Air-based solar systems for building heating with PCM fluidized bed energy storage

Abstract

This work studies the integration of a fluidized bed energy storage unit containing Phase-Change Materials (PCMs) into solar air-based systems for heating of buildings. The use of a PCM fluidized bed energy storage unit in air systems offers an interesting alternative to the usual energy storage media based on packed beds of rocks or pebbles because it enables faster charging (or discharging) of the thermal energy storage (TES), associated with high energy densities provided by the latent heat of the PCM. The airflow rate that passes through the solar collectors is sufficiently high to provide satisfactory fluidization of the bed, achieving high heat transfer coefficients.The results of the simulation study conducted on the proposed air system show that the system can successfully supply a significant part of the heating requirements of a single-family house in locations with mild winter conditions, such as Barcelona and Madrid, where a TES containing between 1000 and 2000kg of PCM achieves solar contributions of about 50%. For locations with more severe winter conditions, such as Zurich and Stockholm, very large storage capacities (up to 5000kg of PCM) combined with large collector areas (20m2) are required to meet between 20 and 25% of the house heating needs.