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

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 HA NOI - 2014 This thesis is completed at UNIVERSITY OF TRANSPORT AND COMMUNICATIONS Scientific Advisers: 1. Ass.Prof.Dr. Cao Trong Hien 2. Ass.Prof.Dr. Dao Manh Hung Opponent 1: Prof.Dr Pham Van Lang Opponent 2: Ass.Prof.Dr Lai Van Dinh Opponent 3: Ass.Prof.Dr Tran Van Nam 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. In Vietnam, LPG application 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. With that situation, calculating and identifying components of exhaust from automobile engines using diesel - LPG dual fuel becomes imperative and incredibly practical. 2. Purposes of the study - To identify the content of emission components when the LPG supply system is fitted into diesel engine. - To assess the effect of reducing emissions of diesel - LPG dual fuel engine. 3. Subjects and scope of the study * The subject of the study: This thesis focuses on engines using diesel - LPG dual fuel mounted on small and medium -sized automobiles. * The scope of the study: This thesis studies the exhaust emission of the selected object on the basis of remaining all the specifications (torque capacity) of the original diesel engine. 4. Methods of the study This study combines theoretical research with empirical research * In theory: Using theory of heat exchange and mass exchange of internal combustion engines, using AVL - BOOST software to simulate the engine working process and calculate the content of emissions. * In empiric: The experiment was carried on the modern test tape according to ECE cycle of Vietnam Register Department to determine the amount of harmful exhaust, and base on the result to adjust the theoretical 2 calculation results. 5. The scientific and practical meanings * 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 the world increased 2.4 % / year in 2000-2008. In 2013, the world supply could reach 260 million tons and is expected to reach 291.7 million tons in 2015. 1.2.1.1. Production of LPG in Vietnam Vietnam has about 3,000 billion m 3 of gas concentrated mainly in our continental shelf . In 2009, Dinh Co gas processing factory began producing 3 LPG (about 29,000 tons / month) serving for industrial and consumer products. From the second quarter of 2009, the Dung Quat oil filtration factory has officially gone into operation and produced LPG to meet the needs of LPG in the whole country. 1.2.2. The utilization of LPG In the world: The use of LPG in the world focuses on four fields: domestic consumption accounts for nearly 50 % , followed by the chemicals field with 24 % , the use of LPG in industry is at the third rank with total consumption accounting for about 13 % , while transport only ranks the fourth with a total annual consumption of 8.8 % . In Vietnam: Demand for LPG in Vietnam in recent years has increased very quickly. In 2015, the demand for LPG is expected to be about 1.5 million tons and 2 million tons by 2020. However, in our country, LPG is mainly used as fuel; the use of LPG for transportation means is not popular. 1.3. Domestic and foreign studies on emissions of diesel engines and diesel – LPG engines 1.3.1. The research results in the world In the world, there have been many studies in this field , as typical : Works of BEROUN and MARTINS , Z.H Zhang , C.S. Cheung , T.L. Chan 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 Based on the advantages and disadvantages of these methods and to meet the research objectives, the study chose to inject the LPG into charging pipe to survey and empiric. The diagram of LPG supply system into diesel engine is presented in Figure 2.4. Figure 2.4. Diagram of LPG supply system and turbochargers diesel fuel system 1. Air filters; 2. Charging air coolers; 3. Exhaust pipe 4. High pressure pump 5. Coarse filters; 6. Turbochargers; 7. Nozzle; 8 . The pipeline takes the pressure loading; 9 . Vaporized LPG Pipeline; 10 . Fuel pump; 11 . LPG flow control valve; 12 . Crystal filters; 13 . LPG cylinders; 14 . LPG Pipeline; 15 Engine cooler; 16. Diesel fuel tank; 17. Vaporized depression . 1 2 3 4 5 6 13 7 8 9 10 11 15 16 12 14 5 -25 25 75 125 175 225 275 -25 25 75 125 175 225 275 340 1 2 4 3 5 1 2 5 360 380 400 420 2.2. Theoretical basic of diesel engine and diesel – LPG engine 2.2.1. Combustion process in diesel engines Combustion process in diesel engines can be divided into 4 phases: Late Fire, rapid fire, main fire ( slow fire ) and dropped fire . 