Downhole heat exchanger

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Bottom end of a Downhole heat exchanger
Top end of a Downhole heat exchanger

A downhole heat exchanger, (DHE) also called a borehole heat exchanger, (BHE) is a heat exchanger installed inside a borehole.[1] It is used to capture or dissipate heat to or from the ground. DHT's are used for geothermal heating, sometimes with the help of a geothermal heat pump.



The heat exchanger usually consists of one or two u-tubes through which the carrier fluid, usually water, circulates. The space around the u-tubes is filled with groundwater or backfilled with thermally conductive grout.

Open pipe[edit]

Another design uses a single open pipe to flow water downward. The water then returns through the annular gap between the pipe and the casing. This design provides better thermal contact than u-tubes, but risks contamination by groundwater. Since this involves practically no downhole equipment, these systems usually only go by the name of borehole heat exchangers (BHT).

Standing column well[edit]

If no casing is installed and groundwater is permitted to charge the system, this arrangement is no longer a BHT, but rather a standing column well.


  1. ^ "Downhole Heat Exchangers" (PDF). Geo-Heat Center - Oregon Institute of Technology. Retrieved 21 April 2013.