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Article

The Effect of Bioalcohol Additives on Biofuel Diesel Engines

by
Chengfang Mao
1,2,
Jiewen Wei
3,
Wangsheng Lan
4 and
Ananchai Ukaew
1,*
1
Faculty of Engineering, Naresuan University, 99 Moo 9 Tapoe Maung, Phitsanulok 65000, Thailand
2
School of Mechanical and Automotive Engineering, Guangxi University of Science and Technology, Liuzhou 545006, China
3
Guangxi Kangsheng Meat Products Co., Ltd., Liuzhou 545000, China
4
Liuzhou Weilan Technology Co., Ltd., Liuzhou 545000, China
*
Author to whom correspondence should be addressed.
Fire 2024, 7(11), 404; https://doi.org/10.3390/fire7110404
Submission received: 7 October 2024 / Revised: 30 October 2024 / Accepted: 31 October 2024 / Published: 4 November 2024
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Abstract

This study experimentally investigated a water-cooled four-cylinder turbocharged diesel engine (DE) under different loads and fuel blend ratios. The integration of Computational Fluid Dynamics (CFD) simulations enables a deeper analysis of the combustion process. Through an in-depth analysis of the combustion process, the focus was placed on investigating the specific impacts of ethanol and n-butanol additives on diesel engine performance. Research shows that a fuel mixture consisting of 70% diesel, 10% biodiesel, and 20% ethanol reduced NOx emissions by 5.56% compared to pure diesel at 75% load. Furthermore, this study explores the combustion performance of diesel/biodiesel blended with butanol/ethanol. The findings indicate that n-butanol improves thermal efficiency, particularly at 100% load, with the D70B10E20 and D70B10BU20 blends demonstrating thermal efficiencies of 9.94%and 8.72% higher than that of diesel alone, respectively. All mixed fuels exhibited reduced hydrocarbon and CO emissions under different loads, with a notable reduction in hydrocarbon emissions of 34.4% to 46.1% at 75% load.

