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Development of a ground-source heat pump system with ground heat exchanger utilizing the cast-in-place concrete pile foundations of buildings.

Author(s) : SEKINE K., OOKA R., YOKOI M., et al.

Summary

Ground-source (geothermal) heat pump (GSHP) systems can achieve a higher COP than conventional air-source heat pump (ASHP) systems. However, GSHP systems are not widespread in Japan because of their expensive boring costs. The authors have developed a GSHP system that uses the cast-in-place concrete pile foundations of a building as heat exchangers to reduce the initial boring cost. In this system, some U-tubes are arranged around the surface of a cast-in-place concrete pile foundation. The heat exchange capability of this system, subterranean temperature changes, and heat pump performance were investigated in a full-scale experiment. As a result, the average values for heat rejection were 186-201 W/m (per pile, 25 W/m per pair of tubes) while cooling. The average COP of this system was 4.89 while cooling, rendering this system about 1.7 times more effective in energy-saving terms than the more typical ASHP systems. The initial cost of construction per unit for heat extraction and rejection is USD 0.79/W for this system, whereas it is USD 3/W for existing standard borehole systems. Therefore, this system is expected to be commercially viable.

Details

  • Original title: Development of a ground-source heat pump system with ground heat exchanger utilizing the cast-in-place concrete pile foundations of buildings.
  • Record ID : 2009-0833
  • Languages: English
  • Source: ASHRAE Transactions. 2007 Winter Meeting. Volume 113, part 1 + CD-ROM.
  • Publication date: 2007/01/27

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