Desalination 213 (2007) 9–17 Presented at the International Conference on New Water Culture of South East European Countries-AQUA 2005, 21–23 October 2005, Athens, Greece. 0011-9164/06/$– See front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.desal.0000.00.000 Evaluation of corrosion problems in a closed air-conditioning system: a case study E. Rakanta*, E. Daflou, G. Batis School of Chemical Engineering, Section of Materials Science and Engineering, National Technical University of Athens, 9 Iroon Polytechniou Str., Zografou Campus, 157 80 Athens, Greece Tel. +30 210-7723186; Fax +30 210-7723184; email: erakanta@central.ntua.gr Received 27 January 2006; revised accepted 3 May 2006 Abstract Chilled water air-conditioning systems are the lifelines of cooling for large commercial, industrial and public buildings. The aim of this paper is to examine and evaluate damages sustained to a large hotel in Greece. The damage that discovered concerns corrosion and salt deposition problems of a chiller in the air-conditioning system. The hotel’s air-conditioning system is part of the facility’s electromechanical infrastructure and is comprised of three centrifugal chillers with chilling capacity equal to 500 tons each. The aforementioned chillers are supplied with water through the public water network, which firstly undergoes a softening process, performed by a softener, and covers all the hotel’s requirements. The chillers supply chilled water to seven central air-conditioning units, which in turn supply with fresh air all the hotel facilities. The above system is not supplied by water continuously, but replenishes with the needed quantity, when necessary, usually due to evaporation during the chilling cycle (closed air-conditioning system). The results of the system’s examination indicated accumulation of salts inside chiller tubes, which create a corrosive electrolytic environment, leading to the oxidation of metal and the creation of abrasion along its length. Keywords: Closed loop air-conditioning system; Softening; Corrosion; Salt deposition 1. Introduction Chilled water air-conditioning systems’ operation is divided into five major steps: (1) Indoor air loop. In the leftmost loop, indoor air is driven by the supply air fan through a cooling coil, where it transfers its heat to chilled water. The cool air then cools the building space. (2) Chilled water loop. Driven by the chilled water pump, water returns from the cooling coil to the chiller’s evaporator to be re-cooled. (3) Refrigerant loop. Using a phase-change refrigerant, the chiller’s compressor pumps *Corresponding author.