1. Introduction

Fossil fuels have been crucial in shaping and advancing human society for centuries, fundamentally driving economic development and technological innovation. The widespread use of energy sources such as coal, oil, and natural gas has triggered revolutionary changes in industry, transportation, agriculture, and lifestyle [1,2].
With the intensification of modernization and industrialization, global energy demand has surged rapidly. Many developing countries face difficulties in meeting their growing energy needs through crude oil imports, leading to an increasingly severe shortage of oil. Beyond concerns about the energy crisis, another pressing issue today is environmental degradation from the combustion of fossil fuels. The findings suggested that SO2 exacerbated the atmospheric greenhouse effect, with nitrogen oxides being recognized as a major pollutant. The environmental impacts of nitrogen oxides include ozone layer depletion, acid rain, smog, and the greenhouse effect resulting from their emissions. Additionally, high particulate-density exposure to these gases poses numerous health risks to humans [3]. Carbon dioxide emissions precipitate global warming, causing rising sea levels and increased frequency of extreme weather events. To confine the global average temperature rise to 2 °C, it is crucial to reduce global greenhouse gas emissions by 40% to 70% compared to 2021 levels by 2025 [4].
To address these issues, scientists are working on efficiently extracting fuels from renewable energy sources. A study was conducted exploring the technology for the simultaneous extraction of oil and in situ transesterification from oil-bearing raw materials in biodiesel production [5]. Another study investigated the methods for extracting biodiesel from algae [6]. Y. R. Shah and D. J. Sen conducted a survey into the production processes of bioalcohols [7].
Among all renewable fuels, biodiesel is deemed an ideal candidate for diesel engines as it requires no modifications to existing engine structures or driving habits. Additionally, biodiesel is oxygenated, non-toxic, biodegradable, and environmentally friendly [8,9].
However, due to its higher viscosity, pure biodiesel can increase NOx emissions by approximately 10–13%, with a significant portion being nitrogen oxides and nitrogen dioxide, which are considered harmful to the ozone layer [10]. To meet the stringent emission criteria for light-duty and heavy-duty diesel engines, many researchers have studied the formation mechanisms, control strategies, and methods for reducing NOx emissions in biodiesel engines. Sudalaiyandi K, K. Alagar, V. Kumar R, Manoj P.V.J, Madhu P [10] investigated a ternary blend of flaxseed oil, rubber seed oil, and diesel fuel in a one-cylinder water-cooled DE. Their study found that B5 and B10 blends could reduce emissions while maintaining the same performance as diesel. Y. Zhong, Y. Zhang, C. Mao, and A. Ukaew [11] propose that, under full load conditions, EE20 can reduce NOx emissions by 29.32% and CO emissions by 39.57% [12,13]. C. D. Rakopoulos, A. M. Dimaratos, E. G. Giakoumis, and D.C. Rakopoulos [14] concluded that the soot value of the biodiesel and n-butanol blend was 38.5% lower than that of D100. L. Wei a, C.S. Cheung a, and Z. Ning [15], after investigating five different engine load conditions, stated that the BBU and BE blends could reduce nitrogen oxide (NOx) emissions by 6.5% and 28.0%, respectively.
Ethanol, like other alcohol-based fuels, has a high content of oxygen, which promotes combustion and significantly reduces CO emissions. Additionally, ethanol’s high latent heat and low vapor pressure help lower the temperature inside the combustor, thereby bringing NOx emissions down [16]. With technological advancements and decreasing costs, the benefits of using ethanol fuel are becoming increasingly apparent. Notably, ethanol is considered a green fuel with positive effects on environmental pollution and human health.
Considering the characteristics of alcohol-based chemicals—e.g., high latent heat, rich oxygen content, low viscosity, and low density—researchers in internal combustion engines have shown great interest in adding small proportions of alcohol additives to biodiesel fuels. L. Wei, C.S. Cheung, and Z. Ning [15] recommend the addition of 5% ethanol to biodiesel as an enhancement to its performance and environmental benefits. BE5 fuel was also studied by Lei Zhu, C.S. Cheung, W.G. Zhang, Zhen Huang [17]; E. Alptekin, M. Canakci, A. N. Ozsezen, A. Turkcan, and H. Sanli [18] conducted research on 5–20% ethanol additives. According to research by E.T. Jimenez, M.S. Jerman, A. Gregorc, I. Lisec, M. P. Dorado, and B. Kegl [19], mixing ethanol with biodiesel at a 3% ratio reduces the biodiesel’s flash point, pour point, and kinematic viscosity. A. Datta and B. K. Mandal [20] simulated a DE with a single cylinder and four strokes to investigate the performance and emissions of mixed ethanol/biodiesel fuels. The findings suggested that ethanol-containing blends, due to their longer ignition delay (ID), exhibited larger peak pre-mixed heat release rates but did not significantly affect CO2 emissions. Nevertheless, the addition of 15% ethanol has effectively reduced nitrogen oxide (NOx) emissions by 30%.
In recent years, n-butanol, as a higher alcohol, has gained extensive attention due to its advantages of lower corrosivity and volatility, which enhance safety in transportation and storage. Alpaslan Atmanli and Nadir Yilmaz [21] have investigated a mixture of 20% n-butanol and 80% biodiesel. G. Goga, B. S. Chauhan, S. K. Mahla, and H. M. Cho [22] investigated a ternary blend of diesel, biodiesel, and n-butanol, noting that the minimum HC emissions for pure diesel under full load was 5.01 g/kWh.
Moreover, n-butanol is miscible with diesel, meaning that the existing engine usage habits do not need to be altered. As an oxygenated compound, it also promotes efficient combustion. n-Butanol can be derived from various sustainable and renewable raw materials, making it a viable biofuel. Typically, butanol can be generated from a range of feedstocks, including agricultural and forest residues, microorganisms, and petroleum. When produced from biological sources, butanol is referred to as biobutanol.
Adding biobutanol to biodiesel decreases the fuel’s viscosity and decreases its energy content, resulting in a smaller BTE and a larger BSFC. The n-butanol and biodiesel mixture has a higher flash point, allowing for a longer air-mixing time, while its lower boiling point facilitates faster atomization. Consequently, the biodiesel–n-butanol blend generally produces a thinner and more homogeneous air–fuel mixture [23]. This characteristic can lead to improved particulate matter and NOx emissions.
Based on a review of the relevant literature, researchers have conducted relatively few comparative analyses between n-butanol and ethanol additives, particularly under the same experimental conditions. This article provides a detailed comparison and analysis of n-butanol and ethanol additives, thereby enriching the research in this field.

