Eco Physics CLD 780 TR - Page 162

E C O P H Y S I C S Gas Phase Titration
CLD 780 TR / July 2000 159
3. Calculate the resulting NO
2
concentrations from:
[NO
2
]
OUT
= [NO]
orig
– [NO]
rem
+ ( F
NO
x [NO
2
]
IMP
) / ( F
NO
+ F
O
+ F
D
) [11]
where:
[NO
2
]
OUT
= diluted NO
2
concentration at the output manifold, ppm
[NO]
orig
= original NO concentration, prior to addition of O
3
, ppm
[NO]
rem
= NO concentration remaining after addition of O
3
, ppm
Note the NO
2
concentration and the corresponding recorder NO
2
and NO
x
responses.
4. While maintaining the same F
NO
, F
O
, and F
D
, adjust the ozone gen-
erator to obtain several other concentrations of NO
2
over the NO
2
range (at least five evenly spaced points across the remaining scale
are suggested). Calculate each NO
2
concentration using equation
[11] and record the corresponding analyzer NO
2
and NO
x
re-
sponses. Plot the analyzer’s NO
2
responses versus the correspond-
ing calculated NO
2
concentrations and draw or calculate the NO
2
calibration curve.
k) Determination of converter efficiency. For each NO
2
concentration ge-
nerated during the preparation of the NO
2
calibration curve, calculate
the concentration of NO
2
converted from:
[NO
2
]
CONV
=[NO
2
]
OUT
– ( [NO
x
]
orig
– [NO
x
]
rem
) [12]
where:
[NO
2
]
CONV
= concentration of NO
2
converted, ppm
[NO
x
]
orig
=original NO
x
concentration prior to addition of O
3
, ppm
[NO
x
]
rem
=NO
x
concentration remaining after addition of O
3
, ppm
Plot [NO
2
]
CONV
(y-axis) versus [NO
2
]
OUT
(x-axis) and draw or calculate
the converter efficiency curve. The slope of the curve times 100 is the
average converter efficiency, W
K
.
The average converter efficiency can be determined automatically by
the CLD 780 TR, in a procedure based on the same GPT method as