• 설비공학논문집
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• 제18권9호
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• pp.714-721
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• 2006

In evaporative cooling applications, the evaporation water is supplied usually sufficiently larger than the amount evaporated to enlarge contact surface between the water and the air. Especially in indirect evaporative coolers, however, if the evaporation water flow rate is excessively large, the evaporative cooling effect is not used for heat absorption from the hot fluid but spent to the sensible cooling of the evaporation water itself. This would result in a decrease in the cooling performance of the indirect evaporative cooler. In this study, the effects of the evaporation water flow rate on the cooling performance are investigated theoretically. The cooling process in an indirect evaporative cooler is modeled into a set of linear differential equations and solved to obtain the exact solutions to the temperatures of the hot fluid, the moist air, and the evaporation water. Based on the exact solutions, it is analyzed how much the cooling performance is affected by the evaporation water flow rate. The results show that the decrease in the cooling effectiveness is substantial even for a small flow rate of the evaporation water and the relative decrease is more serious for a high-performance evaporative cooler.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.743-748
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• 2006

Ren et al. analyzed the performance of the indirect evaporative cooler according to the direction of the flow considering evaporation water flow and wetness. However the effect of NTU of each channel on the performance of the indirect evaporative cooler according to the direction of the flow was not analyzed exactly. In this study the effect of the direction of the flow on the Indirect evaporative cooling performance changing NTU of each channel are investigated theoretically. The cooling process of the indirect evaporative cooler by flow direction is modeled into a set of linear differential equations and solved to obtain the exact solutions to the temperatures of the hot fluid, the moist air, and evaporation water. Based on the exact solution in the case of different NTU of each channel, we study the change of the distribution of the temperature according to each flow direction and at the same time analyze the effect of the flow direction on the cooling performance.

• 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.

• 대한기계학회논문집B
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• 제39권9호
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• pp.743-749
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• 2015

본 연구의 목적은 간접식 증발냉각 장치의 성능을 예측하고, 장치를 공기조화기의 배기열 회수에 적용하였을 경우의 에너지 절약효과를 분석하는 것이다. 플라스틱 열교환기를 사용한 간접식 증발냉각장치의 성능 상관식을 여러가지 조건에서 얻어진 실험 데이터로부터 구하였으며, 이 상관식을 이용하여 환기와 외기의 조건을 변화시켜가면서 장치의 성능변화를 예측하였다. 또한 간접식 증발냉각장치의 배기열 회수에 의한 에너지 절약효과를 우리나라 몇개 도시의 표준기상데이터를 사용하여 분석하였다. 여름철 배기열 회수를 위한 현열냉각장치의 사용율은 평균 44.3%이며 증발냉각장치의 사용율은 96.7% 이다. 증발냉각장치의 배기열 회수에 의한 에너지 절약은 현열냉각장치에 비해서 훨씬 높으며, 서울의 경우 약 3.89 배로 나타났다.

• 설비공학논문집
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• 제23권1호
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• pp.8-15
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• 2011

Cooling load reduction was analysed of a ventilation system adopting a regenerative evaporative cooler. The regenerative evaporative cooler is a kind of indirect evaporative cooler which cools the air down to its inlet dewpoint temperature in principle without change in the humidity ratio. The regenerative evaporative cooler was found able to cool the ventilation air to $18{\sim}21^{\circ}C$ when the outdoor condition ranges $25{\sim}35^{\circ}C$ and 0.01~0.02 kg/kg. When the outdoor humidity ratio is lower than 0.018 kg/kg, the regenerative evaporative cooler was found to provide cooling performance enough to compensate the ventilation load completely and to supply additional cooling as well. Energy simulation during the summer was carried out for a typical office building with the ventilation system using the regenerative evaporative cooler. The results showed that the seasonal cooling load can be reduced by about 40% by applying the regenerative evaporative cooler as a ventilation conditioner. The reduction was found to increase as the outdoor temperature increases and the outdoor humidity ratio decreases.

• 대한기계학회논문집B
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• 제41권1호
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• pp.21-28
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• 2017

물의 증발에 따른 냉각 효과를 이용하는 증발냉각방식은 기존 증기 압축식 방식에 비하여 냉방에 소요되는 에너지를 현저히 감소시킬 수 있고 CFC 냉매를 사용하지 않아 친환경적이다. 본 연구에서는 습채널의 물 퍼짐성이 개선된 플라스틱/종이 재질로 크기 $300mm{\times}300mm{\times}300mm$, 채널 핏치 $5mm{\times}5mm$, $5mm{\times}7mm$, $7mm{\times}7mm$의 직교류 간접증발소자를 제작하고 간접증발효율 및 압력 손실을 측정하였다. 간접증발효율은 채널 핏치가 가장 작은 $5mm{\times}5mm$ 소자의 가장 크게 나타났다. 이는 작은 $5mm{\times}5mm$ 소자의 전열 면적이 가장 크기 때문이다. 또한 간접증발소자 설치로 인해 절약되는 에너지도 $5mm{\times}5mm$ 소자에서 가장 크게 나타났다. 한편 습채널의 압력 손실은 건채널의 값보다 크게 나타났다. 이론 해석 모델은 간접증발효율과 압력손실을 과소 예측하였다.