2. Materials and Methods

2.1. Experimental Equipment

Figure 1 presents a schematic of the experiment settings. The fuel flow rate is assessed using an FCMM-2 fuel flow meter (manufactured in Hubei Province, China), while engine emissions are monitored by an exhaust gas analyzer (Horiba MEXA 1600D/DEGR). Engine load is measured using a hydraulic load measurement device, and the electronic management system controls the engine’s operation. The measurement ranges and permissible error margins for the test devices are detailed in Table 1. Table 2 presents the primary parameters of the engine.
The overall uncertainty in testing is calculated by
T o t a l   u n c e r t a i n t y =   U   o f   P 2 + U   o f   B 2 + U   o f   H 2 + U   o f   N 2 + U   o f   C 2 + U   o f   S 2 = 0.5 % 2 + 0.03 % 2 + 0.11 % 2 + 0.53 % 2 + 0.32 % 2 + 2.8 % 2 = 2.913 % .
where U is uncertainty.

2.2. Development and Validation of the 3D Model

2.2.1. Model Establishment

A geometric model of the combustion chamber was created by SolidWorks based on the actual combustion chamber shape of the diesel engine. The generated model was saved in STL format and then fed into Converge Studio V3.1.8 software. Given the symmetry of the engine cylinder, there are eight identical nozzles. To reduce computation time, a 1/8 model of the engine cylinder was used as the computational domain, simplifying the model. Figure 2 illustrates the geometric model of the 1/8 computational domain within the Converge Studio environment. Mesh-cutting techniques were employed, generating the grids at the intersection of internal mesh and surface STL files. Subsequently, boundary conditions were refined, and computational parameters were set using Converge Studio based on the engine parameters.

2.2.2. Mesh Dependency Verification

To ensure accurate prediction of fuel injection and combustion processes, three different mesh partitioning schemes were established for the 3D model. Figure 3 presents the three models at the TDC position, consisting of sparse, intermediary, and fine mesh configurations. Based on the literature review [24,25,26], we selected three grid configurations. The total number of cells for the sparse, intermediary, and fine mesh schemes are 37,783, 153,179, and 187,759, respectively. As shown in Figure 4, when using diesel as fuel, the intermediary and fine mesh schemes exhibit no remarkable difference in cylinder pressure. Therefore, to balance accuracy and computing time, the intermediary mesh model was chosen here. The AMR level was 0.5 mm.

2.2.3. Model Accuracy Verification

This study investigates the combustion performance when varying ethanol and n-butanol addition ratios in the diesel–biodiesel blend. The 3D fluid dynamics were simulated for a water-cooled four-cylinder turbocharged DE. This model was validated using test results at 25%, 50%, 75%, and 100% load conditions, with the support of CFD simulation.
Figure 5 compares the heat release rate (HRR) model results with experimental data at 100%, 75%, 50%, and 25% loads. Additionally, Figure 6 compares the experimental and simulated cylinder pressure data in the same operating conditions. Figure 7 presents a comparison of NOx and soot simulation data with experimental results.
The relative error between the CFD results and the experimental results was 0.37%.
The three-dimensional simulation results agree well with the experiment data, indicating that the proposed model can accurately predict engine performance and emission characteristics. This research employs the improved RNG k-ε turbulence model [27] and selects the SAGE model as the combustion model, conducting a coupled analysis of combustion mechanisms and reaction kinetics through the CHEMKIN scheme. This study examines a chemical kinetics mechanism encompassing 389 reactions and 69 species. The prediction of NOx emissions is based on the Zeldovich model, while soot predictions rely on the Hiroyasu–Nagle model [28,29]. According to a suggestion from a previous study [30], the influence of residual gases should be neglected in this simulation. Meanwhile, the temperatures of the cylinder wall and cylinder head are set to 343.15 K. The theoretical basis for this study has been described in previous publications [31] and will not be reiterated here.

