Innovative numerical procedure for simulating borehole heat exchangers operation and interpreting thermal response test through MODFLOW-USG code

A New Type in TRNSYS 18 for Simulation of Borehole Heat Exchangers Affected by Different Groundwater Flow Velocities

“…Different efforts were required by the numerical models, both for the geometry description and the calculation phase. In MODFLOW/MT3DMS, the boundary and internal conditions were applied to reproduce the operation of a BHE coupled to a GSHP, whereas in MODFLOW-USG, a specific package, named the connected linear network (CLN) package, was used for the same purpose of the previous version of the software; the numerical results were similar to those discussed in [32,33]. TRNSYS software allows for detailed analyses of the energy performance and comfort conditions related to buildings and systems to be performed.…”

“…Numerical modeling is a helpful tool to design a HVAC system and is one of the essential elements of these systems: the ground heat exchanger (BHE). The reproduction of a BHE system was fully validated in MODFLOW/MT3DMS [25,35] and in a recent updated version of the software MODFLOW-USG [32,33]. The need to validate the same element in TRNSYS, a widely used tool for the dynamic simulation of thermal and electrical energy systems, was high, hence, the reproduction of the same BHE numerical model was carried out in TRNSYS software for the first time in the thesis by Antelmi and Legrenzi [40].…”

“…This is correct, because the higher the distance between BHE, the lower the thermal interference between adjacent BHE; therefore, the energy performance of the GSHP system improves when the BHEs are located at the correct position without interferences between each other. For this specific null flow velocity case, the correct distance between BHE was greater than 8 m, because the thermal plume was radial and not developed along the flow direction [33,44]. When different BHE are installed in hydrogeological settings with high flow velocities, the distance could be reduced because of the different shape of the thermal plume.…”

“…The actual version of MODFLOW/MT3DMS is MODFLOW-USG [30,31], which is able to couple the flow numerical simulations to the heat transport modeling in an aquifer. Antelmi et al [32] developed a numerical model of a single BHE using the connected linear network (CLN) package and showed how the approach results are smart and more expeditious than the usual BHE models; the approach was also verified and validated against numerical solutions with different hydrogeology settings and modeling grids in a thermal response test (TRT) application [33]. Furthermore, different authors [9,10,25,34,35] have also used numerical modeling to demonstrate the influence of the groundwater flow velocity on energy performance: they discussed how the variation in the Peclet number, directly proportional to groundwater flow velocity, and thermal diffusion could cause a different energy performance of the BHE system.…”

Design and optimization of ground‐coupled refrigeration heat exchanger in Dubai: Numerical approach

“…However, the pressure drop increases with decreasing the pitch size between the coils. Meanwhile, Barbieri et al 33 have developed an adapted numerical model that can be used to analyze in situ thermal response tests (TRT) from the BHEs during the simulation procedure. The model has been demonstrated to improve the design of BHEs and to accurately estimate buildings energy demand.…”