On-line Corrosion Monitoring of 70 Cu 30 Ni Alloy in a LiBr Solution under Absorption Heat Pump Flow Conditions

 

R. Urzúa, J. Siqueiros, L. Morales, I. Rosales, J. Uruchurtu*

 

Centro de Investigaciones en Ingeniería y Ciencias Aplicadas, Universidad Autónoma del Estado de Morelos, México

 

Received 26 September 2008; accepted 10 March 2009

 

Abstract

Electrochemical techniques for on-line monitoring were used to study 70Cu-30Ni alloy corrosion in lithium bromide solution under flow operating conditions in an absorption heat pump. The cause of metallic corrosion on the studied alloy is the localized attack of the passive film surface by bromide ions at lower temperatures, and dissolution of the protective film at higher temperatures and flow conditions. Laboratory experiments were performed using the rotating disk electrode (RDE) under dynamic conditions and different temperatures, similar to the operating pump parameters. This was done to understand the corrosion behavior of the copper alloy prior to on-line monitoring assessment. A corrosion probe consisting in three identical copper alloy ring electrodes embedded in Teflon tube sections to isolate them, with the same diameter as the piping to prevent breaking down pipe flow continuity, was designed and installed. Results under various operating conditions were evaluated. Measurements obtained showed the dynamics of this industrial system and the benefits of real time monitoring in understanding corrosion behavior of 70Cu-30Ni alloy in lithium bromide solution used as working fluid and heat absorbent in heat pumps.

Keywords: corrosion monitoring, heat pumps, copper nickel alloy, lithium bromide.

 

 

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* Corresponding author. E-mail address: juch25@uaem.mx