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한호승(Ho-Seung Han),명지현(Ji-hyun Myung),김철환(Cheol-Hwan Kim),김내현(Nae-Hyun Kim) 대한설비공학회 2019 대한설비공학회 학술발표대회논문집 Vol.2019 No.11
Enhanced tubes are widely used in absorption chillers. In this study, steam condensation heat transfer characteristics were investigated for seven different enhanced tubes - Bare Tube, Endcross Tube, Notched Tube, Floral Tube, Endcross Floral Tube, Notched Floral Tube, Corrugated Tube, Endcross, Corrugated Tube - having a wide range of geometrical variation. The saturation temperature was 40oC. Results showed that Endcross Corrugated Tube yielded the highest heat transfer coefficient (2.51 times to that of the plain tube). It was also observed that tube cross-section shape affected the heat transfer coefficient significantly. Generally, corrugated tubes yielded the highest heat transfer coefficients, followed by floral and plain tubes.
흡수식 냉동기의 증발기에 사용되는 전열촉진관에서 물의 유하 액막 증발 열전달에 대한 실험적 연구
박도현(Do-Hyun Park),한호승(Ho-Seung Han),김내현(Nae-Hyun Kim) 대한설비공학회 2019 설비공학 논문집 Vol.31 No.5
Thin film evaporation of water using enhanced tubes is one of the most common mode of heat transfer in absorption chillers evaporators. Proper design of the evaporators require adequate knowledge of evaporation heat transfer coefficient. In this study, seven enhanced tubes with different enhancement geometries were tested at a saturation temperature of 12℃, 15℃ tube-side water inlet temperature and a film flow rate of . The results indicated that the evaporation heat transfer coefficient of the Floral tube was lower than that of the smooth tube, while the Corrugated tube yielded almost the same heat transfer coefficient as the smooth tube. Notched Floral tube yielded a heat transfer coefficient of 72%, which is higher than that of smooth tube. It was found that Notched geometry was better than the End-cross geometry. Moreover, addition of Floral and Corrugated geometry formations to tubes having threedimensional protrusions, such as Notched or End-cross tubes further enhanced the evaporation heat transfer. As for the overall heat transfer coefficient, which accounts for both evaporation and tube-side heat transfer, End-cross Corrugated tube yielded the highest heat transfer coefficient at 57% as compared to smooth tube.