Molten Salt Heat Transfer in Concentrated Solar Power Systems

Concentrated solar power (CSP) utilises arrays of mirrors or optics to focus sunlight onto a receiver, converting solar radiation into thermal energy. Molten salts—typically eutectic mixtures of nitrate or nitrite salts—serve as both heat transfer fluids and thermal energy storage media. Their high heat capacity, stability at elevated temperatures (up to 600 °C), and low vapour pressure enable efficient heat absorption in solar tower and parabolic trough configurations. In a typical solar tower plant, a field of heliostats tracks the sun and concentrates light onto a central receiver, where molten salt circulates through receiver tubes, absorbing heat before being stored in insulated tanks. During periods of low irradiance, stored thermal energy is dispatched through a heat exchanger to generate steam and drive turbines. Key challenges include managing non-uniform heat flux on receiver tubes, minimising thermal stress and material degradation, and optimising flow regimes to enhance convective heat transfer while controlling pressure drop. Advances in computational modelling and experimental rig testing have improved understanding of fluid dynamics, turbulence enhancement devices and thermal losses, supporting the design of more efficient, reliable and cost-effective CSP systems worldwide.

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Molten Salt Heat Transfer in Concentrated Solar Power Systems publication trend

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Technical terms

Molten salt heat transfer fluid: A high-temperature ionic medium, typically nitrate or nitrite mixtures, used to absorb, transport and store solar thermal energy in CSP systems.

Heat transfer coefficient: A parameter quantifying convective heat exchange between a fluid and a solid surface, determining thermal performance of receiver tubes.

Thermal energy storage: The process of retaining heat—often in molten salts—so that electricity generation can continue when solar input is absent.

Direct normal irradiance (DNI): The solar radiation per unit area incident on a surface held perpendicular to the sun’s rays, critical for predicting collector performance.

Solar receiver: The component in a CSP system that absorbs concentrated solar flux and transfers heat to the circulating fluid.

References

1. A Review on the Thermal Modeling Method for Molten Salt Receivers of Concentrating Solar Power Tower Plants. Energies (2025).
2. Experimental research on heat transfer characteristic of HITEC molten salt in evacuated tube solar collector. Frontiers in Energy Research (2023).
3. Dynamic Thermal Transport Characteristics of a Real-Time Simulation Model for a 50 MW Solar Power Tower Plant. Energies (2023).