Multi-injection rate thermal response test with forced convection in a groundwater-filled borehole in hard rock
Journal article, 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.

Multi-injection rate thermal response test

Hard rock


Ground-coupled heat pump


H. T. Liebel

Norwegian University of Science and Technology (NTNU)

Saqib Javed

Chalmers, Energy and Environment, Building Services Engineering

G. Vistnes

Norwegian University of Science and Technology (NTNU)

Renewable Energy

0960-1481 (ISSN) 18790682 (eISSN)

Vol. 48 263-268

Driving Forces

Sustainable development

Areas of Advance

Building Futures (2010-2018)


Subject Categories

Civil Engineering



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