Division 3.5.1 Mass of gaseous emissions

United Kingdom

To calculate the total mass per test of gaseous emission m _gas [g/test], its molar concentration shall be multiplied by its respective molar flow and by exhaust gas molar mass; then integration over test cycle shall be performed [equation (7-104)]:

m_{gas} = M_{gas} \times \int ṅ_{exh} \times x_{gas} \times d t

(7-104)

Where:

M _gas

molar mass of the generic gaseous emission [g/mol]

ṅ _exh

instantaneous exhaust gas molar flow rate on a wet basis [mol/s]

x _gas

instantaneous generic gas molar concentration on a wet basis [mol/mol]

time [s]

Since equation (7-104) has to be solved by numerical integration, it is transformed in equation (7-105):

m_{gas} = M_{gas} \times \int ṅ_{exh} \times x_{gas} \times d t

⇒

m_{gas} = \frac{1}{ƒ} \times M_{gas} \times \sum_{i = 1}^{N} ṅ_{exh i} \times x_{gas i}

(7-105)

Where:

M _gas

generic emission molar mass [g/mol]

ṅ _exh _i

instantaneous exhaust gas molar flow rate on a wet basis [mol/s]

x _gas _i

instantaneous generic gas molar concentration on a wet basis [mol/mol]

data sampling rate [Hz]

number of measurements [-]

General equation may be modified according to which measurement system is used, batch or continuous sampling, and if a varying rather than a constant flow rate is sampled.

(a)

For continuous sampling, in the general case of varying flow rate, the mass of the gaseous emission m _gas [g/test] shall be calculated by means of equation (7-106):

m_{gas} = \frac{1}{ƒ} \times M_{gas} \times \sum_{i = 1}^{N} ṅ_{exh i} \times x_{gas i}

(7-106)

Where:

M _gas

generic emission molar mass [g/mol]

ṅ

_exh

instantaneous exhaust gas molar flow rate on a wet basis [mol/s]

_gas

instantaneous gaseous emission molar fraction on a wet basis [mol/mol]

data sampling rate [Hz]
number of measurements [-]

(b)

Still for continuous sampling but in the particular case of constant flow rate the mass of the gaseous emission m _gas [g/test] shall be calculated by means of equation (7-107):

m_{gas} = M_{gas} \times ṅ_{exh} \times {\bar{x}}_{gas} \times Δ t

(7-107)

Where:

M _gas

generic emission molar mass [g/mol]

ṅ _exh

exhaust gas molar flow rate on a wet basis [mol/s]

{\bar{x}}_{gas}

mean gaseous emission molar fraction on a wet basis [mol/mol]

Δt

time duration of test interval

(c)

For the batch sampling, regardless the flow rate is varying or constant, equation (7-104) can be simplified by means of equation (7-108):

m_{gas} = \frac{1}{ƒ} \times M_{gas} \times {\bar{x}}_{gas} \times \sum_{i = 1}^{N} ṅ_{exh i}

(7-108)

Where:

M _gas

generic emission molar mass [g/mol]

ṅ _exh _i

instantaneous exhaust gas molar flow rate on a wet basis [mol/s]

{\bar{x}}_{gas}

mean gaseous emission molar fraction on a wet basis [mol/mol]

data sampling rate [Hz]

number of measurements [-]

Division 3.5.1 Mass of gaseous emissions

Notes on Division 3.5

Textual amendments