• Transactions of the Korean Society of Mechanical Engineers
• /
• v.16 no.1
• /
• pp.87-94
• /
• 1992

Film boiling heat transfer characteristics in liquid-liquid systems are studied experimentally. Liquid gallium as a heating liquid, n-pentane, freon-113, and ethanol are used as boiling liquids. In gallium-n-pentane and gallium-freon-113 systems the minimum film boiling point occurred at higher temperature than those observed in copper-boiling liquid systems. However MFB point occurred almost at the same temperature for the case of ethanol. This difference are due to the effects of contact angle and interfacial agitations in gallium-boiling liquid systems. Film boiling heat transfer rate, for the gallium-boiling liquid systems considered in this work, found to be approximately 10% higher than those in copper-boiling liquid systems, whose main cause is believed to be gallium-boiling liquid interfacial agitations affected by the density ratio between gallium and boiling liquid.

• Journal of the KSME
• /
• v.25 no.5
• /
• pp.413-418
• /
• 1985

직접 접촉식 교환장치(이하 직접 교환기라 함)에서 액체의 유통형태의 선택은 매우 다양하며 전달계수 역시 개별적인 상황이나 충전물의 종류에 따라서 달라지므로 일률적으로 제시되지 못 하고 있다. 많은 경우 실험을 통하여 열전달 또는 물질전달계수를 측정하게 되나 개수로, 자유 낙하액체막, 액체분류와 같이 이상화가 가능한 경우, 이러한 전달계수를 구하기 위하여 이론적 또는 반실험적인 해석을 수행하기도 한다. 수많은 관련 연구결과들은 층류유동에 관한 것과 난류유동의 경우로 구분되고(예상되듯이 대부분의 직접교환기의 유통영역은 난류쪽이다), 난류 유통의 해석은 다시 표면갱신이론(surface renewal model), 와류확산계수모델(eddy diffusivity model-macroscopic), 미분형와류모델(differential eddy diffusivity model)로 대별된다. 여기서는 수많은 교환기형태의 자료정리보다 상기와 같이 대별된 액체측 유동영역별로 전달현상해석의 방법을 간단히 정리하고자 한다.

• Proceedings of the Korean Nuclear Society Conference
• /
• 2002.05a
• /
• pp.106.2-106
• /
• 2002

• Membrane Journal
• /
• v.21 no.3
• /
• pp.236-246
• /
• 2011

In this study, we used prepared a cylindrical module consisting 100 hollow fibers of commercialized (hydrophobic) polyethylene membrane of $0.4{\mu}m$ pore size and systematically studied performance of direct contact membrane distillation (DCMD) and sweep gas membrane distillation (SGMD) in terms of variation of permeate flux and salt rejection with respect to temperature drop across the membrane, salt concentrations in feed, and flow rates of cooling water and sweep gas. SGMD was regarded as DCMD with a sweep gas layer between permeate-side membrane surface and cooling water. Sweep gas flow decreases the permeate flux from that of DCMD by providing an additional gas-layer resistance. We compared DCMD and SGMD performance by using mass balance with a fitting parameter (${\omega}$), indicating fraction of permeate flow rate.

• Journal of Veterinary Clinics
• /
• v.7 no.2
• /
• pp.521-525
• /
• 1990

The present investigation confirms the zoonotic significance of Microspoum canis infection in five patients who had direct contact with diseased dogs and cats. Typical ringworm type lesions were mainly encountered on the exposed areas of the body. M. canis was isolated from the cutaneous lesions of man ana infected pets ; and also directly demonstrated in skin materials. However, the fungus could neither be recovered from the non-contact group nor from the saprobic environment. The isolates from man, dog, and cat showed similar gross as well as microscopic morphology. Further genetic studies so indicated that all the human and animal isolates of M. canis were(-) mating type. It is believed that transmission of zoophilic dermatophytes from animal to man occurs more commonly with direct exposure. In addition, the epidemiology and preventive measures are also discussed.

• 전기의세계
• /
• v.41 no.3
• /
• pp.45-50
• /
• 1992

완전비접촉부상, 비접촉구동을 실현하는 크린룸용 자기부상반송시스템을 소개하였다. 이 시스템은 스테이션과 각 프로세스장치 사이의 loading/unloading에는 인간이 개입하지만, 스테이션과 각 프로세스장치를 직접 접속하고 loading/unloading도 자도화하면 무인의 완전 무진자동반송시스템을 실현할 수 있을 것이다. (이와같은 문제점을 개선시킨 시스템을 Sumitomo가 개발하여 발효하였고 이에 대해서는 참고문헌를 참고하기를 바란다).

• Proceedings of the KSME Conference
• /
• 2001.06d
• /
• pp.158-163
• /
• 2001

Performance of the water direct contact air conditioning system, in which heat and mass are transferred directly between air and water droplet, is simulated by semi-empirical method. This system improves transport efficiency compared to conventional indirect contact system and cooling, heating, dehumidification and humidification are attained with one unit. In this study, temperature and flowrate for air and water are measured in the various cooling and heating conditions, and correlations for $h_{c}A/c_{pm}$ are derived from these data. Cooling and heating characteristics of the water direct contact air conditioning system are investigated using correlations.

• Nuclear Engineering and Technology
• /
• v.24 no.2
• /
• pp.130-140
• /
• 1992

The physical benchmark problem on the direct-contact condensation under the horizontal occurrent stratified flow was analyzed using the RELAP5/MOD2 and /MOD3 one-dimensional model. Analysis was peformed for the Northwestern experiments, which involved condensing steam/water flow in a rectangular channel. The study showed that the RELAP5 interfacial heat transfer model, under the horizontal stratified flow regime, predicted the condensation rate well though the interfacial heat transfer area was underpredicted. However, some discrepancies in water layer thickness and local heat transfer coefficient with experimental results were found especially when there is a wavy interface, and those were satisfied only within the range.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.16 no.2
• /
• pp.175-183
• /
• 2004

Performance of the water/air direct contact air conditioning system, in which heat and mass are directly transferred between air and water droplet, is simulated using semi-empirical method. Direct contact system improves transport efficiency compared to conventional indirect contact system. In this study, correlations for h$_{c}$A / c$_{pm}$ which represent the capacity of direct contact system are derived as a function of air and water flowrate from the experimental data. Cooling and heating performance of the water/air direct contact air conditioning system are evaluated using these correlations.ons.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.12 no.8
• /
• pp.735-744
• /
• 2000

In order to define the heat transfer characteristics in a spray column direct contact heat exchanger, the development of a multidimensional numerical model and computational algorithm is essential to analyze the inherent multidimensional characteristics of a direct contact heat exchanger. In the present study, it has been carried out numerical calculations using a two-dimensional model for operation of a direct contact heat exchanger. Such operational and system parameters as the injection velocity, void fraction, aspect ratio and injection temperature of each fluid are examined thoroughly to assess their influence on the performance of a spray column. Analyzed results has shown that our two-dimensional model predicts the heat transfer phenomena well in a spray column.