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THE UNIVERSITY OF DANANG UNIVERSITY OF SCIENCE AND TECHNOLOGY STUDY OF COMBUSTION AND EMISSIONS OF BIOGAS/GASOLINE HYBRID FUELING ENGINE Major: Mechanical Powertrains Engineering Code : 9520116 SUMMARY OF DOCTORAL THESIS DANANG - 2021 The thesis is completed at: UNIVERSITY OF SCIENCE AND TECHNOLOGY Science facilitator : …………………………… …………………………… Reviewer : ………………………………………………… Reviewer : ………………………………………………… Reviewer : ………………………………………………… The thesis will be protected in front of the thesis review committee at University of Science and Technology, University of Danang At: ………………………………………………………… INTRODUCTION Rationale of the study Biogas is a renewable fuel what is abundant in tropical countries Using biogas as a fuel for internal combustion engines does not increase the atmospheric CO2 concentration Biogas has CO2 inert gas, so the calorific value of the fuel is low, and the combustion speed is limited These properties affect biogas storage capacity and reduce engine power However, the octane of biogas is high, so it has good anti-knock property The combined using of biogas and gasoline helps to overcome the limitations of biogas, to promote its advantages, and to contribute to the development of renewable fuel applications on internal combustion engines in general and internal combustion engines of vehicles in particular Therefore, the thesis: "Study of combustion and emissions of biogas/gasoline hybrid fueling engine" has such practical meaning The thesis is the initial basis of research on the application of biogas/gasoline hybrid fuel on electronic fuel injection automobile engines The content of thesis focuses on main problems: (1) doing simulation in the process of charging and combustion on engines using biogas-gasoline hybrid fuel, (2) solution in supplying the biogas-petrol hybrid fuel for electronic injection engines, (3) doing experiment features and pollutant emission level of automobile engines is run by gasoline-biogas hybrid fuel to assess simulation results Objectives of study ➢ Overall objectives: Developing technological solutions to apply biogas in automobile engines effectively ➢ Detail objectives: Optimizing the fuel supplying process and organizing the combustion of car engines with biogas-gasoline hybrid fuel to improve efficiency of using fuel and to reduce pollutant emissions Subjects and scope of study: ➢ Subjects of study: Researching was made on DA465QE engine on Truong Hai Towner truck ➢ Scope of study: Doing the basic research which is become an initial foundation for the development of technology using biogas-gasoline hybrid fuel on automobile engines With this research scope, the thesis focuses on the following main contents: ➢ The theory: Studying the general equations system of hydraulic mechanics applied to the turbulent combustion process Turbulent model is for closing the equations system of convective-diffusion Combustion model is for simplifying the element conservation equation Kinetics of NOx production and other pollutant formation mechanisms ➢ The simulation: - Study is on using Fluent software to calculate and simulate the supply process of liquid fuel (gasoline) and biofuel (biogas) on the engine Study is on using Fluent software to calculate the combustion process of spark ignition engines using gasoline-biogas hybrid fuel - Calculating emission pollutants: CO, HC, and NOx - Setting the model and boundary conditions up ➢ The experiment: - Improving the charging entrance of engine to adapt to biogas-gasoline hybrid fuel Finding solutions out for transporting and supplying biogas on experimental engines Installing the test engine on the AVL power dynamometer Measuring the effective power of the engine on the external characteristic curve when changing the gasoline composition in the hybrid fuel and analyzing the CO, HC, NOx pollutants in the corresponding operating regime Comparing experimental results to simulation results Study method Combination of theory, simulation, and experiment: Theory orientates the use of mathematical models in solving the complex problem of turbulent; Simulation is the main method used in this study Experiments are conducted with some regime engine to evaluate simulation results The logic between simulation and experimental results allows to have general conclusions Thesis Structure In addition to the introduction and conclusion, the thesis has chapters: