistance measurement of high performance TIM, including the precise measurement of changes in in-situ materials thickness. Thermal impedances are measured and compared for different directions of heat dissipation. The measurement of the TIM under the practical conditions can thus be used as the thermal criteria for the TIM selection.