PHD dissertation sumary: Research on the use of ULSD biodiesel fuel blend on marine diesel engines

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Object and scope: Small ship diesel engines with the range of power from 50 hp to 100 hp; traditional diesel fuel with 0.05% sulfur content, ULSD with 0.001% sulfur content, and Biodiesel originated from coconut oil; fabrication of ultrasonic wave-based equipment/system to produce homogeneous fuel blend;fuel supply system, exhaust system, and control and test system of the engine; testing equipment for engine power and emissions parameters.

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Nội dung Text: PHD dissertation sumary: Research on the use of ULSD biodiesel fuel blend on marine diesel engines

MINISTRY OF EDU. & TRAINING MINISTRY OF TRANSPORT HO CHI MINH CITY UNIVERSITY OF TRANSPORT TRAN VIET DUNG RESEARCH ON THE USE OF ULSD-BIODIESEL FUEL BLEND ON MARINE DIESEL ENGINES Speciality: Mechanical Engineering Code: 9520116 Supervisors 1: Assoc. Prof. Dr. Hoang Anh Tuan Supervisors 2: Prof. Dr. Le Anh Tuan PHD DISSERTATION SUMARY HO CHI MINH CITY - 2021
This dissertation was completed at Ho Chi Minh City University of Transport Supervisors 1: Assoc. Prof. Dr. Hoang Anh Tuan Supervisors 2: Prof. Dr. Le Anh Tuan Reviewer 1: Reviewer 2: Reviewer 3: This dissertation will be defended before the Dissertation Evaluation Council meets at Ho Chi Minh City University of Transport at .....hours.......minute, date........................................................, 2021. This dissertation can be found at the library: - Library of Ho Chi Minh City University of Transport; - Nationnal Library of Viet Nam. 1
INTRODUCTION Urgency The International Maritime Organization (IMO) mandated the use of ultra-low sulfur diesel (ULSD) fuel in shipping from January 1, 2020. Compliance with the new regulation on sulfur content in the fuel used for ships when ships operate in an emission control area can be achieved by using fuel with a sulfur content of 0,0015% at all times of ship operation or switching from high-sulfur fuel to 0,0015% sulfur fuel when the ship enters an emission control area. Fuel switching during the ship operation can present a number of problems related to fuel characteristics such as viscosity, lubricity, flash point, combustion quality. Therefore, for ships using ULSD fuel, it is necessary to equip a cooler system to overcome the disadvantage of ultra-low viscosity like ULSD. Due to this reason, the combination of two fuel types such as ultra low- viscosity ULSD and high-viscosity Biodiesel (BO) fuel aiming to form a new fuel type, which satisfies not only the required viscosity and renewable properties but also the requirement of reducing the cost of ship operation will have a great significance in terms of economy, technology and emissions. However, the homogeneity of the fuel after mixing is found to depend mainly on the mixing method. Currently, mechanical fuel mixing technologies have been being mainly used, indicating that the quality of mixed fuel only stands at an acceptable level as well as the mixing time is quite long. Meanwhile, using ultrasonic waves to create shocks from the bubbles appearing within the 2 liquid phases is considered as a potential solution to improve the homogeneity of the 2 liquid-phase blend such as ULSD fuel and Biodiesel. Based on the above-mentioned reasons, the method of using ultrasonic waves has been chosen to mix ULSD and Biodiesel fuels to produce a homogeneous fuel type with some properties similar to traditional diesel fuel for the using purpose for ships aiming to meet IMO regulations, to reduce operating costs, and to protect the environment. 2
