• 한국분무공학회지
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• 제17권1호
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• pp.9-13
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• 2012

This study investigates experimentally evaporation characteristics of nanofluid droplets containing 50 nm alumina($Al_2O_3$) particles and the wettability changes on a hydrophilic glass surfaces. From the captured digital images by using a CMOS camera and a magnifying lens, we examined the effect of particle concentration on droplet evaporation rate which can be indirectly deduced from the measured droplet volumes varying with time. In particular, with the use of a digital image analysis technique, the present study measured droplet perimeters and the contact angles to study the wetting dynamics during evaporating process. In addition, we compared the measured total evaporation time with theoretically estimated values. It was found that as the volume fractions of nanofluid increased, the total evaporation time and the initial contact angles decreased, while the droplet perimeters increased.

• 한국분무공학회지
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• 제26권2호
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• pp.73-80
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• 2021

Evaporation characteristics of single butanol gel fuel were investigated in different mass ratios of gellant and ambient temperatures. Gel fuel was made by adding the pure water and hydroxypropylmethyl cellulose (HPMC) into the 1-butanol. Increase of viscosity was observed when the loading of HPMC increased. The evaporation process of gel droplet could be divided into three stages: droplet heating, micro-explosion and crust formation. Elevation of ambient temperature helped boost the evaporation in all experimental cases, but the effect was mitigated when the mass ratio of HPMC increased. Increase of HPMC weight ratio reduced the evaporation rate.

• 한국분무공학회지
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• 제1권3호
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• pp.29-36
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• 1996

The present study systematically investigates the effect of evaporation rate on the combustion characteristics and the flame stabilization in a gasoline engine. A constant volume combustion chamber was used to elucidate a basic combustion characteristics and the premixer was installed to control temperature and equivalence ratio. And the maximum pressure, combustion duration and flame propagation according to the evaporation rate were measured to determine the optimal temperature range for evaparating a gasoline fuel. These experimental results indicate that the combustion characteristics such as combustion chamber pressure and combustion duration were deteriorated by decreasing surrounding temperature of fuel injected. It was also found that the overall gasification process for gasoline fuel was strongly influenced by a combustion chamber temperature rather than a premixer temperature.

• 한국농공학회지
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• 제19권3호
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• pp.4472-4482
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• 1977

In order to estimate furture consumtive use, some statistical characteristics of 22-year pan evaporation data at four selected stations were calculated in this study. Districal distribution, trend analysis and time-series, statistical and periodic analysis for annual, monethly and ten-day values were performed in the statistical analysis. The stations are Seoul, Taeku, Jeonju and Mokpo for monthly data, and Suweon data are compared to the reported Penman values. The results are as followed: 1. Annual evaporation ranged to 990-1,375mm varying with the locations of the stations. The Districal distribution of evaporation in the Republic is shown in Fig. 1. 2. The trend analysis for annual evaporation resulted in detail in Table 2 and Fig. 2, through simple moving average methods. The results show relatively short-period data of about 10 years would be acceptable for field use. 3. The means and dispersions of monthly evaporation at four stations are detailed in Table 3. 4. The monthly evaporation approached to the trend of normal distribution Fig. 3 showed the examples of normal distribution for each typical monthly data. 5. The correlograms detailed in Fig. 4, shows the time-series characteristics of monthly evaporation, whose periodic term should be twelve months. 6. The periodic analysis for monthly evapolation results in Table 4. Fig. 5 shows the comparison of estimated values to actual and the trend approaches Shuster's periodic trend. 7. A periodic description of days after March 1 for irrigation periods was developed to predict ten-day evaporation in Fig. 6. The ten-day etraporation is different in the distribution form and occurence period of maximum values from the reported Penman's man's evapotranspiration.

• 한국전기전자재료학회논문지
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• 제22권11호
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• pp.956-960
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• 2009

The characteristics of organic films can be affected by the temperature of evaporation source because the temperature of evaporation source has an effect on substrate temperature during OLED fabrication process using the thermal evaporation. To investigate the characteristics of OLED devices fabricated by using thermally damaged organic films, I-V-L and half life-time in OLED devices fabricated with various substrate temperatures were measured. During emission layer(EML) evaporation, OLED devices with a structure of ITO(100 nm)/ELM200(50 nm)/NPB(30 nm)/$Alq_3$(55 nm)/LiF(0.7 nm)/Al(100 nm) were fabricated at various substrate temperatures(room temperature, $30^{\circ}C$, $40^{\circ}C$, and $50^{\circ}C$). The characteristics of current density and luminance versus applied voltage in OLED devices fabricated shows that many electrical currents flowed and high brightness appeared at low voltage, but that the lifetime of OLED devices dropped suddenly. This phenomenon explained that the crystallization of $Alq_3$ thin film appeared owing to the substrate heating during evaporation.

