MINISTRY OF EDUCATION AND TRAINING
UNIVERSITY OF TRANSPORT AND COMMUNICATIONS VUONG VAN SON

IDENTIFICATION OF COMPONENTS OF EXHAUST
FROM AUTOMOBILE ENGINES USING
DIESEL – LPG DUAL FUEL

Major: Automobiles and Tractors Engineering
Code: 62.52.35.01

SUMMARY OF THESIS FOR DOCTOR OF ENGINEERING This thesis will be defended at Universitarian dissertation Committee
at University of Transport and Communications.
At …hour….date…month…year.
The thesis can be found at:
National Library
Library of University of Transport and Communications

1

INTRODUCTION
1. Background of the study
Exhaust emission from automobiles using diesel fuel is one of the
factors causing air pollution, particularly in urban areas. Among the
research plans to reduce the emission of toxic substances from the diesel
engine, many scientists are interested in the use of diesel - LPG dual fuel
engine. A lot of developed countries in the world have put finance and
efforts into this research.
When this method is applied, it will help to solve the two following
problems: protecting air environment and taking advantage of available fuel
resources in many parts of the world while fossil fuels are gradually running
out.

* Scientific meaning: The thesis developed simulation models to
evaluate the emissions of diesel – LPG dual fuel engine. The calculation
results were compared and verified by experiment on the system of modern
testing equipment with international standards.
* Practical meaning: The results of the thesis are the basis for
evaluating environmental performance and engine power when using diesel
– LPG dual fuel.

Chapter I. OVERVIEW OF RESEARCH PROBLEMS
1.1. Overview of environmental pollution caused by automobiles’
emissions
1.1.1. The development of transportation in Vietnam
In recent years, along with economic growth, the demand for
transportation of people and goods in Vietnam has increased rapidly. This
has led to the increase of number of transport vehicles, especially ones
using diesel fuel . The increasing number of vehicles while the
transportation infrastructure has not developed causes pressure on the
environment, especially in urban areas.
1.1.2. Environmental pollution caused by automobiles’ emissions in
Vietnam
The increasing numbers of Transportation vehicles in undeveloped
infrastructure causes traffic jams in big cities. Meanwhile we do not have
any effective controlling measures to reduce emissions leading to the
alarming rate of air pollution in big cities, especially in Hanoi and Ho Chi
Minh City .
1.2. Production and utilization of LPG
1.2.1. Production of LPG
1.2.1.1. Production of LPG in the world
The total supply of LPG in the world reached 198 million tons in
2000 and 239 million tons in 2008. The growth rate of the LPG supply in

and C.D. Yao , Bogdan Cornel BENEA and Adrian Ovidiu SOICA , Dong
Jian , Gao Xiaohong , Li Gesheng and Zhang Xintang , Thomas Renald
C.Ja and Somasundaram P , MP Poonia. However, those studies focused
mainly on engines mounted on passenger cars, large trucks and specialized
vehicles. The number of researches using diesel - LPG engines fitted on
small cars is very limited.
1.3.2. The research results in the country
In Vietnam, there have been some studies on the engines using diesel
- LPG dual fuel such as the studies of Bui Van Ga , Pham Minh Tuan , Le
Anh Tuan , Pham Huu Tuyen , Mai Son Hai , Tran Thanh Hai Tung , Le
Minh Xuan and Vu An. The initial results showed that automobiles using
diesel – LPG dual fuel helpes to reduce the harmful emissions, especially its
ability to reduce PM emissions on some engines. However, there have not
been any completed studies of diesel - LPG engine fitted on small cars.
1.4. Conclusion of Chapter I
Among many research plans to reduce the emission of toxic
substances from the diesel engine, the scientiests are very interested in the
use of diesel - LPG dual fuel engine . Many developed countries in the
world have put their finance and efforts into this research.
4

In Vietnam LPG applications for internal combustion engines has
been interested in many studies, but not really in-depth. The research results
only stopped at using LPG fuel for the engine but not interested in
optimizing fuel supplying system, combustion and pollutant formation yet.

