I have 5 Solar Concentrator panels I have built with a 1 meter wide by 3 meter long footprint each. The solar absorber tubes are 3/4" Type M Copper piping that is black chrome coated (98% absorptivity) surrounded by a borosilicate glass envelope (92% transmissivity). There is a hard vacuum between the absorber pipe and the glass (10^-9 Torr), virtually eliminating convective losses and since borosilicate transmits short wavelength IR very well and reflects long wave IR there is almost no radiation losses of heat either. The reflectors are made of aluminized mylar with an efficiency of 97%. The over all efficiency (theoretical) is approximately 87%. Distance between solar panels and boiler is very short (less than 3 meters) so not much heat is lost in fluid transport to the boiler, so overall efficiency reaching the boiler should be around 75% to 80% of input energy. Piping is insulated. The operating temperature of this system will be about 260C. Solar input is per available sun near Phoenix, AZ. Mineral oil will be circulated through it to a small boiler (approximately 7 gallons in size) with a heat exchanger inside it. The working fluid in the boiler is R113 (boiling point of approximately 48C), which when vaporized will go through a 5 hp air motor then to a radiator which will be bathed in a flow of cool water (20C). The condensed R113 will then be picked up and pumped back into the tank. Here is the problem: I do not have the know-how or education to calculate the flow rates of the freon through the system and figure out what kind and size of pump i need to use to pick up the freon flowing through the system.