Halide and Oxy-Halide Eutectic Systems for High-Performance, High-Temperature Heat Transfer Fluids
Optical screening of materials and electrochemical corrosion tests will be used to identify, develop, and demonstrate molten salt eutectics that meet the MURI HOT Fluids targets suitable for CSP applications. Images from The University of Arizona, Arizona State University, and Georgia Institute of Technology
The University of Arizona along with partners at Arizona State University and Georgia Institute of Technology, under the 2012 Multidisciplinary University Research Initiative (MURI): High Operating Temperature (HOT) Fluids funding opportunity, is investigating the use of halide salts with oxy-halide additives as a heat transfer fluid (HTF) in concentrating solar power (CSP) systems operating at temperatures greater than 800°C. By allowing higher temperature operation, CSP systems can achieve greater efficiencies and thereby reduce the overall system cost.
Approach
The research team is investigating mixtures of covalently and ionically bonded halide salts with additives such as oxy-halides. The goal of this project is to discover a salt mixture with the following properties:
- A freezing point below 250°C
- Stability at temperatures greater than 800°C
- Low corrosion of stainless steel and high-nickel content alloys
- A cost of less than $1/kg.
Innovation
The mixture of salts with two different bond types increases disorder in the system, thereby increasing the liquidus range of the salt mixture. The research team is modifying the thermophysical properties of the mixture by introducing Lewis acid/base additives (leading to a generalization of Bronsted acid/base interactions) and/or network forming additives. This allows for the simultaneous tuning of the thermodynamics and transport properties of the HTF in order to meet the needs of a CSP system.
Learn about other DOE competitive awards for concentrating solar power research that are in progress.