• 대한기계학회논문집B
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• 제25권5호
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• pp.666-672
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• 2001

Experiments have been carried out to investigate the evaporation heat transfer characteristics of various tubes on which hydrophilic surface treatment using plasma was employed. Spiral, corrugated and low-finned tubes were selected as test tubes. The evaporator tubes were bundled to form three rows of tubes connected in series, with each row being 400mm long. The results obtained indicate that hydrophilic treated tubes tested exhibit better evaporation heat transfer performance as compared with untreated tubes. It is found that the high wettability of the surface obtained through hydrophilic treatment induces film flow onto the tubes during the evaporation process, while sessile drops are formed on untreated tubes.

• 대한기계학회논문집B
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• 제38권3호
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• pp.255-262
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• 2014

판형열교환기의 증발과정에서 오일에 위한 영향을 알아보기 위해 마이크로 기어 펌프를 이용한 냉매-R134a 순환 성능실험 장치를 구성하여, 증발열전달 실험을 수행하였다. POE 오일을 펌프를 이용하여 냉매 질량 유량에 비례하도록 0~5%를 첨가하여, 오일순환량에 따른 열전달계수 변화를 측정하였다. 오일순환율이 증가할수록 R134a 증발 열전달계수는 감소하며, 압력손실은 증가한다. 질량유량 80 g/s, 증발 온도 $30^{\circ}C$ 일 때, 오일 순환율 2%조건에서 무오일 대비 약 10%의 열전달계수가 감소하였고, 압력손실은 약 10% 증가하였다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.85-87
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• 2009

Despite the success of $Cu(In,Ga)Se_2$ (CIGS) based PV technology now emerging in several industrial initiatives, concerns about the cost of In and Ga are often expressed. It is believed that the cost of those elements will eventually limit the cost reduction of this technology. one candidate to replace CIGS is $Cu_2ZnSnSe_4$ (CZTSe), fabricated by co-evaporation technique. Effects of substrate temperature of $Cu_2ZnSnSe_4$ absorber layer on the performance of thin films solar cells were investigated. As substrate temperature increased, the grain size of $Cu_2ZnSnSe_4$ films increased presumably. At a optimal condition of substrate temperature is $320^{\circ}C$, the solar cell shows a conversion efficiency of 1.79% with $V_{OC}$ of 0.213V, JSC of $16.91mA/cm^2$ and FF of 49.7%.

• 동력기계공학회지
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• 제8권1호
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• pp.41-47
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• 2004

Cooling towers are widely used not only for cooling products and equipment in manufacturing process but HVAC(Heating, Ventilation and Air Conditioning) system. As a cooling tower is the terminal apparatus which discharges heat from industrial process, the efficiency of heat exchange in the cooling tower greatly affects to the overall performance of a thermal system. In this paper, we constituted a new water cooling system by using a Latent heat of evaporation in an enclosed tank, and this system is consisted of an enclosed vacuum tank and water driven ejector system. Several experimental cases were carried out for improvement methods of high vacuum pressure and water cooling characteristics. The ejector performance was tested in case of water temperature variations that flows into the ejector. Based on the vacuum pressure by water driven ejector, the water cooling characteristics were investigated for the vaporized air condensing effects.

• 한국산학기술학회논문지
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• 제17권1호
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• pp.88-98
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• 2016

여름철이 무더운 대한민국에서는 냉방에 많은 전력을 소비한다. 이 경우 간접증발냉각을 동시에 적용하면 전기 사용을 줄일 수 있다. 본 연구에서는 물 퍼짐성을 개선한 플라스틱/종이 재질의 간접 및 재생증발소자에 대해 일련의 실험을 수행하였다. ${\epsilon}-NTU$ 방식의 열 및 물질전달 해석 모델과 비교한 결과 모델의 예측치는 간접 및 재생증발소자의 간접증발효율, 냉각열량, 압력손실을 적절히 예측하였다. 모델 해석 결과 간접 및 재생증발소자 모두 건채널 입구온도와 상대습도가 증가하면 간접증발효율이 증가하였다. 또한 재생증발소자의 간접증발효율이 간접증발소자의 값보다 크게 나타났다.

