• 한국태양에너지학회:학술대회논문집
• /
• 한국태양에너지학회 2009년도 추계학술발표대회 논문집
• /
• pp.80-85
• /
• 2009

Mathematical modeling and performance simulation results were shown for the solar thermal storage system which used heat pipe. The thermal storage system was composed of thermal storage tank and charging/discharging heat exchanger with one by the heat pipes. Heat pipe heat exchanger was attached to system, and could carry out charging and discharging to thermal storage tank at the same time. Height of the thermal storage tank was 600 mm, and that of the charging/discharging heat exchanger was 400 mm. Length of the heat pipe was the same as the total height of thermal storage system, and outer and inner diameter were 25.4 mm(O.D.) and 21.4 mm(I.D.) respectively. Diameter of the circular was 43 mm(O.D.), and fin geometries were considered as the design parameters. High temperature phase change material(PCM), $KNO_3$ and low temperature PCM, $LINO_3$ were charged to storage tank to adjust working temperature. Total size of thermal storage system able to get heat capacity more than 500 kW was calculated and the results were shown in this study. Number of heat pipe was required more than maximum 500, and total length of thermal storage system was calculated to the more than maximum 3 m at various condition.

• 터널과지하공간
• /
• 제24권3호
• /
• pp.201-211
• /
• 2014

본 연구에서는 전산유체역학 코드인 FLUENT를 이용한 열전달 해석을 통해 대규모 열에너지 저장을 위한 다중 암반공동의 이격거리별 열적 성능을 분석하였다. 저장공동 내부의 열성층화와 공동 외부로의 열손실 측면에서 열적 성능을 평가하였으며, 이격거리별로 시간경과에 따른 공동 주변 암반의 히팅 특성을 조사하였다. 분석결과, 주변 암반이 히팅되지 않은 초기 운영단계와 암반이 열적 정상상태에 도달한 장기 운영단계에서는 다중 암반공동의 이격거리에 따른 열적 성능의 차이가 거의 없는 것으로 검토되었다. 그러나 공동간 이격거리가 감소함에 따라 공동 사이의 암반이 열적 정상상태에 더 빠르게 도달하고, 이에 따라 저장공동 외부로의 열손실이 주변 암반의 열적 정상상태 조건에서의 열손실 값으로 빠르게 수렴하는 경향을 보였다. 이러한 결과는 다중 암반공동의 이격거리를 줄임으로써 주변 암반의 히팅에 소요되는 운영비용을 줄일 수 있음을 나타내며, 이로부터 다중 열저장 공동의 이격거리 결정시 공동의 건설비용과 함께 암반히팅에 대한 운영비용을 고려해야 함을 알 수 있었다.

• 한국정밀공학회지
• /
• 제20권8호
• /
• pp.175-184
• /
• 2003

A method of the shape design sensitivity analysis based on the boundary integral equation formulation is presented for two-dimensional inhomogeneous thermal conducting solids with multiple domains. Shape variation of the external and interface boundary is considered. A sensitivity formula of a general performance functional is derived by taking the material derivative to the boundary integral identity and by introducing an adjoint system. In numerical analysis, state variables of the primal and adjoint systems are solved by the boundary element method using quadratic elements. Two numerical examples of a compound cylinder and a thermal diffuser are taken to show implementation of the shape design sensitivity analysis. Accuracy of the present method is verified by comparing analyzed sensitivities with those by the finite difference. As application to the shape optimization, an optimal shape of the thermal diffuser is found by incorporating the sensitivity analysis algorithm in an optimization program.

• 항공우주기술
• /
• 제4권2호
• /
• pp.126-134
• /
• 2005

발사체는 발사되기 수일 전에 발사탑에 세워져 체크과정 및 연료공급 등을 수행하게 되므로 발사까지는 계속 외부의 열환경에 노출되게 된다. 발사체의 페어링에 대한 발사전 가열 해석(Prelaunch Thermal analysis)은 발사시 페어링의 최대/최소 온도 예측 및 공조 설비(air conditioning system)의 성능 예측을 목적으로 수행된다. 본 연구에서는 범용 열해석 프로그램인 Sinda/Fluint 이용하여 Delta II 페어링에 대하여 발사전 가열 해석을 수행하였으며, 그 결과를 Delta II 보고서 자료와 비교 및 분석하였다.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2001년도 추계학술대회(한국공작기계학회)
• /
• pp.363-368
• /
• 2001

Studies on brake system recently are focused on braking performance, especially the consideration on safety of braking system in an extreme situation and reduction of vibration and noise during braking operation. The thermal crack and Judder from the friction between brake disc and pad can bring the threaten of passengers' safety in the end. Braking force comes from the change of kinetic energy to friction energy. Since heat energy is developed from here, the analysis on thermal stress and thermal strain can be the good data when selecting the material of brake pad and designing heat radiation holes on the disc and it will also be the data when designing the thickness of the disc. This paper is intended to show a creative design method by suggesting the thermal analysis data through FEM study and using shape design parameters.

