Content of the project: - Overview of biodiesel fuel that used in Diesel engine - Modeling and simulating the diesel engine that uses renewable fuel - Analyze, evaluate and compare the e
OVERVIEW OF THE RESEARCH TOPIC
Reason for choosing the topic
The environment plays an important role in the life of humans as well as all other creatures on Earth Not only does it provide an ideal living environment, it also gives people resources to economic development, cultural, social Nowadays, environmental pollution has become a difficult problem not only in one country or one region but is a common concern of all humanity In the process of socio-economic development along with population growth in countries around the world, it has led to great impacts on the environment Specifically, global climate change, causing the greenhouse effect, ozone layer degradation, acid rain, etc More pollution is the emission of dust and toxic gases from the engines of motor vehicles This source of pollution greatly affects health, life and many other consequences that people must suffer, especially in large cities, where there is a high density of motor vehicles and population We cannot deny the important role that the internal combustion engine plays, it helps significantly increase human labor productivity, and is also the main driving force for the development of transportation, construction, and mining , … The fuel used by internal combustion engines is derived from petroleum - this is a non-renewable fossil fuel source The rapid increase in vehicles and equipment using internal combustion engines leads to increased exploitation, which leads to the depletion of this resource and increased carbon dioxide (CO2) emissions in the environment
Therefore, to make an important contribution to the mission of environmental protection, car manufacturers, in addition to improving engine features, fuel consumption, etc., need to focus on reducing the amount of emissions released into the environment outside To reduce harmful emissions, many engine manufacturers have been investing in research, from changing engine structures, treating exhaust gases with catalysts and replacing traditional fuels One of the effective solutions to solve this problem is to use alternative fuel sources, of which biofuel is considered the most potential fuel source because it is renewable and environmentally friendly.
Research goals and tasks
The research objective of the project is to learn the theoretical basis of conventional diesel engines switching to using biodiesel fuel with different concentrations Based on that research, AVL Boost software is applied to simulate an engine using biodiesel fuel
Evaluate the effectiveness of technical features and emissions of diesel engines when using biodiesel as an alternative fuel
The research task in the project "Research and application of AVL Boost to simulate diesel engines using biodiesel fuel" is to carry out the following contents:
• Theoretical basis of Biodiesel fuel
• Simulate engine model on AVL Boost software
• Application of AVL Boost to simulate Diesel engine using Biodiesel fuel
Object and scope of the study
- Research object: Engine model using Biodiesel on AVL Boost software
• Overview of the biofuel fuel
• Research using AVL Boost engine simulation software
• Evaluate the technical features of the engine
• Estimated emissions must be caused by the engine.
Research Methods
- Theoretical research method: Apply learned knowledge and collect and gather relevant documents, analyze and research to build a theoretical basis, taking it as the foundation for research
- Methods of looking up and searching for documents: Looking up and searching for documents on libraries, textbooks, the Internet
- Simulation method: Research and design a diesel engine model on AVL Boost software and at the same time use the technical specifications of the D4EB 2.2 L engine combined with the mixing of bio-gasoline fuel to simulate, Analyze and evaluate some results
- Method of consulting experts: Consult directly with the instructor - lecturers of HCMUTE
Layout of the topic
The research topic is divided into 5 chapters:
• Chapter 1: Overview of the research topic This chapter presents the following contents: reasons for choosing the topic, research objectives and tasks, research objects and scope, research methods and layout of the topic
• Chapter 2: Theoretical basis In this chapter, the first step is to learn an overview of biodiesel fuel, an overview of AVL Boost software, preparation methods, fuel standards, basic command blocks in AVL Boost, and main components in AVL Boost program, theoretical basis for selecting fire models for simulation
• Chapter 3: Build a diesel engine simulation model - Biodiesel on AVL Boost software In this chapter, we specifically simulate the D4EB engine using biodiesel fuel
• Chapter 4: Simulation results and discussion Present the results the group achieved after simulating on the software, then provide comments and evaluation
• Chapter 5: Conclusion and development direction This chapter summarizes the results of the research process, the goals achieved as well as the limitations encountered during the research process and proposes directions for development.
THEORETICAL OF THE BIODIESEL FUELS
Overview of Diesel engines
Figure 2.1 Four-stroke Diesel engine cycle
Developed in the 1890s by the German inventor Rudolph Diesel, the diesel engine has gained widespread recognition for its exceptional efficiency and durability Diesel engines are extensively utilized across numerous sectors, including automotive, industrial, marine, agricultural, and power generation applications
Automotive : Diesel engines power many types of vehicles, including cars, trucks, buses, and even some SUVs They are known for their torque, which makes them great for towing heavy loads or hauling cargo
Industrial: In industries such as construction, mining, and manufacturing, diesel engines are used to power heavy machinery like excavators, bulldozers, generators, and compressors Their robustness makes them ideal for rugged environments
Marine: Diesel engines are commonly found in boats and ships of all sizes, from small fishing boats to large cargo vessels and cruise ships They provide reliable power for propulsion and onboard systems, making them essential for marine transportation
Agricultural: In agriculture, diesel engines are used in tractors, combines, irrigation pumps, and other farm equipment Their efficiency and torque help farmers to efficiently manage large fields and heavy tasks like plowing and harvesting
Power Generation: Diesel generators are commonly used as backup power sources in hospitals, data centers, telecommunications facilities, and other critical infrastructure They provide reliable electricity during blackouts or when grid power is unavailable
2.1.1 Advantages and Challenges of diesel engines:
- Fuel Efficiency: Diesel engines typically achieve higher fuel efficiency compared to gasoline engines due to their higher compression ratios and thermodynamic efficiency
- Durability: Diesel engines are renowned for their robust construction and longevity, making them suitable for heavy-duty applications
- Performance: Diesel engines produce high torque at low engine speeds, making them ideal for towing and hauling tasks
- Versatility: Diesel engines find applications in a wide range of vehicles and equipment, including passenger cars, trucks, buses, ships, locomotives, and stationary power generators
- Emissions: Despite their efficiency, diesel engines can produce higher levels of nitrogen oxides (NOx) and particulate matter, necessitating stringent emissions control measures
- Noise and Vibration: Diesel engines tend to produce more noise and vibration compared to gasoline engines, although advancements in engineering have mitigated these issues to a significant extent
- Cold Weather Starting: Diesel engines may face challenges in starting in cold weather conditions due to the need for high compression ratios for ignition
In summary, diesel engines remain vital power sources across various industries due to their efficiency, durability, and versatility, albeit with ongoing efforts to address environmental concerns and improve performance.
