Experimental Research on Heat Transfer Characteristics of Tube Bundles of Different Materials under Vacuum Conditions

Abstract

In order to find an excellent kind of heat transfer element under vacuum condition, the heat transfer performance of tube bundles of different materials in vacuum state was studied through experiments, of which include stainless steel tube, brass tube, Ni-based implanted steel tube and ion implanted brass tube. The relative curves prove that the condensation heat transfer coefficient and the overall heat transfer coefficient of four kinds of bundles all increase with the rising vacuum and increasing Re value, especially of the Ni-based implanted steel tube and the ion implanted brass tube. Under higher vacuum (0.07MPa), for larger Re value (24613), it was found that the condensation heat transfer coefficient of Ni-based implanted steel tube bundle is about 3 times that of the stainless steel tube bundle, the condensation heat transfer coefficient of ion implanted brass tube bundle is about 2.4 times that of the common brass tube bundle as well. Therefore, it is believed that partly dropwise condensation was achieved on the surface of these two implanted tube bundles, and ion implantation is proved to be an effective method of dropwise condensation attainment. According to the conclusion, it is considered that the Ni-based steel tube can substitute more expensive brass tube as heat transfer component to some extent.