Analysis of deep borehole heat exchanger with horizontal branch wells for building heating

The development and application of enhanced geothermal systemand hydrothermal systemare constrained due to high cost and high risk of induced seismicity or heavily reliance on hot water reservoir. Deep borehole heat exchanger (DBHE) technology is independent of hot water reservoir and hydraulic fracturing; however, the poor thermal conductivity of rocks limits its performance improvement. To deal with these problems, a novel technology for acquiring geothermal energy using DBHE with horizontal branch wells (DBHE-HBW) is proposed here. It is found that DBHE-HBWhas better performance than DBHE and, under the condition of nearly equal total cross-sectional area of well tube, the smaller the horizontal well tube diameter, the greater the thermal output and the shorter the payback period of DBHE-HBW. Therefore, DBHE-HBWcan be recommended for large-scale application in building heating sector.