Therefore, the issue of "Research on the use of ULSD-Biodiesel fuel blend on marine diesel engines" was selected as a novel topic in this doctoral dissertation. Goals - Overview on solutions of using ULSD fuel for marine diesel engines; - Research, design, and fabrication of equipment/system using ultrasonic waves to produce homogeneous fuel blend of ULSD and Biodiesel; - Carrying out experimental studies to evaluate the techno-economic aspects, and emission and combustion characteristics, and performance parameters of a marine diesel engine when using the homogenous fuel blend of ULSD-Biodiesel as an alternative fuel. Object and scope - Small ship diesel engines with the range of power from 50 hp to 100 hp; - Traditional diesel fuel with 0.05% sulfur content, ULSD with 0.001% sulfur content, and Biodiesel originated from coconut oil; - Fabrication of ultrasonic wave-based equipment/system to produce homogeneous fuel blend; - Fuel supply system, exhaust system, and control and test system of the engine; - Testing equipment for engine power and emissions parameters. Methodology - Theoretical research methods on the breakup mechanism of molecular structure by ultrasonic waves with experimental studies on determining the relationship between ultrasonic power and wavelength were applied; - Updated models associated with the fuel injection, mixture formation, and combustion in diesel engines as using ULSD-Biodiesel homogenous fuels in order to evaluate the influence of ULSD-Biodiesel homogenous fuels on the economic and technical parameters of the tested diesel engine were studied; - The experimentally controlled method to evaluate the impact of switching marine diesel engines using ULSD-Biodiesel homogenous fuels on the economic and technical parameters compared to the case of using traditional diesel fuel was used. In addition, The injection characteristics of ULSD-Biodiesel homogenous 3
fuels were also performed as a basis for explaining the process of fuel-air mixture formation, combustion, and emissions. Scientific and practical significance Scientific significance The results obtained from this doctoral dissertation are considered as a reliable scientific basis and could be used as a good reference for research institutes and universities in the maritime field for teaching and researching the use of very low sulfur fuel for marine diesel engines. Practical significance Combining ultra-low viscosity fuel (ULSD) with high-viscosity Biodiesel fuel to form a homogeneous blend with the required viscosity, renewable properties, and reduced operating costs has offered great significance in terms of economy, technology, and emissions. Novelty - Building and systemizing the theoretical basis for homogenous mixing of two liquid phases by ultrasonic waves; - Successful design and fabrication of a system for produce a homogenous blend of ULSD-Biodiesel by ultrasonic waves aiming to meet the current technical and quality standards of Vietnam; - Carrying out the standard tests and critical evaluation of the techno-economic characteristics of marine diesel engines when using ULSD-Biodiesel homogenous fuel blend. Structure The doctoral dissertation consists of an introduction, 4 chapters of main study content, a general conclusion, and a development direction. The entire doctoral dissertation is presented in 123 pages, 27 tables, and 56 figures and graphs. CHAPTER 1. OVERVIEW 1.1. Overview of fuels used for marine diesel engines and MARPOL 73/78 Annex 1.2. Overview of ULSD fuel 4
1.2.1. ULSD properties Fuel with sulfur content up to 0.0015% is called ultra-low sulfur fuel (ULSD), up to 0.05% is low sulfur diesel (Low Sulfur Diesel) and up to 0, 5% is conventional diesel. 1.2.2. Study trend on using ULSD 1.2.2.1. Direct use of ULSD Deniz F. Aktas [4] studied the corrosion characteristics of ULSD. Mayekawa [5] investigated and designed the cooling system for MGO and ULSD fuel to equip ships operating in ECA emission control areas. 1.2.2.2. Blending ULSD with Biodiesel The characteristics of ULSD fuel can be overcome by mixing ULSD with 1–2 vol% biodiesel as the research results of Lin et al [7]. Mangus et al. [11] conducted experimental studies by examining low- temperature liquid flow, low-temperature filter clogging and striation points of seven biodiesel types blended with ULSD to provide information and data on the cooling liquid flow of ULSD as used for diesel engines. Andrew M. Duncan [12] reported that after mixing ULSD with Biodiesel at the ratios of 5, 10, 20, 40, 80%, it showed that the fuel viscosity reached the optimum result with the ratio of 5%, 10%, and 20% Biodiesel. Lin et al. [14] conducted a study (canola methyl ester) on blending biodiesel with ULSD and compared the as-prepared fuel blend with standard fuel sources. 1.2.3. Study trend on fuel-mixing technology The mixing chamber with the help of mechanical impellers (turbine-typed impellers) was proposed to mix fuel [21]. 1.3. Scientific basis of the doctoral dissertation The key point of this doctoral dissertation is to find a solution that combines the use of ULSD and biodiesel without the need for a converting device. Therefore, it reduces both costs in operation and harmful emissions to the environment. At the same time, it could meet the requirements when ships operate in SECA. Based on, the experience and research results, it shows that, CO, HC, 5
and soot emissions are reduced, while NOx emissions increase when using Biodiesel. Besides, when using ULSD for ships, it could completely reduce SOx emissions. The combination of these two fuels into a homogenous fuel is the research direction that has been taken into account by some countries around the world, but it has not yet come up with a solution to ensure the homogeneity of the two fuel types after mixing. Thus, the use of ultrasound for blending of ULSD and Biodiesel aiming to produce a homogeneous fuel having a viscosity similar to that of traditional diesel fuel is a very effective solution. In Vietnam, up to now, there have been a number of studies on solutions to convert marine diesel engines to the use of a blend of biodiesel and petroleum through the design of propeller-type stirring mixers to continuously add vegetable oil - diesel blend for marine diesel engines. However, the mass and size of the assemblies are quite cumbersome, difficult to install in the very limited space of the ship's engine room, and the blending quality is not good if it is not heated before mixing. Therefore, in order to improve the homogeneity of the fuel after mixing, and at the same time, to reduce the size and accompanying equipment for the mixing system so that it can be easily integrated into the fuel system on board ships, the solution proposed by the author here is to use ultrasound technology to mix the fuel of biodiesel and ULSD. 1.4. Conclusion of Chapter 1 By understanding the research trend in Vietnam and abroad, the use of the ULSD-Biodiesel fuel blend on ships could be considered as a basis for the author to find the gaps that need to be studied for this doctoral dissertation. Direct mixing of ULSD with biodiesel by applying ultrasound technology is deemed as an effective solution to improve the low-viscosity characteristics of ULSD and to ensure energy security for the shipping industry when fossil fuel resources are depleting. 6
CHAPTER 2. THEORETICAL BASIS OF MIXING ULSD AND BIODIESEL FUEL AND APPLICABILITY IN DIESEL ENGINES OF SHIPS 2.1. General introduction 2.2. Theoretical basis of mixing fuel The mixing of liquids is understood as the transformation of a heterogeneous system into a homogeneous system. A compound of a liquid is said to be homogeneous or homogenized when the fused structure of any volume fraction of a large body of liquid does not differ from the average fused structure of the whole mass. 2.2.1. Some typical mixing principles - The vane type (the simplest one); - Grinding mixers; - Mixing equipment. 2.2.2. Some typical mixing equipment - Straight S-shaped static mixer; - Stirring type mixing device. 2.3. Theoretical basis of calculation for ultrasound-generating device - Formation of bubbles in the solution; - Number of bubbles formed in the solution; - Factors affecting the formation of bubbles in solution; - Mechanism of bubble development and bursting; - Dynamic analysis of bubbles. 2.4. Theoretical basis for evaluating the feasibility of mixing equipment In principle, biodiesel and ULSD are not miscible. This requires equipment capable of disrupting the structure of two fuel molecules. Therefore, ultrasonic mixing is the most advanced method to form emulsions with small sizes at a large processing scale. 2.5. The theoretical basis of combustion of ULSD-Biodiesel fuel blend in marine diesel engines - Combustion process; 7
