Environmental Engineering Reference
In-Depth Information
June 1985. The operating condition of the test plant underwent various changes over the test
period and are not constant. The plant had also experienced several power failures that caused
complete shutdown and the plant had to be restarted manually after the restoration of power.
The power failures that occurred during the test period (January and June 1985) are listed in
table 15.
Table 15. Power failures causing emergency shutdown
Month
Date
Time
January 1985
21
11:10
28
16:30
29
14:30
June 1985
16
0:41
22
9:35
24
13:15
In order to account for the variation in the operating parameters occurring during the
month as well as the emergency shutdowns that occurs during each month, each monthly
period is divided into a number of smaller periods with the operating parameters maintained
constant during each small period. The computer program is run for each small period using
the prevailing operating condition of the test plant. The operating parameters which were
input to the program are:
Collector absorber area in service (January: 1543.5 m
2
- 1837.5 m
2
, June: 1543.5 m
2
)
•
Simulation start and end dates (January: 1
st
- 20
th
, June: 1
st
- 15
th
)
•
Temperature of heat accumulator at the start of simulation period (bottom 64.0
o
C, top
76.5
o
C)
•
Heating water flow rate (16.5 m
3
/hr)
•
Monthly bypass valve open and close temperatures (open: 70.0
o
C, close: 73.0
o
C)
•
Monthly evaporator start and stop temperatures (start: 72.0
o
C, stop: 66.0
o
C)
•
Specification of collector cleaning days (January: 1
st
, 30
th
, June: 8
th
)
•
Figure 26 shows the measured and simulation results of the daily net amount of heat
collected by the solar collector field and delivered to the heat accumulator during the month
of January 1985. This amount is equivalent to the total heat collected minus the heat loss due
to the collector piping system as well the heat loss due to dust effect on the glass tubes of the
collectors. January is usually characterized by severe variations in the daily solar radiation
and this variation is reflected on the daily amount of heat collected as shown in the figure.
Figure 27 shows the measured and simulation results of the daily water production for
January 1985. The simulation results appear to be in reasonable agreement with the measured
values with the exception of January 6 for which there is a large discrepancy between
measured and simulation values. This is because, while the operation of the evaporator was
stopped at 11:30 due a drop in the temperature of the heating water in the actual plant,
operation of the evaporator was continued in the simulation until 19:30 when it was stopped.
This, in turn, was due to the fact that in the simulation the temperature of the heating water
was slightly higher than the set level at which operation was to stop.
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