Advanced, Low-Cost Indoor Heat Exchanger for Geothermal Heat Pump Systems

Geothermal heat pumps have the potential to significantly reduce residential and commercial energy usage for space heating, air conditioning, and hot water. The largest barrier to wider adoption of this technology is the high installation cost relative to conventional air conditioners, gas furnaces, and heat pumps. The high cost of geothermal heat pumps is due to the high cost of the ground loop and the increased cost of the heat pump relative to traditional air-coupled technology. A novel heat exchanger technology will be developed that increases the efficiency of the system while reducing cost. This heat exchanger technology will couple the heat pump to the ground loop, and is a key component influencing the cost and performance of both systems. A first-generation prototype of the heat exchanger design was designed and fabricated. Testing demonstrated that it outperforms a state-of-the-art baseline heat exchanger, exceeding the Phase I performance objectives while using low-cost materials and fabrication techniques. The heat exchanger development will be completed, including improving the design’s thermal performance and manufacturability, scaling the technology, and fabricating prototypes of the final design. The prototypes will be benchmarked against state-of-the-art baseline heat exchangers in laboratory testing and in an instrumented geothermal heat pump. Commercial Applications and Other Benefits: This heat exchanger will reduce the cost of geothermal heat pumps, improving the market penetrationof this technology and reducing energy usage of space heating and air conditioning systems. In addition, the lower cost and improved performance will make it attractive in a number of other applications, including data centers, cogeneration systems, solar thermal systems, and food processing.