Demonstration of a Passive Condenser Loop

Building HVAC consumes significant amount of energy. It is estimated that about 7% of
the total electricity consumed by water cooled chiller is used to drive the condenser water
pump. A passive condenser loop is developed to curb this energy consumption by replacing the open pumped loop to a closed loop thermosyphon system. The loop thermosyphon uses waste heat to circulate the condenser fluid, eliminating the electrical pumping power requirement and the large circulation pump. Since it is a closed loop, it also reduces the maintenance cost and enables both wet and dry cooling modes. A demonstration unit with a riser about 40 feet (12.2 meters) tall is fabricated and tested at powers up to 25 kW. The result has successfully showed that the loop thermosyphon is able to transfer the heat near isothermally (ΔT < 0.4°C) over the long distance without the need of any pump and consuming any electricity.