• Environmental Analysis Health and Toxicology
• /
• 제17권2호
• /
• pp.95-107
• /
• 2002

This study was designed to investigate the characteristics of atmospheric concentrations of toxic volatile organic compounds (VOCs) in Korea. Target compounds included 1,3-butadiene, aromatics such as BTEX, and a number of carbonyl compounds. In this paper, as the first part of the study, the performance of sampling and analytical methods was evaluated for the measurement of selected VOCs and carbonyl compounds in the ambient air. VOCs were determined by the adsorbent tube sampling and automatic thermal desorption coupled with GC/MSD analysis, while carbonyls by the DNPH-silica cartridge sampling with HPLC analysis. The methodology was investigated with a wide range of performance criteria such as repeatability, linearity. lower detection limits, collection efficiency, thermal conditioning, breakthrough volume and calibration methods using internal standards. In addition, the sampling and analytical methods established in this study were applied to real field samples duplicately collected in various ambient environments. Precisions for the duplicate samples appeared to be comparable with the performance criteria recommended by USEPA TO-17. The overall precision of the sampling and analytical methods was estimated to be within 20 ∼ 30% for major aromatic VOCs such as BTEX, whereas the precision for major carbonyl compounds such as formaldehyde and acetaldehyde was within 10 ∼ 20% for field samples. This study demonstrated that the adsorbent sampling and thermal desorption method can be reliably applied for the measurement of BTEX in ppb levels frequently occurred in common indoor and ambient environments.

• 한국대기환경학회지
• /
• 제15권2호
• /
• pp.121-138
• /
• 1999

This study was carried out to evaluate the performance of a sampling and analytical methodology for the measurement of selected volatile organic compounds (VOCs) in the ambient air. VOCs were determined by the adsorbent tube sampling and automatic thermal desorption coupled with GC/FID and GC/MSD analysis. Target analytes were aromatic VOCs, including BTEX, 1,3,5-and 1,2,4,-trimethylbenzenes(TMBs), and naphthalene. The methodology was investigatedwith a wide range of performance criteria such as repeatability, linearity, lower detection limits, collection efficiency, thermal conditioning, breakthrough volume and calibration methods using internal and external standards. standards. Stability of samples collected on adsorbent tubes during storage was also investigated. In addition, the sampling and analytical method developed during this study was applied to real samples duplicately collected in various indoor and outdoor environments. Precisions for the duplicate samples and distributed volume samples appeared to be well comparable with the performance criteria recommended by USEPA TO-17. The audit accuracy was estimated by inter-lab comparison of both duplicate samples and standard materials between the two independent labs. The overall precision and accuracy of the method were estimated to be within 30% for major aromatic VOCs such as BTEX. This study demonstrated that the adsorbent sampling and thermal desorption method can be reliably applied for the measurement of BTEX in ppb levels frequently occurred in common indoor and ambient environments.

• 수산해양기술연구
• /
• 제47권1호
• /
• pp.46-58
• /
• 2011

A steady-state analysis and a simple dynamic model as simplified methods are developed, and results of energy consumption loads are compared with results obtained using computer to evaluate the analytical solution. Before obtaining simplified model a mathematical model is formulated for the effect of wall mass on the thermal performance of four different houses having various wall construction. This analytical study was motivated by the experimental work of Burch et al. An analytical solution of one-dimensional, linear, partial differential equation for wall temperature profiles and room air temperatures is obtained using the Laplace transform method. Typical Meteorological Year data are processed to yield hourly average monthly values. This study is conducted using weather data from four different locations in the United States: Albuquerque, New mexico; Miami, Florida; Santa Maria, California; and Washington D.C. for both winter and summer conditions. The steady state analysis that does not include the effect of thermal mass can provide an accurate estimate of energy consumption in most cases except for houses #2 and #4 in mild weather areas. This result shows that there is an effect of mass on the thermal performance of heavily constructed house in mild weather conditions. The simple dynamic model is applicable for high cycling rates and accurate values of inside wall temperature and ambient air temperature.

• 한국가시화정보학회지
• /
• 제21권2호
• /
• pp.34-45
• /
• 2023

When lithium-ion batteries operate out of the proper temperature range, their performance can be significantly degraded and safety issues such as thermal runaway can occur. Therefore, battery thermal management systems are widely researched to maintain the temperature of Li-ion battery cells within the proper temperature range during the charging and discharging process. This study investigates the cooling performance and isothermal maintenance of cooling materials by measuring the surface temperature of a battery cell with or without cooling materials, such as silicone oil, thermal adhesive, and phase change materials during discharge process of battery by the experimental and numerical analysis. As a result of the experiment, the battery pack filled with phase change material showed a temperature reduction of 47.4 ℃ compared to the case of natural convection. It proves the advanced utility of the cooling unit using phase change material that is suitable for use in battery thermal management systems.

• 한국수소및신에너지학회논문집
• /
• 제34권5호
• /
• pp.465-477
• /
• 2023

In proton exchange membrane fuel cell (PEMFC), proper thermal management of the stack and moisture generation by electrochemical reactions significantly affect fuel cell performance. In this study, the PEMFC dynamic characteristic model was developed through Simcenter AMESim, a development program. In addition, the developed model aims to understand the thermal resin balance of the stack and performance characteristics for input loads. The developed model applies the thermal management model of the stack and the moisture content and permeability model to simulate voltage loss and stack thermal behavior precisely. This study extended the C based AMESet (adaptive modeling environment submodeling tool) to simulate electrochemical reactions inside the stack. Fuel cell model of AMESet was liberalized with AMESim and then integrated with the balance of plant (BOP) model and analyzed. And It is intended to be used in component design through BOP analysis. The resistance loss of the stack and thermal behavior characteristics were predicted, and the impact of stack performance and efficiency was evaluated.