• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.6
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• pp.898-902
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• 1999

During summer season, the weather condition of Korea is hot and humid. So humidity elements are very important relating to building envelope condition. The purpose of this investigation is to measure and analyze characteristics of summer's environmental elements such as relative humidity, dry bulb temperature and air velocity in the clay/cement envelope materials using a granite dome model. According to the variation of exterior humidity, the state of interior relative humidity for clay model has an equal tendency, although a little range of variation is shown in comparison to the cement model.

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.162-169
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• 2009

In summer electrical energy is consumed in very high rate. It is used to operate conventional air conditioning system. Hot and humid air can germinate mould spores, encourage ill health, and create physiological stress (discomfort). Dehumidifier solar cooling effect is the one alternative solution saving electrical energy. We use surplus heat energy in the summer, to get cooling effect and then to get human reach to comfort condition. These devices have two system, dehumidifier and regeneration system. This paper will be focus in dehumidifier system. Dehumidifier system use for absorbing moisture in the air and decreasing air temperature. When the liquid desiccant as strong solution contact with the vapor air in the packed tower, it works. The heat and mass transfer performances of flow pattern in the packed tower of dehumidifier are analyzed and compared in detail. In this experiment was introduced, the flow patterns are parallel flow and counter flow. The performance of these flow patterns will calculate from air side. Which is the best flow pattern that gave huge mass transfer rate? The proposed dehumidifier flow pattern will be helpful in the design and optimization of the dehumidifier solar cooling system.

• Journal of Environmental Science International
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• v.16 no.12
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• pp.1401-1409
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• 2007

The formation mechanism of the snow cells of the Yellow Sea associated with snowfall over the southwestern part of Korea on 4 February, 2004 has been investigated using special upper-air sounding and radar data obtained for the KEOP(Korea Enhanced Observing Period) Intensive Observing Period(IOP). Results show that the types of snow cells for the selected period are classified into L(Longitudinal)-mode, Low-level convergence, and T(Transverse)-mode with their evolution from L-mode to T-mode. In particular, the existence of low-level warm and humid layer associated with temporally southwesterly inflow for about 4 hours provides a favorable condition in forming the T-mode snow cells. The vertical depth of the T-mode snow cells is deeper than that of L-mode ones due to the southeastward penetration of cold and dry air into relatively warm and humid air. In addition, it is found that wind shear vector between 1000 hPa and 600 hPa is one of the factors which control the orientation of snow cells in formation embedded into the snowbands for the both modes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.6
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• pp.23-29
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• 2003

Transonic two-phase flow of Saturated humid air, in which relative humidity is 100%, with various condensation processes around thin airfoils is investigated. The study uses an extended transonic small-disturbance(TSD) model of Rusak and Lee [11, 12] which includes effects of heat addition to the flow due to condensation. Two possible limit types of condensation processes are considered. In the nonequilibrium and homogeneous process, the condensate mass fraction is calculated according to classical nucleation and droplet growth rate models. In the equilibrium process, the condensate mass fraction is calculated by assuming an isentropic process. The flow and condensation equations are solved numerical1y by iterative computations. Results under same upstream conditions describe the flow structure, field of condensate, and pressure distribution on airfoil's surfaces. It is found that flow characteristics, such as position and strength of shock waves and airfoil’s pressure distribution, are different for the two condensation processes. Yet, in each case, heat addition as a result of condensation causes significant changes in flow behavior and affects the aerodynamic performance of airfoils.

• Journal of Fisheries and Marine Sciences Education
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• v.22 no.4
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• pp.604-610
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• 2010

Busan subway transportation system has been established a key role in the society last 20 years. However many people are suffering from hot and humid environment at subway station and platform due to deteriorated ventilation system as well as insufficient air conditioning system in existing stations and platforms. As a result, these systems require revitalization. There is about 5400tons of low temperature underground water is generated from subway stations every day. By using this method and air washer we are trying to lower the temperature. Air washer is commonly used for removing humidity but in this experiment it will be used as air precooling. This research offers result of experiment using air washer system to lower the temperature in large spaces like subway station. The experiment result has shown when L/G was the same, at condition which water spray temperature at $18^{\circ}C$ resulting inlet and outlet temperature difference larger. Also, in the same water spray temperature conditions, larger L/G condition showed a greater temperature difference. LCC evaluation of both system were shown that air washer system of using underground water will save 53% of the initial cost than refrigeration system, and save 75% of operating cost.

