Civil Engineering Reference
In-Depth Information
the consumption of the pump for cold water circulation into the convectors
(0.6 kW). The pump is scheduled to work between the 4 am and 10 pm,
therefore it results an average consumed power of 0.15 kW;
the consumption of the pump for domestic water recirculation (0.202 kW),
when the respective circuit is fully operational. An average power of
0.051 kW corresponds to this circuit;
the consumption of the pump for the water circulation in the solar thermal
collector (0.2 kW). The pump is scheduled to operate between 6 am and
7 pm, therefore it results an average power of 0.108 kW.
s own average consumption in summer regime
is: 0,902 + 1,109 + 0.15 + 0.051 + 0.108 = 2.32 kW and the total average power of
electrical energy consumed during summer is P
c
= 1.58 + 2.32 = 3.9 kW.
C. Energy balance checking
The average power consumed in winter regime is P
c
= 3.204 kW and in summer
regime P
c
= 3.9 kW. Based on these results, the minimal power of the Stirling
engine may be chosen. The inferior limit value of this power is P
St
;
e
¼
As a conclusion the equipment
'
5 kW.
Taking into account a global ef
= 0.7 of the power produced by the
Stirling engine, it results a useful power delivered by the Stirling engine of P
Stu
¼
3
ciency
η
5 kW.
In winter regime the average power generated by the PV source, 0.298 kW, may
also be counted on. Since this source discharges directly into the battery, an effi-
:
-
ciency of its use of 0.85 is also admissible and the average power available in the
load from the PV source is P
PVu
¼
0
:
2533 kW. The total average power available in
this regime is P
d
¼
P
PVu
¼
P
Stu
þ
3
:
753 kW, that is greater than the average power
consumed, P
c
= 3.204 kW.
In summer regime the general average power generated by the PV source is
equal to 0.623 kW and the useful average power in the load is P
s
PVu
¼
:
0
529 kW.
The total average power available in this regime is P
d
¼
P
s
PVu
¼
P
Stu
þ
4
:
029 kW,
that is greater than the average power consumed, P
c
= 3.9 kW.
It results that the average powers of the sources in winter and summer regimes
are greater than the average consumptions in the respective regimes, in difficult
meteorological conditions admissible in achieving the energetic balances (external
temperature is
C in summer).
Further on, the main issue is to determine if the control loops, which ensure the
balance between the produced power and the consumed one in the electrical and
thermal subsystems, operate with admissible errors in the dynamic regime.
Essentially, it is necessary to check if:
17
°
C in winter and +35
°
−
the dynamic error of the voltage loop does not reach excessive values, for which
the battery is practically discharged;
the dynamic error of the temperature loop in the thermal tank does not exceed
the limits of a correct operating regime of the thermal subsystem.
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