Ammonia absorption refrigeration technology was developed in the 19th century and is still used in industrial applications. Energy Concepts has adopted this technology to a machine which uses the sun as the only energy output. The particular advances in the design and configuration have resulted in a low cost and reliable method of making significant quantities of ice in areas without electricity. During the day the solar collector focuses the energy of the sun onto the ammonia generator in the collector trough.
Solar heat distills pure ammonia vapor from the water-ammonia solution in the generator.
The vapor condenses in the cooling coils and collects as liquid ammonia in the receiving tank in the evaporator. At the end of the day, the user switches three valves from the Day to Night position to allow the ammonia to evaporate in the ice compartment, providing the refrigeration to freeze the water. The resulting vapor is absorbed back in the generator. Critical to the operation of Isaac is a passive thermosyphon that operates in the Night mode to remove the heat from the generator and allow the ammonia vapor to absorb into the solution at lower pressure and temperature. At the beginning of the day, the operator harvests the ice from the ice trays, operates a drain sequence to remove traces of absorbent from the evaporator, and places the unit back into Day mode to begin the next cycle.