Steam-PCM heat exchanger design and materials optimization by using Cr-Mo alloys

• Published in: Solar energy materials and solar cells Vol. 178; pp. 249 - 258
• Main Authors: Ruiz-Cabañas, F. Javier, Prieto, Cristina, Jové, Aleix, Madina, Virginia, Fernández, A. Inés, Cabeza, Luisa F.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.05.2018; Elsevier BV
• Subjects: Alloys; Base metal; Chromium; Chromium base alloys; Corrosion; Corrosion and anti-corrosives; Corrosion products; Corrosion rate; Corrosió i anticorrosius; Cr-Mo alloys; Damage detection; Damage localization; Design optimization; Emmagatzematge d'energia tèrmica; Energy storage; Heat; Heat exchangers; Heat storage; Hydroxides; Inspection; Localized corrosion; Mechanical properties; Microscopy; Molybdenum; Optical microscopy; Optimization; Phase change material (PCM); Stainless steel; Steam generation; Thermal energy; Thermal energy storage (TES); Thermal properties; Thermodynamic properties; Phase change material (PCM); Cr-Mo alloys; Hydroxides; Thermal energy storage (TES); Corrosion
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2018.01.038

A387 Gr 91 Cr-Mo alloy corrosion compatibility with LiOH-KOH mixture was evaluated at 315 °C (Test#1) and 360 °C (Test#2). This alloy is studied for a techno-economical optimization of a steam-PCM heat exchanger proposed in the thermal energy storage (TES) system of a direct steam generation (DSG) facility. The corrosion damage was analyzed with visual inspection, optical microscopy, SEM, EDS and XRD, and corrosion rates were also calculated. A387 Gr 91 alloy generates protective oxide layers over base metal. Localized corrosion damages were not detected with these test conditions, while XRD and EDS profiles showed CrO and LiFeO2 as main corrosion products generated by this alloy. On the other hand, corrosion rates decrease with exposure time showing the passivation of the alloy. A387 Gr 91 corrosion performance was compared with A316L stainless steel, which was preliminary proposed by the authors in previous studies. In addition to corrosion performance, parameters such as cost, thermal properties, and mechanical properties are discussed. In conclusion, the use of A387 Gr 91 instead to A316L alloy for the construction of the steam-PCM heat exchanger involves the techno-economical optimization of the equipment. •A387 Gr 91 Cr-Mo alloy corrosion by LiOH-KOH mixture has been evaluated.•Corrosion tests performed at 360 °C and 315 °C.•Alloy generates protective and well adhered oxide layers.•Localized corrosion damages such as pitting, intergranular corrosion, or spalling phenomena were not detected at test conditions.•In addition to corrosion performance, other parameters such as cost, thermal properties, and mechanical properties are discussed.