chapter Overview; chapter Theoretical basics of the mixture process and combustion in internal combustion engines; chapter Simulation of fuel supply and combustion on the biogas/gasoline hybrid engine; chapter Simulation of fuel supply and combustion on the biogas/gasoline hybrid engine New contributions to the science of thesis - Building the model, program of calculating process of supplying the fuel and process of combustion for Biogas/gasoline engines hybrid engine - Designing the loading system of electronically injection engine into a biogas-gasoline fuel supply system - Confirming the optimal gasoline composition in the biogas/gasoline hybrid fuel to have the compromise between engine performance and pollution emission - Seting up the law of variation of indicated work cycle, emission concentration according to composition of fuel, early ignition angle, speed of engine CHAPTER OVERVIEW 1.1 The necessity of using alternative energy In the sources of CO2 emissions, the internal combustion engine is the main cause Therefore, to achieve the COP21 target, within the next decades, alternative/renewable fuel is used in internal combustion engines must be 60% of total energy at least, compare to 10% today This is a big challenge for scientists in the field of internal combustion engines and transportation 1.2 Biofuels 1.2.1 Generations of biofuels Biofuel has gone through generations: - The first generation, - The second generation, - The third generation 1.2.2 Biogas 1.3 Biogas engine 1.3.1 Spark ignition biogas engines converted from gasoline engine 1.3.2 Spark ignition biogas engines converted from diesel engine 1.4 Situation of study and use on biogas engines in the world and in Vietnam 1.4.1 Study projects on biogas engine application in the world 1.4.2 Study and development projects for biogas engines in Vietnam 1.5 Conclusion The biogas-gasoline hybrid fuel solution can overcome the above problems This solution allows the engine to use totally gasoline or biogas or a combination of biogas and gasoline with a flexible ratio Biogas partially replaces fossil fuels This is suitable for fuel storage capacity in car & currently fuel supplying infrastructure To apply the biogas-gasoline hybrid fuel effectively, we need to determine the optimal composition of gasoline in biogas as well as its effect on engine performance and emissions This is a new issued problem, there is no detailed study has been published yet CHAPTER THEORETICAL BASICS OF THE MIXTURE PROCESS AND BURNING IN INTERNAL COMBUSTION ENGINES 2.1 Basic system of equations 2.1.1 General Equations The classical system of equations describes the fluid flow in which is happening a chemical reaction is written in general as follows: - Equation of Conservation of Matter: + div U = t ( ) (2.1) - Equation of Conservation of momentum: U + U grad U = − gradP + div + F t (2.2) - Total enthalpic conservation equation: n h P + U grad h = + div(U ) + div(.gradT + D h gradC j ) − Q ray =1 t t (2.3) This equation does not have a quantity to represent the heat of the reaction because enthalpy contains the energy of formation - Equation of Conservation of element: C + U gradC = div D gradC + R t ( ) 2.1.2 Reynolds analysis 2.1.3 Favre averaging (2.4) 2.1.4 Closeness of the equations system The equations system is written in the form of Favre average and the boundary layer approximation (2.13) - (2.16) is used in this The k- model is often shown by the equation (2.22), (2.23) which is suitable for the fully developed flame 2.2 Non-uniform combustion model 2.2.1 The non-uniform combustion model Approximating conservation quantity is the most used combustion model at the present in similarity of diffuse entangled flame In this model, that is assumed that all elements have the same diffusion coefficient The assumption of fast reaction kinetics is used, since in most cases the reaction rate is very high compared to the mixing rate From this, the thermochemical state of the mixture, such as concentrations of substances, densities, and temperature, can be determined by intermediary of a conserved quantity for which the equation does not contain a produced quantity The mixture ratio is often chosen as the conserved quantity 2.2.2 Non-uniform combustion model through conserved quantity 2.3 Uniform mixture combustion model 2.3.1 Set up the system of combustion equations During pre-mix combustion, the fuel and oxidant are assumed to be