Evaluation of Formate Salt PCM’s for Latent Heat Thermal Energy Storage

This work examines formate salts as potential phase change materials (PCMs) for middle-high temperature (?250 °C) latent heat thermal energy storage applications. The thermophysical properties of three were characterized: pure sodium and binary blends sodium/potassium sodium/calcium formate. stability PCM’s was evaluated by cycling using differential scanning calorimetry where appeared stable over 600 cycles, while exhibited a monotonic decrease in fusion the test period. A longer with led to gas release decomposition salt. FTIR analysis PCM showed degradation oxalate. T-history experiments 50-g quantities demonstrated bulk supercooling only 2–3 °C these salts. Thermal conductivity enhancement 700% achieved embedding aluminum solid PCM. Finally, mild carbon steel immersed molten up 2000 h. Sodium found be non-corrosive, calculated mass loss confirmed cross-sectional high-resolution microscopy. after h shows oxidation at free surface, remained unchanged, further indicating need protect from atmospheric exposure when used