• 한국태양에너지학회 논문집
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• 제21권2호
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• pp.35-43
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• 2001

The results of numerical simulation on the performance of a solar chimney system in building are described. The inside surface temperature of four walls within the solar chimney arc calculated with solar radiation and outdoor temperature in summer. The air within the solar chimney is heated by conduction, convection and radiation. Air temperature distribution from the bottom to the top and outlet air temperature can be obtained by solving energy balance equation. Since the buoyance or stack effect is affected by temperature difference between the bottom and the top within the solar chimney. It is evaluated using inlet and outlet temperatures. It is expected that natural ventilation by the solar chimney of witch the height is 7.8m and the cross sectional area is $4.93m^2$ can provide about $6400m^3/h$ on sunny day.

• Wind and Structures
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• 제8권1호
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• pp.61-78
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• 2005

This paper presents results from an investigation of the structural behaviour of a very slender 90 m high steel chimney erected at V$\ddot{a}$xj$\ddot{o}$ in southern Sweden in 1995. The chimney is equipped with a mechanical friction-type damper at the top. Due to a mistake during erection and installation of the chimney the transport fixings of the damper were not released properly and the chimney developed extensive oscillations in the very first period of service. This caused a great number of fatigue cracks to occur within a few months of service. After the functioning of the damper had been restored and the fatigue cracks were repaired an extensive program was initiated in 1996 to monitor the structural behaviour of the chimney under wind loading. In the investigation data were collected for more than six years of continuous measurements and regular observations of the chimney. The data obtained have some general relevance with respect to wind data, behaviour of a slender structure under wind loading, and the effect of a mechanical damper. Also some theoretical studies were performed as part of the investigation of the chimney.

• 한국태양에너지학회 논문집
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• 제30권2호
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• pp.87-95
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• 2010

This study analyzed the performance of solar chimney system for natural ventilation in underground space. A mathematical model of the solar chimney was proposed in order to predict its performance under varying parameters and Korea climatic condition. Steady state heat transfer equations were set up using a energy balanced equations and solved using a inverse matrix method. Numerical simulation program to analyze system was developed by using MATLAB. As the results, the ventilation performance of the solar chimney was determined by the temperature difference of air channel and inlet, and the temperature difference was influenced by insolation, stack height and distance of air gab. Also the solar chimney system can provide $262.9m^3/h$ of annual average ventilation rate. Because seasonal differences of ventilation rate was calculated within 25%, the solar chimney system can be used for every season in Korea climatic condition. Through this study, performance of solar chimney system for natural ventilation was verified by numerical method. Consequently, the solar chimney system is proved to be effective device for natural ventilation utilizing at all times, and the additional studies should be made through the experimental method for imagineering and commercialization.

• Journal of Advanced Marine Engineering and Technology
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• 제28권5호
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• pp.827-836
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• 2004

The design parameter of the heat loss for the pressurized water reactor has been studied. The heat loss from the reactor vessel through the air gap. insulation are analysed by using the computational fluid dynamics code, FLUENT. Parametric study has been performed on the air gap width between the reactor vessel wall and the inner surface of the insulation, and on the insulation thickness. Also evaluated is the performance degradation due to the chimney effect due to gaps left between the panels during the installation of the insulation system. From the analysis results, the optimal with of air gap and insulation thickness and the value of heat loss are obtained The results show how the heat loss varies with the air gap width and insulation thickness. The temperature and the velocity distributions are also presented. From the results of the evaluation. the optimal air gap width and the optimal insulation thickness are obtained. As the difference between the predicted heat loss and measured heat loss from the reactor vessel is construed Primarily as losses due to chimney effect. the contribution of the chimney effect to the total heat loss is quantitatively indicated.

• Wind and Structures
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• 제31권1호
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• pp.59-73
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• 2020

Wind fragility analysis (WFA) of concrete chimney is often executed disregarding temperature effects. But combined wind and temperature effect is the most critical limit state to define the safety of a chimney. Hence, in this study, WFA of a 70 m tall RC chimney for combined wind and temperature effects is explored. The wind force time-history is generated by spectral representation method. The safety of chimney is assessed considering limit states of stress failure in concrete and steel. A moving-least-squares method based dual response surface method (DRSM) procedure is proposed in WFA to alleviate huge computational time requirement by the conventional direct Monte Carlo simulation (MCS) approach. The DRSM captures the record-to-record variation of wind force time-histories and uncertainty in system parameters. The proposed DRSM approach yields fragility curves which are in close conformity with the most accurate direct MCS approach within substantially less computational time. In this regard, the error by the single-level RSM and least-squares method based DRSM can be easily noted. The WFA results indicate that over temperature difference of 150℃, the temperature stress is so pronounced that the probability of failure is very high even at 30 m/s wind speed. However, below 100℃, wind governs the design.

