This document discusses simulation of cold start emissions from internal combustion engines. It outlines how cold starts result in higher pollutant emissions like hydrocarbons, NOx, CO and particulate matter in the first few minutes of operation due to incomplete combustion and a cold catalytic converter. The document reviews literature on modeling cold start emissions and catalytic converter performance. It describes the assumptions and equations used in the simulation model to predict pollutant emissions and the effect of initial catalyst temperature. The expected outcomes include graphs showing higher transient emissions during cold starts and how the catalytic converter activates after 100-120 seconds of operation.

1. SIMULATION OF COLD START EMISSIONS

2. OUTLINE
• INTRODUCTION
• COLD START AND CATALYTIC CONVERTOR
• LITERATURE SURVEY
• ASSUMPTIONS AND MODEL EQUATIONS
• EXPECTED OUTCOME
• CONCLUSION

3. INTRODUCTION
• ICE Fueled by, petrol, Diesel, Compressed Natural Gas (CNG), and liquified
Natural Gas (LPG)
• Cold start engine operations are major pollutant contributors(HCs, Nox,
CO and PM)
• Air Toxics, such as formaldehyde, acetaldehyde, benzene, toluene,
naphthalene
• Volatile Organic Compounds (VOCs)

4. Con…
• First minutes of engine operations (20-120 seconds)
• Cold start operations results higher amount of pollutant emissions than the
uniform/steady state operations (due to Incomplete oxidation)
• Each of the pollutant species carries potentially serious health and
environmental effects
• Also causes of cardiovascular disease and cancer risk

5. Fig1 Cold start emissions (adopted from Emission values of passenger cars Overview)

6. Effect of cold start on catalytic convertor for HCs,
CO, PM, NOX Emissions and fuel consumptions
Cold starts
Catalytic
convertor
Lubricant too viscous
to effectively
lubricating
Cool lubricants
at piston/linear
interface
Lubricant viscosity at
piston too high to
effectively lubricating and
friction increase
Piston walls
too cool
Cool wall condition
prevents complete
oxidations
Increase fuel
consumptions
Poorer quality
emissions,
Increase HCs, CO,
Nox and PM
Cool combustion
conditions limit exhaust
gas temperature,
preventing catalytic
convertors
Catalytic convertor too
cold to control
emissions

7. Con …
• Catalytic convertor are used to oxidizing and reducing hurtful gases to
lesser one
• Cold start is the major problem in catalytic convertor
• During the first few minute of engine run the convertor catalyst is inactive
for the conversion
• This happened because of lower operating temperature
• The engine emit/release high amount of pollutant gas without converting

8. Con…
Engine 383 K
Working temperature Difference = 90 k
catalyst 473 K
Cold start means
the vehicle was
started with cold
conditions and
emission of
harmful
gases(HCs,CO,Nox
and PM)

9. LITERATURE SURVEY

10. AUTHORS YEAR PUBLISHED TITLE INFERENCES
1. Abdulfatah Abdu Yusuf,
Freddie L. Inambao
2. K. N. Pattas, A. M.
Stamatelos, P. K.
Pistikopoulos,
G. C. Koltsakis, and P. A.
Konstandinidis
3. T. Shamim, H. Shen
S. Sengupta, S. Son
A. A. Adamczyk
2019
1994
2002
Effect of cold start emissions
from gasoline-fuelled engines
of light duty
vehicles at low and high
ambient temperatures
Transient Modelling of 3-Way
Catalytic Converters
A Comprehensive Model to
Predict Three-Way Catalytic
Converter Performance
cold start emission was too early
and the TWC was start to work
after 120 seconds and the
emission of HC, CO and NOx a
factor of temperature
This TWC modeling tasted by
different characteristic cases that
are taken by experimental
database
Light-off is predicted by the
different coding models
Computer coding also optimizing
the system
Used numerical simulation cods
to predict the catalytic convertor,
the coding includes the transit
terms in the governing equations
and the result shows similar
value with the experimental
results with the transit and
steady state conditions

11. AUTHORS YEAR PUBLISHED TITLE INFERENCE
4. S. Simund and J. P. Lecerc,
D. Schweich and M. Prigent
and F. Castagna
5. Tom Jobson, Serena Chung,
Yibo Huangfu, Graham
VanderSchelden
1996
2015
Three-way catalytic monolith
convertors: simulations versus
experiments
Measurements and Modelling
of Vehicle Cold Start Emissions
At a high temperature the
poorly chemical description
and internal diffusion
limitation occurs
Set-up sampling method to
measure tailpipe emission
By conducting different testing
method know the amount of
emission of HC, CO, NOX and
other pollutants in cold start

12. ASSUMPTIONS
• The monolith is a pseudo-homogenous cylinder of circular cross section
• The gas phase is ideal of uniform and constant pressure
• The accumulation term in the gas phase are negligible
• Transfers diffusion and laminar flow are accounted for by the film model
• No heat conduction in the gas phase
• The reactants are much diluted and the chemical expansion flux is
neglected

13. Con…
• Steady state reaction kinetics can be used in the transient state
• Oxidation and reduction of the catalyst (Ceo2, Rh) is not accounted for
• No heat transfer by radiations
• The residual HCs are accounted by a single reaction species
• Only four reactions are accounted for
• No internal diffusion limitation within the wash-coat
• The catalyst dose not deactivate

14. MODEL EQUATIONS
• Mass and energy balance equations
• Thermal conductivity equation
• Specific heat of reaction equations
• Rate constants equation in terms of Arrhenius type expressions
• Approximate thermodynamics data for species and pure substances
• Heat and mass transfer coefficients are correlated from Nusselt and
Sherwood
• Equations and data.docx

15. EXPECTED OUTCOME
Fig 3 The NOx and HCs instantaneous emissions, lambda value of vehicle G3 at both temperature and also cold start transient HCs and NOx emission with fuel injection in the first cycle
(adopted from Ref 13 & 14)

16. Con…
Fig 3 Effect of different initial catalyst temperature on cold start CO and HC emissions during the first 100 s [11]

17. CONCLUSION
• The estimated emissions in cold start with cold temperature around
60-80% of harmful gas for the first few seconds of running time.
• The catalytic convertor become active after 100-120 second
operation to convert CO,HCs and Nox emissions more effectively.