Modeling and simulation of double-boreholes vertical U-shaped pipe heat transfer

Based on Finite Linear Heat Theory, through Virtual Source Method and Green Function Method, in the whole area of double-boreholes vertical U-shape pipe, the heat transfer model outside boreholes in the cylindrical coordinate is established, and the analytical solution of g-function and its modified form are obtained. Using MATLAB, the g-function curve is plotted and the soil temperature field is simulated and analyzed in case that the Ground Source Heat Exchanger works in cooling mode. In the end, the double-boreholes heat transfer process is simulated by PDE toolbox to verify the accuracy of the model.