Heat transfer in a borehole heat exchanger: Frequency domain modeling
Artikel i vetenskaplig tidskrift, 2014

This paper proposes a new frequency domain method to model the heat transfer between the injected/extracted heat and the temperature of the fluid exiting a borehole heat exchanger. The method is based on in situ measurements and focuses particularly on the short-term borehole heat transfer. It uses a rational function of the Warburg variable in the Laplace domain to model the borehole heat transfer. The rational model is transformed to a time domain model using inverse Laplace transformation. This time domain model makes it possible to calculate the temperature response on a random heat variation signal. The paper also demonstrates a new way to perform the classical thermal response test. Instead of injecting a constant amount of heat, the experiments have been performed using multiple short-duration heat injections. In this way, the obtained rational heat transfer model contains information about both the short- and the long-term heat transfer. The results obtained using the proposed modeling method are compared with those obtained from a state-of-the-art analytical method. The time domain model can be used to design a controller to optimize the performance of a Ground Source Heat Pump system, the efficiency of which depends strongly on the temperature of the fluid exiting the borehole.

Heat transfer

Frequency domain

Borehole heat exchanger



Ground Source Heat Pump


Griet Monteyne

Vrije Universiteit Brussel

Saqib Javed

Chalmers, Energi och miljö, Installationsteknik

Gerd Vandersteen

Vrije Universiteit Brussel

International Journal of Heat and Mass Transfer

0017-9310 (ISSN)

Vol. 69 129-139