• Proceedings of the KSME Conference
• /
• 2001.06d
• /
• pp.503-508
• /
• 2001

Experiments on the condensation and evaporation heat transfer characteristics inside plate heat exchanger with R134A are performed in this study. The test plate heat exchangers in 45o, 55o and 70o shevron angle are used. Varying the mass flux of the refrigerant and the saturation temperatures, the average heat transfer coefficients are investigated. It is shown that the heat transfer is increased with increasing shevron angle. Experiments results show that average condensation heat transfer coefficients are decreased with increasing condensation temperature but those of evaporation are increased with increasing evaporation temperature.

• Proceedings of the KSME Conference
• /
• 2001.06d
• /
• pp.708-714
• /
• 2001

Although LP gas has lots of advantages, there has been limitation in application for automotive engine due to the several disadvantages, such as power decrease, complex fuel supply unit, and back fire etc. However LP gas direct injection engine has possibility to solve the problems above mentioned. LEM(Light Extinction Method) was employed for analysis of spacial and temporal distribution of LP gas which is directly injected into combustion chamber under various pressure and temperature conditions. The results from CVC(Constant Volume Chamber) were compared to those of RICEM(Rapid Induction, Compression and Expansion Machine) which simulate early- and late injection of direct injection engine. LPG fuel spray is affected by temperature and pressure in evaporation characteristics but it is more benefit to direct injection engine in every way such as, fuel distribution, evaporating speed and well wetting reduction.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.8 no.1
• /
• pp.18-25
• /
• 1984

The transition boiling of a liquid droplet on a heated flat surface was studied utilizing Kotake's model with the effects of viscosity of a thin vapor layer between the droplet and the hot plate taken into account. This problem was analyzed considering the process of the droplet evaporation which resulted in hydrodynamic instability at the liquid-vapor interface. The results of the study are as follows; (1)The effect of the viscosity in the vapor layer at the interface appears as a dimensionless number N, namely .sigma. .delta.$_{0}$ /.rho.nu.$^{2}$ (2)The time required for evaporation at the transitional region increases with the temperature difference ratio .DELTA. T$_{r}$. The rate of increase of the total evaporation time becomes larger as increasing of N$_{m}$(N number at maximum heat flux) increases.s.

• Preventive Nutrition and Food Science
• /
• v.8 no.3
• /
• pp.225-229
• /
• 2003

Clarified apple, carrot and orange juices were prepared using ultrafiltration and their single and blend juices were further concentrated using ultrafiltration, freeze-drying, and rotary evaporation. Effect of concentration methods on the quality of concentrated single juices and juice blends was investigated. Turbidity values of samples concentrated by evaporation were significantly higher than those prepared by ultrafiltration and vacuum freezing regardless of juice source (i.e., apple, orange or carrot) or blending (p<0.05). The highest soluble solids contents were obtained for the samples concentrated by evaporation process. Concentrated apple juice contained significantly higher amount of vitamin C and soluble solids than concentrated orange and carrot juices regardless of concentration methods (p<0.05). For blended samples, no direct relationships between blend ratio and total amount of vitamin C were found; however, samples contained more apple juice showed the highest value of soluble solids regardless of concentration methods.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.22 no.8
• /
• pp.1064-1072
• /
• 1998

The evaporation of sludge particles in a sludge dryer has been numerically investigated with commercial CFX4.1 code. Gas flow field, gas temperature field, sludge particle trajectories, and the moisture content variation of sludge particles are calculated fort various influencing factors, i. e., gas swirl velocity, initial particle distribution, gas temperature. Evaporation of sludge particles increases with gas swirl velocity, several supplying positions, and gas temperature, respectively due to increased residence time, increased contacting surface area, and increased temperature difference between gas and particle.

• 한국신재생에너지학회:학술대회논문집
• /
• 2008.05a
• /
• pp.438-440
• /
• 2008

Effects of Ga contents of CIGS absorber layer on the performance of thin films solar cells were investigated. As Ga content increased, the grain size of CIGS films decreased presumably because Ga diffusion during 2nd stage of co-evaporation process is more difficult than In diffusion. Performances of corresponding solar cell show systematic dependence on Ga content in which open circuit voltage increases and short circuit current and fill factor decrease as Ga contents increases. At a optimal condition of Ga/(In+Ga)=0.27, the solar cell shows a conversion efficiency of 15.6% with $V_{OC}$ of 0.625 V, $J_{SC}$ of 35.03 mA/$cm^2$ and FF of 71.3%.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2006.05a
• /
• pp.115-119
• /
• 2006

The goal of this research is to develop and apply the generalized regression neural networks model (GRNNM) embedding genetic algorithm (GA) for pan evaporation, which is missed or ungaged and for the alfalfa reference evapotranspiration, which is not measured in South Korea. The GRNNM-GA is evaluated using the training, the testing, and reproduction performance respectively for the estimation of the PE and the alfalfa reference evapotranspiration. Since the observed data of the alfalfa reference evapotranspiration using lysimeter have not been measured for a long time in South Korea, the PM method is used to assume and estimate the observed alfalfa reference evapotranspiration. From this research, we evaluate the impact of the limited climatical variables on the accuracy of the GRNNM-GA. We should, furthermore, construct the credible data of the PE and the alfalfa reference evapotranspiration and suggest the reference data for irrigation and drainage networks system in South Korea.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.27 no.7
• /
• pp.443-447
• /
• 2014

ZnO crystals with different morphologies were synthesized through a thermal evaporation of Zn-Mn mixtures in air. The morphology was dependant on the Mn content in Zn-Mn mixture. The morphology was changed from rod to tetrapod shape with decreasing Mn content in Zn-Mn mixture. The result indicates that the concentration of Mn might be responsible for the different morphologies of ZnO crystals. XRD spectra showed that the ZnO crystals had a hexagonal wurtzite crystal strutures. For all the samples, room temperature cathodoluminescence spectra showed a ultra-violet emission at 380 nm and a green emission at around 500 nm. However, the intensity ratio of ultra-violet emission to green emission was significantly different with the Mn content in the source material.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.25 no.8
• /
• pp.632-638
• /
• 2012

The prepartion of various metal oxide nanostructures via hydrothermal method, hydrolysis, thermal evaporation and electrospinning and their applications to chemoresistive sensors have been investigated. Hierarchical and hollow nanostructures prepared by hydrothermal method and hydrolysis showed the high response and fast responding kinetics on account of their high gas accessibility. Thermal evaporation and electrospinning provide the facile routes to prepare catalyst-loaded oxide nanowires and nanofibers, respectively. The loading of noble metal and metal oxide catalyst were effective to achieve rapid response/recovery and selective gas detection.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.58 no.3
• /
• pp.310-315
• /
• 2009

This investigation was performed to study the characteristics of electricity and heat transfer that occur in the cylinder of electrode type humidifier during the process of water evaporation. Measurements were made to obtain the amount of water evaporation, the consumption of electric power, electrical conductivity, etc according to the materials and shapes of electrode. When the humidifier was in non-drain controlled mode, the number and amplitude of current cycle per minute increased gradually with the lapse of time, whereas for drain controlled mode, it decreased about 40[%] after draining water. It was found that for non-drain controlled mode, the thermal efficiency of humidifier which used SS400, STS316 and wire net electrode type was about 95~96[%] and it was 2~4[%] higher than that of drain controlled mode. Also, it was shown that the thermal efficiency of humidifier which used neighboring six-phase electrode balanced electrically was 4[%] higher than that of existing six-phase type.