Abstract
Shallow geothermal energy is considered as an efficient and sustainable green technology to heat and cool buildings. Incorporating the ground heat exchanging loops (GHEs) inside structural piles, known as energy piles, largely reduces the capital cost. Despite the extensive literature on loops connected in series inside energy piles, optimal distribution or lack of thereof of loops connected in parallel remain largely unexplored. For this purpose, a 3D numerical model has been built to undertake parametric analyses on an energy pile equipped with GHEs connected in parallel. The impact of GHEs misplacement due to construction errors on thermal yield is explored, considering the influence of pile diameter, pile length, pile-to-pile spacing, flow rate, pipe diameter, and ground thermal conductivity. Results show that the GHEs placement generally has a marginal effect of less than 3% on the total thermal yield of the energy pile. However, the heat transfer share between individual loops is highly dependent on its distribution, particularly for certain pile diameters. This may affect maintaining the equilibrium thermal performance. Moreover, in symmetrical loop distributions, an insignificant thermal performance penalisation was observed for a range of separation-to-shank distance ratios from 0.5 to 1.5. While symmetrical and evenly spaced distribution is recommended, the latter result indicates that there is flexibility when installing the GHEs loops, with deviations from design during construction rendering low impacts on overall thermal performance.