• Journal of Environmental Science International
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• v.7 no.5
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• pp.639-645
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• 1998

A Jump model was evaluated for the calculation of hourly mixing height and mean potential temperature within the height. The Sump model was modified for estimation of downward heat fluxes by mechanical convections and surface heat fluxes. The surface heat fluxes were estimated from routine weather data such as solar radiation and air temperature. Total of 8 upper-air data observed at 0000UTC and 0600UTC in Osan station during April 23 to 26, 1996 were analyzed, and compared to the model results in detail. The calculated mixing heights and potential temperatures within the height were comparable to the observations, but some differences were showed. The calculated mixing heights were generally higher than observations. And, when variations of wind directions were large, the large difference of potential temperature was occurred. From the results, it was important to note that vortical motions and advections of air masses would affect to the growth of the mixing height.

• Journal of Advanced Marine Engineering and Technology
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• v.20 no.5
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• pp.76-81
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• 1996

In this paper, a calculation method for fin efficiency of continuous fin is introduced. The continuous fin of in-line and staggered arrangement was divided into many sectors and fin efficiencies of each sectors were calculated by assuming that each sectors be the circular fins. To get the converged fin efficiency which is averaged by the each areas, the number of sectors was increased. The results were compared with equivalnet method by varying the aspect ratios in both cases of in-line and staggered tube arrangement and showed some differences of fin efficiencies.

• Journal of Energy Engineering
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• v.9 no.1
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• pp.1-9
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• 2000

공정연계를 최소호하는 IGCC 시스템에 대한 개념설계를 수행하였다. 공정분석은 상용코드인 ASPEN PLUS를 이용하였다. 가스화기의 적절한 운전조건을 찾기위하여 가스화기를 경계조건으로 하는 액서지 민감도분석을 통하여 투입되는 슬러리와 산소의 조건을 결정하였다. 또한 , 생성가스 냉각시 현열을 최대한 회수학 ldn하여 , 열교환망을 통하여 급수를 에열하고 가스화플랜트의 각 부분에 공급하도록 공정을 구성하였다. 여분의 가열된 급수는 갑압증발시켜 복합사이클에서 동력을 생성시키는데 사용되어진다. 이와 같은 시스템은 , 가스터빈 -ASU-가스화플랜트의 공기에 의한 공정연계와, HRSG-가스냉각 및 정제시스템 간의 증기연계를 가능한 적게함으로써 공정의 운전성과 경제성을 최적으로 유지할 수 있다. 본 연구에서 제시하는 공정의 경우에, 열효율이 약 39%(고위발열량 기준)으로 나타났으며, 단위 기기 및 단위공정들의 최적화를 통하여 40%의 효율달성이 가능할 것이다.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.10 no.4
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• pp.1-7
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• 2014

This paper is performed to investigate of cooling effect and total enthalpy variation on EAHES(Earth-to-Air Heat Exchanger System) that is buried 3m depth and 60m length. Using EAHES, the reduction of the sensible heat is obviously but latent heat is showed increased trend. Although the outdoor average latent heat accounts for 53.2% of total enthalpy, latent heat of the exit air from EAHES was raised as 58%. For improving cooling effect of EAHES, it has to considered that how to remove the latent heat from EAHES.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.294-299
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• 2005

In order to control indoor air quality and save energy. it is needed to install a suitable ventilation system equipped with heat exchanger for heat recovery. Paper heat exchanger can recover $50{\sim}70$ of the enthalpy difference between supply and exhaust air. The purpose of this research is to obtain the experimental correlations for the friction factor, heat transfer coefficient, mass transfer coefficient and permeance of paper heat exchanger, which can be used for the performance prediction of the paper heat exchanger. Pressure drop at various velocities and heat transfer rate at various dry-bulb temperatures, relative humidities, and specific humidities are measured to make experimental correlations. The results of prediction using correlations show fairly good agreement with experimental data.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.3
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• pp.512-520
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• 1995