• Journal of ILASS-Korea
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• v.4 no.1
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• pp.27-33
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• 1999

An experimental study has been conducted to clarify the effect of vapor on droplet evaporation. Droplets of water, ethanol, n-hexadecane and n-heptane were exposed in air stream. Temperature, pressure, and flow velocity in the ambient air are 470K, 1 atm, and 2m/s, respectively. Measurements are carried out for the wide range of water vapor concentration$(0%\sim40%)$. To obtain the time histories of droplet diameter, suspended droplet in hot and humid air stream was synchronized with a back flash light, and enlarged droplet images were taken on a CCD camera. With the vapor concentration increasing, the evaporation rate constant of water droplet decrease slightly and the droplet of ethanol and n-heptane increase actively. The evaporation rate constant of n-hexadecane which has higher boiling point than water increases within around 30% of the concentration.

• Journal of the Korean Ceramic Society
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• v.32 no.11
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• pp.1283-1291
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• 1995

The electrical conductivity, flammable gas response and their humidity effect of porous ZnO, added with 5wt% corn starch as the fugitive phase, were examined. Porous ZnO showed different conductivity curves during increasing and decreasing temperature, and its electrical conductivity decreased rapidly by desorption of OH- between 20$0^{\circ}C$ and 35$0^{\circ}C$ when the temperature increased in dry air. The CO gas sensitivity of starchadded ZnO samples was higher than that of ZnO without starch addition. The sensitivity of porous, starchadded ZnO to 200ppm CO gas was much less in humid atmosphere than in dry atmosphere since water vapor increased the conductivity of porous ZnO in air, but decreased the conductivity in CO. Maximum sensitivity to 200 ppm CO gas balanced by air was about 100 in dry atmosphere and about 15 in RH 23% atmosphere.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.6
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• pp.519-524
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• 2002

An experimental study has been conducted to investigate the effects of surface energy on frost formation. Test samples with two different surfaces are installed in a wind tunnel and exposed to a humid airflow. Dynamic contact angles (DCA) for these surfaces are $23^{\circ}\;and\;88^{\circ}$, respectively. The thickness and the mass of frost layer are measured and used to calculate the frost density while frost formation is visualized simultaneously with their measurements. Results show that frost density increases as time increases at specific test conditions. The air Reynolds number, the airflow humidity and the cold plate temperature are maintained at 12,000, 0.0042 kg/kg and $-21^{\circ}C$, respectively. The surface with a lower DCA shows a higher frost density during two-hour test, but no differences in the frost density have been found after two hours of frost generation. Empirical correlations for thickness, mass and density are assumed to be the functions of the test time and DCA.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.8
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• pp.683-689
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• 2003

The thermal comfort of an indoor swimming pool is different from that of general indoor space because of the characteristics of large space and the wear conditions of swimmers. Dew condensation by humid air not only makes mold on the floor, wall and roof but also decreases the durability of buildings by penetrating into their structures. In this study, the characteristics of the flow field, the temperature field and the humidity distribution in an indoor swimming pool have been examined by the numerical method to estimate the level of thermal comfort and the generation rate of dew condensation. The results showed that the dew condensation regions were spread widely at the eastern parts of the swimming pool due to the insufficient air flow rate with low velocity and temperature. To prevent the generation of dew condensation in a region, a sufficient warm air flow rate should be supplied to make an air mixing. The values of PMV at horizontal plane of 1.5 m height have the range of -1.0∼1.2, which means the suitable level for swimmers.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.4_2
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• pp.565-572
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• 2022

The white plume from the cooling tower can be generated by mixing between discharging hot and humid air and cold air outside. This causes various problems such as icing, traffic disturbances, and fire factors in the vicinity, moreover it can also damage the image of a company. Various methods can be used to prevent white plume, one of them is to install a heat exchanger at the outlet of the cooling tower so that the heat exchanger transfers as much heat as possible to lower the temperature. Therefore the air flow path in the cooling tower should be optimized. Installation of the filler can be used to make the air flow better, thus we investigate the effect of filler on the air flow using CFD method. The pressure and velocity profile in the cooling tower could be acquired by the calculations. The filler made the velocity of the air entering the heat exchanger uniform this was because high flow resistance of the filler suppresses the generation of eddy in the cooling tower. But the total air pressure drop increased about 2 times with filler because the pressure drop by the filler accounted for about 60% of the total pressure drop.