• Membrane and Water Treatment
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• 제7권2호
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• pp.87-100
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• 2016

A numerical simulation of membrane evaporation process was carried out in this work. The aim of simulation is to describe transport of water through porous membranes applicable to the concentration of aqueous solutions. A three-dimensional mathematical model was developed which considers transport phenomena including mass, heat, and momentum transfer in membrane evaporation process. The equations of model were then solved numerically using finite element method. The results of simulation in terms of evaporation flux were compared with experimental data, and confirmed the accuracy of model. Moreover, profile of pressure, concentration, and heat flux were obtained and analyzed. The results revealed that developed 3D model is capable of predicting performance of membrane evaporators in concentration of aqueous solutions.

• 동력기계공학회지
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• 제15권2호
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• pp.25-30
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• 2011

A fresh water generation system is designed for converting brackish water or seawater into fresh water. In this paper fresh water generation by distillation process that evaporates feed water and subsequently condenses vapor as evaporation product to get fresh water was studied and city water was employed as feed water. The system uses the ejector to create a vacuum, under which liquid can be evaporated at lower temperature than it at normal or atmospheric condition, hence less energy consumption. The effect of various operating conditions i.e. temperature of feed water and different orifice diameters were studied experimentally to investigate the characteristic of the system. It was found that these parameters have significant effect in the performance of fresh water generation system with low pressure evaporation.

• 한국분무공학회지
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• 제21권1호
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• pp.53-57
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• 2016

The present study aims to experimentally investigate the evaporative heat transfer characteristics of Oxi-nitriding SPCC surface. Moreover, the heat transfer coefficient was examined with respect to surface temperature during droplet evaporation. In fact, the nitriding surface showed significant enhancement for anticorrosion performance compared to bare SPCC surface but the thermal resistance also increased due to the formation of compound layer. From the experimental results, the evaporative behavior of sessile droplet on nitriding surface showed similar tendency with the bare surface. Total evaporation time of sessile droplet on the nitriding surface was delayed less than 5%. The difference in heat transfer coefficient increased with the surface temperature, and the maximum difference was estimated to be around 11% at $80^{\circ}C$ surface. Thus, this nitriding surface treatment method could be useful for seawater heat exchanger industries.

• 한국태양에너지학회 논문집
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• 제22권2호
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• pp.11-17
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• 2002

This paper is concerned with the development of a new method for making, separating ice and storage floated ice by installing an evaporation plate at under-water within a storage tank. In a conventional harvest-type ice storage system, a tank saves ice by separating an ice from an installed evaporation plate, which is located above an ice storage tank as an ice storage system. Developed new harvest-type method shows good heat transfer efficiency than a convectional method. It is because the evaporation panel is directly contacted with water in a storage tank. Also, at a conventional system a circulating pump, a circulating water distributor and a piping are installed, however these components are not necessary in a new method. In this study ice storage systems are experimentally investigated to study the charge and discharge of thermal energy. The results show the applicable possibility and performance enhancement of a new type.

• 연구논문집
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• 통권30호
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• pp.15-23
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• 2000

In this study, develop the thermal pump using water evaporation and condensation. Vapor from heating room moves up to pumping room and press the water of pumping room. Consequently water is pumped out to water tank. Then hot vapor direct contact with cold water in condensing room after pumping process. At this time, pressure of condensing room is down to-5kPa and suck in water of tank. This pump executes self ping and good durability because of no mechanical moving parts. Thermal pump is pumped cyclic so that, this pump is not used single. Therefore thermal pump of hot water boiler used to multi-stage for stable pumping rate. As the result of performance test, the developed thermal pump proves pumping action of water evaporation/condensation. And total volume flow rate is 500liter during one hour. If three thermal pump is installed parallel, this pump can use to the hot water boiler in the 300,000kcal/h class.