This study investigates the simultanceous heat and mass transfer between a falling desiccant film and air in cross flow at the interface. The application of this work is the optimization of falling film evaporators for use in potential hybrid air conditioning systems. The specific geometry considered is liquid TEG films falling along the vertical cooled surfaces of a channel with air in cross flow. The equations to describe the coupled heat and mass transfer between a falling desiccant film and air in cross flow for a falling film evaporator have been presented and solved numerically. The effects of important design and operating variables on the evaporator performance predicted by the parametric numerical analysis and suggestions for performance improvements of the evaporator are presented.

• 한국기계연구소 소보
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• s.16
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• pp.17-28
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• 1986

전열교환기는 최근 대형건물 및 생산공장 등의 에너지 다소비 장소의 공기조화설비의 에너지 절감기기로서 크게 각광 받고 있다. 그 중에서도 특히 알루미늄 박판에 실리카-겔 분말을 코팅한 Honey comb형 로터는 현열 및 잠열 즉 전열을 흡수할 수 있어 폐에너지 회수용 전열교환기의 전열소자로서 점차 이용되고 있다. 그러나 국내에서는 현재까지 전열교환기의 핵심부품인 상기 로터를 전량 수입에 의존하여 왔다. 본 연구에서는 백륜공업(주)와 공동출연으로 실리카-겔 분말 코팅된 알루미늄 소재 박판만 수입하여 성형공정 기술을 개선, 향상시켜 국산로터의 시제품을 제작하고 그 성능을 시험하여 수입로터와 비교, 평가하였다. 연구결과, 국산개발 알루미늄 로터 시제품의 전열효율이 수입로터 보다 급배기 조건에 따라 1~5%정도 향상되었다. 또한 알루미늄 로터의 최적운전조건(11-13 r.p.m) 및 급배기 공기량비에 대한 적정조건도 연구결과로 얻어졌다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.4
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• pp.517-526
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• 1997

This study is focused on the development and selection of the optimal cool tube system to maximize its thermal performance. Cool tube is devised to reduce the heating and cooling load of building by preheating or refreshing of intake air with buried pipes. Finite volume method is adopted to solve the conduction problem between the cool tube and earth. We examine the cool tube system for two operating periods, a short term(12 hours) and a long term(3 months). The results of short term operations reveal that condensation significantly influences and raises the exit air temperature. For long term operations, optimum conditions of cool tube system are obtained with variations of flow-rate, depth, length and diameter of cool tube.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.2
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• pp.68-73
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• 2017

Recently, energy recovery ventilators (ERVs) have been installed for energy saving in many multi-residential buildings in Korea. The performance of the heat exchanger of an ERV is analyzed in this study under specific indoor and outdoor conditions in a test-cell measurement. However, the performance of the heat exchanger varies according to the indoor and outdoor condition. In this study, the performance of energy recovery of the ventilation system was therefore analyzed in actual weather conditions using field measurement. Experiments were conducted under winter conditions in a multi-residential building for 20 days. Based on the measurement results, the characteristics of sensible heat and latent heat exchange rates were analyzed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.5
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• pp.589-601
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• 1997

A computer simulation program of a high efficiency condensing heat exchanger is developed. The flue gas flows outside bare tube bundles both in strong cross flow and in weak counter flow and the cooling water inside the tubes. Condensing heat exchangers achieve high efficiency by reducing flue-gas temperatures to a level at which most of the water vapor in the flue gas is condensed and the latent heat associated with phase change of the water is recovered. The computer model has been verified by comparison with measured data. To verify the model, heat transfer coefficient was adjusted, along with the mass transfer diffusion coefficient and pressure drop coefficient, to achieve agreement between predicted and measured data. The efficiencies of heat exchanger increase 2.3 ~ 8.1% by condensations of 6.3 ~ 62.6% of the water vapor in the flue gas.