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마이크로/나노 표면 개질 공법을 이용한 응축 열전달 성능 향상 연구
신영훈,이권영,황운봉 한국정밀공학회 2023 한국정밀공학회지 Vol.40 No.9
Condensation is an important research topic that ensures increased energy efficiency. Our researchers aimed to optimize heat transfer in industrial heat exchanger tubes through surface modification. We first succeeded in fabricating superhydrophilic and superhydrophobic tubes using surface modification. We observed the condensation phenomenon on the outside of the tube and evaluated the heat transfer performance through a condensation experimental facility. As a result, we found that the condensation heat transfer efficiency of superhydrophobic tubes is superior to that of conventional tubes. However, the heat transfer efficiency of the superhydrophobic tube reduced with an increase in saturation. To improve performance degradation, superhydrophilic and superhydrophobic hybrid tubes were fabricated and evaluated for their potential to improve heat transfer efficiency. As a result, we found that the liquid film generated by filmwise condensation on the superhydrophilic surface swept past the residual droplets generated by dropwise condensation on the superhydrophobic surface, resulting in the best heat transfer performance. Our results break the stereotypes of previous studies and provide a new paradigm for achieving optimal heat transfer performance on large-area curved surfaces. This research is expected to be widely applied in a variety of industries where energy efficiency is critical.
오일 도포 표면의 온도에 독립적인 오일 파울링 저감 성능
오승태(Seungtae Oh),이주영(Jooyoung Lee),서동현(Donghyun Seo),이충엽(Choongyeop Lee),남영석(Youngsuk Nam) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12
Oil-fouling on surfaces which happens during oil production and transportation has been a detrimental problem in industries. Here, we fabricated lubricant-impregnated surfaces (LIS) and investigated their anti-oil fouling performance at a wide range of operating temperature (20~90℃). Two types of lubricant oils which have different chemical components were impregnated into SAM-coated CuO nanostructures. The oil-fouling tests were conducted in a temperature-controlled oil-fouling experimental setup, and the performance was characterized by measuring mass of adhered fouling on the surfaces. LIS showed the best anti-oil-fouling performance. The operating temperature significantly changed the size of the emulsion and it resulted in various oil-fouling results of the other surfaces. However, the lubricant oil layer on LIS effectively prevented any crystallization of the emulsions and provided almost steady good anti-oil fouling ability at a wide range of operating temperature. The adhesion strength between the emulsion and the surfaces was analyzed to understand the different anti-oil fouling performance, and the effect of the types of the impregnated oils on LIS was investigated by using thermodynamical energy criteria. We believe that our works help to understand the role of the surface wettabilities during oil fouling process and offer a guideline to fabricate stable LIS for oil-fouling applications.