uniformly mixed at the molecular size prior to ignition The combustion process starts at the ignition location and spreads to the unburnt mixture Modeling combustion of pre-mixed mixtures is much more difficult than combustion of unmixed mixtures This is because the combustion of the premix takes place in a thin, mobile flame and is affected by turbulenc For subsonic flows, the overall flame spread is determined simultaneously by the laminar flow and the turbulence level The laminar flame velocity is determined by the diffusion of the element and the heat upstream of the flow into the reactants and combustion To determine the laminar flow rate, we must know the internal structure of the flame as well as the details of the chemical dynamics and molecular diffusion process In fact, the thickness of the laminated flame is about mm or less, the requirements for the solution are often unreasonable 2.3.2 Spread of membrane flame 2.3.2.1 flame spread speed 2.3.2.2 Experimental Formulas for Basic burning 2.4 Local uniform combustion model The local uniform combustion system is a flame whose mixture composition (equivalence factor) is not completely uniform due to imperfect mixing This model is suitable for engines using hybrid 2.6 Conclusion In order to simplify the problem in turbulent flow, scientists have proposed suitable combustion models for the interaction between fuel and oxidant Two basic models are combustion of nonuniform mixtures and combustion of uniform mixtures For engines using hybrid fuel, the locally uniform combustion model is suitable for the type of the fuel supply process The local uniform combustion model is the intermediate model between the combustion of the non-uniform mixture and the combustion of the uniform mixture The combustion process is represented through two conserved quantities, that is, the mixture composition f and the process of combustion c The position of the flame and the characteristic parameters of the combustion process can be determined through these two parameters CHAPTER SIMULATION OF FUEL SUPPLY AND COMBUSTION ON THE BIOGAS/GASOLINE HYBRID ENGINE 3.1 Purpose, simulated objects Simulation calculation of fuel supply and combustion process to guide engine improvement and experimental research Simulation is performed on DA465QE engine when using biogas-gasoline hybrid fuel 3.2 Geometric model of the engine and simulated boundary conditions Figure 3.1: Survey sections on the intake line In order for the engine to use on biogas-gasoline, the engine intake is added with a venturi throat and biogas injector The (a) (b) Figure 3.21: Variation of temperature and pollutant emissions (a), variation of cycle indicator work and engine power (b) by equivalence coefficient (M6C4-20G, n=3000 rpm, s=20oCA) 3.4.2 Compare engine performance when running on biogas/gasoline Figure 3.23: Comparison of cycle indicator work and engine power when using different fuels We see that when running on methane (M100), the cycle indicator work is reduced by 13% due to the reduction in the intake coefficient as explained above When running on M6C4 biogas , the cycle indicator is reduced by 27% compared to gasoline, 17% compared to methane and 10,5% compared to biogas M8C2 10 Figure 2.25: Comparison of pollutant emissions when engines run on different fuels at 3000 rpm, equivalent coefficient =1, s=20oCA 3.4.3 Effect of gasoline components added to biogas 3.4.3.1 M6C4 Biogas Figure 3.28: Effect of gasoline component on the variation of heating rate and pressure in the cylinder to the crankshaft angle 3.4.3.2 M7C3 Biogas (a) (b) Figure 3.33: Variation of cycle indicator work, temperature, and pollutants concentration to gasoline component in biogas M7C3 11 3.4.4 Effect of speed engine (a) (b) Figure 3.35: Variation of Wi (a), temperature and concentration of pollutants (b) with engine speed (M7C3-30G, =1, s=25oCA) Thus, to improve performance and reduce pollutant emissions, we need to ignite earlier when increasing engine speed 3.4.5 Effect of ignition angle (a) (b) Figure 3.37: Variation of cycle indicator work and engine power (a); variation of pollutant emission (b) with pre-ignition angle (MC320G,=1, n=3000 rpm) 3.5 Harmony: Wi and NOx 12 280 270 260 250 n(rpm) : 2000 ▪ : 3000 : 4000 : 5000 12000 10000 8000 : NOx : Wi 2000 230 20 30 40 n(rpm) : 2000 ▪ : 3000 : 4000 : 5000 240 6000 220 s(CA) 10 260 4000 240 NOx (ppm) Wi (J/cycle) 290 Wi-NOx_M7C3-0HHO_Vf2_vs-fis_function-n 