Renewable Energy,
Год журнала:
2023,
Номер
217, С. 119170 - 119170
Опубликована: Авг. 11, 2023
Pit
thermal
energy
storage
(PTES)
is
an
efficient
renewable
technology
widely
used
in
large-scale
solar
district
heating
systems.
Accurate
modeling
of
mixing
a
PTES
due
to
inlet
flow
key
calculating
heat
performance.
However,
the
commonly
one-dimensional
models
fail
consider
three-dimensional
nature
flow.
This
research
adopts
model
analyze
dynamic
behavior
inside
PTES.
The
validated
against
measurements
Dronninglund
To
quantify
impact,
two
performance
indicators
(i.e.,
penetration
height
(Z)
and
distribution
ratio
(ηj))
are
proposed.
parametric
analysis
revealed
that
Z
more
dependent
on
Reynold
(Re)
number
than
Froude
(Fr)
number,
while
both
Re
Fr
numbers
influence
ηj.
According
dimensional
theory,
shows
power-law
relation
with
time.
For
ηj,
time
seen,
although
asymptotic
formula
needed
region
negative
buoyancy
jet.
Finally,
inflow
characterized
under
various
operating
conditions
by
empirical
correlations.
results
this
study
could
be
improve
current
terms
mixing.
Journal of Energy Storage,
Год журнала:
2022,
Номер
55, С. 105455 - 105455
Опубликована: Авг. 13, 2022
An
accurate
and
less
time
demanding
model
is
required
when
integrating
pit
thermal
energy
storage
(PTES)
into
solar
heating
systems.
Multi-node
(1D)
models
are
commonly
used,
but
these
face
challenges
calculating
PTES
stratification
heat
loss.
Therefore,
a
full-scale
computational
fluid
dynamics
(CFD)
of
inclusive
water
soil
regions
developed
using
FLUENT
to
improve
the
accuracy
transfer
calculation
multi-node
model.
The
CFD
validated
against
Dronninglund
measurements
regarding
stratification,
inlet/outlet
flow,
temperature
distribution.
corresponds
well
in
three
aspects:
(i)
maximum
difference
1
K
region;
(ii)
2
(iii)
outlet
3
K.
indicator
RΔT/δ
defined
as
ratio
between
thermocline
thickness
proposed
assess
suitable
grid
size
for
models,
quantitative
relationship
recommended.
Investigations
with
range
sizes
show
that
by
recommended
size,
prediction
TRNSYS
Type
343
significantly
improved.
root
mean
square
deviations
predicted
MIX
number
decreased
11–43
%
different
years,
relative
differences
monthly
charge/discharge
from
measurement
within
5
%.
findings
this
study
provide
guidance
selecting
appropriate
achieve
better
large-scale
PTES.
Abstract
Space
heating
applications
account
for
a
high
share
of
global
greenhouse
gas
emissions.
To
increase
the
renewable
heat
generation,
seasonal
thermal
energy
storage
(STES)
can
be
used
to
make
from
fluctuating
sources
available
in
times
demand.
A
popular
STES
technology
is
pit
(PTES),
where
stored
underground,
using
water
as
medium.
evaluate
use
PTES
an
system,
easily
adaptable,
publicly
accessible
and
tool
independent
models
are
needed.
In
this
paper,
we
improve
existing
model
developed
Modelica
modeling
language.
The
cross-compared
with
more
detailed
previously
validated
COMSOL
model,
considering
different
amounts
insulation,
showing
deviation
2–13%
observed
annual
charged
discharged
amount
heat.
results
indicate
that
presented
well
suited
early
design
stage
exemplary
case
study
performed
demonstrate
its
applicability
system
context.
Dimensions
components
optimized
levelized
cost
(LCOH),
both
without
subsidies,
highlighting
importance
subsidies
transition
towards
climate
friendly
solutions,
boiler
reduced
47.6%
2.7%.
Renewable Energy,
Год журнала:
2023,
Номер
217, С. 119170 - 119170
Опубликована: Авг. 11, 2023
Pit
thermal
energy
storage
(PTES)
is
an
efficient
renewable
technology
widely
used
in
large-scale
solar
district
heating
systems.
Accurate
modeling
of
mixing
a
PTES
due
to
inlet
flow
key
calculating
heat
performance.
However,
the
commonly
one-dimensional
models
fail
consider
three-dimensional
nature
flow.
This
research
adopts
model
analyze
dynamic
behavior
inside
PTES.
The
validated
against
measurements
Dronninglund
To
quantify
impact,
two
performance
indicators
(i.e.,
penetration
height
(Z)
and
distribution
ratio
(ηj))
are
proposed.
parametric
analysis
revealed
that
Z
more
dependent
on
Reynold
(Re)
number
than
Froude
(Fr)
number,
while
both
Re
Fr
numbers
influence
ηj.
According
dimensional
theory,
shows
power-law
relation
with
time.
For
ηj,
time
seen,
although
asymptotic
formula
needed
region
negative
buoyancy
jet.
Finally,
inflow
characterized
under
various
operating
conditions
by
empirical
correlations.
results
this
study
could
be
improve
current
terms
mixing.