Chapter II. THEORETICAL BASIS OF CALCUALTING
COMPONENTS OF EXHAUST EMISSION FROM DIESEL AND
DIESEL – LPG ENGINES
2.1. Mixture of diesel – LPG dual fuel

3
4
5
6
13
7
8
9
10
11
15
16
12
14
5

-25
25
75
125
175
225
275
-25
25
75
125
175
225
275


75, 9 diesel + 24, 1 %

Crank’s angle of rotation(Degree)
Figure 2.8. Calorific process in diesel – LPG engine

2.2.3. Modeling basic of producing the mix and combustion in Diesel -
LPG dual fuel engine
Modeling basic of producing the mix and combustion are based on the
following rules:
Speed of calorific (J/CA)
Speed of calorific (J/CA)
6

- The first thermodynamics equation
- Solvent mixture model is described by the components forming the
mixture including diesel fuel, LPG (C
3
H
8
, C

engine speed, fuel components, pressure, temperature, air intake coefficient
λ, volume and mass, burning time as well as areas of burning.
2.4.2. Calculating the CO emission
CO is combustion product lack of O
2
, mainly produced from the
incompleted combustion. Therefore, CO can be calculated based on the
responses according to A. Onorati:
CO + OH ↔ CO
2
+ H;
CO
2
+ O ↔ CO + O
2
.
2.4.3. Calculating the HC emission
For diesel engines, HC component generated in the process of
working is negligible, so most of the research on exhaust of diesel engine
has not mentioned the calculation of this component.
2.4.4. Calculating the soot emission (Soot)
Soot emission is calculated according Hiroyasu model. In this model ,
the change of the soot volume is calculatedvia the formula:
s,f s,ox
s
dm dm
dm
dt dt dt

(2.36)

The main chemical composition of diesel fuel are hydrocarbon
compounds, general formula is C
n
H
2n+2
.
3.2.2.2. Liquefied petroleum gas (LPG)
The chemical composition of LPG is mainly paraffinic hydrocarbon
types, general formula is: C
n
H
2n+2
such as : Propane (C
3
H
8
), Butane (C
4
H
10
),
Pentane (C
5
H
12
)… In addition, in LPG there are Ethane (C
2
H
6
), Ethylen


After developing the model, the input data was entered basing on the
specifications of the engine, then run the program and export the results.
3.2.4. Verifying the accuracy of the model
The accuracy of the model was assessed by comparing the results
such as power, torque between the experimental results (the manufacturer
has tested and recorded in catalog before taking out the factory) with
simulation results. The simulation results showed that the highest deviation
range of the engine capacity was 6.48 % at the speed 1400 vg/ph and the
lowest is 1.13 %, this deviation range is acceptable.
3.2.5. Developing diesel - LPG engine model on AVL - BOOST.
The basic difference between combustion model in diesel – LPG
engine and diesel engine is the fuel component for the cycle. However,
various factors such as late combustion characteristics, heat exchange
coefficient , combustion speed when replacing LPG into diesel fuel has
been defined by the definition the nature of the fuel using (although the
general formula for the calculation is the same). Besides the basic
parameters such as low calorific value, A / F ratio, fuel is defined through
the thermodynamic parameters (heat capacity, enthalpy, entropy ) for the
process of calculating and conversion chemical energy into calorific energy.
The developed model will be verified experimentally (it will be conducted
in the next part of this study). If simulation results are much different from
empirical results, it can be adjusted the parameter a, m of Vibe 2 zone fire
model when building the model.
To build the diesel – LPG engine model on AVL - BOOST, it must be

Figure 3.2 The simulation model of FAWDE- 4DX23-110 engine on AVL-BOOST

9


Figure 3.5. Simulation model of diesel - LPG engine on AVL-BOOST

I
1

10 The simulation results in Figure 3.8 above shows that the
concentration of NOx in diesel- LPG engine decreased, In the LPG mode
replacing 10 % diesel, the average reduction is 3,427 % and the LPG mode
replacing 20 % diesel, the average reduction is 6,178 % comparing with 100
% diesel .
For soot emission, the result shows that when using dual fuel, soot
level fell average 16.76 % in the LPG mode replacing 10 % diesel and the
average reduction is 25.4 % in the LPG mode replacing 20 % diesel. Figure 3.7. CO emission in the simulation modes according to ECE R49 cycle
Figure 3.8. NOx emission in the simulation modes according to ECE R49 cycle