2.2.2. Combustion process in diesel – LPG dual fuel engines Combustion process in diesel – LPG dual fuel engines is rather complicated because of the combination of combustion in gasoline engines and diesel engines. Besides late fire and dropped fire as the diesel fuel engine, the combustion process can be divided into 3 main phases. - Phase 1: The rapid fire with diesel fuel and a small portion of fuel gas. - Phase 2: The rapid fire with most of LPG fuel and a portion of diesel fuel. - Phase 3: The diffusion fire of diesel and remaining gas. 100 % diesel 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: S p e e d o f c a lo ri fi c ( J /C A ) S p e e d o f c a lo ri fi c ( J /C A ) 6 - The first thermodynamics equation - Solvent mixture model is described by the components forming the mixture including diesel fuel, LPG (C3H8, C4H10), O2, N2, CO2, H2O, CO, and H2 - Heat transfer model is calculated according to the Woschni formula 1978. - Use Vibe 2 zone fire model, the reactions of Zeldovich chain with speed coefficient to calculate the amount of NOx, the reactions according to A. Onorati to calculate CO, Hiroyasu model to calculate soot emissions in the exhaust of diesel engines and diesel- LPG engines. 2.3. The exhaust components Toxic products of combustion in diesel engines and diesel - LPG engines included the following materials: HC, NOx, SO2, and dust particles (PM). 2.4. Calculation base of emission component in diesel engines and diesel – LPG engines 2.4.1. Calculating the NOx emission The formation of NOx is calculated based on parameters such as 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 O2, mainly produced from the incompleted combustion. Therefore, CO can be calculated based on the responses according to A. Onorati: CO + OH ↔ CO2 + H; CO2 + O ↔ CO + O2. 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,oxs dm dmdm dt dt dt   (2.36) 2.5. Conclusion of Chapter II In the plans of using of diesel – LPG dual fuel engine, the plan to 7 inject LPG into charging pipe of the original diesel engine was selected as the research plan. This plan has several advantages such as compact structure, simple installation, no improvement to the original diesel engine. The study used Vibe 2 zone fire model, the reactions of Zeldovich chain with speed coefficient to calculate the amount of NOx, the reactions according to A. Onorati to calculate CO, Hiroyasu model to calculate emissions of soot in the exhaust of diesel engines and diesel- LPG engines. Chapter III. DEVELOPING MODEL TO IDENTIFYING COMPONENTS OF EXHAUST FROM DIESEL ENGINE AND DIESEL – LPG ENGINE 3.1. AVL BOOST software Based on the objectives and content of the study, the researcher chose to calculate the emission of diesel engine by the simulation software. With the available features and tools, AVL - BOOST can develop the model and calculate the exhaust components of the engine. 3.2. Application of AVL - BOOST software in calculating exhaust components of the FAWDE - 4DX23 engine 3.2.1. The basic parameters of FAWDE - 4DX23 engine FAWDE - 4DX23 - 110 engine is the turbocharged diesel engine made in China. This engine is used on passenger cars and small and medium trucks. Rated power at 2800 rev / min is 81 KW, max torque at 1800 rev / min is 320 Nm. 3.2.2. Diesel fuel and LPG fuel 3.2.2.1. Diesel fuel The main chemical composition of diesel fuel are hydrocarbon compounds, general formula is CnH2n+2. 3.2.2.2. Liquefied petroleum gas (LPG) The chemical composition of LPG is mainly paraffinic hydrocarbon types, general formula is: CnH2n+2 such as : Propane (C3H8), Butane (C4H10), Pentane (C5H12)… In addition, in LPG there are Ethane (C2H6), Ethylen (C2H4), Butadiene (C4H4) but they account for a very small percentage. 3.2.3. Developing the diesel model on AVL - BOOST Based on the structure of motor in fact, the elements defined in AVL - BOOST and the specifications of the engine, FAWDE 4DX23 - 110 - engine model can be built as in Figure 3.2. The function name of the elements on the simulation model are presented in Table 3.4 . 8 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 based on the layout of LPG supply system into diesel engine and the way to mix them. According to the selected plan, LPG will be injected into the engine's charging pipe. Thus on the model of diesel – LPG engine , apart from the basic elements such as original diesel engine model will have more injector ( I1 ) to simulate the process of providing LPG . In the declaration on the input parameters for the model, in Classic Specles Setup Section, after selecting fuel for diesel engine, it is necessary to declare the chemical compositions of LPG, rate of Propane and Butane. 