How does it work?
The system consists of two separate circuits: a power circuit and a cooling circuit.
> See animated explanation of the technology here.
Heat is circulated from a solar heating system through a buffer tank. The water evaporates due to low pressure in the tank (ex. 90°C at 0,8 bar abs.). The evaporated steam is let through a tube, heated up by excess heat from the cooling circuit, and sent into the expander as overheated steam - the sketch below shows the circuits & no internal heat circle. The expander drives/rotates the compressor, which is mounted on the same spindle. The steam from the expander flow condensates through condenser and the condensed water pumps back to the buffer tank.
The cooling circuit is more or less a traditional cooling circuit with compressor, condenser, and evaporator. The refrigerant is simply water. The water boils / evaporates at 15-17°C due to the low pressure in the cooling system (≈ 20 mbar, abs.), and delivers a high flow of steam removed by the turbine compressor for instant cooling. The high heated steam from the compressor outlet is transferred to the expander side, where it overheats the expander steam before it enters the expander. The process repeats itself continuously.
The compressor and expander have are designed to operate by overheated steam under low pressure.
The energy turnover from heat to rotation in the expander demands that the coupled expander/ compressor spindle must rotate within 100.000 - 120.000 RPM to provide the designed 10 kW cooling capacity. The resulting maximum tip speed of the turbine wheels are designed not to surpass the speed of sound. This demands special methods of calculation.
The process uses water as medium in both the driving and the cooling circuits and therefore is environment friendly.
Compared to other heat-driven cooling processes, AC-Sun is the most energy efficient, meaning that 1 kW heat turns into 1 kW cooling: (COP_heat = Cooling [kW] / Heating [kW]; Coefficient Of Performance).
COP heat = 1
The AC-Sun sketch below shows the different energy stages in the cooling proces using solar or waste heat as the main source of energy supply.