• 대한기계학회논문집B
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• 제26권12호
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• pp.1707-1714
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• 2002

This paper deals with the development of a new method that can obtain heat transfer coefficient and reference free stream temperature simultaneously, The method is based on transient heat transfer experiments using two narrow-band TLCs. The method is validated through error analysis in terms of the random uncertainties in the measured temperatures. It is found that the errors could be reduced more than 2 times less. The general method described in this paper is applicable to many heat transfer models with unknown free stream temperature.

• Nuclear Engineering and Technology
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• 제53권8호
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• pp.2488-2498
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• 2021

The wall film-wise condensation plays an important role in the heat transfer processes of heat exchangers, refrigerators, and air conditioner. In the field of nuclear engineering, steam condensation is often utilized in safety systems to remove the core decay heat under both transient and accident conditions. In particular, passive containment cooling system (PCCS), are designed to ensure containment safety under severe accident conditions. A computational fluid dynamics (CFD) scale analysis has been conducted to calculate the heat transfer rate of the PCCS. However, despite the increase in computing power, there are challenges in the long-term transient simulation of containment using CFD scale codes. In this study, a heat structure coupling between the CFD and system analysis codes was performed to efficiently analyze PCCS. In addition, the component unstructured program for interfacial dynamics (CUPID) was improved to analyze the condensation behavior of ternary gas mixtures. Thereafter, the condensation heat transfer on the primary side was calculated using the improved CUPID and CFD code, whereas that on the secondary side was simulated using MARS. Both the coupled codes were validated against the CONAN facility database. Finally, conjugate heat transfer simulations with wall condensation in the presence of non-condensable gases were appropriately performed.

• 대한기계학회논문집B
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• 제23권9호
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• pp.1121-1128
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• 1999

A single blow, transient testing method for determining the heat transfer characteristics of heat exchanger surfaces are presented. The exponential inlet temperature variations were made using screen mesh with small time constant and frontal velocities of the test section. The system is used to investigate the usefulness of a model with exponential inlet temperature variations. A data reduction program is developed to calculate the temporally and spatially averaged heat transfer coefficient using the measured disturbance and response of the fluid temperature. The results are compared with the existing theoretical and experimental data for parallel plate stacks. It was recommended to take an average for the time greater than the 99% of the final temperature had reached in order to obtain fairly good results.

• 항공우주시스템공학회지
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• 제4권1호
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• pp.32-37
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• 2010

Guided weapon is very excellent strategy system than conventional weapons. Recently, several devices and a technology developed much developing more, inertia measuring device is one example. Inertia measuring device is device that is used to improe more accuracy of guided weapon, this device is operated by sensors of inside. Sensors of inside are parts that is very sensitive about impact or shock, heat that interact when shoot, it is main purpose that verify durability of sensor by heat delivered from outside in this study.

• 한국산학기술학회논문지
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• 제10권7호
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• pp.1484-1488
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• 2009

본 논문은 LED조명기구의 상용화에 가장 큰 문제로 제기되는 방열설계에 관한 논문으로서, COMSOL을 이용한 방열해석을 통하여 문제해결의 방법을 제시한다. COMSOL Multiphysics에 있는 Heat Transfer Module의 Transient Analysis를 활용하여 해석한 결과, 시뮬레이션 값과 시작품 제작 후 측정 온도와의 차이가 10[$^{\circ}C$]이하로 도출되었으며, Led Lamp가 설치되는 실내.외의 환경조건의 온도변화에 따른 제 요소들을 잘 활용하면 실제 작품의 목표치에 근접하는 결과를 얻을 수 있음을 확인할 수 있었다.

• 한국추진공학회지
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• 제16권5호
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• pp.37-46
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• 2012

로켓엔진 연소실에서 막냉각을 고려한 열전달 해석을 위한 모델을 수립하였다. 연소실 내에서의 대류, 복사, 막냉각 효과는 로켓엔진을 위한 경험식을 사용하였으며, 벽 외부는 일반적인 대류, 복사 식을 적용하였다. 또한 벽 내부는 유한체적의 격자를 구성하여 시간전진법에 의해 비정상 열해석을 수행하였다. 연소압 50 기압의 액체산소/케로신 엔진을 예로 해석하였으며, 이 경우 4% 유량의 막냉각까지는 벽온도를 낮추는데 크게 기여하였으나, 그 이상의 공급은 막냉각 유량에 비해 효과가 미비함을 확인하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.867-868
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• 2011

LOx/케로신 로켓엔진 연소시 연소실로 전달되는 열전달과 그에 따른 벽온도 변화를 비정상 해석하였다. 막냉각이 없는 경우와 연료 막냉각이 있는 경우를 계산하였으며, 연소실 내측의 대류, 복사는 로켓엔진에 대한 경험식을 이용하였고, 벽 내부의 전도는 2차원 축대칭의 형태로 수치해석 하였다. 본 해석을 통하여 막냉각 냉각효과에 의한 벽면 온도의 시간에 따른 변화, 최대온도 지점의 변화등을 분석하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.303-308
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• 1994

The finite element method has been used to model and analyze the heat transfer phenomena during manufacturing process of MoSi $_{2}$ by SHS. For this urpose nonlinear transient heat transfer analyses by using ANSYS have been performed to compute the temperature distributiuon and the peak temperature in the test specimen. The effects of manufacturing process parameters such as a pre-heating temperature, the velocity of reaction zone have also been investigated. The results of the analysis have been compared with the experimental results.

• 설비공학논문집
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• 제4권3호
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• pp.191-203
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• 1992

To analyze the unsteady heat transfer phenomena in radiant heating panel, a mathematical model was considered. Numerical analysis for solving the governing equations was conducted by using the finite difference method with boundary-fitted meshes. Transient temperature distributions and thermal responses in heating panel were obtained for various design parameters such as pipe pitches, pipe diameters and pipe depths. Experimental results were also obtained to verify the results of calculation.

• 설비공학논문집
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• 제16권10호
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• pp.889-894
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• 2004

Infrared (IR) detectors are widely used for many applications, such as temperature measurement, intruder and fire detection, robotics and industrial equipment, thermoelstic stress analysis, medical diagnostics, and chemical analysis. Quantum detectors commonly need to be refrigerated below 80 K, and thus a cooling system should be equipped together with the detector system. The cooling load, which should be removed by the cooling system to maintain the nominal operating temperature of the detector, critically depends on the insulation efficiency of the cryochamber housing the detector. Thermal analysis of cryochamber includes the conduction heat transfer through a cold well, the gases conduction and gas outgassing, as well as radiation heat transfer, The transient cooling characteristics of an infrared detector cryochamber are investigated experimentally in the present study. The transient cooling load increases as the gas pressure is increased. Gas pressure becomes significant as the cooling process proceeds. Cool down time is also increased as the gas pressure is increased. It is also found that natural convection effects on cool down time become significant when the gas pressure is increased.