Wednesday, August 10, 2011

Ground-Assisted Air-Source Heat Pump

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

1 comment:

  1. Similar work on a "hybrid GSHP," with valuable lessons learned for commercial & industrial applications