Overview of Biofuels
2.2.1 Crucial need for exploring and using biofuels
In the contemporary era of industrialization, energy resources and fuels stand as paramount determinants shaping the economic and societal development of nations Concurrently with the socio-economic advancement, urbanization progresses rapidly, elevating human standards of living Consequently, there emerges an escalated global demand for transportation and transit, notably pronounced in developing nations The proliferation of vehicles contributes to an exponential rise in the utilization and consumption of fuels
Figure 2.6 Worldwide Fossil Fuel Consumption from 1965 to 2022
The resultant surge in vehicular density augments the aggregate demand for fossil fuels, thereby necessitating commensurate increments in extraction, refinement, and distribution infrastructures This heightened reliance on fossil fuels not only accentuates concerns pertaining to resource depletion but also exacerbates environmental degradation through heightened emissions of greenhouse gases and pollutants The confluence of these factors underscores the imperatives of cultivating sustainable energy paradigms and embracing alternative fuel sources
In response to the escalating demand for fuel, nations worldwide are intensifying their exploration and utilization of all available energy sources Among these, fossil fuels are being exploited and consumed excessively, leading to a state of gradual depletion of these non-renewable resources Moreover, the utilization of fossil fuels constitutes one of the primary causes of environmental pollution and global climate change, contributing to the phenomenon of global warming through the greenhouse effect It is evident that the emission of carbon dioxide (CO2) worldwide is substantial, as illustrated by the graph below
Figure 2.7 Annual CO2 Emissions Worldwide from 1965 to 2022
In light of these exigencies, the imperative of researching and integrating biofuels into the energy matrix assumes heightened significance Biofuels, derived from organic matter, offer a promising avenue for mitigating reliance on finite fossil fuel reserves while ameliorating environmental footprints The cultivation, refinement, and utilization of biofuels entail multifaceted considerations spanning agrarian practices, technological innovation, and policy formulation Moreover, the efficacy of biofuels hinges on intricate interdependencies encompassing economic viability, energy efficiency, and environmental sustainability
Biofuels, also known as “biocarburants” in French, are a class of fuels derived from compounds originating from plant or animal matter These fuels can be synthesized from vegetative animal fats (animal fats, coconut oil, etc.), from various grains (wheat, corn, soybeans, etc.), from agricultural waste (straw, manure, etc.), and from industrial waste products (sawdust, waste wood, etc.)
One notable characteristic of biofuels, in comparison to conventional fuels such as coal or petroleum, is their renewable nature They are derived from organic materials that can be replenished through natural processes, making them environmentally friendly alternatives Additionally, biofuels contribute to reducing dependency on non-renewable fossil fuels, thus mitigating concerns related to resource depletion and environmental degradation associated with their extraction and combustion
Biofuels represent a sustainable energy solution that aligns with the principles of environmental conservation and energy security By harnessing renewable resources and minimizing greenhouse gas emissions, biofuels play a crucial role in transitioning towards a more sustainable and resilient energy landscape
2.2.3 Advantages and Challenges of Biofuels:
- Enviromental Friendliness: Biofuels burn cleanly and completely, containing fewer harmful compounds and emitting lower levels of greenhouse gases (such as CO2,
CO, N2O) compared to traditional fuels This reduces environmental pollution significantly
- Renewable Fuel Source: Derived from agricultural, industrial, and forestry activities, biofuels are renewable resources that can be replenished, thereby reducing reliance on non-renewable traditional fuel sources
- Energy Security: The development of biofuels enables countries to be self-reliant and less dependent on imported fuels, particularly beneficial for nations lacking in oil and coal resources Furthermore, the growth of biofuels helps stabilize global energy markets amidst fluctuating oil prices
- Economic Stability in Rural Area: Production of biofuels, such as ethanol from cassava in Vietnam, provides a stable market for rural farmers, particularly in regions like Northwest and Central Highlands This ensures a steady income for farmers and encourages agricultural innovation and productivity enhancements
- High Technological Investment: Advanced biofuel production technologies require significant capital investment, posing challenges for slow-developing or developing countries in fostering biofuel development
- Storage and Preservation Challenges: Biofuels are more prone to degradation over time compared to traditional fuels, necessitating advanced storage and preservation methods, which can be more complex and costly
- Land Use Competition: If biofuels are derived from plant sources, they may require large agricultural land areas, potentially competing with food crops This competition can drive up food prices, posing threats to food security Additionally, plant- based production is heavily reliant on weather conditions and susceptible to diseases, leading to production intermittency during unfavorable conditions
- Biodiesel, a renewable liquid fuel, possesses properties similar to conventional diesel and can serve as a direct substitute for traditional diesel fuel
- It is derived from various sources of biological fats, predominantly vegetable oils and animal fats, through a process primarily involving transesterification with common alcohols like methanol
- The choice of feedstock for biodiesel production varies across regions based on climatic conditions and agricultural practices European countries primarily utilize soybeans, rapeseed (canola), and waste animal fats Meanwhile, Asian countries rely heavily on palm oil, sesame oil, sunflower seeds, soybeans, rubber seed oil, coconut oil, and various types of algae
- Biogasoline is a liquid fuel that incorporates ethanol as an additive into gasoline, replacing traditional lead additives It can fully substitute for gasoline containing lead additives
- Widely used globally, biogasoline is prominently supported in countries like the United States and Brazil through policies favoring ethanol-blended gasoline These countries primarily utilize ethanol produced from sugarcane and corn Additionally, Canada utilizes waste wood, sawdust, and by-products of wood processing, while Asian countries rely on ethanol produced from crops such as sugarcane, cassava, and coconut
- Biogas, composed mainly of methane and other equimolar gases, is generated through the anaerobic digestion of organic waste biomass, predominantly cellulose-rich materials
- Germany stands as a significant producer of biogas in Europe, primarily sourcing feedstock from post-harvest corn stalks Conversely, in Asia, most countries utilize animal waste and household waste as primary sources, including Vietnam, Thailand, and China.
Biodiesel
Biodiesel represents a clean-burning alternative fuel derived from renewable resources, primarily vegetable oils, animal fats, and greases Through a chemical process known as transesterification, natural oils and fats are reacted with an alcohol, resulting in the conversion of these feedstocks into fatty acid methyl esters (FAME), the molecules that constitute biodiesel It's important to note that biodiesel is distinct from pure vegetable oil and requires refining to achieve the desired properties for combustion in diesel engines
However, it's crucial to distinguish genuine biodiesel from alternative products that may not meet established quality standards Biodiesel must adhere to ASTM D6751 specifications, ensuring that it has undergone rigorous refinement processes to remove impurities and meets recognized quality parameters Proper certification is essential to qualify for tax credits and to guarantee compatibility with diesel engines
Table: 2.1 Biodiesel composition and properties are comparable to that of petro-diesel fuel:
- Density: Density of oil varies according to the nature of feedstock which influences the efficiency of fuel atomization
- Kinematic Viscosity: The viscosity of biodiesel is influenced primarily by the experimental conditions and the extent of the transesterification reaction Biodiesel have high viscosity will deteriorate the fuel atomization, vaporization and directly affects the engine combustion thereby reduces the efficiency
- Flash point: It is the temperature during which the fuel blows up to liberate heat energy Flash point of biodiesel is higher than the diesel For fuel safety in terms of storage, handling and transportation the flash point of fuel must have peak value
- Pour point: Ability to pour the fuel at lowest temperature is called pour point and at this point the fuel becomes semisolid and loses the ability to flow freely The impurities presented in the unpurified biodiesel will raise the cloud and pour points
- Cloud point: The fuel when formed as wax like crystals at a certain temperature pertaining to cooling surrounding is said to be cloud point temperature Cloud point is mainly used to determine the low temperature operability of biodiesel
- Calorific value: The calorific value indicates the amount of heat energy liberated out during complete combustion of a unit quantity of fuel The minimum heating value required for fuel is 35 MJ/kg
- Cetane number: the cetane number of diesel fuel plays a crucial role in determining engine performance, efficiency, emissions, and overall reliability Fuels with higher cetane numbers are favored for their superior combustion characteristics and their ability to enhance engine operation across a wide range of operating conditions
- Sulphur content: In the presence of a high level of sulfur in diesel fuel, progressive damage is caused to the engine of the machinery The main effect is corrosive wear, especially in the low temperature areas of the pistons and cylinder liners
Biodiesel has the versatility to be derived from over 300 varieties of both edible and non-edible vegetable oils The majority of these feedstocks exhibit a high biodiesel productivity owing to their elevated concentrations of triglycerides
