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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

STUDY ON UNDERGROUND HEAT EXCHANGER FOR GROUND SOURCE HEAT PUMP THAT USE DIRECT EXPANSION METHOD

Get access (open in a dialog) DOI: 10.1615/IHTC16.nee.023415
pages 7659-7666

Abstract

Ground source heat pumps (GSHPs) can an electric energy by making good use of underground thermal energy. In addition, releasing the heat of the air-conditioning to underground can reduce environmental impacts, including the heat island effect. In GSHP, two types of systems are applied, namely, an indirect method and a direct expansion method. In the direct expansion method, a refrigerant transfers thermal energy through a primary loop without mediation. Therefore, it is expected that thermal energy is transferred effectively and performance is promoted. In the experiment, the depth of the borehole was 30m, and the refrigerant used was R410A. We used two underground heat exchangers to keep the amount of heat acquired from the underground. The underground heat exchanger with a depth of 20m was inserted into the casing pipe. The coefficients of performance (COP) were obtained for this type GSHP operating in both the cooling and heating modes. The experimental results can be summarized as follows. The COP is approximately 11.3 in the cooling mode and 7.2 in the heating mode. The advantages of this direct expansion method is to reduce the power consumption of the GSHP. It can be also reducing the borehole depth. Therefore, the GSHP that use the direct expansion method are advantageous from the viewpoint of the cost.