Numerical modeling and parametric study of a vertical earth-to-air heat exchanger system. (1st April 2019)

• Record Type: Journal Article
• Authors: Liu, Zhengxuan; Yu, Zhun (Jerry); Yang, Tingting; Roccamena, Letizia; Sun, Pengcheng; Li, Shuisheng; Zhang, Guoqiang; El Mankibi, Mohamed
• Is Part Of: Energy. Volume 172(2019)
• Page Start: 220
• Page End: 231
• Publication Date: 2019-04-01
• Subjects: Earth-to-air heat exchanger -- Numerical model -- Parametric study -- Thermal performance; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Energy consumption -- Periodicals; 333.7905
• DOI: 10.1016/j.energy.2019.01.098
• Languages: English
• ISSNs: 0360-5442

Abstract

Abstract: A numerical model of a vertical earth-to-air heat exchanger (VEAHE) system was developed for the first time. Compared to conventional EAHE system models, the developed model considered the vertical distribution of soil temperature and thermal conductivity. The model validation against experimental data showed a good agreement. A parametric study was then conducted to investigate the effects of tube parameters, insulation parameters, mass flow rates and soil types. Results indicate that a system with a smaller tube diameter provides more thermal capacity with a fixed air mass flow rate, while a larger tube diameter can enhance the system's COP. An increase in tube depths causes the outlet air temperatures to decrease/increase in summer/winter, with a smaller daily oscillation. Compared to PVC and PE, stainless steel can be recommended as the most appropriate tube material, taking into account both heat exchange and soil pressure. Polyurethane, rubber or rock wool as insulation materials can be used as thermal barriers to shield the undesirable heat gains from the shallow soil with the almost same insulation effects. A thickness of 30 mm and a length of from 4 to 5 m can be recommended as the most appropriate insulation parameters for this proposed system. Highlights: A numerical model of a VEAHE system was developed for the first time. Vertical distribution of soil temperature and conductivity were considered. Model validation against experimental data showed a good agreement. Effects of different parameters on the system performance were analyzed.