Evaluation of geometric factors influencing thermal performance of horizontal spiral-coil ground heat exchangers. (5th November 2018)

• Record Type: Journal Article
• Authors: Kim, Min-Jun; Lee, Seung-Rae; Yoon, Seok; Jeon, Jun-Seo
• Is Part Of: Applied thermal engineering. Volume 144(2018)
• Page Start: 788
• Page End: 796
• Publication Date: 2018-11-05
• Subjects: Ground source heat pump -- Horizontal spiral-coil GHE -- Laboratory thermal response test; Heat engineering -- Periodicals; Heating -- Equipment and supplies -- Periodicals; Periodicals; 621.40205
• DOI: 10.1016/j.applthermaleng.2018.08.084
• Languages: English
• ISSNs: 1359-4311

Abstract

Highlights: Thermal performance evaluation of a horizontal spiral-coil GHE was conducted. A laboratory thermal response test on the horizontal spiral-coil GHE was performed to validate the numerical model. The numerical modeling were in good agreement with the experimental results. The optimal specification in terms of thermal performance was suggested. Abstract: This study aims to estimate the thermal performance of a horizontal spiral-coil ground heat exchanger (GHE), focusing on the geometry factor of the spiral-coil. Prior to the thermal performance evaluation, an indoor thermal response test (TRT) was conducted with a 5 m x 1 m x 1 m steel box filled with dry Joomunjin sand and TRT equipment was used to validate the numerical analysis using the commercial program COMSOL Multiphysics 5.2a, which is based on computational fluid dynamics (CFD). Next, the number of analysis cases was set by selecting the key factors affecting the thermal performance of a horizontal GHE: installation depth, fluid velocity, thermal conductivity of the ground, and numerical studies were conducted on the 16 cases. As a result of the analysis, it was observed that the pitch does not affect thermal performance if the pitch exceeds 0.6 m. These same results were derived even when additional changes in the key factors were taken into consideration. In addition, it was revealed that the spiral diameter does not affect the thermal performance of the horizontal spiral-coil GHE. Therefore, we concluded that the geometric factor that determines the optimal thermal performance of the horizontal spiral-coil GHE is not the spiral diameter but the pitch, and the 0.6 m pitch of the horizontal spiral-coil GHE can provide a compromise between the thermal performance and installation land space.