Facts and Myths Associated with Choosing the Right Construction Materials for Evaporative Condensers

摘要

Evaporative condensers are used almost exclusively in industrial refrigeration systems,especially with ammonia applications in the United States.Their unparalleled heat rejection efficiency,associated with the lowest first costs,comes from evaporative cooling,which means that the inside of the condenser constantly exposed to aerated water for most of its operation time.Choosing the right construction materials is critical,not only for protecting the equipment investment and maintaining maximum efficiency,but also for safety and structural integrity.The most common materials used in evaporative condensers are galvanized steel [hot-dipped galvanized carbon steel(HDG)and hot-mill-galvanized carbon steel [HMG)J and 300 series austenitic stainless steel(SSJ.Galvanized steel has been,and still is,the dominant material due to its good corrosion resistance and heat transfer characteristics.However,300 series SS has become a viable alternative over the past five years,thanks to lower costs due to improved control of alloy composition and other manufacturing cost reductions.Even though evaporative condensers have been widely used for decades,the changing backdrop of complexity and variation of water chemistry and metallurgy and the multiple environmental restraints encountered have resulted in a poor understanding and a lack of guidelines on when upgrading to SS makes sense.