Latent Thermal Energy Storage System for Heat Recovery between 120 and 150 °C: Material Stability and Corrosion

Abstract

Thermal energy represents more than half of the energy needs of European industry, but is still misspent in processes as waste heat, mostly between 100 and 200 °C. Waste heat recovery and reuse provide carbon-free heat and reduce production costs. The industrial sector is seeking affordable and rugged solutions that should adapt the heat recovery to heat demand. This study aims to identify suitable latent heat materials to reach that objective: the selected candidates should show good thermal performance that remains stable after aging and, in addition, be at a reasonable price. This paper details the selection process and aging results for two promising phase change materials (PCMs): adipic and sebacic acid. They showed, respectively, melting temperatures around 150 °C and 130 °C, degradation temperatures (mass lost higher than 1%) above 180 °C, and volumetric enthalpy of 95 and 75 kWh·m−3. They are both compatible with the stainless steel 316L while their operating temperature does not exceed 15 °C above the melting temperature, but they do not comply with the industrial recommendation for long-term use in contact with the steel P265GH (corrosion speed > 0.2 mm·year−1).