• 설비공학논문집
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• 제20권7호
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• pp.462-469
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• 2008

A regenerative evaporative cooler has been fabricated and tested for the evaluation of cooling performance. The regenerative evaporative cooler is a kind of indirect evaporative cooler comprised of multiple pairs of dry and wet channels. The air flowing through the dry channels is cooled without any change in the humidity and at the outlet of the dry channel a part of air is redirected to the wet channel where the evaporative cooling takes place. The regenerative evaporative cooler fabricated in this study consists of the multiple pairs of finned channels in counterflow arrangement. The fins and heat transfer plates were made of aluminum and brazed for good thermal connection. Thin porous layer coating was applied to the internal surface of the wet channel to improve surface wettability. The regenerative evaporative cooler was placed in a climate chamber and tested at various operation condition. The cooling performance is found greatly influenced by the evaporation water flow rate. To improve the cooling performance, the evaporation water flow rate needs to be minimized as far as the even distribution of the evaporation water is secured. At the inlet condition of $32^{\circ}C$ and 50%RH, the outlet temperature was measured at $22^{\circ}C$ which is well below the inlet wet-bulb temperature of $23.7^{\circ}C$.

• 한국산학기술학회논문지
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• 제21권11호
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• pp.892-897
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• 2020

본 연구에서는 간접식 증발냉각 장치의 냉각 성능을 예측하고 다양한 공기 유량 및 물 분무 유량 조건을 만족하는 성능 상관식을 제안한다. 기존의 플라스틱 열교환기는 공조 공간의 크기에 따라 금형을 새로 제작해야 하기 때문에 높은 효율에도 불구하고 잘 사용하지 않았다. 한편 단프라시트는 일반적으로 두께가 얇아 열교환이 우수하고, 특히 제작이 매우 용이하다. 따라서 열교환기를 단프라시트로 제작할 경우 금형이 별도로 필요하지 않아 열교환기 제작 비용을 크게 절감할 수 있다. 이에 본 연구에서는 단프라시트로 다채널 열교환기를 제작하여 간접식 증발냉각 장치를 제작하였다. 성능 실험장치는 열교환기, 물 분사 노즐, 터보홴, 항온조, 순환 펌프, 온도 센서, 습도 센서, 차압식 유량계 및 자료획득 장치로 구성하였다. 증발냉각 시 공기 유량이 증가하면 유용도가 감소하였고, 수공비에 따라 유용도 최적점이 존재하였다. 등온 조건에서 냉각 성능을 예측하는 상관식과 실내 환기 온도와 외기 상태를 반영하는 성능 상관식을 제안하였다. 상관식들의 냉각 성능 오차는 4 % 이내였다.

• 한국수소및신에너지학회논문집
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• 제30권2호
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• pp.136-146
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• 2019

A solid oxide fuel cell (SOFC) based hybrid desiccant cooling system model is developed to study the effect of fuel utilization rate of the SOFC on the reduction of energy consumption and $CO_2$ emission. The SOFC-based hybrid desiccant cooling system consists of an SOFC system and a Hybrid desiccant cooling system (HDCS). The SOFC system includes a stack and balance of plant (BOP), and HDCS. The HDCS consists of desiccant rotor, indirect evaporative cooler, electric heat pump (EHP), and heat exchangers. In this study, using energy load data of a commercial office building and SOFC-based HDCS model, the amount of ton of oil equivalent (TOE) and ton of $CO_2$ ($tCO_2$) are calculated and compared with the TOE and $tCO_2$ generation of the EHP using grid electricity.

• 한국수소및신에너지학회논문집
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• 제34권6호
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• pp.773-784
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• 2023

In this study, a comparative analysis between an electric heat pump cooling system and a hybrid desiccant cooling system is conducted. Desiccant cooling is a thermal driven system with potentially lower electric power consumption than electric heat pump. Hybrid desiccant cooling system simulation includes components such as a desiccant rotor, direct and indirect evaporative coolers, heat exchangers, fans, and a heat pump system. Using dynamic simulations by climate conditions, house cooling temperatures and power consumption for both systems are analyzed for 16 days period in the summer season under climate scenarios for the year 2100 prediction. The results reveal that the hybrid desiccant cooling system exhibits a 5-18% reduction in electric consumption compared to the heat pump system.