Abbreviations, Subscripts and Symbols
Clasification Society 2024 - Version 9.40
Statutory Documents - IMO Publications and Documents - International Codes - NOx Technical Code (2008) - Technical Code on Control of Emission of Nitrogen Oxides from Marine Diesel Engines - Abbreviations, Subscripts and Symbols

Abbreviations, Subscripts and Symbols

 Tables 1, 2, 3 and Table 4 below summarize the abbreviations, subscripts and symbols used throughout the Code, including specifications for the analytical instruments in appendix 3, calibration requirements for the analytic instruments contained in appendix 4, the formulae for calculation of gas mass flow as contained in chapter 5 and appendix 6 of this Code and the symbols used in respect of data for onboard verification surveys in chapter 6.

  • .1 Table 1: symbols used to represent the chemical components of marine diesel engine gas emissions and calibration and span gases addressed throughout this Code;

  • .2 Table 2: abbreviations for the analysers used in the measurement of gas emissions from marine diesel engines as specified in appendix 3 of this Code;

  • .3 Table 3: symbols and subscripts of terms and variables used in chapter 5, chapter 6, appendix 4 and appendix 6 of this Code; and

  • .4 Table 4: symbols for fuel composition used in chapter 5 and chapter 6 and appendix 6 of this Code.

Table 1 Symbols and abbreviations for the chemical components

Symbol Definition
CH4 Methane
C3H8 Propane
CO Carbon monoxide
CO2 Carbon dioxide
HC Hydrocarbons
H2O Water
NO Nitric oxide
NO2 Nitrogen dioxide
NOx Nitrogen oxides
O2 Oxygen

Table 2 Abbreviations for Analysers for measurement of marine diesel engine gaseous emmissions (refer to appendix 3 of this Code)

CLD Chemiluminescent detector
ECS Electrochemical sensor
HCLD Heated chemiluminescent detector
(H)FID (Heated) flame ionization detector
NDIR Non-dispersive infrared analyser
PMD Paramagnetic detector
ZRDO Zirconium dioxide sensor

Table 3 Symbols and subscripts for terms and variables (refer to chapter 5, chapter 6, appendix 4 and appendix 6 of this Code)

Symbol Term Unit
A/Fst Stoichiometric air to fuel ratio 1
c x Concentration in the exhaust (with suffix of the component nominating, d=dry or w=wet) ppm/% (V/V)
E CO2 CO2 quench of NOx analyser %
E H2O Water quench of NOx analyser %
E NOx Efficiency of NOx converter %
E O2 Oxygen analyser correction factor 1
λ Excess air factor: kg dry air/(kg fuel · A/Fst) 1
f a Test condition parameter 1
f c Carbon factor 1
f fd Fuel-specific factor for exhaust flow calculation on dry basis 1
f fw Fuel-specific factor for exhaust flow calculation on wet basis 1
H a Absolute humidity of the intake air (g water / kg dry air) g/kg
H sc Humidity of the charge air g/kg
i Subscript denoting an individual mode 1
k hd Humidity correction factor for NOx for diesel engines 1
k wa Dry to wet correction factor for the intake air 1
k wr Dry to wet correction factor for the raw exhaust gas 1
n d Engine speed min-1
n turb Turbocharger speed min-1
%O2I HC analyser percentage oxygen interference %
p a Saturation vapour pressure of the engine intake air determined using a temperature value for the intake air measured at the same physical location as the measurements for pb and Ra kPa
p b Total barometric pressure kPa
p c Charge air pressure kPa
p r Water vapour pressure after cooling bath of the analysis system kPa
p s Dry atmospheric pressure calculated by the following formula: p s = p b - R a· p a /100 kPa
p sc Saturation vapour pressure of the charge air kPa
P Uncorrected brake power kW
P aux Declared total power absorbed by auxiliaries fitted for the test and not required by ISO 14396 kW
P m Maximum measured or declared power at the test engine speed under test conditions kW
q m ad Intake air mass flow rate on dry basis kg/h
q m aw Intake air mass flow rate on wet basis kg/h
q m ew Exhaust gas mass flow rate on wet basis kg/h
q m f Fuel mass flow rate kg/h
q m gas Emission mass flow rate of individual gas g/h
R a Relative humidity of the intake air %
r h Hydrocarbon response factor 1
ρ Density kg/m3
s Fuel rack position  
T a Intake air temperature determined at the engine intake K
T caclin Charge air cooler, coolant inlet temperature 0C
T caclout Charge air cooler, coolant outlet temperature 0C
T Exh Exhaust gas temperature 0C
T Fuel Fuel oil temperature 0C
T Sea Seawater temperature 0C
T SC Charge air temperature K
T SCRef Charge air reference temperature K
u Ratio of exhaust component and exhaust gas densities 1
W F Weighting factor 1

Table 4 Symbols for fuel composition

Symbol Definition Unit
WALF* H content of fuel % m/m
WBET* C content of fuel % m/m
WGAM S content of fuel % m/m
WDEL* N content of fuel % m/m
WEPS* O content of fuel % m/m
α Molar ratio (H/C) 1
*Subscripts "_G" denotes gas-fuel fraction.
"_L" denotes liquid-fuel fraction. 		 
Parent topic: NOx Technical Code (2008) - Technical Code on Control of Emission of Nitrogen Oxides from Marine Diesel Engines
Copyright 2022 Clasifications Register Group Limited, International Maritime Organization, International Labour Organization or Maritime and Coastguard Agency. All rights reserved. Clasifications Register Group Limited, its affiliates and subsidiaries and their respective officers, employees or agents are, individually and collectively, referred to in this clause as 'Clasifications Register'. Clasifications Register assumes no responsibility and shall not be liable to any person for any loss, damage or expense caused by reliance on the information or advice in this document or howsoever provided, unless that person has signed a contract with the relevant Clasifications Register entity for the provision of this information or advice and in that case any responsibility or liability is exclusively on the terms and conditions set out in that contract.