280 Wi (J/cycle) NOx (ppm) Wi-NOx_NOx-T_M7C3-30HHO_Vf3_vs-fis_function-n : NOx : Wi 6400 4800 3200 200 1600 s(CA) 180 50 8000 10 20 30 40 50 (a) (b) Figure 3.41: Effect of engine speed on variation of Wi and NOx tos when the engine using fuel M7C3-30G (a) and using M7C3 biogas (b) ( = 1, full load) 3.6 Conclusion The above research results allow us to show the conclusions: - The equivalence factor of the mixture decreases sharply with increasing engine speed and when the throttle is opened The current popular solution of supplying gas with a vacuum valve is not suitable for supplying poor biogas to the engine With this solution, if the mixture is adjusted properly at low speed, at high speed the mixture is too thin; if the mixture is adjusted properly at high speed, then at low speed the mixture is too thick - When the engine runs on biogas-gasoline with the equivalent coefficient in the range of 0,9-1,15, the combustion temperature only changes slightly, the NOx concentration has the maximum value, while the concentration of CO and HC increases very strong when >1 The cycle indicator work and engine power has the maximum value to the optimal equivalence coefficient of about =1,1 - When running on methane (M100), the cycle indicator work is reduced by 13% compared to when the engine runs on gasoline When running on M6C4 biogas , the cycle indicator is 27% lower than gasoline, 17% lower than methane and 10,5% lower than M8C2 biogas 13 - When the engine runs on methane, the emission of HC and CO is the smallest, when the engine runs on gasoline, the emission of NOx is highest, and when the engine runs on biogas M6C4, it emits the highest CO but the lowest NOx emission The combination of gasoline/biogas is gasoline/methane/carbonic combination, can help the engine have a harmony between technical features and pollutant emissions - Cycle indicator work and NOx concentration increased very quickly while CO, HC emissions decreased sharply with the content of gasoline mixed into biogas when the gasoline content was less than 30% After this value, the improvement in engine performance is negligible The average optimal gasoline compoment for M7C3 biogas is 30% - When increasing the speed from 2000 rpm to 5000 rpm , the cycle indicator work decreased by 25%, CO emissions increased 3.9 times, HC emissions increased 2.5 times, NOx emissions decreased times for with fuel M7C3-30G In order to improve performance and reduce pollutant emissions, the engine pre-ignition angle needs to be adjusted when changing engine speed - An engine speed and fuel, the maximum cycle indicator work corresponds to the optimal pre-ignition angle In the case of engines use biogas- gasoline hybrid , the optimal pre-ignition angle lies on the envelope of the Wi-NOx curves, fluctuating in the range 28CA 35CA when the engine is running at 5000 rpm and be supplied with any biogas fuel mixed with 30% gasoline This optimal early ignition angle is reduced by 3CA compared to when the engine runs on biogas CHAPTER EXPERIMENTAL RESEARCH AND ASSESSMENT OF SIMULATION RESULTS OF ENGINE USING HYBRID FUEL BIOGAS-GASOLINE 4.1 Purpose and limitations of the experimental study 14 The purpose of the experimental study in this chapter is to reevaluate the results by the simulation on performance and pollutant emission of engines using biogas-gasoline hybrid fuel The experiment was conducted on the DA465QE engine using gasoline and biogas The engine intake is added with a venturi throat and a gas fuel supply valve Experiment on the DA465QE engine using the initial ignition angle, which does not interfere with tthe engine ignition angle Experimental measurement parameters include engine power on the external characteristic curve, concentrations of pollutants CO, HC, NOx to engine speed, biogas composition and gasoline composition Experimental equipment includes AVL engine, MGT emission analyzer and auxiliary equipment for biogas fuel 4.2 Characteristics of the fuel system on the DA465QE engine The electronic fuel injection system of the DA465QE engine is a D-EFI (type controlled by intake manifold pressure), using the intake pressure sensor on the intake lineto detect the amount of intake air by intake air density 4.3 Design of the biogas-gasoline hybrid supply system 4.3.1 Principle of continuous and intermittent gas supply Among these, two gas fuel supply options of the vacuum type have been proposed: intermittent