Analysis of influence of pipe group arrangement and heat exchanger type on operation performance of the ground source heat pump

Arrangement of pipe group and type of ground heat exchangers (GHEs) are crucial engineering design factors affecting the ground source heat pump system (GSHPS) performance. Taking an office building as the object, based on the built three-dimensional simulation platform considering heat and moisture transfer, seepage and freezing, the influence of these two design factors on the GSHPS is simulated. Results show that the influence of moisture transfer on heat transfer of GHEs is smaller. When the pipe group is arranged in staggered and square arrangements and the type of GHEs is single-U, the soil freezing degree is more serious. After 5 years of operation, the effect of pipe group with linear arrangement and GHEs with W and double-U types on improving the system performance is more obvious. Average coefficient of performance (COP) with linear arrangement increases by 14.82% and 12.10% in cooling mode, and 20.62% and 16.98% in heating mode, compared with staggered and square arrangements. Average COP with W and double-U types increases by 20.30% and 25.49% in cooling mode, and 23.77% and 29.43% in heating mode, compared with single-U type. Moisture transfer, seepage and freezing can improve the heating COP, but only seepage can improve the cooling COP.