Slinky-coil 式地中熱交換器の管内圧力損失に関する実験的検討

• Published in: Nihon Chinetsu Gakkai shi Vol. 39; no. 2; pp. 93 - 99
• Main Authors: 小野, 雅敏, 藤井, 光, 小助川, 洋幸
• Format: Journal Article
• Language: Japanese
• Published: Tokyo 日本地熱学会 01.01.2017; Japan Science and Technology Agency
• Subjects: Coiling; Coils; Flow velocity; Friction factor; Heat exchangers; Mathematical analysis; Polyethylenes; Pressure loss; Tubes
• ISSN: 0388-6735; 1883-5775
• DOI: 10.11367/grsj.39.93

Slinky-coil type ground heat exchangers (GHEs), which are commonly used in horizontal ground heat exchangers, have an extended spiral shape to effectively collect the heat from the ground. Due to the complicated shape of the GHEs, a reliable method to estimate the pressure loss caused by the flow of circulation fluid is not well-developed yet. In this work, field measurements of pressure loss in Slinky-coils were carried out using a polyethylene tube of 25mm ID whose overlaps between loops were set as 0, 25, 50 and 75%, respectively.The results of the measurement showed that the percentage of overlaps does not significantly affect the pressure loss. It was also found that the pressure loss in the Slinky-coil was slightly higher than that in straight tubes; the difference increased with the increase of flow rate. To predict the pressure loss in Slinky-coils, the friction factor in the pressure loss calculation was corrected to obtain a good matching between the measured and calculated pressure losses for different tube length and heat medium temperature. The use of the corrected friction factor enabled the easy calculation of pressure loss in Slinky-coils.