Civil Engineering Reference
In-Depth Information
Table 13 Fuel consumption and performance indicators
Month
System load
PV and ST panels load
Fuel
PES
(%)
EFF
(%)
e
sys
(kWh/
m
2
)
q
sys
(kWh/
m
2
)
e
PV
(kWh/
m
2
)
q
TP
(kWh/
m
2
)
q
fuel
(kWh/m
2
)
Jan
3.12
18.64
0.23
1.53
23.82
27.25
85.04
Feb
3.12
16.07
0.33
2.17
20.09
31.97
84.93
Mar
3.12
12.70
0.54
3.58
14.43
43.02
85.26
Apr
3.12
8.27
0.75
4.98
11.86
40.10
64.79
May
3.12
9.75
0.93
6.19
10.95
49.38
71.21
Jun
3.12
11.89
1.01
6.74
10.53
56.66
82.04
Jul
3.12
14.13
1.02
6.83
11.60
57.22
88.66
Aug
3.12
14.13
0.90
5.99
12.75
52.98
87.85
Sep
3.12
9.70
0.66
4.43
12.27
43.12
73.85
Oct
3.12
8.65
0.46
3.09
13.27
34.48
69.90
Nov
3.12
12.33
0.25
1.65
16.64
33.05
83.29
Dec
3.12
16.58
0.19
1.24
21.94
27.31
84.33
Total
37.42
152.84
7.26
48.43
180.16
41.38
80.10
Conventionally, the reference system is the one, which produces heat and power
with ef
ciency reference values
η
Href
and
η
Eref
, respectively. PES is calculated with
relation
62
in Chap.
“
”
where were
considered the ef
ciency reference value for heat production
η
Href
= 0.8 and the
ef
η
Eref
= 0.33.
The second indicator namely EFF sets the correlation between the primary and
useful energy and shows how much of the primary energy is found to be useful
energy and is given by the relation
63
in Chap.
ciency reference value for power production
“
.
To calculate the two indicators PES and EFF, we need to determine the speci
”
c
fuel consumption of CCHP system. Speci
c fuel consumption is sum of fuel input
for cogeneration unit and additional boiler. Its determination involves knowledge of
the cogeneration unit and boiler energy production, as well as of the cogeneration
unit and boiler ef
ciency.
If the overall ef
ciency of additional
boiler is 90 %, and using the monthly data from Table
12
, the results are those
recorded in Table
13
for the whole CCHP system.
ciency of CHP unit is 80 % and the ef
7.2 Performance Improving
Improving the performance indicators of the system is achieved by analyzing the
speci
c energy production system components and through actions to reduce losses
but especially by diminishing the excess energy produced. The off-grid system
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