Diesel
LPG_10
LPG_20

5,460
-3,427
5,305
-6,178
Soot
g/kW.h
0,299
0,249
-16,76
0,223
-25,40

3.3. Surveying the effect of some structural parameters on the emission
of diesel- LPG engine by simulation method
3.3.1. Effect of early spray on the emission of diesel- LPG engine
Based on engine model built, the study changed the time for spraying
diesel and considering its effect on the emission components in the LPG
mode replacing 20 % of diesel with 100 % loading of the engine is 1800 rev
/ min. According to the original engine, the timing of the fuel injection of
nozzle will be early 9
0
, and stared at 351
0
at crankshaft rotation .To change
this value into two directions, increasing and decreasing spraying angles
and investigating its effect to the engine's emission .
Emission result on Figure 3.10 and 3.11 shows that, while reducing
early, the NOx reduced, CO and soot increased. This phenomenon is due to
the time of most intense burning fuel in the engine cylinder is pushed
backward , while the piston has gone down over the course of expansion ,

speed 1800 rev / min according to early spraying angle
1800 v/ph

347 348 349 350 351 352 353 354 355
347 348 349 350 351 352 353 354 355
13

Component
Unit
Original
Decreasing
4º
Comparing
%
Increasing
4º
Comparing
%
CO
g/kW.h
3,699
3,569
-3,515
4,313
16,61
NOx
g/kW.h
5,305
5,246
-1,102

emissions, however , there should have more experimental research to find
more solutions so that grain dust emission do not exceed the limitation .
Chapter IV. EXPERIMENT AND EVALUATION
4.1 . The purpose and content of experiment
4.1.1 . The objective of experiment
- Accurately measure the exhaust components of the original diesel
engine and the diesel engine after being converted to use diesel – LPG dual
fuel.
- Evaluate the emission effectiveness of diesel engine when using
diesel - LPG dual fuel.
- Evaluate the accuracy of the theoretical calculation method based on
14

experimental results .
4.1.2 . The content of experiment
- Determine the toxic emission of original diesel engine according to
ECE R49 cycle .
- Determine the toxic emission of diesel - LPG engine according to
ECE R49 cycle .
- Measure parameters to serve assessing the performance
characteristics of the engine such as power, torque , the engine's smoke
4.2 . Experimental Equipment
The contents of the experiment were conducted on a ETC01 high
dynamic test tape in the laboratory of engine emission under NETC-
Vietnam Registry Department.
4.2.1 . Diagram of experimental equipment
Diagram of the experimental equipement is shown in Figure 4.2 .
The basic components of experimental equipement including :
- Power Brakes APA 404/6 PA
- Water Cooling Device AVL 553


LPG is contained in a 3mm steel cylindrical container with the
capacity of 12 liter. LPG flow fed into the engine is adjusted by quantitative
valve, this valve is controlled by the knob. During the running process, the
amount of LPG will change, depending on the pressure in the charging pipe
of the engine. Every parts of the selected LPG system has a simple and
lightweight structure, it can be easily arranged in the engine compartment
without reconstructing the structure of car. Diagram of the LPG supply to
the engine is shown in Figure 4:12 . WATER COOLER
CONDITIONẺ AVL
553C
CONTROL

404/6PA
Figure 4.2. Diagram of experimental equipment

16
1. Filters;
2. Reduced pressure
vaporizers;
3. Pipeline connected
to the load pressure
sensor;
4. LPG pipeline to the
nozzle;
5.Intake Manifold;
6. Generators;
7. Blowers;
8. Belt;

9. Pipes to water
tanks;
10. High pressure
pumps;
11. Hot water pipe in;
12. Hot water pipe
out;
13. Filters;
14. LPG line;
15. LPG tank.

corresponding to the largest torque and 100 % loading, observe fuel level
supplying for the cycle on the control screen ( Figure 4.16 ) . AVL Fuel
Mas Flow Meter Fuel Measuring Equipment connected directly with the
display will indicate the amount of fuel providing for the cycle.
Step 2 . Adjust the brace rod to reduce diesel fuel consumption down
to 90 % , observe the fuel reduction for cycle on the control screen .
Step 3 . Keep the amount of diesel fuel and adjust the LPG amount
spraying into charging pipe until engine ‘s power displayed on the screen is
equipvalent to the initial value when running 100 % diesel .
When the engine is running stably , conducting the same experimental
steps with diesel engine .
Continue to decrease the amount of diesel down to 80 % and conduct
the same steps as above .
After finishing the running test, separate the results and weigh volume
18

