Sharp JX-9400 Informacje Techniczne Strona 49

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Przeglądanie stron 48
Simplest way
A method providing all airflow rates with the simplest solutions hence
probably the least sensitive to measurement errors is given below .
The results are provided with their confidence intervals, calculated under
the assumption that random and independent errors affect the measurements
of tracer gas concentration and injection rates. In this case, the confidence
interval of any result, for example an airflow rate, is (see Chapter 7, ‘Error
analysis’):
½Q Q; Q þ Q with Q ¼ TðP;
ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
X
i
@Q
@x
i
2
x
2
i
s
ð2:22Þ
where:
TðP; is the Student coefficient for having the actual value within the confi-
dence interval with probability P ,
x
i
is for all variables (other airflow rates, tracer gas concentration and
injection rates) on which Q depends,
x
i
is for the standard deviation of the variable x
i
, assumed to be a
random variable of mean x
i
.
The various airflow rates are then:
Intake airflow rate
Q
12
¼
I
11
C
1
0
1
C
11
ð2:23Þ
with
Q
12
¼ TðP ;
ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
ðC
1
0
1
C
11
Þ
2
I
2
11
þ I
2
11
ðC
2
1
0
1
þ C
2
11
Þ
ðC
1
0
1
C
11
Þ
4
s
ð2:24Þ
Supply airflow rate
Q
24
¼
I
43
C
3
0
3
C
33
ð2:25Þ
with
Q
24
¼ TðP ;
ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
ðC
3
0
3
C
33
Þ
2
I
2
43
þ I
2
43
ðC
2
3
0
3
þ C
2
33
Þ
2
ðC
3
0
3
C
33
Þ
4
s
ð2:26Þ
Note that C
6k
¼ C
4
0
k
, as long as there are no leakages into the air handling unit
between locations 4
0
and 6.
Extract airflow rate
Q
46
¼
I
62
C
4
0
2
C
42
ð2:27Þ
28 Ventilation and Airflow in Buildings
Przeglądanie stron 48
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