Borehole heat exchanger

Ground-source loops, sized right

U-loop outlet temperature across the full laminar-to-turbulent range, cross-checked against COMSOL Multiphysics (an independent commercial simulator) with the same internal-film physics.

0.08 °C
outlet agreement at the design point
0.38 °C
within, across the flow range
laminar→turbulent
full flow range covered
Model definition

What the model solves

SystemSingle U-loop borehole / ground-source heat exchanger
PhysicsConjugate heat transfer with internal convective film and Darcy–Weisbach pressure drop
SweepCarrier-fluid flow from laminar to turbulent
Validation referenceCOMSOL Multiphysics (same internal-film physics)
Output trackedLoop outlet temperature and pressure drop
Agreement vs COMSOLWithin 0.38 °C across the flow range; 0.08 °C at the design point
The case

Outlet temperature across the whole flow range

A borehole heat exchanger is a vertical U-loop buried in the ground. Carrier fluid is pumped down one leg and back up the other, harvesting heat from the soil along the way. The temperature it leaves with sets the heat-pump duty, and it depends on the internal-film physics inside the pipe as the flow shifts from laminar to turbulent.

Terra resolves the coupled pipe↔soil heat exchange directly, so the outlet temperature follows the same internal-film behaviour as COMSOL across the entire operating range. At the design point the two agree to 0.08 °C, and they stay within 0.38 °C of each other from laminar through turbulent flow. That margin is what lets you size a ground loop with confidence rather than padding it for safety.

3-D view

The collector, in three dimensions

The full serpentine collector and its supply / return risers, 4 m down in the ground, floating above a translucent slice of the soil temperature it produces — the embedded 1-D pipe network and the 3-D ground on one shared temperature scale.

Three-dimensional view of the buried serpentine ground-heat-recovery collector with its two vertical risers, above a translucent slice of the surrounding soil temperature, at the day-1 minimum, inside the soil domain
Collector pipe + risers (fluid temperature) above a translucent slice of the ground temperature it produces at 4 m depth, day-1 minimum. Coupled finite-element solve: 3-D soil plus an embedded 1-D pipe network.
Real simulation

A buried ground collector, solved hour by hour

The actual Terra finite-element ground-temperature field around a serpentine ground-heat-recovery collector over its first 24-hour operating cycle — cross-validated against COMSOL to within about 0.1 °C.

Real ground-heat-recovery field, first 24-hour cycle; outlet minimum −2.58 °C, within about 0.1 °C of COMSOL.
Interactive

Sweep the design and watch outlet temperature move

Drag the key inputs and the predicted loop performance updates in real time — the surrogate evaluates thousands of candidate designs as fast as you can move a slider.

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