PRODUCT INFORMATION
INDEX
DATE
Dep.2
IC-C-D-40-001e C
November 2015
EMISSION UNITS CONVERSION
2/3
1.2.
Converting ppm to g/kWh
The formula reproduced below is approximate; the exact computation method is defined in ISO 8178-1.
q
m gas
(g/h) = Emis (ppm)
w
x factor
gas
x Flow rate of wet exhaust gas (kg/h) / 1000
Emis (g/kWh) = q
m gas
(g/h) / Power (kW)
where:
- factor
gas
is the relative density-to-air ratio (or molecular weight ratio):
Diesel
Natural
Gas
Propane
Ethanol
Nitrogen Oxides, NOx
1.586
1.621
1.603
1,609
Sulfur Dioxide, SO
2
2.21
Carbon Monoxide, CO
0.966
0.987
0.976
0.98
THC (C/H ratio 1.85)
0.479
0.565
0.512
0.805
Methane, CH
4
0.553
0.565
0.559
0.561
Formaldehyde, CH
2
O 1.035
1.058
1.046
1.050
- the exhaust gas flowrate appears on the thermal balance sheets; it is a wet basis concentration value. The
emission value in ppm used in the formulae must be a wet basis value (usually NOx, SO2 and CO are
measured in dry basis) and the calculation of NOx requires correction to account for the ambient humidity,
defined in ISO 8178-1 (2006).
For Kohler gas engines, the Qexh / Power factor normally lies between 5 - 6.
- To change from a dry basis concentration “Emis (ppm)
d
“ to a wet basis concentration “Emis (ppm)
w
“ use the
following equation:
Emis (ppm)
w
= Emis (ppm)
d
x factor
W/D
where factor
W/D
is in the order of:
Diesel engines:
0.92 (
0.03)
Lean gas engines: 0.88 (
0.03)
Rich gas engines:
0.81 (
0.01)
Methanol engines: 0.84 (
0.03)
(3)
The factor
W/D
in the above equation can be calculated accurately, by applying the definition in ISO
8178-1 (2006).
When using g/bHPh units, the equivalence is 1 bHP = 0.7457 kW.
In the case of ISO 8178-4 cycle performance, see paragraph 1.3
(3) Hydrated Ethanol, 5% of water
4.1.46
O&M_2.002211.810_A_10_2016