fueling (Figure 4.3a) and continuous fueling (Figure 4.3b) Figure 4.3: graph of intermittent gas supply valve (a) and continuous gas supply valve (b) 4.3.2 Biogas supply system for DA465QE engine 15 (a) (b) Figure 4.4: Average pressure variation at the surveyed crosssections when supplying biogas continuously (a) and when supplying biogas intermittently With continuous gas supply, the pressure curve changes equally as when no gas is supplied The pressure pulse appears only at the time of opening and closing the gas supply valve In the case of intermittent gas supply, the pressure fluctuates greatly The vacuum value at the peak pulse is greater than the average vacuum value at the corresponding cross-section when the gas is continuous 4.4 Biogas/gasoline hybrid fuel supply system for DA465QE engine Khơng khí 10 Khơng khí ECU Biogas 11 Xăng Biogas Figure 4.6: graph of vacuum valve biogas supply system The principle of supplying biogas for the engine is as above Due to the combination of two fuels, the throttle control system is connected according to the principle that the biogas throttle opens at a larger angle than the gasoline throttle when pushing on the gas The 16 ratio of these throttle opening angles depends on the gasoline/biogas ratio that needs to be supplied to the engine When the engine is running at full load, the biogas throttle is fully open, but the mixture has not reached the theoretical equivalent of combustion, the oxygen sensor will act so that the ECU controls the fuel injector to supply more fuel As a result, the mixture composition always has the optimal value and the engine can power equivalent when running on gasoline when working on the characteristics curves 4.5 Structure of vacuum valve for biogas 4.6 Introduction of experimental system 4.6.1 Overview of engine power dynamometer Experimental study on engine performance using biogasgasoline at the AVL internal combustion engine laboratory of University of Science and Technology - University of Danang The experimental layout is shown in Figure 4.7 This is a laboratory with synchronous equipment of AVL 4.6.2 Power dynamometer: APA 204/08 In this experiment, we did not measure the pressure in the combustion chamber, only measured the crankshaft output torque and engine speed in different regime APA 204/E/0943 engine dynamometer produced by AVL, Austria, with a maximum capacity of 220 kW, a maximum moment of 934 Nm and a maximum speed of 8000 rpm The characteristic curve of the engine Dynamometer is shown in Figure 4.8 4.6.3 Equipment for supply and measure fuel consumption 733S 4.6.4 Equipment: AVL 553 4.6.5 Intake air flow meter 4.6.6 Control computer All measurements from PUMA are connected to the control PC Interface on the computer screen as shown in Figure 4.11 17 4.6.7 Exhaust gas analyzer: MGT 4.7 Experimental research on biogas-gasoline hybrid fuel engine 4.7.1 Experimental system layout Figure 4.12 introduces the layout diagram of the experimental system for the DA465QE engine using biogas-gasoline hybrid fuel The test engine, after having modified the intake manifold and fuel supply system as described above, is mounted on the AVL dynamometer The mounting of the test engine was done out in accordance with the technical procedures according to the instructions of the engine laboratory 4.7.2 Prepare fuel Because the laboratory is far from where biogas produced, biogas is compressed into pressure vessels for transportation Biogas is filtered H2S by bentonite The average composition of biogas after filtration is 60% CH4 and 40% CO2 without removing CO2 To enrich biogas, we filter CO2 with NaOH In this case, biogas has an average composition of 70% CH4 and 30% CO2 4.7.3 Install the engine on the power dynamometer Figure 4.15: Installing the DA465QE engine on the AVL dynamometer 4.7.4 Experiment regime As described at the initial chapter, the experiment was performed limited to the external characteristic curve (for biogas) The test regime to speed, biogas composition and gasoline composition 18 The gasoline composition and biogas is determined according to the molar composition After each stable measurement, we can determine the volume of biogas consumed and the volume of gasoline consumed On that basis, we calculate the number of moles of gasoline and the number of biogas moles, from determining the gasoline cocomposition 4.8 Experimental results and comparison with simulation results 4.8.1 Compare