Experimental verification and programming development of a new MDF borehole heat exchanger numerical model

• Experimental validation of a borehole heat exchanger MDF model.
• Programming development of MDF model in ANSYS software.
• Comparison of CFX, q3D, Diersch and MDF models.
• A significant shortening of calculation time with good accuracy.

Numerical models of borehole heat exchanger (BHE) systems are of high practical importance in borehole thermal energy storage technologies. Therefore, this article shows the experimental verification and results comparison of Multi-Degree-of-Freedom (MDF), Diersch, quasi-three-dimensional (q3D) and ANSYS CFX numerical models of heat transport in a single U-tube vertical BHE. Emphasis has been put on verification of a new MDF model and its programming development in ANSYS software using user programmable features (UPFs). Accordingly, a significant reduction of CPU time and good agreement with experiment data are gained, thus rendering the MDF and Diersch model suitable for utilisation in engineering practice.