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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

Thermal Performance and Characteristics of SpiraL-Tube Ground Heat Exchanger for Ground-Source Heat Pump

Get access (open in a dialog) DOI: 10.1615/IHTC15.hex.009412
pages 3527-3540

Abstract

This study investigates thermal performance and characteristics of spiral-tube ground heat exchanger (GHE) for ground source heat pump in laminar and turbulent flows. The thermal performances are evaluated by numerical method using CFD code. Various models of spiral-tube GHEs installed in a borehole and backfilled with silica-sand were simulated. In comparison with the conventional U-tube GHE, the performance of spiral-tube GHE increases of 62.7 % in the laminar flow and of 33.5 % in the turbulent flow. Due to the interesting of applying the GHE in concrete foundation piles, the spiral-tube GHE installed in a concrete pile is also simulated. Its performance shows a slight better performance of 5 % in the laminar flow and 6 % in the turbulent flow compared with that of in the borehole backfilled with silica sand. Furthermore, the performance of spiral-tube GHEs with pipe installed inside and outside spiral tube in the borehole and varying spiral pitches of p = 0.05 m; 0.1 m and 0.2 m are investigated. The effects of pipe positions to the performances are shown. The spiral-tube with pipe installed outside gives a better performance of 2 % in the laminar flow and 10 % in the turbulent flow than that of the outlet pipe installed inside. Water temperature distributions of the both spiral-tube GHEs are presented. Varying spiral pitches affects significantly to the performance of the spiral-tube GHEs. Increasing the spiral pitch reduces the number of spiral tube per meter borehole depth.