Coaxial Pipes Used as Ground Buried Heat Exchangers—A Review of Research in Recent Years
Buildings,
Год журнала:
2025,
Номер
15(2), С. 243 - 243
Опубликована: Янв. 15, 2025
The
efficient
utilization
of
geothermal
energy
depends
heavily
on
high-performance
ground
heat
exchangers.
Coaxial
pipe
is
a
high-efficiency
exchanger
composed
two
nested
tubes
different
diameters.
In
this
paper,
the
structure
and
thermal
exchange
characteristics
coaxial
exchangers
are
introduced,
which
superior
to
single-U
double-U
in
respect
installation,
transporting,
deep
application.
Thermal
test
research
investigated.
Relevant
studies
recent
years
factors
affecting
performance
exchangers,
including
configurations,
circulating
fluids,
subsurface
conditions,
flow
patterns,
operational
modes,
reviewed.
addition,
impact
ground,
as
well
applications
for
summarized.
Recommendations
made
potential
future
It
believed
that
results
these
will
help
raise
awareness
continue
promote
their
Язык: Английский
Impact of Corrugated Fins on Flow and Heat Transfer Performance in Medium-Deep Coaxial Underground Heat Exchangers
Energies,
Год журнала:
2025,
Номер
18(9), С. 2212 - 2212
Опубликована: Апрель 26, 2025
To
enhance
the
efficient
development
of
geothermal
energy,
this
study
investigates
heat
transfer
enhancement
mechanisms
in
medium-depth
coaxial
underground
exchangers
(CUHEs)
integrated
with
corrugated
fins,
using
computational
fluid
dynamics
(CFD)
simulations.
Nine
distinct
fin
geometries
were
modeled,
and
streamlines,
velocity
fields,
temperature
turbulent
kinetic
energy
analyzed
across
Reynolds
numbers
(Re)
ranging
from
12,000
to
42,000.
The
results
demonstrate
that
fins
significantly
promote
turbulence
mixing,
thereby
augmenting
convective
transfer.
Compared
smooth
inner
tubes,
Nusselt
number
(Nu)
is
enhanced
by
a
factor
1.43–2.19,
while
friction
(f)
increases
2.94–6.79.
performance
evaluation
criterion
(PEC)
improves
increasing
width
decreasing
spacing.
optimal
configuration,
featuring
15
mm,
spacing
60
thickness
achieves
maximum
PEC
value
1.34
at
Re
=
12,000,
indicating
substantial
improvement
within
acceptable
pressure
drop
limits.
This
research
innovatively
explores
CUHEs
high
Re,
systematically
elucidates
influence
geometric
parameters
on
flow
resistance,
employs
index
optimize
structural
design.
provides
significant
theoretical
support
for
engineering
application
utilization.
Язык: Английский
Performance investigation of double tube ground heat exchanger by adjusting the inner tube position and consideration of bending effect
Geothermics,
Год журнала:
2025,
Номер
131, С. 103406 - 103406
Опубликована: Июнь 3, 2025
Язык: Английский
Effect of long-term nanofluid usage on horizontal ground source heat pump performance
Renewable Energy,
Год журнала:
2024,
Номер
237, С. 121777 - 121777
Опубликована: Ноя. 1, 2024
Язык: Английский
Numerical Performance Analysis of Modified Vertical U-tube Ground Heat Exchangers by Adjusting the Impact of Leg Spacing
International Journal of Thermofluids,
Год журнала:
2024,
Номер
24, С. 100959 - 100959
Опубликована: Ноя. 1, 2024
Язык: Английский
Numerical investigation on various geometric configurations of vertical helical tube ground heat exchanger for enhancing thermal performance
Journal of Renewable and Sustainable Energy,
Год журнала:
2024,
Номер
16(5)
Опубликована: Сен. 1, 2024
The
helical
tube
ground
heat
exchanger
(GHE)
surpasses
all
other
types
of
vertical
exchangers,
such
as
the
U-tube,
double
triple
W-tube,
and
double-tube
type
in
terms
thermal
performance.
In
present
study,
performance
several
helix
configurations
that
have
an
external
outlet
pipe
is
investigated
compared
with
a
conventional
U-tube
exchanger.
Another
motive
this
research
to
find
best
configuration
transfer
rate
pressure
drop.
Water
employed
working
fluid
fixed
flow
2
L/min
under
laminar
consideration
constant
inlet
temperature
300.15
K.
To
determine
optimal
among
17
independent
models,
parameters
are
considered,
including
exchange
rate,
temperature,
drop,
criterion
coefficient
(COP)
improvement
factor.
Furthermore,
effects
using
different
materials
for
backfill
on
GHE
evaluated.
comparison
it
found
modified
model
0.2
m
pitch
distance
between
pipes,
but
upper
portion
kept
straight
8
m,
provides
consumes
highest
pumping
power.
It
has
average
configurations,
which
42.69%
higher
GHE.
increased
by
6.54%
steel
material
polyethylene.
By
concrete
backfill,
there
5.41%
silica
sand.
worst
Язык: Английский
Numerical analysis of thermal performance of various types of horizontal ground heat exchangers
AIP Advances,
Год журнала:
2024,
Номер
14(9)
Опубликована: Сен. 1, 2024
In
this
paper,
three
types
of
horizontal
ground
heat
exchangers
(GHEs)
such
as
U-tube,
spiral,
and
slinky
were
numerically
analyzed
to
investigate
their
thermal
performance
in
cooling
mode
for
7
days
continuous
operation
with
specific
boundary
conditions
where
a
rectangular
trench
5
m
length,
2
width,
depth
served
the
basis
modeling
each
exchanger.
The
pipe
material
was
selected
be
high
density
polyethylene
higher
durability
corrosion
resistance,
well
soil
working
fluid,
which
clay
water.
To
confirm
accuracy
simulation
results
reduce
computational
time,
mesh
independence
test
performed,
models
validated.
There
four
modifications,
all
cases,
GHE
has
better
performance.
For
instance,
exchange
rate
per
unit
length
20.72
W/m,
is
than
U-tube
spiral
tube
9.75
13.62
maximum
53%
28%
U
GHE,
respectively,
same
wall
thickness
different
volumes
GHEs.
pressure
drop
also
(maximum
87%
tube).
balance
drop,
capability
(TPC)
examined.
highest
cases.
From
energy
point,
TPC
valued
1.72
volume
thickness.
effectiveness
investigated
examine
temperatures,
showed
Finally,
examined
lengths
excavation
work
reduction
reduced
length.
With
decrease
decreased.
GHEs
1.5
1
remained
that
3.5
m.
Язык: Английский