2.3. Sample Preparation

Different n-butanol, ethanol, and biodiesel blends were used in this study. The fuel names and their compositions are detailed in Table 3. The compositions and intrinsic characteristics of the chemicals are provided in Table 4. The combinations and physical properties of the blends are presented in Table 5. The diesel used in the experiment was MDO available on the Chinese market. Utilizing the validated reaction mechanism [32,33,34] as input into the 3D model.

3. Results and Discussion

3.1. Engine Performance

3.1.1. ISFC

Figure 8 illustrates the ISFC of eight types of fuel under three different load conditions. At 100% load, the ISFC of all fuels decreases because of higher fuel utilization efficiency than that in other load conditions. The addition of ethanol and n-butanol reduces the ISFC of D70B30 fuel, indicating a beneficial effect of alcohol additives on ISFC. This trend aligns with the conclusions drawn by I. A. Khan, SK Singh, A. K. Yadav, U. Ghosh, and D. Sharma [36]. Notably, at low load conditions, biodiesel significantly increases the ISFC of diesel fuel, which may be attributed to unfavorable combustion conditions prevalent at low loads. In such adverse environments, the high viscosity of biodiesel can hinder sufficient mixing during the pre-mixed phase, leading to inadequate fuel utilization at the phase of diffusion combustion. Conversely, under 100% load, the impact of alcohol additives on ISFC becomes negligible since the high oxygen content in alcohol additives enhances combustion efficiency at high loads, thereby mitigating the adverse effects associated with their lower calorific value. Similar results have been reported previously [15], thereby corroborating our observations. Furthermore, L. X. Cai, Y. J. Guang, Z. W. Gao, and H. Zhen [37] and S. Yu, C. Cao, and W. Lv [25] suggested that BSFC increased with the amount of ethanol added.

3.1.2. ITE

Figure 9 illustrates the thermal efficiency of pure diesel and blends under the three different load conditions. At 100% load, the ITE of diesel is the lowest, falling short by 4.55%, 5.45%, 6.37%, 8.03%, 5.75%, 6.82%, and 9.16% compared to D70B30, D70B25BU5, D70B20BU10, D70B10BU20, D70B25E5, D70B20E10, and D70B10E20, respectively. The data indicate that ethanol has a more pronounced effect on enhancing the engine’s ITE, particularly for D70B10E20.
n-Butanol improves the hypoxic environment during the volatilization process by extracting hydroxyl (-OH) radicals from the carbon atom positions attached to the hydroxyl group [38]. Simultaneously, the low viscosity of n-butanol contributes to a reduction in the overall viscosity of the blended fuel, facilitating effective atomization during the pre-mixed phase and resulting in complete combustion that enhances ITE. Alpaslan Atmanli [39] and I.A. Khan, SK Singh, AK Yadav, U. Ghosh, and D. Sharma [36] observed results consistent with our findings. However, B. T. Nalla, Y. Devarajan, G. Subbiah, D. K. Sharma, V. Krishnamurthy, and R. Mishra [40] suggested that adding n-butanol may lead to a reduction in ITE at high loads.
The trend of ethanol’s effect on ITE is consistent with that of n-butanol, both of which increase with rising proportions. This observation is corroborated by findings from de Oliveira A. de Oliveira, A.M. de Morais, O.S. Valente, and J.R. Sodré [41] and E. Öztürk and Ö. Can [42]. The specific reasons behind this variation will be discussed in the following section.

