4LUND J W, FREESTON D H, BOYD T L. Direct utili- zation of geothermal energy 2010 worldwide review[J]. Geothermics, 2010, 40: 159-180.
5REES S J, HE M M. A Three-dimensional numerical model of borehole heat exchanger heat transfer and fluid flow[J]. Geothermics, 2013, 46: 1-13.
6FUCHS S, SCHUTZ F, FORSTER H J, et al. Evalua- tion of common mixing models for calculating bulk the- rmal conductivity of sedimentary rocks: Correction cha- rts and new conversion equations[J]. Geothermics, 2013, 47: 40-52.