Experimental investigation on dynamic thermal storage and extraction performance of seasonal thermal storage

Abstract

The initial investment for a buried pipe system using soil as a seasonal thermal storage medium is costly and not suitable for small rural buildings. To promote the cost-effective heating in rural areas, this study proposes a novel seasonal thermal storage system utilizing water and soil as thermal storage medium with copper rods to enhance thermal transfer between water tank and the surrounding soil. An experimental platform was established to discuss the temperature variation characteristics and investigate the thermal performance under different operating modes and experimental parameters. The results show that the temperature of the soil without copper rods is linearly related to the depth, while the highest temperature at the end of the copper rods occurs at the middle depth. The soil with short copper rods exhibits the most rapid thermal storage response and a relatively shorter thermal extraction response time. Intermittent operation can significantly enhance the thermal extraction rate and outlet temperature of the thermal storage unit, whereas the energy storage efficiency decreases with the extension of the downtime. The soil contribution rate of the thermal storage unit is influenced by the operational duration, initial temperature of the water tank and outdoor ambient temperature.

Keywords

• Dynamic performance
• Thermal storage and extraction
• Seasonal thermal storage
• Experimental study