• 해양환경안전학회지
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• 제27권7호
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• pp.1116-1123
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• 2021

해수에 유출된 유류는 대기와 해수와의 접촉을 통해 다양한 풍화 과정(증발, 확산, 분산, 유화, 용해, 산화, 침전 및 생물분해 등)을 통해 물리·화학적 변화와 함께 생물학적 분해과정을 겪는다. 본 연구에서는 여러 가지 풍화작용 중 가장 즉각적이고 빠르며 오염물질의 질량에 가장 큰 영향을 미치는 인자라고 알려진 증발(evaporation)에 대한 영향을 확인해보고자 하였다. 휘발유, 등유, 경유를 대상으로 25 ℃(해수 연평균 온도)와 35℃(적도 부근 온도) 조건에서 유류의 휘발특성을 비교하였다. 이를 위해, 일정 기간마다 채취한 유류를 전처리하여 GC/MS 분석을 수행하고, 탄화수소의 변화량을 계산하여 비교하였다.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1998년도 학술발표회 발표논문집
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• pp.338-343
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• 1998

This study is to select appropriate probability distributions for ten days evaporation data for the purpose of representing statistical characteristics of real evaporation data in Korea. Nine probability distribution functions were assumed to be underlying distributions for ten days evaporation data of 20 stations with the duration of 20 years. The parameter of each probability distribution function were estimated by the maximum likelihood approach, and appropriate probability distributions were selected from the goodness of fit test. Log Pearson type III model was selected as an appropriate probability distribution for ten days evaporation data in Korea.

• 설비공학논문집
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• 제18권5호
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• pp.393-401
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• 2006

The regenerative evaporation water cooler is devised and analysed in this study. The regenerative evaporation water cooler is composed of a sensible heat exchanger to cool the incoming air, followed by a latent heat exchanger to cool the water evaporatively with the cooled air flowing out of the sensible heat exchanger. By linearizing psychrometric characteristics, the heat and mass transfer in the regenerative evaporation water cooler is analyzed theoretically. The results show that the water can be cooled down even lower than the wet-bulb temperature of the inlet air. When the inlet air is $32^{\circ}C$ and 20% in relative humidity, and the inlet temperature of the water is $20^{\circ}C$, the regenerative evaporation water cooler provides a larger cooling capacity than the conventional evaporation water cooler if the effectiveness of the latent heat exchanger is higher than 0.6 and that of the sensible heat exchanger is higher than 0.5.

• 한국분무공학회지
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• 제26권2호
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• pp.88-95
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• 2021

This study aims to investigate the influence of the droplet volume on the evaporation characteristics of the sessile droplet. In particular, the effect of the free convection in the vapor domain on the evaporation rate was analyzed through the numerical simulation. The commercial code of the ANSYS Fluent (V.2020 R2) was used to simulate the heat transfer in the liquid-vapor domain. Moreover, we used the diffusion model to estimate the evaporation rate for the different droplet volume under the room temperature. It was found that the evaporation rate significantly increases with the droplet volume because of the larger surface area for the mass transfer. Also, the effect of free convection on the evaporation rate becomes significant with an increment of droplet volume owing to the increase in the droplet radius corresponding to the characteristic length of the free convection.

• 대한기계학회논문집B
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• 제25권6호
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• pp.845-852
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• 2001

The characteristics of evaporation cooling of single droplet on a heated surface were studied experimentally. The two kinds of heater modules were tested to measure cooling characteristics of metal surface (high conductivity) and Teflon surface (low-energy surface, low conductivity). The results showed that time averaged heat flux during droplet evaporation increased exponentially with initial surface temperatures of brass, copper and steel. The heat flux and evaporation time did not varied with metal conductivities. However, the temperature drop after the deposition of droplet was larger on Teflon than on the metals. Thus, the correlation of interface temperature between liquid droplet and metal surface was proposed as a function of the initial surface temperature of heating materials, which could be applied to both metal and non-metal ones.