An air-source heat pump could run more efficiently and be sized smaller if part of the coolant loop ran through the ground around a building's foundation. Such a loop could be laid at virtually no additional cost while the foundation is newly dug.
Heat pumps are a very efficient way to heat and cool buildings. They use a pumped coolant to transfer heat back and forth between the building and an outside "sink." Ground-source heat pumps use the Earth as the sink, and have the best efficiency...but the highest cost (due to drilling and digging expenses).
Air-source heat pumps use the atmosphere as the sink. They do not perform quite as well, but they cost less.
This idea proposes a hybrid of the two. If an average home requires 3 geothermal wells to be dug (200ft deep each) to provide the sink for a ground-source heat pump, this will cost around $10,000. Laying a coil of pipe in the cavity around a newly dug foundation could approximate the performance of 1 of those geothermal wells... at only the cost of the pipe itself. The remainder of the coil would pass through the air-to-air heat exchanger that is standard in an air-source heat pump.
All that would then be required is to optimize the unit's control system for the various permutations of operating conditions imposed by the coolant's hybrid coil.
CATEGORY: Energy, Construction
IDEATION: July 2011