Effectiveness of using spiral ground heat exchangers in ground source heat pump system of a building for district heating/cooling purposes: Comparison among different configurations

Highlights: • Thermal performance of the spiral GHEs are investigated experimentally and computationally. • Thermal interactions between nine spiral GHEs are analyzed numerically. • Linear quadrilateral and circular formations of the nine spiral GHEs are investigated. • Effective average space area of the building which can be heated or cooled is determined. • Relative performances against average working fluid and ground temperature are determined. - Abstract: This paper presents the thermal behavior of the four different configurations of spiral ground heat exchangers (GHEs), experimentally and computationally. In an experimental study, two different configurations of them (N = 1 and 9, linear and quadrilateral configurations) are tested separately for 150 h. Experimental study cases are also simulated by using COMSOL environment and their results are validated by experimental ones. Long term heat transfer rate of a single and nine spiral GHEs are examined computationally under the most critical working conditions. Then, thermal behavior of the four different models (two linear quadrilateral models and two circular ones) are investigated numerically. Additionally, the average effective space area of building that can be heated or cooled by spiral GHEs (space heating/cooling and domestic hot water) is examined for above mentioned four different models. Finally, the effects of working fluid and ground temperature on thermal performance of spiral GHE are analyzed.