Performance of Uncoated and Coated Nonferrous Heat Exchangers in a Temperate Marine Environment for Two Years

摘要

Twelve finned tube heat exchangers - four pieces of three different materials or material combinations - were operated in a marine environment (1) uncoated, (2) coated with an electrostatically applied polyester enamel, (3) coated with a specification alkyd system, or (4) coated with a zinc inorganic silicate material. Temperature drops across each exchanger were monitored for 24 months and heat transfer capacities were calculated for selected periods. Copper tube/copperfin exchangers coated with any of the three different coating systems were superior in thermal efficiency to the uncoated units. The opposite was true for the all aluminum units and for the copper tube/aluminum fin units. Based on 1978 prices, coating of copper tube/copper fin exchangers increases their cost from 48 to 60%. It is believed this can be justified on the basis of increased life expectancy alone. (Author)