• Earthquakes and Structures
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• 제7권2호
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• pp.233-250
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• 2014

In this paper, a three dimensional soil-structure interaction (SSI) is numerically simulated using finite element method in order to analyse the foundation moments in annular raft of tall slender chimney structures incorporating the effect of openings in the structure and the effect of soil flexibility, when the structure-soil system is subjected to El Centro (1940) ground motion in time domain. The transient dynamic analysis is carried out using LS-DYNA software. The linear ground response analysis program ProShake has been adopted for obtaining the ground level excitation for different soil conditions, given the rock level excitation. The radial and tangential bending moments of annular raft foundation obtained from this SSI analysis have been compared with those obtained from conventional method according to the Indian standard code of practice, IS 11089:1984. It is observed that tangential and radial moments increase with the increase in flexibility of soil. The analysis results show that the natural frequency of chimney decreases with increase in supporting soil flexibility. Structural responses increase when the openings in the structure are also considered. The purpose of this paper is to propose the need for an accurate evaluation of the soilstructure interaction forces which govern the structural response.

• Structural Engineering and Mechanics
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• 제43권6호
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• pp.835-845
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• 2012

This paper focuses on the stochastic response analysis of industrial masonry chimneys to surface blast-induced random ground motions by using a three dimensional finite element model. Underground blasts induce ground shocks on nearby structures. Depending on the distance between the explosion centre and the structure, masonry structures will be subjected to ground motions due to the surface explosions. Blast-induced random ground motions can be defined in terms of the power spectral density function and applied to each support point of the 3D finite element model of the industrial masonry system. In this paper, mainly a parametric study is conducted to estimate the effect of the blast-induced ground motions on the stochastic response of a chimney type masonry structure. With this purpose, different values of charge weight and distance from the charge centre are considered for the analyses of the chimney. The results of the study underline the remarkable effect of the surface blast-induced ground motions on the stochastic behaviour of industrial masonry type chimneys.

• 한국전자통신학회논문지
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• 제18권4호
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• pp.661-668
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• 2023

농업용 시설하우스의 난방을 위해서는 많은 양의 연료가 필요하고, 최근 연료 가격의 상승으로 인하여 많은 농가가 난방 비용에 대한 부담을 겪고 있다. 본 논문은 산업용 굴뚝 폐열을 활용하여 인근에 있는 농업용 시설하우스 난방을 지원하는 공급시스템을 제안하고, 난방비 절감 모델 적용과 효과에 대해 분석한다. 굴뚝 폐열 시스템을 기반으로 시스템을 설계하였고, 제안한 모델을 기반으로 시설하우스 난방비 절감 모델 적용 및 효과 분석을 수행하였다. 고열의 굴뚝 폐열을 이용하면 인근 농가의 시설하우스 난방 공급에 활용이 가능하다는 것을 확인하였다. 산업단지 인근 대규모 시설하우스에 난방을 공급한다면 국내 농가의 생산성 향상 및 경쟁력 제고에 이바지할 것으로 기대된다.

• 한국지반공학회논문집
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• 제24권5호
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• pp.99-106
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• 2008

본 논문에서는 보강토 옹벽에 있어서 보강토체 배면에 설치되는 연직배수층의 강우시 간극수압 증가 억제효과에 대한 내용을 다루었다. 이를 위해 먼저 다양한 배수시스템 설치 조건에 대해 유한요소해석 법에 근거한 부정류 침투해석을 수행하였으며 그 결과를 토대로 연직배수층의 간극수압 저감 메카니즘을 고찰하였다. 또한 매개변수 연구 결과를 토대로 다양한 연직배수층의 최적설치 높이를 검토하였다. 그 결과 보강토체 배면에 설치되는 연직배수층은 강우시 보강토체 내외부에 모관흡수력이 감소하는 현상을 억제시킴으로서 전단강도 저하를 억제할 수 있는 것으로 나타났으며 옹벽높이의 50% 정도 높이로 설치할 경우 최적의 효과를 발휘할 수 있는 것으로 검토되었다.

• 에너지공학
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• 제8권2호
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• pp.285-292
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• 1999

한국표준원전의 원자로용기 단열재 설치시 설계인자에 대한 수치해석적 연구를 전산 유체유동 코드인 FLUENT를 이용하여 해석하였다. 단열재 두께 및 원자로용기 벽과 단열재의 내부표면간의 공간간격에 대한 인자에 대해서 연구를 수행했다. 또한 단열재 설치시 단열재판넬 사이의 틈새 간격 때문에 발생하는 chimney effect으로 인한 단열재의 성능저하를 평가하였다. 수치해석 결과 최적의 공간 간격 및 단열재 두께를 얻을 수 있었다.