# US 10,767,903 B2 · Coaxial ground heat exchanger and method for installing said ground heat exchanger in the ground

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- Number: US 10,767,903 B2
- Document ID: US10767903B2
- Status: Granted
- Kind: B2
- Application number: 14/541,666
- Filed: 2014-11-14
- Published: 2015-03-12
- Granted: 2020-09-08
- Earliest claimed: 2012-05-14
- Assignees: Broder AG
- Applicants: Broder AG
- Inventors: Mathias Broder
- Web page: https://patentgrep.com/patent/US10767903B2

## CPC

- F24T 10/10: with circulation of working fluids through underground channels, the working fluids not coming into direct contact with the ground
- E21B 36/00: Heating, cooling or insulating arrangements for boreholes or wells, e.g. for use in permafrost zones
- F24T 10/17: using tubes closed at one end, i.e. return-type tubes
- F24T 10/30: using underground reservoirs for accumulating working fluids or intermediate fluids
- F24T 2010/53: {Methods for installation}
- F28D 7/12: the surrounding tube being closed at one end, e.g. return type (F28D7/14 takes precedence)
- Y02E 10/10: Geothermal energy
- F24T: GEOTHERMAL COLLECTORS; GEOTHERMAL SYSTEMS
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- F28D: HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT (fluid heaters having heat generating means and heat transferring means F24H; furnaces F27; details of heat-exchange apparatus of general)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A coaxial ground heat exchanger and installation method are disclosed where the heat exchanger has a central core tube that can be provided with a thermally insulating casing and an outer tube that delimits an annular gap which extends radially outwards from the core tube. The core tube and the annular gap can be configured such that a flowable heat transfer medium can flow through. The outer tube is formed by a tubular expandable cover that directly adjoins a wall of a ground heat exchanger borehole when the heat exchanger is installed.

## Claims

### Claim 1

A coaxial ground heat exchanger mounted within a ground heat exchanger hole, comprising:
a central core tube; and
an expandable jacket tube which encloses said central core tube, wherein an inner wall of said expandable jacket tube and an outer wall of said central core tube delimit an annular gap, the annular gap extending along a central axis of said coaxial ground heat exchanger and being adapted to accommodate a heat transfer medium, wherein the heat transfer medium circulates from the annular gap through a length of the central core tube or vice versa,
wherein the expandable jacket tube is formed by an expandable hose covering that will expand radially in response to an elevated internal pressure in said annular gap, the expandable hose covering encasing the central core tube in a folded state, the expandable hose covering arranged to be brought into a stable end shape by the heat transfer medium when the heat transfer medium is fed into said annular gap with overpressure,
wherein the expandable hose covering in the stable end shape encloses said central core tube along an entire circumference of the expandable hose covering, and an outer wall of said expandable hose covering adjoins an inner wall of the ground heat exchanger hole along an entire internal circumference of the ground heat exchanger hole in said stable end shape, and
wherein the expandable hose covering comprises an unfolded diameter that is selected to be larger than a diameter of the ground heat exchanger hole.

### Claim 2 (depends on 1)

The coaxial ground heat exchanger according to claim 1, wherein the core tube and the annular gap are configured to be flushed with water as a heat transfer medium.

### Claim 3 (depends on 1)

The coaxial ground heat exchanger according to claim 1, wherein an area of the hose covering that is closer to a surface of the ground heat exchanger hole and that adjoins loose soil in a mounted state is configured in a water-impermeable manner.

### Claim 4 (depends on 1)

The coaxial ground heat exchanger according to claim 1, wherein the expandable hose covering is formed by a plastic composite film, which has a wall thickness of 3 mm to 15 mm.

### Claim 5 (depends on 1)

The coaxial ground heat exchanger according to claim 1, wherein the central core tube comprises a thermally-insulating casing.