A fast and accurate semi-analytical method to determine the thermal response of bore fields

The design and simulation of a borehole-heat-exchanger (BHE) field is usually performed by simplified models that yield either an overestimation or an underestimation of the thermal response. An accurate semi-analytical method to determine the g-function of a bore field with the real condition of BHEs fed in parallel with equal inlet temperature was developed by Cimmino (Int J Heat Mass Tran 91). An alternative semi-analytical method, conceptually simpler and equally precise, is presented in this paper. The method is implemented in a C++ program, available at the open-source online data repository of the University of Bologna (see data availability). Thanks to several optimizations, the program yields a very accurate thermal response of bore fields of any shape with an extremely short computation time. The program is employed to analyze the inaccuracies caused by the assumptions of uniform heat rate and uniform surface temperature of the BHEs.