STIEBEL ELTRON Heat pumps, Техническое руководство

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geotHeRmal pRobes
Geothermal probes
Geothermal probes comprise of a
probe foot and endless vertical probe
pipes (pipe diameter 25 x 2.3 mm
down to a depth of 60 m and
32 x 3 mm down to a depth of
150 m). the adjacent diagram shows
an example of a double U-shaped
probe with a welded foot. this probe
is inserted into a drilled hole in the
ground. After inserting the pipes, the
holes are filled under pressure with
a suspension (e.g. bentonite). After
curing, this must provide a dense,
permanent and physically stable
connection between the geothermal
probe and the surrounding rock. that
ensures a good thermal transfer.
Sizing
the system is sized in accordance
with the flow of groundwater and the
thermal conductivity of the ground.
in larger systems, several probes are
connected in parallel to extract the
required cooling capacity from the
ground.
Extraction rate of geothermal probes
(specific extraction rate per metre of
geothermal probe). without knowing
the soil condition, an average specific
extraction rate (cooling load) of
55 w/m can be used as calculating
basis.
Extraction rate: (VDi 4640)
Ground with a high groundwater
throughput 100 w/m
solid rock with a high thermal
conductivity 80 w/m
solid rock with normal subsoil 55
w/m
Poor subsoil, dry sediment 30 w/m
Note:
Accurate assessments are subject to
soil condition and the water-bearing
ground strata and can therefore only
be made in situ by the contractor.
U-shaped pipe probe
4 pipes
Injection pipe
Bending radius 40 cm
Sand bed 20 cm
Cement-opalite
suspension
Hole diameter
110 – 133 mm