In the view of improving the efficiency of Solar Thermal Power Plants much research is going on the field of Heat transmitting Fluid. Liquid Metal, Pressurized gas, Ceramics and Nano fluids are the prospective materials to be used as HTF.
Sodium has high working temperature and very low solidification temperature. I intended to know the reasons of not using it as a HTF other than its vigorous reaction with water.
Liquid sodium has been used in heat exchangers in the nuclear industry. At one time, MSA sold a liquid sodium transport and heat exchanger system. The biggest drawback is the chemical reaction of sodium with most materials. Any metal coming into contact with liquid sodium (piping, pumps, heat exchanger plates; etc.) must be stainless steel. Cost has been an over-riding issue vs. efficiency in heat transport.
Also sodium ignites in contact with air. Liquid sodium was tested in an experimental solar tower power plant in a research solar platform. A leak of sodium caused an explosion and since then researchers of the research center have stopped the test of this option.
Hi KM
Actually sodium *is* being used as a heat transfer fluid in CSP plants. The Australian startup company Vast Solar is pioneering the development of a low-cost modular CSP field that makes use of liquid sodium to transfer heat from the multiple towers back to the power block.
http://www.vastsolar.com/
I was co-author in a review of this as well as earlier efforts to make use of sodium in CSP, see here. The safety risks are addressed as part of that review.
Article A review of sodium receiver technologies for central receive...
BTW you might like to meet up with Klarissa Niedermeier and Jonathan Flesch. They are both (I believe still) at KIT there with you, doing research on the use of sodium in CSP. Perhaps you already know them. Klarissa and colleagues have made a comparison of molten salt storage with packed-bed sodium storage. This relates to one of the issues of sodium, which is that it is too expensive for dual use as HTF and energy storage medium, since large quantities are required for storage even if only small quantities are required for heat transfer. The result is that an *additional* heat transfer step is required, such as to a packed-bed filler material as in this study.
Article Performance of molten sodium vs. molten salts in a packed be...
You can find Klarissa and Jonathan here:
https://www.iket.kit.edu/english/337.php
Cheers
JP
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