An Experimental Study of Heat Transfer Enhancement in the Circular Channel with Almond Shape Dimples

Heat transfer coefficients were measured in a circular tube with dimpled surface. The almond type dimples were fabricated, the tube diameter (D) 19mm and dimple depth 3 mm ratio was kept constant, while holding diameter 10mm of dimple is required length 21.5mm because of the elongated shape. The Reynolds number based on the channel hydraulic diameter was varied from 25000to 95000. An experimental study was conducted for the staggered configuration of the dimple and compare with the base line results of plain tube. In addition to this numerical investigation was carried out for similar experimental conditions with addition to align array of dimple. It was found that staggered array of dimple in circular tube has 66% greater thermal performance factor than align dimple configuration. Heat transfer results are compared with the base line with plain tube. Heat transfer measurement results showed that high heat transfer was induced downstream of the dimples due to flow reattachment. As the Reynolds increased, the overall heat transfer coefficients also increased. For the staggered dimple arrangement, the heat transfer coefficients and the thermal performance factors were higher for the same mass flow rate.