3.2.6. Computational simulation results The simulation results of exhaust components of diesel engine and diesel - LPG engine when running under ECE R49 cycle are showed in the figure (3.7), (3.8), (3.9) and Table 3.8. The simulation results in Figure 3.7 above shows that , when running according to ECE R49 test cycle ,there is an increase of CO , the average increase in LPG mode replaced 10 % of diesel by 77.42 % and in LPG mode replace 20 % diesel by 151.8 % compared with using 100 % diesel . Figure 3.5. Simulation model of diesel - LPG engine on AVL-BOOST I1 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 Diesel LPG_10 LPG_20 11 Table 3.8. Average emission according to ECE R49 cycle Component Unit Diesel Diesel_10 Comparing (%) Diesel_20 Comparing (%) CO g/kW.h 1,469 2,606 77,42 3,699 151,8 NOX g/kW.h 5,654 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 , the volume of the combustion chamber increased leading to the temperature and the pressure decreased effecting on the emission Figure 3.9. Soot emission in the simulation modes according to ECE R49 cycle Diesel LPG_10 LPG_20 12 components. 3.3.2. The effect of gas distribution phase to the emission of diesel – LPG engine To survey the influence of gas distribution phase to the emission of the engine, changing simultaneously the value of opening angle of loading value and exhaust valve towards increasing early opening angle and late closing angle. The exhaust gas composition will change as shown in Table 3.9. Table 3.9 . The simulation results of emission components of diesel- LPG engine according to ECE R49 cycle when changing air distribution angle Figure 3.11. Soot emission at 100% loading with engine speeds according to early spraying angle Figure 3.10. NOx and CO emissions at 100% loading, engine 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 5,481 3,333 Soot g/kW.h 0,223 0,224 0,191 0,228 2,087 The above results show that early spray angle can be decreased to reduce CO and NOx emission , however, there should have more experimental research to find the best solutions to effectively reduce emission of toxic . 3.4 . Conclusion of Chapter III Application of AVL BOOST software to caculate emission components properties of FAWDE - 4DX23 - 110 engine fitted with LPG injection system shows that : - The amount of NOx reduced , the reduction in LPG mode replacing 10 % diesel is 3,427 % and in LPG mode replacing 20 % diesel is 6,178 % compared with using 100 % diesel . - The amount of CO in diesel - LPG engine increased, the increasing in LPG mode replacing 10 % diesel is 77,42% and in LPG mode replacing 20 % diesel is 151,8% compared with using 100 % diesel . - Soot emission while using dual fuel reduced, the reduction in LPG mode replacing 10 % diesel is 16,76% and in LPG mode replacing 20 % diesel is 25,4% compared with using 100 % diesel . The thesis examined the influence of some structural parameters on the emission of diesel engine when using diesel - LPG dual fuel. The results show that, early spray angle can be adjusted to reduce CO and NOx 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 - Oil Cooling Device AVL 554 - Rub out Controller THA 100 - Fuel consumption Measuring AVL Fuel Mas Flow Meter - Gas Emission measurement system - Particulate Sampler System - PSS i60) - Smoke Measuring Device AVL 439 ( Equipped available in the lab ) 4.3 . Selection and installation of LPG supply system into experimental diesel engine Based on the advantages and disadvantages of LPG supply systems, the study chose LPG supply system manufactured by WTV - United Kingdom (UK ). 15 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 PANNEL ENCOMP400 FEM CABLE BOOM RUB OUT PULLING THA 100 GREASE COOLER AVL554 FUEL AIR CONDITIONER 573C P C P C Engine FAWDE WEIGHTING FUEL AVL 735S PUMA POWER BRAKES APA 404/6PA Figure 4.2. Diagram of experimental equipment 16 1 . F il te rs ; 2 . R ed u ce d p re ss u re va p o ri ze rs ; 3 . P ip el in e co n n ec te d to t h e lo a d p re ss u re se n so r; 4 . L P G p ip el in e to t h e n o zz le ; 5 .I n ta ke M a n if o ld ; 6 . G en er a to rs ; 7 . B lo w er s; 8 . B el t; 9 . P ip es t o w a te r ta n ks ; 1 0 . H ig h p re ss u re p u m p s; 1 1 . H o t w a te r p ip e in ; 1 2 . H o t w a te r p ip e o u t; 1 3 . F il te rs ; 1 4 . L P G l in e; 1 5 . L P G t a n k. F ig u re 4 :1 2 . L a yo u t o f L P G s u p p ly a n d e n g in e fu el s ys te m 17 4.4 . Experimental procedure 4.4.1 . Experimental conditions To ensure stable operation of the engine during the testing, all the engine’s parts must be tested and maintained before installation. Test strips are also tested and calib devices (?) before testing. LPG fuel and diesel fuel are inspected by Quality - Measurement Testing Center , Petroleum Company I. 4.4.2 . The experiment of measuring exhaust from original diesel engine * Testing Cycle The study selected running mode according to ECE R49 test cycle to indentify the engine's emission. *The content of experiment : Experimental procedure was conducted according to the following steps : Step 1 . Measuring power , torque motors : Step 2 . Measuring the smoke . Step 3 . Entering the parameters of the test cycle on the controlling software . Step 4 . Measuring engine ‘s exhaust according to the cycle set. Step 5 . Weigh the filter paper to determine PM emission . 