열전달 향상을 위하여 이차유동을 발생시켜 열전달을 증가시키는 방법에는 여러 가지가 있다. 본 연구에서는 수평채널에 딤플과 돌출을 설치하여 각각의 깊이와 높이를 변화시켰을 때의 압력강하 및 열전달 특성을 수치해석을 통하여 연구하였다. 딤플과 돌출은 수평채널의 윗면과 아래면 에 설치되었으며, 깊이 및 높이를 0.125, 0.25, 0.25, 0.3, 0.375로 하였다. 딤플의 경우, 후면부에서 높은 Nusselt 수가 나타났고 깊이가 커질수록 평균 Nusselt 수가 감소하였다. 돌출의 경우, 전면부에서 높은 Nusselt 수가 나타났고 높이가 커질수록 Nusselt 수가 증가하였다. 딤플과 돌출 모두 유속이 증가함에 따라 열전달이 향상되는 경향을 보였지만 성능계수는 감소하였다. 성능계수는 유속이 낮은 영역에서 가장 크게 나타났다.
In this study, numerical analyses were performed on pressure drop and heat transfer characteristics in a rectangular horizontal channel with dimple and protrusion arrays of different height. The dimples/protrusions were installed at both top and bottom walls of the rectangular channel. The dimple and protrusion depths are 0.125, 0.2, 0.25, 0.3, and 0.375 times diameter. In case of the dimple, the highest Nusselt number occurred at the rear side of the dimple, and the average Nusselt number tended to decrease slightly with increase of depth. In case of protrusion, on the other hand, the highest Nusselt number occurred at the front side of the protrusion, and the average Nusselt number was increased with the increase of height. In both dimple and protrusion, the average Nusselt number and pressure drop were increased with the increase of velocity. Performance factor was decreased with the increase of velocity, and it was found that the best performance factor was obtained in the low velocity region.