- Emission formation mechanism: Including NOx, soot, HC, and CO emissions. 2.6. Conclusion Chapter 2 In Chapter 2, the author has learned the theoretical basis of calculation, the equipment for mixing fuel by ultrasonic waves to create the basis for the calculation and design of the ULSD and biofuel mixing system. At the same time, the theories of combustion and emission formation of diesel engines when using ULSD-Biodiesel blend were also studied by the author as a basis for experimenting with ULSD-Biodiesel blend on diesel engines. CHAPTER 3. DESIGN, MANUFACTURING, AND ASSESSMENT OF ULTRASOUND MIXING-EQUIPMENT QUALITY FOR ULSD AND BIODIESEL 3.1. General introduction Based on the theoretical bases presented in Chapter 2, the author successfully calculated and designed the ultrasound mixing system for ULSD and Biodiesel, satisfying the technical requirements in QCVN 1:2015/ BKHCN. 3.2. Design of ultrasound mixing device 3.2.1. System overview The central controller has the role of generating a variable frequency ultrasonic signal, the ultrasonic signal is fed into the buffer and isolation controller. Then the ultrasonic signal is fed to a large power amplifier to drive the speaker to generate ultrasonic waves through the mixing tank. 3.2.2. Control system hardware design - Control block; - Power amplifiers; - Ultrasonic transmitter. 3.2.3. Calculation and selection of liquid fuel tanks in ultrasonic processing Building technical criteria for the continuous mixing equipment of coconut oil-based biodiesel and ULSD oil is based on the following standards: 8
- SOLAS Code 74 specifies requirements for fuel systems for marine diesel engines and safety requirements; - Technical standards for liquid mixing equipment to achieve the quality of the liquid blend after mixing. The technical standards here are related to the mixing time, the size of the mixing tank, the working mode of the mixing process; - Flow pattern of the liquid in the mixing tank when different ultrasonic frequencies are applied. The equipment for continuous mixing of coconut oil-based biodiesel and ULSD is built on the basis of using ultrasonic generators for the purpose of producing a fuel blend of high quality. The continuous mixing device ensures a constant supply to the engine and a balance between the amount of fuel supplied to the mixer and the fuel consumption of the engine. For mixing equipment of coconut oil-based biodiesel with ULSD for marine diesel engines, the volume requirement of the mixing tank has not been specified. However, for ships using heavy oil (FO) and diesel fuel (DO), there is also a mixing tank on board but only used for the purpose of mixing when converting fuel type. Figure 3. 11. System model with vertical amplifier 3.3. System model design There are two system layout options: A system model with a horizontal amplifier and a system model with a vertical amplifier. The principle of operation of the ultrasonic mixing device is suitable for all subjects. When powered on, the system operates in the default mode of 28KHz of 9
ultrasonic waves. Users can set the operating mode of the system such as allowing to set the parameters of system operating time and ultrasonic power. From the above analysis, and in accordance with the processing conditions and equipment available in the country today, the study will choose a system with a fuel tank with a vertical amplifier as shown in Figure 3.11, with the following parameters: - Dimensions of the fuel tank (length, width, height): LxBxH = 250mmx250mmx250mm - Number of ultrasonic amplifier heads: 9 (pieces) - Ultrasonic source with power: 900W. 3.4. Evaluation of the blend quality of ULSD and Biodiesel The author conducted experiments with 8 samples at different blending ratios to prepare ULSD and COB blends based on the correlation of viscosity in order to find the optimal blending ratio for ULSD and COB. As a result, the stability of the ULSD-COB emulsion reached 98.5% after 17 min of ultrasonic treatment with a mixing ratio of 50% (ULSD): 50% (COB) in the case of ultrasonic horn tip to tip distance of 90 mm. In addition, the similarity of injection characteristics, penetration length, and cone angle, for ULSD-COB emulsion compared with diesel oil was reported. The ultrasonically generated ULSD-COB emulsion provides ultra-low sulfur fuel and increased oxygen content. The fuel mix diagram in this test is arranged as H.3.12. Figure 3. 12. Diagram of ultrasound-based fuel mixing system 10
3.4.1. Selection of ULSD-COB blending ratio It can be clearly seen that the viscosity (µ) of the ULSD-COB blend with 50% ULSD and 50% COB is 3.70 cSt compared with 3.60 cSt of DO at 30°C. The viscosity (µ) of the ULSD-COB blend is 2.7% higher than that of DO. But since the deviation is less than 5%, the mixing ratio of the ULSD-COB blend as presented is considered as the most suitable value. The 50%:50% blending ratio for ULSD and COB was selected to perform the next experiments. 3.4.2. Effect of horn tip position on the stability of the ULSD-COB blend The effect of ultrasonic horn tip position on the stability of the ULSD-COB emulsion for a blend of 50% COB and 50% ULSD prepared after 10 min of ultrasonic treatment is shown in Figure 3.13. Figure 3. 13. Relationship between SEP (stability of emulsion phase, %) and the distance from the bottom to the top of the ultrasonic horn tip h (mm) The relationship between the distance from the ultrasonic horn tip to the bottom of the emulsification chamber h (mm) and the degree of stability of the produced ULSD-COB emulsion is clearly observed in Figure 3.13. The lowest stability of the ULSD-COB emulsion is only 86.2% when h = 5 mm, and it increases with the increase of h distance. The highest degree of stability is 98.5% with the longest distance h = 90 mm. 3.4.3. Properties of ULSD–COB emulsion After 10 min of ultrasonic treatment, the properties of the ULSD-COB emulsion were determined and measured on the basis of the above-mentioned instruments. The results on three characteristics of ULSD-COB emulsion including density, kinematic viscosity, and surface tension are given in Table 3.1. However, the remaining key parameters were LHV and CN related to the 11
combustion of the ULSD-COB emulsion which was predictable and the CN of COB was higher than ULSD and DO. Meanwhile, the LHV of COB was not significantly lower than that of ULSD and DO. Table 3.1. Properties of ULSD-COB emulsion after mixing Propertes ULSD-COB COB ULSD DO 3 Density, kg/m 856 880 832 852 Kinematic viscosity, cSt 3,68 7,2 1,9 3,6 Surface tension, N/m 25,3 26,5 24,4 25,2 From Table 3.1, higher values of the three properties of the ULSD-COB emulsion compared with the DO could be seen. Specifically, the kinematic viscosity, density, and surface tension are 1.02%, 0.47%, and 0.40% higher than that of DO fuel. However, these values still meet the requirements of the fuel used for diesel engines. The obtained results from a blending ratio of 50%:50% ULSD and COB is considered as the optimal one. Besides, the error in kinematic viscosity between the calculated value (3.7 cSt) and experimental result (3.67 cSt) is very small, equal to 0.54%. Finally, the SEP and µ of the ULSD-COB emulsion as a function of the ultrasonic treatment time at a distance (h) of 90 mm are plotted in Figure 3.14. Figure 3.14. Change of SEP (%) and kinematic viscosity (KV) of ULSD-COB emulsion with various ultrasonic times (t) at h = 90mm. Figure 3.14 shows the change of SEP and this change increases sharply in the first 10 min. After that, the SEP changed insignificantly and was kept relatively stable. Similar changes in µ also occurred after 10 min of ultrasonic wave treatment. However, the trends of SEP and µ seem to occur in opposite directions, 12
but their values show asymptotes to stable values. Specifically, the SEP value is close to 100% and the µ value is equal to 3.68 cSt. The ULSD-COB emulsion with the dispersion of phases against DO and BO (COB) is shown in H.3.15. Figure 3.15. Dispersion of phases: (A) diesel oil, (B) ULSD-COB emulsion, (C) Coconut oil-based biodiesel. Micrographs were used to examine the microstructure of the ULSD-COB emulsion (Figure 3.15B) after ultrasonic treatment with a volume ratio of 50% (ULSD): 50% (COB). Figure 3.15 shows the micrographs sampled from the upper part of the ULSD-COB emulsion. According to the naked eye, the blend of ULSD and COB has formed a homogeneous emulsion after ultrasonic treatment. Furthermore, the components of coconut oil-based biodiesel are fully integrated into the components of ULSD. The average droplet size of the ULSD-COB emulsion was larger than that of DO (Figure 3.15A) but smaller than that of COB (Figure 3.15C). It is clear that the energy of the ultrasonic waves broke the ULSD- COB surface tension, resulting in dispersed phases with droplets in their emulsions. In addition, the physical properties of the ultrasonic-assisted emulsion such as viscosity, density, and surface tension are also stabilized after long-term use. 3.5. Conclusion of Chapter 3 Based on the theoretical bases, the author has successfully calculated and designed a device to mix ULSD and Biodiesel fuel by ultrasonic waves to satisfy the technical requirements in QCVN 1:2015/BKHCN. Calculations and selections are appropriate for the volume and speed of each batch, and the ultrasonic generators are capable of meeting the requirements for the frequency and intensity of the emitted ultrasonic waves to maintain the highest number of nano-sized bubbles in the mixing solution. 13
