Evaluation of Thermal Anomalies in Multi-Boreholes Field Considering the Effects of Groundwater Flow

Abstract

Abstract:In this paper, the performance of multiple boreholes (multi-BHEs) field is evaluated by considering the groundwater flow. Optimization strategies are presented to mitigate thermal anomalies in the BHEs field. This study shows that groundwater flow greatly improves the heat transfer but causes thermal anomalies downstream. To overcome this problem, a heat transfer model is established for multi-boreholes based on temperature field superposition and moving finite line source model (MFLS). The MFLS multi-boreholes model considers the axial effect and groundwater flow and produces results in agreement with the field tested data of a 4ˆ4 boreholes field. Using a dynamic annual load pattern, the long-term performance of the 4ˆ4 boreholes field is analyzed. Three dynamic diurnal cooling load models are proposed to evaluate the temperature changes in the underground. The intermittent load model could reduce the local temperature anomalies in downstream tubes. The optimization model for cooling cases for multi-BHEs is elaborated to keep the outlet temperature as low as possible and minimize the extreme temperature anomalies, and by this, ultimately improve the system performance. Furthermore, the temperature variations and thermal anomalies downstream of multi-BHEs are investigated by evaluating the arrangement optimization and load optimization. The results show that the optimization could mitigate thermal anomalies downstream and reduce the rate of temperature imbalance of the BHEs field.

Visualization Method for Porous Groundwater Seepage Flow Field Based on Particle Flow: Case of Yancheng City in the East Coast of China

“…The groundwater level of grid points and original monitoring wells obtained via Kriging interpolation statistics was used to establish the trend surface of groundwater level dynamic change [40]. If the point is Pðx, yÞ, then the radius R is defined and a circle with Pðx, yÞ as the center and R as the radius is drawn.…”

“…Visualization. The dynamic adaptive grid in the study area was generated via the finite element method and the AFT algorithm on the basis of existing boundary data of the study area [40]. The monitoring wells that are evenly distributed in the study area and have a large average variation of groundwater level were selected and inserted into the generated grid.…”

Numerical simulation of ground source heat pump systems considering unsaturated soil properties and groundwater flow

“…Initial ground temperature profile and far-field boundary temperatures are represented by Eq. (14) and (16). The circulating fluid is water and parameters used in the numerical analysis are shown in Table 2.…”

“…Generally, all or part of a BHE is located above the groundwater table [14,15]. Also in some cases, groundwater flow may be present in the saturated regions, which has the potential to greatly influence the heat transfer behavior of BHEs [16,17]. However, most existing models either regard the heat transfer between BHEs and their surrounding ground as a pure heat conduction process or assume the ground to be a fully saturated homogeneous porous.…”

Influence of groundwater flow on cost minimization of ground coupled heat pump systems

“…Given the influence of groundwater flow on GCHP systems [21]- [24] and the advantages of a design method based on cost minimization, this paper introduces a new sizing methodology that takes in account groundwater flow. The total cost is in fact composed of the initial and operational costs, which both depend on different design parameters and are influenced by groundwater flow.…”