An experimental study was performed to investigate the effects of the angle of rotation on pool boiling heat transfer of a V-shape tube array. Two smooth stainless steel tubes of 19 mm outside diameter and the water at atmospheric pressure were used for the test. The angle was varied from 0 degrees to 180 degrees in steps of 30 degrees. The heat flux of the lower tube was set as equal to the upper tube. The heat transfer is enhanced clearly when the rotation angle is 90. The convective flow and liquid agitation enhance heat transfer while the coalescence of the bubbles deteriorates heat transfer. (C) 2018 Elsevier Ltd. All rights reserved.