engine performance (a) (c) (b) Figure 4.20: Comparison of the characteristic curves in addition to the moment and power by the model and experiment when the engine` runs on gasoline (a), M7C3 biogas (b) and fuel M7C330G (:Experimental power, • : Experimental moment) The result of Figure 4.20 shows that the maximum moment at the engine speed position is about 3500 rpm This is logical with the data published by the manufacturer Experimental results at most measuring points are about 10% smaller than simulation results on average This is because the actual combustion does not have in the ideal way as assumed in the simulation The early angle in practice is 19 pre-installed by the manufacturer into the ECU for gasoline fuel, not completely suitable for biogas and biogas combined with gasoline Other side, the pressure variation on the intake manifold is also not included in the simulation conditions correctly, leading to errors between simulation and experiment 4.8.2 Compare emissions by simulation and experiment results The results of Figure 4.22 show that the simulation results are logic with the experimental results in the high-speed region because the temperature on NOx formation is slightly reducedlow speed region, the NOx concentration by the experiment is about 15% smaller than the value by the simulation on average This is because the effect of temperature on NOx formation is greater when the time of the mixture at high temperature is prolonged (a) (b) (c) Figure 4.22: Comparison of the effect of speed to CO (a), HC (b) and NOx (c) emissions by simulation and experiment (M7C3-30G, =1, s=25oCA, n=3000 rpm, ━ :simulation, •: experiment) 4.9 Summary of factors affecting hybrid engine performance 20 coefficient Wi (J/xl/ct) 259 CO (%) 0,21 HC (%) 0,08 NOx (ppm) 2000 Qlt (J/xl/ct) 797 Figure 4.23: Effect of fuel on hybrid engine performance The results of Figure 4.23 show the correlation between the parameters of the combustion process when using the above fuels We see that when the engine runs gasoline fully, the fuel energy into the cylinder for each cycle is the largest, so the cycle ndicates workthe largest is borned What's more, the engine runs on gasoline is that CO and HC emissions are also the lowest of the used fuels The weakness of gasoline fuel is the highest NOx emission coefficient Pe-total (kW) 34 CO (%) 0,36 HC (%) 0,1 NOx (ppm) 3500 Figure 4.24: Effect of performance and pollutant emissions of engines using hybrid fuel When the engine runs at 2000 rpm, CO emissions are reduced by 80%, HC emissions are reduced by 90% but NOx emissions increase by 90% and engine power is reduced by 75% compared to when the engine runs at speed 5000 rpm As analyzed above, when the engine runs on hybrid fuel, in a given regime, CO and HC emissions are lower than when running on biogas Other side, when the engine runs at high speed, NOx emissions decrease as shown in Figure 4.24 Therefore, when using 21 hybrid fuel, the engine can run at high speed to increase capacity and reduce NOx emissions, and at the same time not increase CO, HC compared to when the engine runs on biogas 4.10 Conclusion The results of this chapter allow to have the following conclusions: - The vacuum valve combination includes a continuous gas supply valve and an intermittent gas supply valve through the venturi throat mounted in parallel with the intake line of the gasoline fuel system, allowing the equivalent coefficient to be adjusted to adapt to different regime - The simulation results are logical with the results of the engine performance test on the AVL dynamometer and the specialized exhaust gas analysis The differences between simulation and experimental results are logical, consistent with theory and practice - The experimental results of measuring the CO, HC in the exhaust gas are higher than the results by the simulation; In contrast, the NOx concentration by the experiment is lower than the simulation result because the supply and burning conditions in reality are not as ideal as in the simulation calculation, causing local incomplete combustion, leading to the actual combustion temperature is lower than the theoretical one - Experimental results confirm the conclusions have from simulation The cycle indicator work of engines running on biogasgasoline hybrid fuel increases with the gasoline content in the fuel mixture When the gasoline composition is less than 30%, the increase in cycle