All heat pipe parts, including stainless steel heat exchangers, end caps, exhaust pipes, core materials and core supports, must be thoroughly cleaned before assembly. The cleaning process varies with different conditions, different materials, working medium and manufacturing process require different cleaning fluids and cleaning procedures. For the case of sintering the core directly in the shell, it has been cleaned before sintering, so there is no need to clean it again.
The purpose of cleaning is:
(1) Remove grease and ensure good wetting performance on the metal surface;
(2) Remove any impurities so as not to hinder the penetration flow of liquid in the tube core or cause adverse reactions;
(3) Some materials require surface passivation to prevent inconsistencies, and some working materials require removal of metal oxides.
Work with sodium metal stainless steel tubes, in all the inner wall of tube and shell parts, tube core material and stents should not have oxide layer on the surface, because of these oxide layer under the condition of high temperature oxygen will be unusually lively personality sodium replacement and generate sodium oxide, and sodium oxide by high melting point that in the working temperature is not melting, thus may clog capillary channels.
If the stainless steel heat exchanger tube used to make the shell has an oxide layer on the inner wall, and in the process was not removed, it should be soaked with sodium hydroxide solution to wash off the oxide layer, and then neutralized with acid. If the material does not have an oxide layer, this cleaning procedure is not necessary. Instead, clean the metal surface with trichloroethylene or acetone.
Deoiling cleaning operation should be repeated and the cleaning fluid should be replaced until there is no oil point or floating foam on the surface of the cleaning fluid. In particular, the capillarity of the oil is not easy to remove, must be carefully checked. It is best that using the ultrasonic cleaning machine to clean. Rinse with water repeatedly after removing the oil to rinse off the residual lotion.
