refrigerants for abrorption air conditioning

Hello,
I am a DOD contractor in Afghanistan. I have been studying absorption air conditioning. Two obvious problems are cost of solar collectors and crystallization with bromide based refrigerants in certain temperature ranges in certain outside ambient temperature ranges. One solution was a patent that was sold out to a company in Spain by Carrier, a centrifuge built into the absorption AC unit.
To reduce cost of solar reflectors a simple approach is to use a parabolic reflector with intense heat concentrated at the focal point. There lies my question, what type of refrigerant can be used to run through the focal point of a parabolic reflector and it's very high temperatures to achieve a higher temperature refrigeration cycle? This would eliminate the higher cost of arrays of roof top solar collectors. I would like to build an absorption air conditioning cycle using the parabolic reflector.
My trade is a retired Electronic Tech working on satellite terminals here. I want to build a prototype and understand this is going to cost alot of money to try to put together.
Advanced thanks to all,
Mike

Is it possible to use water at a high flow rate to keep the temp below boiling point? Then if you used say a glass heat exchanger in the dish you could use a pv cell behind that as the water would take our more of the IR range (heat) leaving the rest for the PV cell. The PV power could be used as a feedback for pump speed or even power the pump.