CFR

1065.642—SSV, CFV, and PDP molar flow rate calculations.

This section describes the equations for calculating molar flow rates from various flow meters. After you calibrate a flow meter according to § 1065.640, use the calculations described in this section to calculate flow during an emission test.

(a) PDP molar flow rate. Based upon the speed at which you operate the PDP for a test interval, select the corresponding slope, a 1, and intercept, a 0, as calculated in § 1065.640, to calculate molar flow rate, n as follows:

Where:

Example:

a1 = 50.43 (m3/min) = 0.8405 (m3/s)

fnPDP = 755.0 rev/min = 12.58 rev/s

pout = 99950 Pa

pin = 98575 Pa

a0 = 0.056 (m3/rev)

R = 8.314472 J/(mol·K)

Tin = 323.5 K

Cp = 1000 (J/m3)/kPa

Ct = 60 s/min

Vrev = 0.06383 m3/rev

n = 29.428 mol/s

(b) SSV molar flow rate. Based on the C d versus Re # equation you determined according to § 1065.640, calculate SSV molar flow rate, n during an emission test as follows:

Example:

At = 0.01824 m2

pin = 99132 Pa

Z = 1

Mmix = 28.7805 g/mol = 0.0287805 kg/mol

R = 8.314472 J/(mol.K)

Tin = 298.15 K

Re# = 7.232.105

γ = 1.399

β = 0.8

Δp = 2.312 kPa

Using Eq. 1065.640-7,

rssv = 0.997

Using Eq. 1065.640-6,

Cf = 0.274

Using Eq. 1065.640-5,

Cd = 0.990

n = 58.173 mol/s

(c) CFV molar flow rate. Some CFV flow meters consist of a single venturi and some consist of multiple venturis, where different combinations of venturis are used to meter different flow rates. If you use multiple venturis and you calibrated each venturi independently to determine a separate discharge coefficient, C d, for each venturi, calculate the individual molar flow rates through each venturi and sum all their flow rates to determine n. If you use multiple venturis and you calibrated each combination of venturis, calculate n as using the sum of the active venturi throat areas as A t, the square root of the sum of the squares of the active venturi throat diameters as d t, and the ratio of the venturi throat to inlet diameters as the ratio of the square root of the sum of the active venturi throat diameters, d t, to the diameter of the common entrance to all of the venturis, D. To calculate the molar flow rate through one venturi or one combination of venturis, use its respective mean C d and other constants you determined according to § 1065.640 and calculate its molar flow rate n during an emission test, as follows:

Code of Federal Regulations

Example:

Code of Federal Regulations

C d = 0.985

Code of Federal Regulations

C f = 0.7219

Code of Federal Regulations

A t = 0.00456 m2

Code of Federal Regulations

p in = 98836 Pa

Code of Federal Regulations

Z = 1

Code of Federal Regulations

M mix = 28.7805 g/mol = 0.0287805 kg/mol

Code of Federal Regulations

R = 8.314472 J/(mol.K)

Code of Federal Regulations

T in = 378.15 K

Code of Federal Regulations

n = 33.690 mol/s

Code of Federal Regulations

[75 FR 23047, Apr. 30, 2010, as amended at 75 FR 68464, Nov. 8, 2010]

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