of particles the same as running the original engine .
4.5 . Testing results and evaluation
4.5.1 . EURO standard on the emission of diesel engine
Our country is applying EURO II standard. EURO standard on
emission of diesel engine is presented in Table 4.1 .
4.5.2 . Evaluation the results of testing engine
The results in Figure 4.17 shows the characteristic of FAWDE -
4DX23 engine. The experimental results show that the engine achieved
maximum torque of 308.9 Nm at the rate of 2000 rounds / minute and
maximum power of 82.03 kW at a speed of 2800 rounds / minute . Capacity
and torque value obtained from experiments are not much different from
specifications of the manufacturer .
4.5.3 . Assessing the quality of emission of diesel engine when using diesel
– LPG dual fuel

engine, the HC and CO emission increased. Average CO value at the modes
with LPG rate replacing 20 % of diesel increased by 2 times compared with
CO value when using the original diesel, the highest increase of HC in LPG
Figure 4.20. HC emission in the testing modes
according to ECE R49 cycle

Figure 4.21. NOx emission in the testing modes
according to ECE R49 cycle

Diesel
LPG_10
LPG_20
Diesel
LPG_10
LPG_20
20

mode replacing 20 % is up to 335 % .
The results in Figure 4:21 shows that, when using diesel - LPG dual
fuel, the content of NOx is reduced. In LPG mode replacing 10 % , the Nox
average emission when testing according to ECE R49 mode decreased by
2.8 % . In LPG mode replacing 20 % , the Nox average emission decreased
by 4.1% .
4.5.3.4 . The smoke
Results of smoke of diesel - LPG engine is presented in Table 4.4 .
Table 4.4 . Results of measuring the smoke of diesel – LPG engine
The smoke at 100% loading (1/m)
Engine’s
speed
(v/ph)

-10,0
1800
0,068
0,062
-8,8
0,058
-14,7
2000
0,081
0,074
-8,4
0,068
-16,0
2200
0,120
0,110
-8,2
0,101
-15,9
2400
0,182
0,160
-12,0
0,142
-22,0
2600
0,252
0,217
-13,9
0,186

CO
g/kW.h
1,502
2,701
3,85
HC
g/kW.h
0,179
0,45
0,78
NO
X

g/kW.h
5,853
5,685
5,61
PM
g/kW.h
0,341
0,291
0,268

4.5.4 . Evaluation of simulation and experimental results
4.5.1.1 . Comparison of simulation and experimental results for the original
engines according to ECE R49 cycle
Table 4.7 . Results of comparison of emission between simulation and experiment
of the original engine ECE R49 cycle
Component
Unit

replacing 20 % of diesel is 3,5 % and 3,9 % .
With NOx, deviations between simulation and experiment in LPG
mode replacing 10 % of diesel is 3,9 % and LPG mode replacing 20 % of
diesel is 5.4 % .
22

Table 4.8 . Results of comparision of the emission between simulation and
experiment of diesel - LPG engien according to ECE R49 cycle The value of soot emission / PM between simulation and experiment
in LPG mode replacing 10 % of diesel is 14.4 % , LPG mode replacing 20
% of diesel is up to 16.7 % .
4.6. Conclusion of Chapter IV
The study selected suitable LPG supply system, installed this system
into FAWDE 4DX23 - 110 diesel engine and conducted the research to
determine the composition of the exhaust when using diesel engine and
diesel - LPG dual fuel engine on the modern equipment system.
The empirical results showed that :
When spraying LPG into the diesel charging pipe:
- The smoke reduced at all speeds of running mode .
- CO and HC increased but still met EURO II standard .
- The amount of NOx is 4.2 % when LPG replacing 20 % of diesel
- The amount of PM is 21,4 % when LPG replacing 20 % of diesel
The comparison between simulation and experiment has not much
difference , it showed that the use of AVL - BOOST software to calculate
the components of diesel- LPG emission is acceptable .

3,699
3,850
-3,9
NOX
g/kW.h
5,460
5,685
-3,9
5,305
5,610
-5,4
Soot/PM
g/kW.h
0,249
0,291
-14,4
0,223
0,268
-16,7
23

pollutant formation yet. This research has studied the combustion process of
diesel - LPG engine and identified exhaust components released into the
environment .
2 . The study has developed a computational model of FAWDE
4DX23 - 110 turbocharged diesel engine’s emission when using diesel fuel
and diesel - LPG dual fuel on AVL BOOST software. The comparison
between simulation and experiment has not much difference, it showed that
the use of AVL - BOOST software to calculate the components of diesel-
LPG emission is a proper solution.