3.2. Combustion Properties

3.2.1. ICP

The results of fuel ICP as the load varies are displayed in Figure 10. As reported in Refs. [35,43], biodiesel has a higher volumetric modulus than ordinary diesel. A greater volumetric modulus indicates lower compressibility of the fuel. Consequently, biodiesel is injected at an earlier moment due to its lower compressibility. In the subsequent HRR analysis, we can observe that the ICP varies with the crank angle starting from fuel injection. The ICP increases with the rising engine load. Under high loads, D70B10E20 exhibits the highest cylinder pressure, while at low loads, it shows nearly the same performance as D70B10BU20. This is attributed to the larger CN and LHV of n-butanol than those of ethanol, with CN having a dominant effect in low-load environments. Across all loads, the ICP gradually increases when more alcohol fuels are added. This is partly because the high oxygen content in alcohol fuels creates a rich oxygen region in the cylinder, thus promoting combustion. Additionally, during the pre-mixed phase, the low viscosity and high volatility of alcohol fuels decrease the viscosity of the blend caused by the addition of biodiesel, facilitating adequate fuel–air mixing. Similar conclusions have been reached by Nalla, B. T. [40], Liu, Kai [44], and Devarajan, Y. [45].

3.2.2. HRR and ICT

As the crank angle rises, the combustion transitions into the diffusion phase following the pre-mixed combustion stage. The presence of alcohol additives enhances the oxygen concentration in the mixture, thereby increasing the combustion rate due to the intensified oxidation processes at the initial and main stages of the diffusion combustion phase, particularly in rich-fuel regions. This analysis is illustrated in Figure 11. Panels with 100% and 75% loads demonstrate that the D70B10BU20 and D70B10E20 fuels exhibit the highest heat release peaks during pre-mixed combustion at high load conditions, indicating optimal fuel utilization during this process [46]. This improvement is likely due to the addition of alcohol fuels, which increases the injection cone angle and enhances the combustion environment [15,47]. However, different behavior is observed at low loads, attributed to the specific in-cylinder combustion conditions present in this regime. In this environment, the influence of the fuel’s latent heat dominates, and with the SOI occurring earlier, the instantaneous heat release is not high. Similar experimental conclusions have been reached by D. C Rakopoulos, C. D.Rakopoulos, D. T. Hountalas, E. C. Kakaras, E. G. Giakoumis, and R. G. Papagiannakis [14] and L. Wei a, C.S. Cheung a, and Z. Ning [15].
Figure 12 and Figure 13 display the ICT curves and contour plots during combustion. The cylinder temperature increases with higher loads; all alcohol additives lead to higher temperatures, except at 75% load. Notably, Figure 10 shows that the cylinder pressure with alcohol additives is the highest, suggesting that at 75% load, the elevated temperature does not translate to higher pressure. The diffusion combustion stages for all fuels tend to converge, indicating that an earlier Start of Combustion (SOC) leads to a longer combustion duration while simultaneously shortening the pre-mixed combustion phase. The literature [14] mentions that the presence of alcohol additives results in a lower CN for the test fuels. Furthermore, studies [8,48] indicate that with a reduced ID, biodiesel exhibits a higher peak HRR, ignition temperature, and cylinder pressure.

3.3. Emission

3.3.1. NOx

The high NOx emission of biodiesel is a significant reason why it has not been widely adopted in diesel engines [49,50,51,52]. Figure 14 shows that as the load increases, the NOx emissions of the fuels under discussion increase. Compared to diesel, alcohol additives do not reduce NOx emissions under low loads, but the opposite is true at high loads. Among them, D70B25BU5 and D70B10E20 perform the best. Under full load conditions, D70B10E20 is shown to reduce NOx emissions by 4.2% and 2.0% compared to D100 and D70B30, respectively. The change in NOx emissions is primarily related to the in-cylinder combustion conditions [53,54]. It is generally known that high temperatures and high pressures can lead to more NOx formation [55,56,57], but this is also affected by the number of oxygen atoms in the combustion environment, although this influence is not dominant [58,59,60]. The LHV of ethanol-blended fuels may contribute to increased flame temperatures [20]. Nonetheless, under high load conditions, the ignition delay effect results in a shorter overall combustion duration for ethanol-blended fuels. Additionally, the high oxygen content of alcohol fuels provides supplementary oxygen for in-cylinder combustion, which aids in reducing combustion temperatures [61] and thereby serves as one factor in the reduction in NOX emissions. E. Alptekin, M. Canakci, A. N. Ozsezen, A. Turkcan, and H. Sanli [18] reported the same phenomenon.