In order to evaluate the mixability and quality of the fuel blend after mixing by the designed system, the author has conducted to blend of two fuels with many differences in characteristics (such as ULSD and coconut oil-based biodiesel) to use for research purposes. The optimal distance from the bottom of the emulsifying chamber to the horn tip is 90 mm. After conducting ultrasound-based mixing with 28 kHz frequency and 100 W ultrasonic power at a height of 90 mm of the ultrasonic horn tip distance from the bottom of the emulsification chamber, the highest stability of the emulsion was obtained, corresponding to 98.5% after 17 minutes. The kinematic viscosity of the ULSD-COB emulsion was 3.68 cSt after 10 min. This result proves that the ultrasound-based fuel mixing device completely meets the quality criteria of the fuel, and shows outstanding advantages in terms of mixing time and homogeneity of the fuel compared with mechanical stirring methods. CHAPTER 4. EXPERIMENTAL STUDY 4.1. Purpose and scope of experiments 4.1.1. Experimental purpose The process of the engine experiments on the testbed is to evaluate the influence of ULSD-Biodiesel fuel on the engine behaviors such as engine power, fuel consumption, combustion characteristics, and emission characteristics. Thus, the experimental study is based on the influence of the after-mixing ULSD- Biodiesel properties by ultrasonic mixing device on the internal and external features of the test engine. This doctoral dissertation has evaluated the impacts of ULSD-Biodiesel fuel with the various mixing ratios of Biodiesel with ULSD (at 0%, 10%, 20%, 30%, and 50% of biodiesel) on technical and economic characteristics and engine emissions in the laboratory. Evaluation of the influence of some input parameters of the engine when using ULSD-Biodiesel fuel blend on the engine performance was also critically performed. 4.1.2. Experiment object and scope 14
- ULSD fuel, biodiesel fuel (coconut oil base); - Diesel engine; - Engine and emission testing equipment and systems. - ULSD-Biodiesel blends (B10, B20, B30, B50) are mixed by volumetric ultrasonic equipment. The testing process was carried out on the D243 diesel engine with the change in engine loads and engine speed. All experiments were carried out in the Key Lab of Internal Combustion Engine of Hanoi University of Science and Technology. 4.2. Equipment and test procedures 4.2.1. Test equipment The test system includes the following main equipment: Electric brake APA 100; AVL 554 lubricating oil cooler; AVL 553 cooling water cooler; Fuel consumption measuring device AVL 733S; Fuel temperature stabilizer AVL 753; Throttle controller THA 100. 4.2.2. Test engine and fuel 4.2.2.1. Tested engine The D243 engine is a 4-stroke, 4-cylinder in-line diesel engine, with a working order of 1-3-4-2, but without turbocharged. The engine uses a forced water cooling system with a closed-loop, with a centrifugal water pump, a suspension valve arrangement, a camshaft located in the body, and a cam profile is a three- arc convex cam. Currently, in Vietnam, the number of D243 engines is being used a lot in the fields of roads, rivers, power generation, and small ships. This engine has been studied quite a lot, so the technical documents of the motor are relatively complete and accurate. Therefore, the author chooses the D243 engine as the research object to apply for this experimental Chapter. 4.2.2.2. Tested fuel - Commercial ULSD (diesel 0.001%S); - Biodiesel fuel derived from coconut oil is mixed with ULSD at the ratio of 10% (B10), 20% (B20), 30% (B30), 50% (B50); 15