indicator work according to the gasoline composition is much higher than when the gasoline composition is more than 30% - In the same engine regime, CO and HC emissions decrease while NOx emissions increase according to the gasoline composition 22 in the fuel mixture When gasoline composition is higher than 30%, emissions pollutants are less affected by fuel composition - With the same fuel composition, when the engine speed increases, the cycle indicator work decreases along with the reduction of NOx emissions while the CO and HC emissions increase When the engine runs at 2000 rpm, CO emissions are reduced by 80%, HC emissions are reduced by 90%, but NOx emissions increase by 90%, and engine power is reduced by 75% compared to when the engine is running at 5000 rpm CONCLUSIONS AND DEVELOPMENT PROPOSALS The results of the thesis allow to have the following conclusions: - The vacuum valve combination includes a continuous throttle supply valve and an intermittent throttle supply valve through the venturi unit installed in parallel with the intake line of the gasoline fuel system, allowing the equivalence coeficent to be adjusted to suit different regimes when using biogas-gasoline hybrid fuel - Engine running biogas-gasoline hybrid with the equivalent coefficient in the range of 0,9-1,15; the combustion temperature only changes slightly, NOx concentration has the maximum value, while the concentration of CO and HC increases very much strong when >1 The cycle indicator work and engine power have the maximum value corresponding to the optimal equivalence coefficent of about =1,1 When the hybrid engine runs on methane, the cycle indicator work is reduced by at most 13% compared to when the engine runs on gasoline When running with M6C4 biogas, the cycle indicator decreased the most by 27% compared to gasoline, the most by 17% compared to methane and 10,5% compared to M8C2 biogas - Hybrid engines using methane have the smallest HC and CO emissions, when engines run gasoline have the highest NOx emissions, and when M6C4 biogas engines have the highest CO emissions but the lowest NOx emissions The combination of 23 gasoline/biogas is gasoline/methane/carbonic combination, can help the engine achieve a harmony between performent and pollutant emissions - The average optimal gasoline composition for adding into M7C3 biogas is 30% Cyclic indicator work and NOx concentration increased very quickly while CO, HC emissions decreased sharply with the gasoline composition added into biogas when the gasoline composition was less than 30% - With the same fuel composition, when the engine runs at 2000 rpm, CO emissions are reduced by 80% at most, HC emissions are reduced by 90%, but NOx emissions increase by 90% at most, while engine power decreases 75% more than when the engine is running at 5000 rpm - Biogas-gasoline hybrid engine, optimal ignition angle ranges from 28CA-35CA when the engine runs at 5000 rpm and is supplied with any biogas fuel with 30% gasoline This optimal early ignition angle is reduced by 3CA compared to when the engine runs on biogas DEVELOPMENT PROPOSALS Within the limited scope of the content of the thesis, the new thesis solves the basic problems of engines using gasoline-biogas hybrid fuel The thesis can continue to develop in the following: ✓ Study the biogas injection system according to the injection map to make sure the ratio between gasoline and biogas, in logical with the engine regime ✓ Research on technology to optimize biogas storage for engines using gasoline-biogas hybrid fuels on vehicles ✓ Measure the indicated pressure in the combustion chamber engine to compare with the simulated indicated pressure ✓ Researching and developing applications of gas/liquid hybrid fuel solutions on installation motorbike 24 ... the gas is continuous 4.4 Biogas/ gasoline hybrid fuel supply system for DA465QE engine Không khí 10 Khơng khí ECU Biogas 11 Xăng Biogas Figure 4.6: graph of vacuum valve biogas supply system The... in the process of charging and combustion on engines using biogas- gasoline hybrid fuel, (2) solution in supplying the biogas- petrol hybrid fuel for electronic injection engines, (3) doing experiment... Simulation of fuel supply and combustion on the biogas/ gasoline hybrid engine; chapter Simulation of fuel supply and combustion on the biogas/ gasoline hybrid engine New contributions to the science
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