Edible oils, derived from vegetable resources, are primarily utilized for direct human consumption due to their nutritional content and health benefits Common edible oil feedstocks for biodiesel production include palm oil, soybean oil, sunflower oil, rapeseed oil, and peanut oil These oils have high triglyceride concentrations, making them productive sources for biodiesel For instance, palm oil, a significant edible oil, is extracted from palm seeds and is utilized extensively in both food and industrial applications Similarly, soybean oil, known for its health advantages, is a major feedstock for biodiesel production, particularly in regions like the USA and Brazil Rapeseed oil, derived from yellow-flowered plants primarily in Europe and Canada, is another important feedstock known for its high productivity in biodiesel conversion
Non-edible oils, unsuitable for human consumption due to health concerns, find applications in various industrial sectors such as biofuels, soap, detergents, and paints Common non-edible oil feedstocks for biodiesel production include jatropha oil, castor oil, waste cooking oil, animal fat, and algae oil Jatropha oil, extracted from jatropha seeds, is particularly promising for biodiesel production in regions with elevated temperatures, such as Asia and Africa Castor oil, sourced from castor beans, exhibits distinct physical properties, including a low cloud and pour point, making it suitable for winter conditions Waste cooking oil, sourced from households and restaurants, is an economical and renewable alternative for biodiesel production, albeit requiring treatment to reduce free fatty acid content Animal fat, including animal tallow, offers a cost-effective raw material for biodiesel production, especially in regions where its use as animal feedstock is prohibited Algae oil, derived from various algae species, presents an innovative and economically viable option for biodiesel production due to its high oil content and ease of conversion through transesterification processes
Table 2.2 Comparison “Edible Oil” and “Non-edible” Oil
Feature Ediable Oil Non-edible Oil
Source Derived from vegetable sources such as oil seed grains and plant fruits
Comprised of vegetable oils, petroleum oils, or animal fat
Use Primarily intended for direct human
Utilized in the production of detergents, paints, soaps, fuels, and biofuels
Composition Contains various nutrional elements
Lack the healthiness and validity for human consumption
Oil Extraction Typically extracted without the need for chemical treatment
Requires different chemical treaments for extraction
Price Generally higher due to its use in food industries
Typically lower due to industrial applications and less demand
Example Soybean, sunflower, rapeseed, linseed, safflower, peanu
Castor, jatropha jojoba, used cooking oil, animal tallow
Biodiesel is a renewable and biodegradable fuel derived from organic sources such as vegetable oils, animal fats, and recycled cooking oils It can be used in diesel engines with little or no modification, offering a more sustainable alternative to traditional petroleum-based diesel The increasing demand for cleaner fuels has spurred significant research and development in biodiesel production technologies Each method for producing biodiesel has distinct advantages and challenges, influencing its suitability for different applications Here is an extensive overview of the main biodiesel production methods:
Transesterification is the most widely used method for producing biodiesel This process involves a chemical reaction between triglycerides (the primary components of fats and oils) and an alcohol (typically methanol or ethanol) in the presence of a catalyst (such as sodium hydroxide or potassium hydroxide) The reaction converts the triglycerides into methyl or ethyl esters (biodiesel) and glycerol
• Preparation: The feedstock, which can be vegetable oil, animal fat, or waste oil, is first filtered to remove impurities and water content This step is crucial as impurities can hinder the efficiency of the reaction and the quality of the biodiesel
• Reaction: The filtered feedstock is then mixed with the chosen alcohol and catalyst This mixture undergoes transesterification, where the triglycerides are converted into biodiesel and glycerol
• Separation: After the reaction is complete, the mixture separates into two layers: crude biodiesel and glycerol The separation is typically achieved through settling or centrifugation
Production processes of biodiesel from various sources
Figure 2.12 Overview of the biofuel productions from the Palm oil
Figure 2.13 Overview of the biofuel productions from the Microalgae
Figure 2.14.: Overview of the biofuel productions from the Soybean
Figure 2.15 Overview of the biofuel productions from the Waste Cooking Oil
2.4.1 Preliminary treatment of raw materials
The process of seed drying is crucial to ensure that the raw materials are devoid of moisture prior to oil extraction If the moisture content is not adequately reduced during the oil separation phase, it can negatively impact both the efficiency of the oil pressing procedure and the effectiveness of the ester translocation reaction necessary for biodiesel production By minimizing moisture, the seed drying process thus plays a vital role in optimizing the conditions for subsequent biodiesel synthesis
Figure 2.16 Process of using drying machine
The process of solvent extraction involves converting the crude oil present in raw materials into a solvent through molecular diffusion and counter-diffusion This method's core principle relies on using a solvent to attract and dissolve the oil constituents within the seeds Post-extraction, a rotary evaporator is employed to separate the solvent from the oil solution Several factors influence the effectiveness of the oil solvent extraction process, including the type of solvent used, separation temperature, solvent-to-material ratio, particle size of the raw material, and duration of extraction Common solvents for vegetable oil extraction are n-hexane and petroleum ether Experimental studies reveal that this extraction mechanism occurs in two stages Initially, the concentration of oil in the extraction solution rises rapidly because the solvent remains uncontaminated and in its pure state The subsequent stage of extraction progresses more slowly due to the outward diffusion of excess solute into the solution One significant advantage of the solvent extraction method is that it yields a relatively pure oil with minimal impurities, reducing the effort and cost associated with refining the raw oil However, this method has its drawbacks Achieving a high yield requires a lengthy extraction time, and the cost of extraction solvents is substantial Additionally, the amount of oil obtained per extraction cycle is relatively small, and the initial setup of the extraction system is expensive
There are various methods to extract oil from seeds, but the screw press method is prevalently used in industrial applications due to its simplicity, continuous operation, ease of use, and safety The primary components of a screw press machine include the feed hopper, intermediate storage compartment, screw, oil outlet, and residue outlet, along with engines and transmission systems The screw press's design must meet specific requirements to facilitate inspection and maintenance, such as ensuring easy lubrication of parts and allowing independent disassembly and installation of the drive unit and screw
The screw, which consists of a rotating shaft and screw blade, plays a crucial role in the pressing process The screw arm can be constructed by either cutting or welding multiple spiral segments, with each segment's length corresponding to one twist step Twisted wings are typically made using stamped wings During the pressing process, the seeds are subjected to gravity and the friction forces between the seeds, the screw blades, the screw shaft, and the inner wall of the press The screw blades and the screw's rotation facilitate the transportation of particles within the machine Increasing the screw blade thickness enhances the pressing force and pressure, thereby breaking the grain structure Pressure increases progressively throughout the pressing process, ranging from 40 to 350 bar depending on the type of machine and input material Some shaft presses are equipped with an additional oil filter underneath As the seeds pass through the press, the oil is expelled and flows through the filter screen, through the oil drain hole, and is collected by the array beneath the press The filter mesh size and shaft rotation speed may vary depending on the type of seeds processed
Pre-heating the seeds before pressing increases the flexibility of the oil molecules and reduces the clumping of the oil cake within the machine However, careful attention must be paid to the pre-heating process as it can affect the oil's quality Generally, the maximum temperature used is 60 degrees Celsius; temperatures higher than this can cause phosphorus compounds from the cell membrane to be expelled with the oil High phosphorus content can negatively impact the specifications of biodiesel fuel, leading to sludge formation and adhesion in the engine
2.4.2.3 Treatment of 'gum' in oil
The term "gum" denotes a complex amalgamation of various substances, encompassing phospholipids, impurities, and residual metal salts Primarily, its composition is dominated by phospholipids, which are derivatives of triglycerides These phospholipids form through the replacement of one of the three fatty acid radicals by a phosphoric acid radical, subsequently esterified by an alcohol containing an amino group
A minor portion of the gum comprises metallic ions and a sparse presence of other impurities Within the composition of phospholipids, the predominant constituents are phosphatidyl choline (PC) constituting approximately 60.5%, phosphatidyl inositol (PI) comprising around 24%, and phosphatidyl ethanolamine (PE) making up approximately 15.5%
In the process of preparing Jatropha curcas L oil for biodiesel production, the elimination of phospholipids is imperative during the gum removal phase The presence of phospholipids during the biodiesel reaction poses challenges in separating the biodiesel layer from the glycerine layer Hence, the removal of phospholipids holds significant economic value in biodiesel production endeavors
Phospholipids exhibit notable solubility in chloroform-methanol solutions while remaining insoluble in acetone The bonds formed between phosphoric acid and glycerol, as well as between phosphoric acid and other constituents such as inositol, exhibit stability in alkaline environments but are susceptible to hydrolysis under acidic conditions Notably, phospholipids exist in two forms: hydrated (HPL) and non-hydrated (NHPL), both of which can be effectively eliminated through degumming processes The majority of phospholipids present in crude oil are typically hydrated and can thus be removed via water degumming techniques
Characterized as amphiphilic compounds, phospholipids display dual hydrophilic and hydrophobic properties Upon dissolution in water, the formation of hydroxide groups renders them hydrophilic, thereby enhancing their solubility in water and facilitating their separation through centrifugation methods
Figure 2.19 "Gum" removal process diagram for Jatropha curcas L oil.
