Pay-Out and Energy/Cost Ratios 

 Comparative Example of Coated Heat Exchanger Applications 



Pay-outs and energy/cost (E/C) ratios are presented in tables 1-4 

 for four postulated coil types at four locations considered typical of 

 the range of atmospheric corrosivity experienced at Navy shore activities, 

 worldwide„ Calculations were made for the following locations: 



a» Severe environment - Table 1 — Guam, Marshall Islands 



bo Moderate environment - Table 2 — Pearl Harbor, HI 



Table 3— Charleston, SC 



Co Mild environment - Table 4 — El Centro, CA 



These locations not only represent a range of atmospheric corrosivity! but 

 also ranges of cooling requirements, power costs, and costs of construction/ 

 maintenance work» 



Coil Types 



The four coil types considered were termed the "standard" coil, an 

 "improved" coil, a "superior" coil, and a "lifetime" coilo Where greater 

 resistance to atmospheric corrosion can be justified than that of the 

 standard commercial coil normally supplied as part of packaged equipment 

 units, the improved, superior and lifetime coils are intended to provide 

 successively higher levels of overall, life-cycle performance „ Higher 

 performance can be achieved by a combination of more corrosion resistant 

 and mutually compatible materials for fins and tubing, the use of pro- 

 tective coatings or finishes, and increased coil heat transfer area. 

 Because of the high cost of coil replacement it is desirable that a coil 

 have the same economic lifetime as other components of the cooling unito 



Research by the U. S. Army Natick Laboratories on quantitative measurement 

 of saltfall as a factor in atmospheric corrosivity is discussed in a Code 

 L03B file memo dated 9 Apr 1979 entitled, "Estimating Coil Life and Rela- 

 tive Heat Transfer Based on Exposure" 



2 

 Industry, generally, has optimized condenser coil design variables that 



are more closely related to manufacturing operations and initial cost, 

 such as fin thickness and mechanical properties, fin spacing and configura- 

 tion for maximum heat transfer, and mechanical bonding methods that assure 

 good conductivity between fins and tube No changes to improve performance 

 would be contemplated for these details 



3 

 Per NAVFAC P-442, economic lifetime is the least of the mission life, the 



physical life, or the technological life and is the period of time during 



which positive benefit is provided to the Navy„ 



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