3.3.2. Soot

H.F. Liu, X.J. Bi, M. Huo, C. F Lee, and M.F. Yao [62] pointed out that when the fuel’s oxygen mass fraction reached 27–35%, emissions of soot reached their minimum level. This aspect has also been studied in the literature [63,64]. Other physical properties of fuel can also influence soot emissions. Figure 15 illustrates the soot emissions in this study. At low load conditions, variations in fuel composition have a negligible effect on soot emissions. However, under high-load conditions, more alcohol additives create an oxygen-rich zone that facilitates the oxidation of soot particles, resulting in a gradual reduction in soot emitted from the cylinder. This finding is consistent with the earlier conclusion that increasing the oxygen atom content reduces soot emissions. The incorporation of ethanol also reduces the initial free radicals responsible for soot formation, fundamentally decreasing the quantity of soot generated [17]. The low viscosity of bioalcohols dilutes the viscosity of the blended fuel, which facilitates more thorough fuel atomization within the combustion chamber, thereby further enhancing the combustion process [25]. As the load decreases, soot emissions also gradually decline, primarily because of the lower ICT under low-load conditions, which is unfavorable for soot formation.

3.3.3. Hydrocarbon (HC)

Figure 16 illustrates the HC emissions from this study. HC emissions decrease with a rising load. The addition of alcohol fuels significantly reduces HC emissions, particularly at 75% load. Although alcohol additives decrease the CN of the fuel, which reduces its auto-ignition performance and may cause quenching in the cylinder under lean mixture conditions [65], they also enhance the atomization of biodiesel. This improvement allows the fuel to mix thoroughly with air during the pre-mixing phase, facilitating complete combustion in the combustion stage and preventing the condensation of high hydrocarbons. Additionally, the high oxygen content in alcohol additives can oxidize unburned hydrocarbons. Together, these factors contribute to reduced emissions of unburned HC expelled from the cylinder. At a 75% load, the HC emissions of D70B25E5, D70B20E10, D70B10E20, D70B25BU5, D70B20BU10, and D70B10BU20 are reduced compared to diesel fuel. However, researchers have not reached a consensus regarding the effects of alcohol additives on HC emissions. Mahmut Beyaz [66] suggested that when fuel was injected in a mist form, excessive dilution occurred in the peripheral regions of the spray, which resulted in an increase in HC emissions. Some literature [65,67,68] suggests that the addition of butanol increases HC emissions, while M. Pan, C. Tong, W. Qian, F. Lu, J. Yin, and H. Huang [69] argue that the incorporation of n-butanol can significantly reduce HC emissions.

3.3.4. CO

The emissions of CO primarily stem from the oxidation process of fuel carbon reacting with air oxygen during combustion. This indicates that the fuel’s carbon content directly determines the amount of CO emitted [70]. Most literature [71,72,73,74] suggests that biodiesel can effectively lower CO emissions, primarily attributed to the increased oxygen concentration in the blended fuel [75]. The alcohol fuels with a high oxygen content further enhance this trend, as the oxygen in alcohol fuels can facilitate the further oxidation of CO to CO2. In this study, as shown in Figure 17, under the 100%load conditions, the CO emissions of D70B10BU20 are reduced by 16.27% compared to D100. P.V. Bhale, N. V Deshpande, and S. B. Thombre [76] noticed a CO emission reduction when blending peanut biodiesel and ethanol. G. Goga, B. S. Chauhan, S. K. Mahla, and H. M. Cho [22] also found that adding n-butanol effectively reduced CO emissions.