2.4.3 Process of ester translocation reaction performing
2.4.3.1 Factors influencing ester translocation reaction
The transesterification process is influenced by many different factors related to the reaction conditions used These effects include:
The influence exerted by free fatty acids and moisture levels is paramount in the transesterification process of vegetable oils Both the acid index and moisture content significantly impact the metabolic pathways of these oils during the transesterification process The use of a base catalyst necessitates that the free fatty acid index remains below 3% Elevated levels of acid index in the oil correspond to decreased conversion efficiency, with exceeding limits potentially resulting in insufficient base catalyst quantities for reaction and potential soap formation
In the initial stages, employing a base catalyst for the alcohol separation reaction is imperative Triglycerides possess a lower acidity index, and the constituent ingredients are typically not anhydrous However, excessive addition of NaOH to counteract acid neutralization may inadvertently lead to soap formation, thereby increasing viscosity or yielding gelatinous formations that impede glycerol separation Failure to adhere to the aforementioned conditions may result in substantial ester reduction
Maintaining methoxide and hydroxide of Na or K in an anhydrous state is crucial, necessitating precautions to prevent moisture infiltration Prolonged exposure to atmospheric air can inadvertently compromise catalyst efficacy due to interactions with water vapor and CO2 Thus, strategies to minimize catalyst exposure to atmospheric elements are vital for ensuring optimal transesterification outcomes Presently, the prevailing technique for biodiesel synthesis entails the utilization of methanol and a base catalyst to transform cooking oil However, a considerable volume of inferior-grade oils and fats is also subjected to biodiesel conversion A notable obstacle in this endeavor stems from the high concentration of free fatty acids inherent in these substandard oils and fats, impeding their efficient conversion into biodiesel via base reagents exclusively To surmount this challenge, a dual-stage transesterification methodology has been posited for botanical source materials
In this bifurcated process, the initial phase entails pre-acid catalysis, wherein free fatty acids are initially converted into fatty acid methyl esters Subsequently, in the second stage, the transesterification process is finalized via base catalysis to achieve comprehensive reaction completion Advances in this procedure were initially demonstrated through the synthesis of mixtures incorporating 20% and 40% free fatty acids, utilizing palmitic acid as a precursor Detailed elucidation of process parameters such as the alcohol-to-oil molar ratio, alcohol type, total acid catalysis, reaction duration, and free fatty acid index delineates a clear procedural roadmap for effecting the conversion of free fatty acids into utilizable esters Notably, the initial material's elevated acid index is attenuated to less than 1% in the inaugural stage The reaction blend is allowed to undergo settling intermissions between successive water removal steps
Demonstrations of biphasic reactions have been conducted using animal-derived fats, encompassing yellow fat exhibiting approximately 12% free fatty acids and fat with 33% free fatty acids Following the reduction of the oil's free fatty acid index to below 1%, the transesterification reaction culminates via base catalyst to engender biodiesel Triglycerides serve as the principal substrates for the transesterification process facilitated by base catalysis, yielding fatty acid alkyl esters that are extracted, while the glycerine phase is invariably generated during the transesterification of triglycerides ắ influence of catalyst type and concentration
Overview of AVL Boost Software
Table 2.3 Basic commands in AVL Boost
STT Biểu tượng Chức năng
2 Adjust the direction of the flow
3 Change the connection order between selected elements
4 Rotate the element counterclockwise by angle 90 0
6 Open the general control window
8 Enter parameters for the model
9 Set string parameters for the model
11 Show the instant page of the running model
12 See the summary of the model run
13 View messages from model run
14 View the results of running the model
AVL Boost uses elements in engine simulation and they are listed in table 3.2 below:
Table 2.4 Main elements in the program
Indicates traffic parameters and other gas conditions at any location in the pipeline
Enter parameters for elements that are difficult to determine determined.
Shows the correlation of the model Calculate with parameters set by the user.
Boundary conditions for exhaust gas treatment
Shows the correlation of the emissions analysis model with the due parameters user setup
Provide boundary conditions for model calculations.
Block the flow Indicates pressure loss at any location of the system in the pipeline.
Controls the air flow in the tube throttle opening.
Control the air flow in the tube according to the crankshaft rotation angle and time.
Check valve It is a pressure regulating valve to prevent backflow.
Injector Used for engines to form external gas mixture to supplement fuel and air in the intake system.
Connector element Used to connect 3 or more pipes In caseof 3 tubes, a new model arrives pipe connection element can be used.
This must take into account geometric parameters such as the area ratio of the connecting tubes or the connection angle between the tubes.
The element is stable in pressure and temperature.
Consider the change in volume and surface area of the pressure regulator over time.
The tube has perforations in the tube
One element represents 2 pipes One tube perforated inside and a tube outside
The instantaneous pressure loss is calculated from the pressure loss in a reference point at steady state
Catalyst kit The pressure loss in the catalyst must be defined according to a standard mass flow rate Its properties are determined from normative conditions and additional geometrical parameters The chemical reactions in the catalyst partly determine the characteristics and toxicity of the exhaust gas.
Air cooler The operation of an air cooler is similar to an air filter Pressure loss, cooling characteristics and steady state mass flow rates shall be defined according to normative values.
Used in diesel engine exhaust analysis mode, simulating toxic residues in engine exhaust.
The turbocharger element allows the use of both simple and filled models enough, highly complex.
2.5.2 Notes working with AVL BOOST
In order for Boost software's calculation results to be highly accurate and reliable as well as quick execution time, Boost software users need to pay attention to the following issues:
- Analyze engine structure before building the model
- Determine the number of elements for the model, the location of elements for the model
- Determine standard condition data, data for the general control part and separate elements in the model
- If possible, some results of the model should be tested experimentally.