4.4.3 . The experiment of measuring exhaust of diesel – LPG dual fuel engine Step 1 . The engine runs on the dynamometer at speed mode 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 4.5.3.1 . CO Emission Figure 4.19. CO emission in the testing modes according to ECE R49 cycle Diesel LPG_10 LPG_20 19 4.5.3.2. HC Emission 4.5.3.3. Nox Emission The results in Figure 4.19 and 4.20 show the CO and HC emission of the testing engine when using orginal diesel and diesel - LPG dual fuel. The results on the graph shows that, the LPG injection on charging pipe of diesel 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) Diesel Diesel_10 Comparing (%) Diesel_20 Comparing (%) 1000 0,394 0,379 -3,8 0,370 -6,1 1200 0,207 0,197 -4,8 0,187 -9,7 1400 0,142 0,134 -5,6 0,125 -12,0 1600 0,086 0,080 -6,9 0,077 -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 -26,2 2800 0,342 0,280 -18,1 0,227 -33,6 Average -9,1 -16,6 The smoke decreased due to when spraying LPG into, the rate of cacbon compared to hydro of LPG is smaller than diesel, ie the volume of C in LPG fuel is lower than diesel so it should reduce the possibility of formation of soot , lead to the smoke of diesel - LPG lower than the original diesel engine . 4.5.3.5 . Average emission Average emission according to ECE R49 test cycle of testing engine is shown in Table 4.5 . 21 Table 4.5 . Average emission of diesel – LPG dual fuel engine Component Unit 100% Diesel Diesel_10 Diesel_20 CO g/kW.h 1,502 2,701 3,85 HC g/kW.h 0,179 0,45 0,78 NOX 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 Simulation Experiment Difference (%) CO g/kW.h 1,469 1,502 -2,21 NOX g/kW.h 5,654 5,853 -3,40 Soot/PM g/kW.h 0,299 0,341 -12,28 Table 4.7 shows the results of FAWDE - 4DX23 - 110 engine emission based on the ECE R49 cycle when making the simulation and experiment . The results showed that the different value between simulation and experiment for NOx and CO emission are not much. 4.5.4.2 . Comparison of simulation and experimental results for diesel - LPG engine according to ECE R49 cycle The comparison shows that CO and NOx emission calculated according to ECE R49 cycle between simulation and experiment has not much difference . The different value between simulation and experiment for CO emission in LPG mode replacing 10 % of diesel and LPG mode 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 . GENERAL CONCLUSIONS AND RECOMMENDATIONS I. General conclusion 1 . The engines using diesel - LPG dual fuel is catching attention of many scientists. Many developed countries in the world have put their finance and effort into this issue. 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 engines but not interested in optimizing fuel supplying system, combustion and Compon ent Unit Diesel_10 Mode Diesel_20 Mode Simul ation Experi ment Differen ce (%) Simula tion Experi ment Difference (%) CO g/kW.h 2,606 2,701 -3,5 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. 3 . The study selected and installed completely of LPG supply on FAWDE 4DX23 - 110 turbocharged diesel engine to convert a diesel engine into diesel - LPG dual fuel engine. The installation of LPG supply system does not change the structure of the original engine . 4 . Experimental results on sync dynamometer on modern emission of AVL ( Austria ) at National Testing Centre showed that When replacing 20 % LPG by diesel , the smoke reduced in all working speeds of the engine , CO and HC increased but still met EURO II standard , NOx ‘s reduction is 4,2 % , PM is 21.4 %. II . Recommendations Based on the research results, the thesis has some recommendations : 1 . Applying research’s plan to reduce dust and solve the requirements of energy replacing the diesel engine mounted on cars running in major metropolitan areas. 2 . Using gases oxidising filters to solve the increase of CO and HC of engine using diesel - LPG dual fuel. 3 . There should have more researches to optimize the mixing rate of LPG in diesel- LPG dual - fuel engine.