HEAT TRANSFER PIPE FOR HEAT EXCHANGER OF ABSORPTION FREEZER AND MANUFACTURE THEREOF

摘要

PROBLEM TO BE SOLVED: To improve heat transfer performance by reducing a contact angle of a fluid dropped or sprayed onto a heat transfer surface by applying a blast processing to a surface of a heat transfer pipe preferably used for a heat exchanger of an absorp tion freezer, and then heating the heat transfer pipe in an oxygen atmosphere to form a fine uneven oxide film. SOLUTION: For an evaporator of an absorption freezer a shell and coil type or shell and tube type heat transfer pipe is used. In this case, for the heat transfer pipe there is performed a blast processing of blowing a nonmetal polishing member having a relatively large particle diameter to a heat transfer pipe surface to form a fine uneven surface on the heat transfer pipe surface, and, thereafter a heating processing is applied to form an oxide film on the surface. Hereby, hydrophilic property is improved and hence the uneven surface is further made finer. When a fluid 6 is dropped onto the heat transfer pipe surface 7 subjected to such processings, the fluid 6 spreads over an entire pipe owing to an improvement of the hydrophilic property and to a capillary tube phenomenon, and an effective heat transfer area of the heat transfer pipe is increased, and further a sharp improvement of heat transfer performance is ensured.