Theoretical basis simulation AVL Boost software
Figure 2.21 Energy Balance of Cylinder
In an internal combustion engine, the combustion process is an irreversible process that converts chemical energy into heat energy Determining the state of the medium at each time of the process requires specific knowledge of the intermediate reactions that transform the initial mixture into the final combustion product Until now, such reactions have only been identified for simple fuels such as hydrogen and methane However, in all cases, we can use the first law of thermodynamics to determine the correlation between the initial and final states of the combustion process
The first law of thermodynamics shows the relationship between the change in internal energy (enthalpy) and the change in heat and work In an internal combustion engine, the combustion process is an irreversible process that converts chemical energy into heat energy To determine the states of the medium at each time of the process, it is necessary to specify the intermediate reactions that transform from the initial mixture to the final combustion product; however, we can determine the correlation Relationship between the initial and final states by applying the first law of thermodynamics
The calculation of the thermodynamic state of the cylinder is based on the first law of thermodynamics:
On the basis of energy balance in the engine cylinder, the change in the mass of refrigerant inside the cylinder is calculated as the total mass of refrigerant entering minus the mass of refrigerant leaving the cylinder
𝑑 : Change of the internal energy in the cylinder
𝑑 : Enthalpy flow due to blow-by
𝑚 𝑐 : Mass in the cylinder u: specific internal energy
𝑑𝑚 𝑖 : Mass element flowing into the cylinder
𝑑𝑚 𝑐 : Mass element flowing out of the cylinder
ℎ 𝑖 : Enthalpy of the in-flowing mass
ℎ 𝑐 : Enthalpy of the mass leaving the cylinder
𝑞 𝑒𝑣 : Evaporation heat of the fuel f: fraction of evaporation heat from the cylinder charge
This equation is used for both engine cases with the formation of a gas mixture inside and outside the cylinder However, for the mixture formation methods of the two cases are different
Regarding the process of forming the gas mixture inside the cylinder, we have the following assumptions:
- Fuel supplied to the cylinder is burned immediately
- Combustion products mix immediately with the gas entering the cylinder to form a homogeneous mixture
- The A/F ratio gradually decreases from the maximum value at the beginning of the combustion process to the final value at the end of the combustion process
Regarding the process of forming the gas mixture outside the cylinder, we have the following assumptions:
- The mixture is homogeneous at the beginning of the combustion process
- A/F ratio remains constant throughout the combustion process
- Combustible and non-flammable mixtures have the same temperature and pressure even though they have different ingredients
Solving the above equation depends on the combustion process model, heat dissipation law and heat transfer process through the cylinder wall, as well as pressure, temperature and gas mixture composition Along with the equation of state, establish the relationship between pressure and temperature
From Equation (2.1), use the Runge – Kutta method To determine the temperature inside the cylinder, the pressure will be determined through the state equation (2.3)
The mass flow rates at the intake and exhaust ports are calculated from the Equations for isentropic orifice flow under consideration of the flow efficiencies of the ports determined on the steady state flow test rig
From the energy Equation for steady state orifice flow, the Equation for the mass flow rates can be obtained:
(2.5) p2: downstream static pressure k: ratio of specific heats
𝑘+1 (2.6) The actual effective flow area can be determined from measured flow coefficients:
4 (2.7) 𝜇𝜎: flow coefficient of the port
𝑑 𝑣𝑖 : Inner valve seat diameter (reference diameter)
The flow coefficient varies with valve lift and is determined on a steady-state flow test rig The flow coefficient, 𝜇𝜎, represents the ratio between the actual measured mass flow rate at a certain pressure difference and the theoretical isentropic mass flow rate for the same boundary conditions The flow coefficient is related to the cross section area of the attached pipe
The inner valve seat diameter used for the definition of the normalized valve lift can be seen in the following figure:
Figure 2.22 Inner Valve Seat Diameter
The Mixing Controlled Combustion (MCC) model is utilized to predict the combustion characteristics in direct injection compression ignition engines
This model is appropriate for the chosen engine (D4EB), considers the effects of the premixed (PMC) and mixing (MCC) controlled combustion processes according to:
In this regime the heat release is a function of the fuel quantity available (f1) and the turbulent kinetic energy density (f2):
𝑄 𝑀𝐶𝐶 : Cumulative heat release for the mixture controlled combustion [kJ]
𝐶 𝐶𝑜𝑚𝑏 : Combustion constant [kJ/kg/deg CA]
K: local density of turbulent kinetic energy [m2/s2]
𝑚 𝐹 : Vaporized fuel mass (actual) [kg]
LCV: lower heating value [kJ/kg]
𝑂𝑥𝑦𝑔𝑒𝑛,𝑎𝑣𝑎𝑖𝑙𝑎𝑏𝑙𝑒: Mass fraction of available Oxygen (aspirated and in EGR) at SOI [-]
Conservation equation for the kinetic energy of the fuel jet:
Since the distribution of squish and swirl to the kinetic energy are relatively small, only the kinetic energy input from the fuel spray is taken into account The amount of kinetic energy imparted to the cylinder charge is determined by the injection rate (first term on RHS) The dissipation is considered as proportional to the kinetic energy (second term on RHS) giving: for "Revised" TKE calculation:
𝑚 𝐹,𝐼 (1+𝜆 𝐷𝑖𝑓𝑓 𝑚 𝑠𝑡𝑜𝑖𝑐ℎ ) For "Default" TKE calculation (this is an older status of the model):
𝑚 𝑠𝑡𝑜𝑖𝑐ℎ : Stoichiometric mass of fresh charge [kg/kg]
𝜆 𝐷𝑖𝑓𝑓 : Air Excess Ratio for diffusion burning [-]
The ignition delay is calculated using the Andree and Pachernegg 1 model by solving the following differential equation:
As soon as the ignition delay integral 𝐼 𝑖𝑑 reaches a value of 1.0 (= at 𝛼 𝑖𝑑 ) at the ignition delay 𝜏 𝑖𝑑 is calculated from𝜏 𝑖𝑑 = 𝛼 𝑖𝑑 − 𝛼 𝑆𝑂𝐼
𝑄 𝑟𝑒𝑓 : Reference activation energy, f (droplet diameter, oxygen content, ) [K]
𝛼 𝑆𝑂𝐼 : start of injection timing [degCA].
A Vibe function is used to describe the actual heat release due to the premixed combustion:
𝑄 𝑃𝑀𝐶 : Total fuel heat input for the premixed combustion = 𝑚 𝑓𝑢𝑒𝑙,𝑖𝑑 𝐶 𝑃𝑀𝐶
𝑚 𝑓𝑢𝑒𝑙,𝑖𝑑 : Total amount of fuel injected during the ignition delay phase
Droplet heat-up and evaporation model:
According to Sitkei 39 the equilibrium temperature for the droplet evaporation can be calculated iteratively from:
2.15) Using the equilibrium temperature the velocity of the evaporation results from:
The value of 0.70353 can be changed through user input (expert parameters) Finally the change in droplet diameter (and the corresponding change in droplet mass) over time can be calculated:
𝜆 𝑐 : Thermal conductivity of the cylinder [W/ms]
𝑇 𝑑 : Equilibrium temperature of the isothermal droplet evaporation [K]
𝑝 𝑐 : Pressure in the cylinder [Pa]
The heat transfer to the walls of the combustion chamber, i.e the cylinder head, the piston, and the cylinder liner, is calculated from:
𝑄 𝑖 : Wall heat flow (cylinder head, piston, liner).
𝐴 𝑖 : Surface area (cylinder head, piston, liner)
𝑇 𝑐 : Gas temperature in the cylinder
𝑇 𝑖 : Wall temperature (cylinder head, piston, liner)
In the case of the liner wall temperature, the axial temperature variation between the piston TDC and BDC position is taken into account:
𝑇 𝐿 1 𝑇𝐷𝐶 : Liner temperature at TDC position
𝑇 𝐿 1 𝐵𝐷𝐶 : Liner temperature at BDC position
𝑋: Relative stroke (actual piston position related to full stroke)
The heat transfer coefficient can be calculated using one of the following models:
Woschni 1978, Woschni 1990, Hohenberg, Lorenz (only used for engines with separated combustion chambers), AVL 2000 Model, Bargende Among them, the Woschni heat transfer model published in 1978 is often used in research
The Woschni model published in 1978 48 for the high pressure cycle is summarized as follows:
𝑝 𝑐 1 𝑜 Cylinder pressure of the motored engine [bar]
𝑇 𝑐 1 𝑜 Temperature in the cylinder at intake valve closing (IVC).
