Castles, John Thom2023-04-202023-04-201946http://hdl.handle.net/10919/114661The effect of a single spray coating of 60.9% D.C. 801 silicone resin, with a 0.3% cobalt on the dry resin basis, on (1) the initial overall heat transfer coefficient, (2) the overall heat transfer coefficient under accelerated scale forming conditions, and (3) the corrosion resistance of 1.5” o.d. mild steel evaporator tubes, 12 B.W.G. was investigated. Preliminary tests were made with silicone resins D.C. 801, 993 and G.E. 9975, 9982, 9989 to select the resin to use in the above tests and to develop a precoating treatment for the evaporator tubes. The evaporator used for the investigation was an experimental, horizontal tube evaporator using the two 1.5” o.d., 21” mild steel tubes, 12 B.W.G., having an effective heating area of 1.113 ft.². The operating conditions for the test were steam, 85% quality, at 45.75-46.25” Hg. abs. and body pressure of 7.8-8.5” Hg. abs. giving an effective temperature drop of 80-85°F. Evaporator feed for the “Normal Tests” was tap water; for the “Accelerated Tests” was gypsum solution, saturated at 55-65°F.; for the “Corrosive Medium Tests” was 3% NaCl solution. The coated tubes had an initial overall coefficient of heat transfer, “U”, 11% lower than that of commercially clean tubes. In the accelerated scale forming tests the “U” of the coated tubes decreased 24.6% in 32 hours; while that of the commercially clean tubes decreased 47.4% in 24 hours. The silicone resin coating protected the tubes from corrosion in 3% NaCl, boiling in natural convection, for the duration of a 24 hour test.[ii], 124 leavesapplication/pdfenIn CopyrightLD5655.V855 1946.C378Files and raspsGums and resinsThesis