Teledyne PEM-9004 - Portable emissions analyzer - Manual (Page 19)

Portable Emissions Monitor Operational Theory
Teledyne Analytical Instruments 7
2.4.2 Calculating the Waste Gas Loss
The analyzer uses the measured oxygen concentration and the
exhaust gas and ambient temperature of the stack to calculate the total
energy loss in the exhaust gas. The total energy loss is calculated by
adding in the work done to expand the exhaust gas against atmospheric
pressure and the heat required to vaporize the water generated in the
burning process.
The waste gas loss calculation involves multiplying the heat
capacity of each component by the difference in temperature between
ambient air and exhaust gas. The following equation is used to calculate
the waste gas loss (qA) in %:
Where: T
gas
is the waste/flue gas temperature in °F or °C
T
air
is the combustion ambient temperature in °F or °C
A2 and B are fuel-specific factors stored internally in the
PEM-9004 database.
2.4.3 Calculating the Combustion Efficiency
The combustion efficiency of a combustion process is determined
from the relation:
Efficiency = (E
fuel
- E
lost
) 100
The instrument subtracts the waste gas loss as previously calculated
for a specific fuel from the total energy of the selected fuel to arrive at
the overall combustion efficiency (Eta). The PEM-9004 uses the
following equation:
Where: Eta is the combustion efficiency expressed as a
percentage.
qA is the heat loss calculated for the given fuel.
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
+ × =
B
A
2
air gas
-O 21
2
) T - (T qA
qA - 100 Eta
=