DIESEL ENGINE D4EB MODELING
Simulation research object
The student group selected the D4EB diesel engine utilized in the Hyundai Santa Fe (CM) (2007-2009) SUV model.Hyundai Santa Fe diesel engines are widely regarded as some of the best common rail engines globally
The engine in the Hyundai Santa Fe is a front-wheel drive (FWWD) 2.2-liter, 4- cylinder, single overhead cam (SOHC) diesel engine The key technical parameters of the engine are outlined in the following table
Table 3.1 Technical specifications of D4EB engine (Hyundai SantaFe)
No.1 Specifications Symbol Value Units
8 Max Power at 4000 rpm Pmax 114 kW
9 Max Torque at (1800 – 2500) rpm Tmax 335 N.m
Engine simulation model built
To simulate the engine, two main stages are needed: model building and calibrate the model The process of building a simulation model from a real engine on AVL software goes through the following steps:
Important and indispensable elements in the model include: Engine, Cylinder, Air cleaner (air filter), Injector, Plenum (pressure stabilizer), Restriction (resistance element), Pipe (connecting pipe) and System Boundary (lip elements field) The location of the above elements is on the left side of the main screen interface in the "Components" window To use, you need to double click on the elements' icons, then they will appear on the screen The main elements used in the D4EB engine simulation model are as shown below
Figure 3.1 Main elements used for D4EB engine simulationThe number of elements used in the simulation model is shown in the following table
Table 3.2 Number of elements used in the simulation model.
After selecting the necessary elements for building the simulation model, arrange the appropriate positions for the elements, followed by building the model The essence of
"model building" is to link elements together through the "Pipe" pipe element Icons of various types of pipes can be found in the first position on the left of the toolbar, depending on the purpose of use, make the appropriate choice
To build an initial simulation model without entering data of the D4EB engine as shown in Figure 3.4 below, by connecting the elements with pipes
Figure 3.2 Simulation model without data input
3.2.3 Engine Model Setup: Data Input and Configuration
The first step is to configure the simulation settings Navigate to the menu bar, then select 'Simulation' followed by 'Control'
Choose simulation tasks based on the purpose of the simulation Depending on the new tasks, at least one of the following should be selected before starting with the model:
Cycle Simulation: Gas exchange and combustion BOOST™ calculation
Aftertreatment Analysis: Simulation of chemical and physical processes for aftertreatment devices
Linear Acoustics: Frequency domain solver to predict the acoustic performance of components
The next step involves setting up "Cycle Simulation," specifically deciding on the species transport mode There are two options available: "classic mode" and "general mode." By default, the classic mode is selected, but it's important to justify this choice over the general mode The classic mode is preferred because in the general mode, users need to define their own fuel data This includes specifying the number and type of chemical species, as well as the composition of the fuel in terms of these species' numbers, types, and ratios This process demands significant effort, although it ultimately yields the same results as the classic mode However, for professional purposes, one may choose the general mode despite the additional workload it entails
In Figure 3.8, the "Non-Engine Application" option is unavailable, indicating that the
"Engine elements" are already integrated into our model
In steady-state simulations, it's vital to select a sufficiently long interval to ensure stable calculation results Using a multiple of the cycle duration is recommended The duration required to achieve stable conditions varies depending on the engine configuration
Figure 3.7 Classis Species Setup subgroup
Figure 3.10 illustrates the configuration of fuel properties The "User-defined fuel" option is selected to define a range of biodiesel ratios in the fuel mixture using the "Boost Gas Properties Tool." Fuel combustion properties are automatically calculated and updated upon applying new fuel in the "Boost Gas Properties Data File."
In the "Gas Property Generator," add biodiesel (defining its properties) and diesel, and choose the fraction ratio type as "Liquid volume fraction." In the "Fraction ratio [(-)]" field, specify the ratio of biodiesel to diesel In Figure 3.11, the mixture contains 0% biodiesel, indicating it is pure diesel Diesel serves as the standard fuel, and biodiesel needs definition according to Table 3.12 to complete the fuel setup Following this, a series of fraction ratios between biodiesel and diesel, such as B10, B20, B50, etc., are created
In "Cycle Simulation," select "Initialization" to set the initial condition parameters for the simulation process, including: Pressure, Gas Temperature, Combustion Product,
Figure 3.10 Initialization settings for Cycle Simulation
These values are set as global parameters to configure the initialization of pipes and system boundaries, and so forth, for further customization
Figure 3.11 Engine Icon Table 3.3 Setting parameters for engine element (Engine)
In the engine element we need to set the parameters: Engine Speed (speed engine), Cycle Type (engine type), Firing Order (engine firing order), definitions mechanical loss of the engine in the “Engine Friction” section
"Engine speed" is set as the global parameter to control the case setup in the simulation run steps The following figure illustrates how to configure a global variable.
Figure 3.13 Assign global parameter “Engine Speed”
Next, set the firing order of engine to 1-3-4-2 Select the option "Identical Cylinder" to synchronize all four cylinders
Select "Friction[1]" and set its value according to Table 3.3
The cylinder element is the most crucial part of the engine model Setting the correct parameters for it is essential; if any parameter is incorrect, the entire model will not function properly
The basic parameters are taken from Table 3.2 Sections such as "User-defined Piston Motion" and "Chamber Attachment" are not selected "User-defined Piston Motion" is used for specifying unconventional motions, while "Chamber Attachment" is utilized for engines with divided combustion chambers However, since the focus of the engine model is on the fuel's effect on performance and emissions, and it is a direct injection engine, these options are not applicable The perfect mixing model is the standard scavenging model for the simulation of 4-stroke engines
Setting up and selecting the combustion model for a direct injection compression ignition engine The suitable combustion model is the AVL MCC model The model considers the effects of the premixed (PMC) and diffusion (MCC) controlled combustion processes
Figure 3.19 AVL MCC Model setup
- "Physical Properties" are set according to the user manual of the common rail system "Normalized Model Parameters" are left as default "Rate of Injection" uses a normalized injection rate
Figure 3.20 Normalized Rate of Injection Input
Heat transfer in the combustion chamber is calculated according to available researched models AVL Boost provides users with many heat transfer models such as: Woschni 1978, Woschni 1990, Hohenberg, Lorenz 1978, 1990 or AVL 2000 In According, the Woschni 1978 heat transfer model is quite commonly used in research The parameters in the model that need to be determined such as the area and temperature of the piston and cylinder, the team has researched and calculated, are shown specifically in Figure 3.23
Figure 3.21 Heat Transfer model parameters
The cylinder head surface area is approximately equal to the bore area, and the piston surface area is the cylinder head area multiplied by (1.4-16), according to the AVL Boost user manual The liner surface area is calculated from an estimated piston-to-head clearance multiplied by the circumference of the cylinder
- Valve port Specification : Set parameters for the main mixing system is to set data for “Intake Valves” and “Exhaust Valves” (exhaust valve), specifically as shown in Figure 3.18 and Figure 3.19
