Civil Engineering Reference
In-Depth Information
For sizing the heat/cold storage tank, is necessary the following:
(a) Determining the energy demand Q
demand
:
max
,
in the month in which the
demand is the biggest:
Q
demand
:
max
¼
A
TFA
q
sys
:
max
ð
KWh
=
month
Þ
ð
30
Þ
(b) Determining the produced energy in a day of this month, Q
demand
:
day
:
Q
demand
:
max
N
days
Q
demand
:
day
¼
ð
kWh
=
d
Þ
ð
31
Þ
On this basis, the tank is then dimensioned, that is the volume of the thermal
agent (water) in the tank is determined. On the other hand, the maximum quantity
of heat which may be stored by the thermal agent is given by the equation:
Q
demand
;
day
¼
Q
max
:
stored
¼
q
V
c
p
D
#
ð
kWh
Þ
ð
32
Þ
where: Q
max
:
stored
—
maximum stored heat, [kWh];
ˁ—
density of thermal agent, [kg/
m
3
]; V
volume of the thermal agent, [m
3
]; c
p
—
—
speci
c heat of the thermal agent,
ʇ
K];
D#
¼
#
max
#
min
is the width of the temperature domain [
#
max
,
#
min
]
[kJ/kg
for the thermal agent, [
C].
For simple systems, with one source and one consumer only, dimensioning is
simply based on the application of this relation. For example, in case of heat for
heating tank, the volume of tank is given by the relation:
°
Q
H
:
max
q
V
H
¼
ð
33
Þ
c
p
D#
H
where: V
H
—
volume of the tank for heating, [m
3
];
D#
H
is the temperature domain
of the thermal agent which
fill this tank.
With certain simple systems, there is the possibility of using a simpli
ed rela-
tion, which has in view the experience accumulated. For example, in the case of
solar thermal panel, dimensioning may be achieved according to the relation:
V
¼
k
A
ST
ð
34
Þ
cient, [l/m
2
], A
ST
,
absorber area of the ST panel, [m
2
].
where k
—
dimensioning coef
—
100 l/m
2
. For applications perfected especially
through systems of energy management, k = 25 l/m
2
.
For combi type systems, there are more sources of heat, which supply water at
different temperatures, and more consumers, which ask for water at different tem-
peratures. An example of such a combi system is that in which the sources are solar
thermal panel and boiler while the consumers are the residence heating systems and
the domestic hot water systems.
For most applications, k = 50
-
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