4. Conclusions

This study considered a four-cylinder, turbocharged, water-cooled test bench using CFD simulation technology to model the combustion of eight fuel mixtures. The following conclusions were drawn:
  • Adding both n-butanol and ethanol decreases the ISFC of D70B30 fuel. Specifically, at 25% load, D70B10BU20 achieved a reduction of 1.7% in ISFC. Both ethanol and n-butanol positively impact the increase in ITE, with ethanol showing the most significant effect at full load;
  • Alcohol additives play a positive role in reducing NOx emissions under high loads, but the effect is not obvious under low loads. At 75% load, D70B10E20 reduced NOx emissions by 5.56% compared to diesel;
  • Alcohol additives effectively reduce soot and HC emissions, particularly at high loads. At 75% load, D70B10E20 achieved a reduction of 17.02% in soot emissions and 46.1% in HC emissions compared to pure diesel;
  • Compared to pure diesel, alcohol additives with high oxygen content in blended fuels result in lower CO emissions. Specifically, D70B10BU20 had 16.27% lower CO emissions under a 75% load than diesel fuel.
The addition of bioalcohol demonstrates a positive effect on enhancing the performance of fuels and improving emissions. This study, based on a single engine, comparatively investigated the effects of n-butanol and ethanol additives on biodiesel fuels, enriching research in this field. This study employs experimental testing and CFD simulations to investigate engine performance and emissions, reflecting a practical and potentially more sustainable fuel composition for DE. Among all the tested fuels, E20 exhibits noteworthy characteristics, warranting further investigation in future research endeavors.

Author Contributions

Conceptualization, C.M. and A.U.; methodology, C.M.; software, W.L.; validation, A.U.; resources, W.L. and J.W.; data curation, C.M.; writing—original draft preparation, C.M.; writing—review and editing, C.M. and A.U.; visualization, J.W.; supervision, A.U.; project administration, C.M. and A.U.; funding acquisition, W.L. All authors have read and agreed to the published version of this manuscript.

Funding

This research received no external funding.

Data Availability Statement

The article contains all the supporting data in this study.

Conflicts of Interest

Author Jiewen Wei was employed by the company Guangxi Kangsheng Meat Products Co., Ltd. Author Wangsheng Lan was employed by the company Liuzhou Weilan Technology Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Nomenclature

ISFCIndicated specific fuel consumption
NOxNitrogen oxideITEIndicated Thermal Efficiency
COCarbon monoxideICPIn-Cylinder Pressure
IDIgnition delayCNCetane Number
BTEBrake Thermal EfficiencyLHVLower Heating Value
BSFCBrake-Specific Fuel ConsumptionICTIn-cylinder temperature
TDCTop dead centerSOIStart of Injection
CFDComputational Fluid DynamicsSOCStart of Combustion
HRRHeat release rateHCHydrocarbon
SO2Sulfur dioxide MDOMarine Diesel Oil
DEDiesel engineAMRAdaptive Mesh Refinement

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Fire 07 00404 g001
Figure 1. Schematic of Experiment Settings.
Figure 1. Schematic of Experiment Settings.
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Figure 2. Localized Model of the Combustion Chamber.
Figure 2. Localized Model of the Combustion Chamber.
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Figure 3. Calculation meshes: (a) sparse, (b) intermediary, and (c) fine.
Figure 3. Calculation meshes: (a) sparse, (b) intermediary, and (c) fine.
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Figure 4. Pressure under the three calculation grids.
Figure 4. Pressure under the three calculation grids.
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Figure 5. Comparison of CFD Simulated HRR with Experimental HRR Under Different Loads: (a) 100%; (b) 75%; (c) 25% (d) None.
Figure 5. Comparison of CFD Simulated HRR with Experimental HRR Under Different Loads: (a) 100%; (b) 75%; (c) 25% (d) None.
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Figure 6. Cylinder pressure of four kinds of loads.
Figure 6. Cylinder pressure of four kinds of loads.
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Figure 7. Comparison of NOx and soot.
Figure 7. