Comprehensive review on packed-bed sensible heat storage systems

Packed-bed thermal storage (PBTS) systems have emerged as a viable thermal energy storage solution for several applications. This literature review examines PBTS systems designed for sensible heat storage using solid-phase materials as packing elements (PEs). The classic cylindrical PBTS systems can achieve a storage capacity cost ranging from 1-93€/kWhth. First, typical physical phenomena during PBTS operation, parameters and key performance indicators are discussed. For operational phenomena like heat transfer fluid (HTF) flow channeling, heat storage in the wall materials and HTF buoyancy flows, particular attention is given to criteria and conditions leading to their minimization. Next, properties and requirements for PE materials and HTFs are discussed. To this end, experimental data from literature on the resistance of PE materials to thermal cycling and their chemical compatibility with the HTFs are comprehensively presented in a table, using a color-code score. This overview reflects the condition of tested samples for different circumstances and can assist in the selection of suitable (combinations of) PEs and HTFs. Finally, the different PBTS designs are categorized based on the PEs structure type and the storage tank geometry and the main operational characteristics and research gaps of the PBTS designs are highlighted. The research gaps expose relevant topics for future research including criteria of buoyancy effects and operational phenomena for other PBTS designs than the cylindrical. Special attention is also given on research gaps about thermodynamic (i.e. thermocline expansion, heat losses to the environment and pressure drop) and technoeconomic characteristics of the different designs.