论文和技术资料

A numerical investigation of the long-term performance of double U-tube borehole heat exchanger (BHE) fields, in the case of non-negligible effects of groundwater movement, is performed by means of COMSOL Multiphysics. Two time periodic heat loads, with a period of one year, are studied: Q1, with a partial compensation between winter heating (principal load) and summer cooling; Q2, with no summer cooling. The results show that, for the heat load Q1, a water speed of 10^(-7) m/s is sufficient to obtain an acceptable long term performance for all the considered configurations; on the other hand, a water speed of 10^(-6) m/s ensures an excellent long term performance of the ground coupled heat pumps also in the most critical case of four staggered lines subjected to the heat load Q2.