Thermal Response Measurement and Performance Evaluation of Borehole Heat Exchangers: A Case Study in Kazakhstan

The purpose of the present work was to determine thermal performance borehole heat exchangers, considering influences their geometric configurations and thermophysical properties soil, grout pipe wall material. A three-dimensional model developed for mass transfer in soil (a porous medium) grout, together with one-dimensional conductive through walls convective fluid circulating pipes. An algorithm solve mathematical equations model. COMSOL Multiphysics software used implement perform numerical simulations. apparatus designed, installed tested response test (TRT) method. Two wells depth 50 m were drilled Almaty region Kazakhstan. Gravel till/loam mainly found, which are accordance stratigraphic map local geological data. In each well, two exchangers installed, an integral part ground source pump. TRT measurements conducted using one exchanger well data obtained. found be good agreement those available literature. results agreed data, root-mean-square-deviation within 0.184 °C. predictions line-source analytical model, utilized conductivity (λg = 2.35 W/m K) resistance from (Rb 0.20 K/W). then predict efficiencies various dimensions. simulation show that spiral extracts highest amount heat, followed by multi-tube, double U-type parallel, cross single U-type. It is also configuration can save 34.6% drilling compared conventional one, suggesting best terms maximum extracted. showed (i) more extracted a higher material, range 0.5–3.3 K; (ii) remained unchanged material than 2.0 K (experiments 0.24–0.42 K); (iii) volumetric flow rate water 1.0 m3/h (experimental 0.6 m3/h); (iv) increased increase 0.4–6.0 K). tool developed, obtained great value design optimization as studying other important factors such during charging/discharging, freezing factor interference.