A novel hybrid design algorithm for spiral coil energy piles that considers groundwater advection. (5th March 2015)

• Record Type: Journal Article
• Authors: Go, Gyu-Hyun; Lee, Seung-Rae; Kang, Han-Byul; Yoon, Seok; Kim, Min-Jun
• Is Part Of: Applied thermal engineering. Volume 78(2015:Mar.)
• Page Start: 196
• Page End: 208
• Publication Date: 2015-03-05
• Subjects: Hybrid GSHP system -- Groundwater advection -- Numerical analysis -- Energy pile -- Spiral coil heat exchanger; Heat engineering -- Periodicals; Heating -- Equipment and supplies -- Periodicals; Periodicals; 621.40205
• DOI: 10.1016/j.applthermaleng.2014.12.060
• Languages: English
• ISSNs: 1359-4311

Abstract

Abstract: This paper presents a novel hybrid design algorithm for spiral coil energy piles that considers groundwater advection. The design algorithm considers the groundwater advection effect using an analytical model. During this study, the accuracy of the analytical model was verified for its design application using a finite element (FE) numerical model, and the effect of groundwater advection on the design results was investigated. According to these results, groundwater advection attenuates thermal interference between piles, as well as long-term ground thermal resistance, which contributes to the economical design of energy piles. Moreover, when there is an extreme disparity between cooling and heating loads, hybrid design was achieved using hourly building energy load data calculated by the design builder program. Hybrid design decreases the total heat exchanger length of the energy piles, and reduces the entering water temperature (EWT) variance caused by heat interference. Furthermore, the pile arrangement can influence the impact caused by separation distance. For a square arrangement of piles, the shorter the separation distance, the less the effect from the hybrid system. In contrast, for a linear arrangement of piles, there is no influence caused by the separation distance, and generally, a high reduction rate of heat exchanger length is shown. Highlights: New design algorithm for spiral coil energy piles is proposed. Effect of groundwater advection on the design length of heat exchangers is investigated. Heat advection due to the groundwater flow can considerably influence the thermal interference effect. Hybrid GSHPs design can provide suitable alternatives that reduce the total heat exchanger length.