Civil Engineering Reference
In-Depth Information
On the other hand, for the same volume of hot water resulting from the calculus,
a single storage tank or more may be chosen. The use of one tank only (usually a
cylinder
—
vertical one) has the disadvantage associated with the dif
culty in
positioning and transportation, but has the advantage of a reduced speci
c loss of
heat. If two or more smaller tanks are used, then the surface that heat is lost through
is wider. A better insulation of the tanks might diminish the losses. Another idea is
that of applying the solution of
In this case, a large tank is
chosen, with a V
H
volume, inside which the tank for domestic hot water, with a
V
DHW
volume, is inserted. The total volume is the sum of the two:
“
tank inside tank.
”
Q
H
:
max
q
V
H
¼
ð
35
Þ
c
p
D#
H
Q
DHW
:
max
q
V
DHW
¼
ð
36
Þ
c
p
D#
DHW
If the two tanks are co-axial,
then the following relation applies to their
temperatures:
D#
H
¼
D#
DHW
The total volume is:
1
V
T
¼
c
p
D#
H
Q
DHW
:
max
þ
ð
Q
H
:
max
Þ
ð
37
Þ
q
E. The hydraulic circuits
In an mCCHP system, the thermal energy (similarly with the electrical energy)
must be transported from suppliers to heat storage and further to consumers. The
energy
“
carriers
”
are the thermal
fluids (similarly with the electrons, in case of
electrical energy) that
flow along the hydraulic circuits, especially designed for the
transport of heat (similarly with the electrical circuits).
Each hydraulic circuit is designed to connect two main components of the
mCCHP system in order to transfer the heat from one to other. The thermal
fluid.
takes the heat from one component (e.g., from the boiler), so that its temperature
increases with
D#
, and transfers it to the other (e.g., heat storage tank), after which
the temperature will drop with the
D#
, also.
Outside the two components, along the circuit are placed
fittings, devices for
monitoring, control, and protection, and other elements, as well as a pump that
moves the
fluid.
Sizing a hydraulic circuit means (i) establishing the technical characteristics of
the elements that make up the circuit, and (ii)
finding the real values of the oper-
ating parameters of the circuit.
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