• Solar Energy
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• v.18 no.1
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• pp.91-98
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• 1998

The study of mixed convection in a room with heated bottom surface and various partitions has been numerically investigated using a finite volume method. The parameters studied here are, 50$\overline{Nu}=\overline{Nu_n}{\cdot}(1+c(Re/Gr^{1/2})^d)$, where $\overline{Nu_n}$ corresponds to pure natural convextion.

• Nuclear Engineering and Technology
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• v.20 no.3
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• pp.197-202
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• 1988

A finite slab approximation method was developed to predict the long-term teachability. It is based on the assumption that the diffusional characteristics of radionuclides in a waste matrix are not dependent on matrix geometry but dependent on volume to surface ratio V/S) and diffusion coefficient. Consequently it can be expressed as the solution of the equations obtained from a finite slab with an equal V/S ratio (imaginary diffusion length). The calculational results by the finite slab approximation method have been compared with the results obtained for finite cylinder and sphere with corresponding diffusional analysis. The results of this simple model have showed a good agreement and presented a general applicability for the long-term prediction of the radionuclide leaching behavior.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.10
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• pp.1963-1970
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• 1992

An oscillatory motion of the natural convection in a two dimensional, partially divided square enclosure heated from below, and fitted with a partition is investigated numerically. The enclosure was composed of the lower hot and the upper cold horizontal walls and the adiabatic vertical walls, and a partition was situated perpendicularly at the mid-height of the one vertical insulated wall. The governing equations are solved by using the finite element method with Galerkin method. The computations were performed with the variation of the length and the thermal conductivity of the partition, and Rayleigh number based on the temperature difference between horizontal walls and the enclosure height with water(Pr=4.95). also, the effect of the inclination angles was studied for the transition to the oscillating flow. As the results, it was found that the intensity and frequency of oscillatory motion were affected significantly by the Rayleigh number and the length of partition. The effect of oscillatory motion was weaken with the increase of the thermal conductivity of partition. The inclination angle for the transition was raised with the increase of Rayleigh number and the length of partition.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.12
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• pp.1230-1235
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• 2001

The laminar convection heat transfer in a ventilated space with various horizontal partitions was studied numerically and experimentally. The experimental results by holographic interferometer showed good agreements with the numerical results. For the numerical study, the governing equations were solved by using a finite volume method for $46.6\leqRe\leq1332,\;1460\leqGr\leql1585$, Pr=0.71 and the variations of partition lengths. The isotherms and velocity vectors have been represented for various parameters. As the length of partition increases, the convection heat transfer decreases. Based on the numerical data, a correlation was obtained for the dimensionless mean Nusselt number in terms of $Gr/Re^2$. In the region of $Gr/Re^2$<1, the mean Nusselt number was very small, but in the region of $Gr/Re^2\geq1$, the mean Nusselt number was constant.

• Journal of the Korean Society of Visualization
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• v.6 no.1
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• pp.27-33
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• 2008

Air flow inside an automotive HVAC module has been investigated using a high-resolution PIV technique with varying the temperature operation mode. The PIV system consists of a 2-head Nd:YAG laser (125 mJ), a high-resolution CCD camera (2K$\times$2K), optics and a synchronizer. A real automotive HVAC module was used directly under real operating condition. Some casing parts of the HVAC module were replaced with transparent windows for capturing clear flow images with laser light sheet beam illumination. Time-averaged velocity fields were obtained for two different temperature control modes. Flow characteristics of the air-conditioned air flow inside the automotive HVAC system for the two temperature baffle conditions were evaluated.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.3
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• pp.302-314
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• 1994

The effects of the inclination of enclosure and partition on natural convective flow and heat transfer were investigated numerically. The enclosure was composed of the lower hot and the upper cold horizontal walls and the adiabatic vertical walls, and a partition was positioned perpendicularly at the mid-height of one vertical insulated wall. The governing equations are solved by using the finite element method with Galerkin method. The computations were performed with the variations of the partition length and Rayleigh number based on the temperature difference between two horizontal walls and the enclosure height with water(Pr=4.95). The effects of the inclination angle of enclosure and partition on the heat transfer within an enclosure were also studied. As the results, the increase of the inclination angle of enclosure rapidly raised the heat transfer rate, while the inclination angle for the maximum Nusselt number was retarded with the increase of the partition length and the decrease of the heat transfer rate became larger in proportion to the increase of the partition length. The Nusselt number obtained by the inclination of partition was smaller than that of the inclination of enclosure. However, the difference of the heat transfer rates was considerably decreased at the longer partition lengths and the trends for the variation of the average Nusselt number were more similar with that of the inclination of enclosure. The upward oriented partition increases the convective heat transfer distinctly in contrast to that of the inclination of enclosure as the partition length increases.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.10
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• pp.549-555
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• 2017

The purpose of this study is to investigate how ozone-dissolution-tank structure affects micro-ozone-bubble distribution, energy consumption and water treatment efficiency. The partition walls inside the ozone-dissolution-tank generate pressure changes, shear forces, and swirling flows, which change the size of the bubble diameter. The size of the bubble diameter differs by 10.5% depending on the partition walls. Changes in ozone-bubble diameter are related to energy consumption. As the ozone-bubble becomes smaller, the bubble generation energy increases, but the ozone production energy decreases as the dissolution efficiency increases. Therefore, an ozone-dissolution-tank should be determined by means of an optimal condition producing a micro-ozone-bubble with a minimum sum of bubble generation energy and ozone production energy. The energy consumed to inject the same amount of ozone into the effluent differs by 2.5% depending on the partition walls. However, considering the water treatment efficiency, the conditions for selecting the ozone-dissolution-tank are variable. This is because the free radicals that increase as the ozone-bubble gets smaller are very efficient for water treatment. Even at the same ozone injection concentration, the water treatment efficiency differs by 10.4% according to the partition walls. Therefore, we have studied ozone-dissolution-tank structure which produces reasonable ozone-bubble considering water treatment efficiency and energy efficiency.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1990.10a
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• pp.41-46
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• 1990

본 논문은 다공관의 바깥쪽 공간을 칸막이로 분할한 형태의 칸막이형 소음 기에 관하여 연구한 것이다. 일차원 해석을 통하여 각 요소의 전달 행렬을 구하여 소음 성능을 계산하고 격판의 위치, 유공률(porosity)등을 변화시키면 서 소음기의 성능을 실험하여 계산결과와 비교한 후 결론을 내렸다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.9
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• pp.2304-2314
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• 1993

Natural convective flow and heat transfer in a two-dimensional square enclosure fitted with a horizontal partition are investigated numerically. The enclosure was composed of the lower hot and the upper cold horizontal walls and the adiabatic vertical walls, and a partition was situated perpendicularly at the one vertical insulated wall. The governing equations are solved by using the finite element method with Galerkin method. The computations were carried out with the variations of length, position and thermal conductivity of the partition, and Rayleigh number based on the temperature difference between two horizontal walls and the enclosure height with water(Pr=4.95). As the results, an oscillatory motion of natural convection is resulted in a sudden rise of overall heat transfer, but the increase of length of partition is significantly restrained the increase of Nusselt number. The maximum heat transfer was shown just before the transition of the direction of oscillating flow. An oscillatory motion of flow was perfectly shown the stability with the decrease of the length of partition and Rayleigh number. Also, the heat transfer was raised with the increase of the thermal conductivity in proportion to the increase of the length of partition. The stability and oscillation of flow are affected by the position of partition.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.80.1-80.1
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• 2011

This study was carried out in order to estimate the effect of heat pump performance by use of thermal tank with 3 seperation plates which were able to divide thermal tank into 3 chambers that have different temperatures levels. For testing the effect of developed thermal tank which was installed for supplying the heat to the paprika greenhouse in Jinju city. The volume of thermal storage tank was designed for $110m^3$ which was able to cover 30% of heating capacity. The temperature difference was 3 degree Celcius between high temperature and low temperature when only heating circulation was made from heat pump to thermal tank. but 5.5 degree Celcius difference was made when heating circulation of heat pump to thermal thank and hot water supplying circulation of thermal tank to greenhouse was done simultaneously. As a result of this study showed that COP of heat pump was increased by 15% or more than that of using normal thermal tank because heat pump was able to take 3 ~ 5 degree Celcius lower thermal thank water constantly.