Latent Thermal Storage Unit Using Form-Stable High Density Polyethylene; Part I: Performance of the Storage Unit

Abstract

A latent thermal storage unit of 30 kWh using form-stable high density polyethylene (HDPE) rods has been developed mainly for solar thermal applications, and heat transfer experiments have been carried out. A direct contact heat transfer technique between HDPE rods and ethylene glycol (EG: a heat transfer fluid) is adopted. Charge and discharge characteristics have been obtained for various thermal input/output and different initial temperature profiles in the storage unit. The direct contact heat transfer and a formation of a clear thermocline provide a good performance for all the cases. Discussions are given of thermal efficiency, storage density, and thermal insulation.