different heat transfer fluid

Good afternoon

I only see CSP power tower using molten salt or steam as a HT. I need a higher temperature (700 C), is there any way to used air as a HT?

Air HTF power tower systems use a different heat transfer, fluid transport, thermal storage, and power conversion approach than molten salt systems, so the performance model in SAM for molten salt or direct steam are not really applicable for what you're trying to do. You could use the Generic CSP model in SAM to approximate optical, thermal, and thermodynamic performance in an annual simulation. This requires more background work to come up with accurate performance curves, but the Generic model is flexible enough to handle this type of analysis.

Mike