LIAG-Seminar

Tuesday, 14.05.2024, 11:00

Victorien Djotsa Nguimeya Ngninjio:  An experimental and numerical study of thermally induced
convection along a high-temperature borehole heat exchanger

Abstract:

Thermally induced convection along borehole heat exchangers (BHE) in porous
media influences the heat transfer behaviour between the BHE and the surroun-
dings and thus its performance in term of both heat recovery and storage. In our
study, a combined experimental-numerical analysis of the effects of convection
on heat transfer was conducted on a laboratory-scale BHE analogue over a wide
temperature range. This was done by installing a grouted coaxial high-tempe-
rature BHE in a fully saturated porous sand medium in a cylindrical container
under spatially extensive temperature monitoring. Transient heat charging/
discharging experiments were carried out at different charging temperatures of
30, 50, 70, and 90 °C and the occurrence and extent of convection was analysed.
With minimal calibration, our numerical model can accurately reproduce the
experimental data from all experiments and help to quantify the contribution of
convection to the total heat transfer at each temperature level.