Integration of solar thermal collectors and heat pumps with thermal energy storage systems for building energy demand reduction: A comprehensive review

Abstract

Solar energy, coupled with innovative technologies, holds the promise of propelling buildings towards net-zero and carbon neutrality. In this regard, this review explores the integration of solar technologies, heat pumps, and thermal energy storage systems to reduce building energy demand. It thoroughly examines various types of solar thermal collectors (STCs), including both concentrating devices like compound parabolic concentrators and parabolic troughs, as well as non-concentrating designs such as flat plate and evacuated tube collectors. It examines innovative strategies for enhancing STC performance, such as alternative profiles for compound parabolic concentrators and the insertion of thermal fins in absorber tubes. Furthermore, the review categorizes solar-assisted heat pumps (SAHPs) into indirect expansion (IDX) and direct expansion (DX) systems, describing their advantages and limitations. It performs a comparison between IDX-SAHPs and DX-SAHPs, explaining their effectiveness and applicability. Eventually, the review explores thermal energy storage materials, categorizing them into sensible heat storage, latent heat storage, and thermochemical heat storage (TCHS). It discusses the advantages and disadvantages of each category, as well as notable materials within them. A comparative examination between open and closed systems for TCHS further enriches the discussion. Throughout the review, recent advancements and key findings from relevant studies are summarized in separate tables, offering valuable information into practical strategies for sustainable building energy systems. Regarding the provided sections, this review plays a crucial role in introducing scholars to practical methods employed in recent years to integrate the STCs with heat pumps and thermal energy storage systems.