Progress in heat transfer research for high-temperature solar thermal applications

•Comprehensive review of heat transfer research for high-temperature solar thermal applications.•Principles of solar concentration.•Convection heat transfer in solar receivers.•Liquid–metal heat transfer.•Heat transfer in two-phase particle-gas flows and gas-saturated-porous structures. High-temperature solar thermal energy systems make use of concentrated solar radiation to generate electricity, produce chemical fuels, and drive energy-intensive processing of materials. Heat transfer analyses are essential for system design and optimisation. This article reviews the progress, challenges and opportunities in heat transfer research as applied to high-temperature solar thermal and thermochemical energy systems. The topics discussed include fundamentals of concentrated solar energy collection, convective heat transfer in solar receivers, application of liquid metals as heat transfer media, and heat transfer in non-reacting and reacting two-phase solid–gas systems such as particle–gas flows and gas-saturated porous structures.