ā Evacuated Solar Energy Collector Technical Reference

PCU 20-
60
Sys.
Kit
PCU 90-
240
C ollector
Area [m²]
Number
of Tubes
2 - 4 20 – 40
5 - 6 50 – 60
7 - 9
Table 5
70 – 90
(240)
As the flow rate V S is already determined
(see chapter 5.2) the pressure drop
�p s in [Pa] of the sy stem has to be calculated.
The sy stem pressure drop �p s
equals the sum of all single pressure drops
of components in the installation connected
in series (not parallel). Mainly
these are - Solar Collector,
- Pipe Work and
- Heat Exchanger.
The pressure drop of the solar collector
�pc [Pa] can be chosen from Figure 9 as a
function of the flow rate V S.
As this is for a
single collector the value has to be multiplied
by the number of collectors n installed
in series.
The pressure drop of the pipe work��p p
in [Pa] can be found in standard plumbing
tables or in the manufactures information.
Please remember to multiply the values in
the tables given with 1.3 to take into account
that antifreeze and not water is
flowing through the system.
12
Sy stem design
As for the pipe work the pressure drop
for the heat-exchanger �p he in [Pa] can be
found in the manufacturers information.
The same as for the pipe work applies in
regard to the values given.
According to the information given
above, the overall pressure drop of the
sy stem �ps in [Pa] can be calculated using
equation 5.6.
�p
S
(5.6)
�
n
� �p
� n
� �p
20 C20
30 C30
p he
10000
� �p
� �p
with … �p s … Sy stem pressure drop [m]
n20 … Number of 20 tube collectors [-]
n30 … Number of 30 tube collectors [-]
�pC20 … Pressure drop of 20 tube
collectors [Pa]
�pC30 … Pressure drop of 30 tube
collectors [Pa]
�p p … Pressure drop of pipe work
[Pa]
�phe … Pressure drop of heatexchanger
[Pa]
10000 … [Pa] to [m]
Figure 10 shows the relationship between
the flow rate and the head pressure
of the pump used in the pump control unit
PCU 20-60.
For installations larger than 60 tubes a
pump control unit with a bigger pump, the
PCU 90-240 PCU, should be chosen. The
pump diagram is shown in Figure 11.
In the System Kit / Active Pack a pump
with 5 m head pressure is used as shown
in Figure 12.