Figure 3.23 Geometric dimensions of the intake valve
Figure 3.24 Geometric dimensions of exhaust valve
D4EB Engines equipped with 8 intake valves and 8 exhaust valves, the valve parameters have been learned and calculated from the actual engine model For more details, please refer to Appendix 2.1
In addition to setting the valve geometry, the drag coefficient must be determined Determine the valve lift degree according to the crankshaft rotation angle, early opening and late closing angle of the valve, flow coefficient, etc
Calculated data information of the intake and exhaust valves is shown in detail in Appendix 2.2
Figure 3.25 Parameters of Intake Valves in the air conditioning system
Figure 3.26 Information of exhaust valves in the air distribution system
On the intake manifold, an air filter is located, determined by the data in the table 3.12 below
Figure 3.27 Air filter element setup
Figure 3.28 Air filter element setup
Figure 3.29 Air filter element setup
Table 3.4 Air cleaner element parameters (Air cleaner)
Length of Filter Element 200 mm
AVL Boost allows the Plenum element to be used as a voltage regulator element to represent the intake manifold Because, on the intake pipe there is also a plastic intake manifold, which improves the temperature and volume of intake air, reducing heat transfer from the engine cover The long intake manifold branches optimize the shape of the intake manifold combined with the spiral shape of the intake manifold to create a fluid flow effect that increases the amount of intake air per cycle, which helps improve torque and power emitted when the engine runs at low and medium speeds Besides, the diameter of the intake manifold is designed to be large (dR mm), which reduces the drag coefficient for the intake manifold
Setting parameters for the Plenum element is detailed in Appendix 1.3, it is important to ensure the following factors:
• Gas temperature (gas mixture temperature)
• Combustion Products (fire products) Ratio Type (ratio between air and fuel)
3.2.4.5 System Boundary element (Boundary conditions)
SIMULATION RESULTS AND DISCUSSION
Evaluate simulation results compared to experiment
Actual testing of the D4EB engine at the engine laboratory is difficult to conduct due to limited equipment, so to evaluate the model simulation results relative to the experiment, the research team used Use the S.R Lay Decman formula to build power and torque based on the number of revolutions and proven experimental coefficients
𝑃 𝑒 , 𝑛 𝑒 - The effective power of the engine and engine speed correspond
𝑃 𝑒𝑚𝑎𝑥 , 𝑛 𝑒 𝑝 - Maximum effective power and engine speed correspond
𝑇 𝑒 - The effective toque of the engine
𝑇 𝑛𝑚𝑎𝑥 – The effective torque at maximum engine speed
𝑛 𝑇𝑚𝑎𝑥 – The engine speed at maximum torque
Finally, we obtain a = 1, b = 0.925, c = 0.925 for the given engine specifications Below are the model simulation results compared to the relative experimental results presented in table 4.1
Table 4.1 Simulated running power and torque compared to experiment
Simulation Experiment Error Simulation Experiment Error
Based on the results from the table above, the simulation outcomes appear to be relatively reliable, with the maximum error being 7.87% Below is a chart detailing the deviations across the corresponding engine speed ranges
Figure 4.1 Power comparision between S.R Lay Decman formula and AVL Boost model
Figure 4.2 Torque comparison between S.R Lay Decman formula and AVL Boost model.
Engine Performance
In-cylinder pressure serves as a key indicator for combustion characteristics and heat release in diesel engines It is particularly dependent on the combustion rate during the premixed stage.
Figure 4.3 In-cylinder pressure with different blended ratio of biodiesel
Analysis of the results depicted in Figure 4 reveals that diesel exhibits notably higher in-cylinder pressure in contrast to biodiesel-diesel blended fuels This discrepancy can be attributed to the inherent characteristics of biodiesel, characterized by its lower calorific value alongside higher viscosity and density These properties contribute to the formation of larger fuel droplets, impeding the formation of a homogeneous air-fuel mixture and subsequently hindering combustion efficiency Consequently, the incomplete combustion process leads to reduced cylinder pressure in engines utilizing biodiesel
The engine power is a crucial factor for comparison and evaluation purposes The graph presented below illustrates simulation results conducted using AVL Boost software according to predefined explorer cases Subsequently, data were aggregated, resulting in the following:
Figure 4.4 Effective power results data of the D4EB engine model with various biodiesel blend ratios
Table 4.2 Effective Power Data (Numerical Format)
RPM B100 (kW) B50 (kW) B20 (kW) B10(kW) DIESEL(kW)
Table 4.3 Percentage deviation in Power of different Biodiesel blend ratios compared to pure
Based on the presented graphs and tables, it can be summarized that the engine power exhibits an inverse relationship with the proportion of biodiesel blended into the fuel The reduction in power is negligible when using B5 However, for B100, the average power decrease exceeds 11% across all speed ranges
The decline in power with increasing biodiesel proportions can be attributed to several factors Firstly, biodiesel possesses a lower calorific value compared to petroleum diesel, leading to a reduction in the energy content available for combustion Additionally, the heightened viscosity of biodiesel adversely impacts the atomization process during combustion, impeding the efficient mixing of fuel and air Consequently, this hinders heat release within the engine, culminating in decreased power output
As power decreases with higher biodiesel content, engine torque also declines due to compromised combustion Therefore, the torque graph likely decreases as biodiesel percentage increases in the fuel blend
Figure 4.5 Effective Torque results data of the D4EB engine model with various biodiesel blend ratios
Table 4.4 Effective Torque Data (Numerical Format)
Table 4.5 Percentage deviation in Torque of different Biodiesel blend ratios compared to pure
From the above data, it's evident that the deviation in torque is quite significant when using B100 (approximately 13.34% at 4000 rpm), whereas for B10 and B20, the average deviation ranges from 1-2%, which is relatively minimal compared to engines using traditional fuels
In summary, regarding engine performance, it can be observed that B10 and B20 are two feasible blend ratios for diesel engines, disregarding emission characteristics
The fuel consumption of the engine simulated below was determined by the research team opting for internal fueling Thus, the fuel blending ratios were not explicitly depicted, but to some extent, they reflect the influence of various blend ratios
The deviation of Brake Specific Fuel Consumption (BFSC) for B10, B20, B50, B100, and diesel is depicted in Figure xx It is evident that different biodiesel blends exhibit higher BSFC than diesel This can be attributed to the blends' higher viscosity and poor volatility (Table nào mà có cái nhiên liệu đặc tính á), leading to inadequate atomization and mixture formation during combustion Specifically, the BSFC for pure biodiesel (B100) is higher compared to that of a 20% biodiesel blend (B20) This is primarily because pure biodiesel has a lower heating value, necessitating a greater fuel quantity to maintain the engine's power output at the same level
Among the various biodiesel blends, B20 demonstrated a lower BSFC compared to other blends, closely resembling diesel fuel
Figure 4.6 Brake Specific Fuel Consumption of the D4EB engine model with various biodiesel blend ratios
Table 4.6 BFSC Data (Numerical Format)
RPM B100(g/kWh) B50(g/kWh) B20(g/kWh) B10(g/kWh) Diesel(g/kWh)
Table 4.7 Percentage deviation in BFSC of different Biodiesel blend ratios compared to pure
In general, the trend shows that as the proportion of biodiesel in the blends increases, fuel consumption also proportionally rises, reaching approximately 12.5% at its highest level The fuel consumption ratio significantly impacts the economic viability and is a decisive factor in considering the feasibility of biodiesel utilization.
