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Experimental Study of Evaporative Heat Transfer Characteristics of R-134a with Channel-Bending Angle in Microchannel Heat Exchangers

마이크로채널 열교환기에서 채널 굽힘 각도에 따른 R-134a의 증발열전달 특성에 관한 연구

  • Lee, Hae-Seung (Energy System Technology Center, Korea Institute of Industrial Technology) ;
  • Jeon, Dong-Soon (Energy System Technology Center, Korea Institute of Industrial Technology) ;
  • Kim, Young-Lyoul (Energy System Technology Center, Korea Institute of Industrial Technology) ;
  • Kim, Seon-Chang (Energy System Technology Center, Korea Institute of Industrial Technology)
  • 이해승 (한국생산기술연구원 에너지설비기술지원센터) ;
  • 전동순 (한국생산기술연구원 에너지설비기술지원센터) ;
  • 김영률 (한국생산기술연구원 에너지설비기술지원센터) ;
  • 김선창 (한국생산기술연구원 에너지설비기술지원센터)
  • Received : 2009.12.31
  • Accepted : 2010.04.05
  • Published : 2010.06.01

Abstract

Experimental investigations have been carried out to examine the evaporative heat transfer characteristics of R-134a with the channel-bending angle (CBA) in microchannel heat exchangers. In this study, we examined the effects of evaporation temperature and Reynolds number of R-134a on the evaporative heat transfer characteristics of R-134a in microchannel heat exchangers with CBAs of $120^{\circ}$, $150^{\circ}$, and $180^{\circ}$ under counterflow conditions. Experimental results show that the evaporative heat transfer rate and evaporative heat transfer coefficient increased with an increase in the Reynolds number of R-134a. Further, the evaporative heat transfer rate corresponding to CBAs of $120^{\circ}$ and $150^{\circ}$ increased to values greater than the evaporative heat transfer rate corresponding to $180^{\circ}$ by approximately 17.1% and 13.3%, respectively, for evaporating temperatures in the range $4.9-14.9^{\circ}C$. The evaporative heat transfer coefficient was affected by the channel angle with increasing evaporative heat transfer coefficient at small channel bending angle.

마이크로채널 열교환기에서 채널 굽힘 각도에 따른 R-134a의 증발열전달 특성에 관하여 실험적 연구를 수행하였다. 본 연구에서는 채널의 굽힘 각도가 $120^{\circ}$, $150^{\circ}$$180^{\circ}$인 마이크로채널 열교환기에서 R-134a의 증발온도와 Reynolds수 변화에 따른 열전달 특성을 대향류 조건에서 실험하였으며, 실험결과 마이크로채널 열교환기에서 증발열전달량과 증발열전달계수는 R-134a의 레이놀즈수 증가에 따라 증가하였다. 또한 채널의 굽힘각도가 $120^{\circ}$$150^{\circ}$인 마이크로채널 열교환기는 증발온도 $4.9{\sim}14.9^{\circ}C$ 에서 채널굽힘 각도가 $180^{\circ}$인 마이크로채널 열교환기와 비교하여 평균 약 17.1% 및 13.3%로 증발열전달량이 증가하였으며, R-134a의 증발열전달계수는 채널의 굽힘 각도가 작을수록 증발열전달계수가 증가하는 것으로 나타났다.

Keywords

References

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