An Experimental Investigation on the Relation between Corrosion and Thermohydraulic Behavior in Heat Exchangers for Geothermal Applications

• Published in: Metals (Basel ) Vol. 14; no. 2; p. 217
• Main Authors: Simons, Arne, Faes, Willem, Depover, Tom, Lecompte, Steven, De Paepe, Michel, Verbeken, Kim
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.02.2024
• Subjects: Brines; Carbon steel; Carbon steels; Corrosion; Corrosion effects; Corrosion products; Corrosion rate; Corrosion tests; Entrances; Experiments; GDP; Geothermal power; Gross Domestic Product; Heat exchange; heat exchanger; Heat exchangers; Heat transfer; Heat transfer coefficients; localized corrosion; Metals; Pipes; Pressure drop; Pressure effects; Sensors; Steel; Steel tubes; Temperature; thermohydraulic behavior; uniform corrosion
• ISSN: 2075-4701; 2075-4701
• DOI: 10.3390/met14020217

The potential use of carbon steel in CO2-saturated brine is studied for its potential use in heat exchangers in geothermal applications. A dedicated setup, including a double-pipe heat exchanger, is developed to study the relation between corrosion and the thermohydraulic behavior inside heat exchangers. Hot brine flows inside the inner carbon steel tube, thus corroding the inner surface of this tube. The thermohydraulic behavior of the heat exchanger, i.e., the pressure drop over the pipe and the heat transfer rate through the pipe, are continuously monitored. On the other hand, weight-loss experiments and microscopic analyses are performed on samples that are periodically removed from the setup. The corrosion rate is studied as a function of temperature, i.e., the entrance vs. the exit of the heat-exchanging section, and flow. Therefore, an experiment with static brine and a uniform temperature is used as a reference. The corrosion rate is generally higher in dynamic compared to static conditions. Furthermore, the corrosion rate increases with increasing temperature in dynamic conditions, whereas it decreases with increasing temperature in static conditions. These observations might be explained by the different corrosion products that formed. The corrosion products have no significant effect on the pressure drop over the pipe, but clear fluctuations in the heat transfer coefficient are observed. The origin of these fluctuations should be further studied before the observed heat transfer coefficient can be used as a measure for corrosion.