- Blended fuel ULSD-Biodiesel is mixed by ultrasonic equipment designed and manufactured by the author (Figure 4.7 and Figure 4.8): ULSD, B10, B20, B30, B50. The physicochemical properties of the test fuel shown are shown in Table 4.2. Table 4. 2. Properties of Test Fuels Properties Unit ULSD B10 B20 B30 B50 B100 3 Density at kg/m 838.8 846.4 850.3 856.2 861.8 880 15oC Kinematic mm2/s 1.60 3.524 3.882 4.116 4.425 7.2 o Vi. at 40 C Surface N/m 0.025 0.0257 0.026 0.0264 0.0263 2.65 tension at 8 30oC Lower MJ/k g 42.8 42.03 41.65 41.06 40.5 37.78 heating value Cetane - 45 46.05 46.5 47.5 48 41 number o Flash point C 66 72.55 84.12 95.45 102.25 200 %C % 0.86 0.84615 0.83875 0.82165 0.81275 0.7602 %H % 0.134 0.13215 0.13075 0.1295 0.1275 0.1363 %S % 0.001 0.00085 0.00076 0.00065 0.00052 0.0002 %O % - 0.01345 0.02597 0.03895 0.05195 0.1023 4.2.3. Test procedure Before measuring the parameters, it should have proceeded as follows: - The first stage, the test of an engine fueled with DO for a period of 10 minutes without load was set up. After that, it needs to check the parameters of the engine for stable operation and check the operating status of the measuring devices; 16
- The second stage, the engine was set up to work at 50% load mode, speed 1500 rpm for 30 minutes to stabilize the thermal state and working condition of the engine. Criteria for evaluating the engine working stably could be presented as follows: Stable measurement parameters, and a small degree of fluctuation of the measured parameters. - The third stage, after the engine is working stably, the measurement of the economic, technical, and emission criteria of the tested engine running on with DO according to the internal features of the engine (in the case of engine loads = 10%, 25%, 50%, 75%, and 100%) at 1500 rpm and 2000 rpm, and external features of the engine (1000, 1200, 1400, 1500, 1600, 1800 and 2000 rpm) at 100% load. - The fourth stage, the engine was tested with the same conditions and experiments as the third stage. However, the fuel samples in this stage were ULSD-Biodiesel with various blending ratios. Each measurement point for 05 types of fuel is performed 03 times and the average result is taken. 4.2.4. Test conditions ETB high dynamics test bench equipped at Key Lab of Internal Combustion Engine, School of Transportation Engineering, Hanoi University of Science and Technology, is a testbed provided by AVL of Austria as shown in Figure 4.9. Figure 4. 9. Experimental layout on the ETB high dynamics testbed 17
4.3. Experiment results and discussion 4.3.1. Engine performance 4.3.1.1. Engine power 59 51 Power (kW) ULSD 43 B50 B30 35 B20 B10 Engine speed, rpm 27 1000 1200 1400 1500 1600 1800 2000 Figure 4. 11 Engine power versus engine speed at 100% load as using different fuels Figure 4.11 shows that the power of the engine fueled with ULSD decreases as compared to diesel fuel, while the engine power with increasing the biodiesel blending ratio could be found to decrease. The reduced power of the engine using biodiesel fuel is due to the lower calorific value of biodiesel fuel. On average value, the engine power running on B10, B20, and B30 fuel decreases compared to ULSD by 1.08%, respectively; 2.16% and 3.00%. Meanwhile, the fuel consumption rate decreased respectively: 1.21%; 2.45% and 3.40%. 4.3.1.2. Torque characteristic The results in Figure 4.12 show that when the biofuel blending ratio increases, the engine torque tends to decrease. As the percentage of biodiesel blend was increased, the crank angle at which the maximum temperature occurred was delayed due to the influence of viscosity on fuel atomization. When a higher viscosity fuel is injected into the combustion chamber, the fuel droplets are larger, resulting in poor evaporation. 18
Torque (N.m) 315 305 ULSD 295 B50 285 B30 275 B20 B10 265 1000 1200 1400 1500 1600 1800 2000 Engine speed, rpm Figure 4. 12 Engine torque versus engine speed at 100% load as using different fuels 4.3.2. Economic characteristics 4.3.2.1 Specific fuel consumption ULSD B50 B30 B20 B10 280 consumption(g/kWh) 270 Specific fuel 260 250 240 Engine speed, rpm 230 1000 1200 1400 1500 1600 1800 2000 Figure 4. 13 Specific fuel consumption versus engine speed at 100% load as using different fuels Brake-specific fuel consumption (BSFC) can be calculated using engine torque, engine speed, and mass consumption rate of fuel. BSFC decreases with increasing engine load for all different tested fuels. For each test mode, the higher 19