Latent heat thermal storage using salt hydrates for distributed building heating: A multi-level scale-up research

Abstract

Latent heat storage using sodium acetate trihydrate is a promising heat storage technology for distributed building heating. However, the industrial and economic feasibility of this heat storage technology has not been proven yet. This work comprehensively carried out industrialization-oriented investigations on this technology from multi-level aspects of (i) thermal characterization and life-cycle assessment of industrial-grade storage materials, (ii) thermal design and performance evaluation of practical-scale heat storage equipment, and (iii) system integration and economic analysis of a practical heating project. The results indicate that the industrial-grade modified storage medium is of similar heat storage and transfer capability but a much lower cost, compared with the analytical reagent. However, it suffers from a more serious attenuation (7.3% vs. 4.9% after 300 cycles) in total heat storage capacity. The developed latent heat storage reservoir can perform stable charges and discharges, with a 24-h thermal loss of around 3.5%. The averaged storage thermal efficiency, total efficiency and specific operational cost of the electric-powered demonstration heating system within a 22-day continuous operation are 96.5%, 90.0% and 0.371 RMB (5.2 cents) kWh−1, respectively. The results prove a great application potential of latent heat storage using salt hydrates for the heat dispatch of distributed building heating.