Effects of tube inclination on pool boiling heat transfer

Effects of tube inclination angles on nucleate pool boiling heat transfer of water at atmospheric pressure have been investigated experimentally. Experiments were performed for seven angles (0, 15, 30, 45, 60, 75, and 90degrees) with two tubes (12.7 and 19.1 mm in diameter) of 540 mm in length. Through the study, it can be concluded that tube inclination gives much change on nucleate pool boiling heat transfer. When the tube is near the horizontal and the vertical positions, the maximum and minimum of heat transfer coefficients are expected, respectively. The decrease in bubble slug formation on the tube surface and easy liquid access to the surface are thought to be the causes for the enhanced heat transfer. (C) 2002 Elsevier Science B.V. All rights reserved.