IIR document

Thermal performance of ground source heat pumps that use direct expansion system.

Number: pap. n. 477

Author(s) : TAKEDA T., TANAKA D., YOKOYAMA D., et al.


Ground source heat pumps (GSHPs) use buried pipes to extract heat from the ground. This heat can be used in radiators, in under-floor and warm-air heating systems, and in hot water heaters in houses. In a conventional GSHP, which uses an indirect heat exchange method, vertical systems use two long pipes connected by a U-shaped fitting at the bottom of a hole bored in the ground. These pipes form part of a closed loop, through which a mixture of water and antifreeze circulate. In contrast, a GSHP that uses a direct expansion method circulates a mixed refrigerant through the ground loop. In our tests of this method, the depth of the borehole was 30 m, and the refrigerant was R410A. The coefficients of performance (COP) were obtained for the direct expansion type of GSHP running in the cooling and the heating mode. It was found that the COP in the cooling mode and the heating mode was over 9 and 4.8, respectively.

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  • Original title: Thermal performance of ground source heat pumps that use direct expansion system.
  • Record ID : 30015918
  • Languages: English
  • Source: Proceedings of the 24th IIR International Congress of Refrigeration: Yokohama, Japan, August 16-22, 2015.
  • Publication date: 2015/08/16
  • DOI: http://dx.doi.org/10.18462/iir.icr.2015.0477


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