Emissions
Figure 4.6 Nox emssions of the D4EB engine model with various biodiesel blend ratios
NOx emissions escalate in direct proportion to the concentration of biodiesel in the blend, peaking with B100 (Fig 3) The emission of NOx primarily hinges on factors such as the total oxygen content within the combustion chamber, as well as parameters like
B100 B50 B20 B10 Diesel temperature, pressure, compressibility, and sound velocity Since all biodiesel variants inherently contain oxygen bound to their chemical structures, this could prompt the formation of NOx Furthermore, as biodiesel serves as an oxygenated fuel, it introduces additional oxygen into the combustion chamber alongside the air, potentially exacerbating NOx formation Additionally, the improved combustion efficiency associated with biodiesel, characterized by a greater portion of combustion occurring prior to TDC due to reduced ignition delay, maybe lead to higher combustion temperatures, futher amplifying NOx emissions
Figure 4.7 CO emissions of the D4EB engine model with various biodiesel blend ratios
Table 4.8 CO emissions data (Numerical Format)
RPM B100(g/kWh) B50(g/kWh) B20(g/kWh) B10(g/kWh) Diesel(g/kWh)
The observed decrease in CO emissions from biodiesel and its blends can be primarily attributed to the additional oxygen content in the fuel, which significantly enhances combustion within the engine cylinder This improved combustion efficiency is a key factor in reducing CO emissions Moreover, biodiesel possesses a higher cetane number compared to conventional diesel fuel A higher cetane number indicates better ignition quality, which helps in reducing the formation of fuel-rich zones that are prone to incomplete combustion and, consequently, higher CO emissions
In addition to its higher cetane number, biodiesel is less compressible than diesel fuel This lower compressibility results in earlier fuel injection, which leads to a longer combustion duration The advanced injection timing associated with biodiesel further contributes to more efficient combustion A shorter ignition delay, due to the high cetane number, allows for a longer period during which the fuel can combust completely, thereby increasing the regions of complete combustion reactions
Figure 4.8 SOOT emissions of the D4EB engine model with various biodiesel blend ratios
Table 4.9 SOOT emissions Data (Numerical Format)
RPM B100(g/kWh) B50(g/kWh) B20(g/kWh) B10(g/kWh) Diesel(g/kWh)
Soot is produced as a result of incomplete combustion The oxygen content in B100 and its blends with diesel fuel can enhance combustion efficiency, leading to a reduction in soot opacity compared to petro-diesel Biodiesel introduces additional oxygen into the combustion chamber along with the air intake, which improves the combustion process Furthermore, biodiesel typically has a higher cetane number, resulting in a shorter ignition delay This shorter delay allows for a more complete combustion of the fuel, thereby further reducing soot formation.
CONCLUSIONS AND DEVELOPMENT DIRECTIONS
Conclusions
The primary aim of this study is to illustrate the construction of an internal combustion engine model that uses biodiesel fuel with varying blending ratios Specifically, the research presents foundational knowledge about fossil fuels and their environmental pollution issues, as well as the benefits and characteristics of biofuels Furthermore, the study utilizes AVL Boost software to analyze and evaluate the technical performance of the engine and its emissions After conducting this research, the student team has accomplished several key outcomes:
- Overview of Biofuels and Vehicles: This section emphasizes the urgency of researching and adopting green fuels It provides a comprehensive overview of the production origins of biodiesel and details the basic concepts and characteristics of vehicles equipped to use flexible fuel systems
- AVL Boost Software and Engine Simulation: The software is introduced, including its applications, basic features, and the functions of common components Detailed steps for constructing the simulation model and setting parameters based on actual engine data are presented
- Blending and Using Biodiesel Fuel: This section outlines the process of blending biodiesel at different ratios and running simulations on the D4EB engine model It includes analysis and evaluation of the engine's technical performance and the impact of emissions on the environment
After extensive research and the development of an engine simulation model using biodiesel at various blending ratios, the student group presents the following evaluations and conclusions, along with necessary considerations for implementing biofuel use in engines:
Engine Characteristics: When utilizing biodiesel fuel, both torque and power experience reductions, while specific fuel consumption increases from B0 to B100 Biodiesel with a low percentage causes minimal reductions in power and torque For instance, using B10 and B20 results in power reductions of 1.34% and 2.8%, and torque reductions of 1.35% and 2.81%, respectively, compared to traditional diesel fuel However, higher biodiesel percentages (B50 and B100) lead to significant reductions in power and torque across the speed range of 1000–4000 RPM Specifically, the average power reduction for B50 is 5.5%, and for B100, it is 12.3% The average torque reduction for B50 is 7.96%, and for B100, it is 11.5% Regarding fuel consumption, the use of biodiesel results in increased specific fuel consumption as the concentration rises (E20 increases by 3%, B100 increases by 12.5% compared to traditional diesel fuel)
Emissions Characteristics: When using biodiesel with higher concentrations, emissions of CO and soot decrease across the entire speed range compared to diesel fuel However, NOx values tend to increase with higher biodiesel concentrations, although the increments become less significant at higher concentrations
It is important to note that engines using biodiesel with low concentrations do not require modifications However, when using biodiesel with concentrations exceeding 20%, it is necessary to adjust factors such as fuel supply, advanced injection timing, and engine material structure to suit the biodiesel ratio in the fuel blend These adjustments ensure engine longevity and maintain technical performance
In summary, the use of biodiesel fuel at appropriate ratios can balance economic and technical factors while reducing environmental pollution B20 is identified as the most suitable blend, offering minor changes in power (1-2%) compared to traditional engines, requiring no engine modifications, and reducing CO and soot emissions with acceptable NOx levels
A limitation of this research is that it was conducted solely through computer simulations using software, without real-world testing on vehicles to validate the simulation results Consequently, the research outcomes are relatively preliminary and provide a directional insight into the use of biodiesel fuel in internal combustion engines.
Development Directions
Based on the achieved results, new development directions are proposed for further research that the group has not been able to undertake due to various constraints The suggested development directions include:
- Researching New Additives: Investigate blending new additives to enhance the effectiveness of using high-ratio biodiesel without the need for engine modifications
- Improving Engine Model: From the completed engine simulation model, continue research to improve technical performance and accurately calculate emissions for better environmental compliance
- Reducing NOx Emissions and Fuel Consumption: Focus on reducing NOx emissions and fuel consumption when using high-ratio biodiesel blends
- Adjusting Fuel Supply and Ignition Timing: Study the effects of adjusting the fuel supply and ignition timing to suit different fuel types
- Assessing Engine Longevity: Investigate the impact of using biodiesel on the longevity of traditional engines and propose engine modifications to accommodate various fuel types effectively
In conclusion, further research and development in these directions can enhance the viability of biodiesel as a sustainable alternative fuel, balancing performance, economic feasibility, and environmental benefits The proposed areas for future study aim to address the current limitations and optimize the use of biodiesel in internal combustion engines, thereby promoting a cleaner and more efficient energy source for the automotive industry
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Service Manual Hyundai Santafe D4EB
APPENDIX APPENDIX 1 ADDITIONAL SPECIFICATIONS OF SIMULATION
Appendix 1.3 Friction coefficient value according to material and pipe
APPENDIX 2 CALCULATION OF PARAMETERS RELATED TO VALVE Appendix 2.1 How to calculate the Scale Factor in the valve model
Multi-valve model and how to calculate the Scale Factor
- Intake valve diameter is 28.5 mm
- Exhaust valve diameter is 24.4 mm
Appendix 2.2 How to calculate valve lift parameters
Appendix 2.2.1 How to calculate valve lift
The lift of the intake and exhaust valves is determined by the following formula:
L: the valve lift at the opening angle cr
𝑳 𝒎𝒂𝒙 : The maximum lift of the valve
𝒄𝒓 : The instantaneous rotation angle of the crankshaft
𝒐𝒑 : The valve angle begins to open
𝒄𝒍 : The valve angle begins to close
Appendix 2.2.2 Intake valve lift table
No.1 Angle (degree) Lift(mm)
Appendix 2.2.3 Exhaust valve lift table
No.1 Angle (degree) Lift (mm)