Experimental study of multi tubular sensible heat storage system fitted with wire coil inserts

Abstract

Sensible heat storage depends on the material, geometry, and storage fluid medium. The formation of multi-tubular cavities in a concrete based storage system has better performance than the solid storage system. Inserts are being used to enhance the heat transfer rates in a confined flow passage. The present study aims to examine the performance of a sensible heat storage system made of concrete with wire coil inserts to store 8 MJ thermal energy from heated air. The wire coil insert is fitted inside multiple tubular cavities of 0.019 m diameter and pitch to diameter ratio of the insert is varied from 0.5 to 1. The maximum energy efficiency and capacity factor correspond to the system of multi-tubular cavities with wire coil insert having a pitch to diameter ratio of 0.5. The proposed system can be easily integrated with the solar air heater in the temperature range of 45–75 °C. The results show that the Energy efficiency of a sensible heat storage system with wire coil insert is found to be 85.9% at the pitch ratio of 0.5 after 2 h whereas the system with smooth cavities yields an efficiency of 76.9% after the same duration.