Multi-injection rate thermal response test with forced convection in a groundwater-filled borehole in hard rock
Artikel i vetenskaplig tidskrift, 2012

Convection is shown in earlier studies to improve the thermal contact between heat exchanger and borehole wall in water-filled boreholes. This study investigates the effect of convection on the required borehole length for a ground-coupled heat pump installation. Artificial convection was induced by an ordinary groundwater pump during a multi-injection rate thermal response test (MIR-TRT). For comparison, a second MIR-TRT was performed without pumping of groundwater. The required borehole length was estimated for a ground-coupled heat pump installation supplying a Swedish single-family house. The estimates are based on the results from the MIR-TRTs for thermal conductivity and borehole resistance. The results show linear decrease in required borehole length with increasing heat input rate during the MIR-TRT without pumping of groundwater due to buoyancy-driven convection. An artificial convection stronger than buoyancy-driven convection during the MIR-TRT with pumping of groundwater reduced the required borehole length by 9 %-25 % depending on the heat input rate.

Hard rock


Ground-coupled heat pump

Multi-injection rate thermal response test


H. T. Liebel

Norges Teknisk-Naturvitenskapelige Universitet

Saqib Javed

Chalmers, Energi och miljö, Installationsteknik

G. Vistnes

Norges Teknisk-Naturvitenskapelige Universitet

Renewable Energy

0960-1481 (ISSN)

Vol. 48 263-268


Hållbar utveckling


Building Futures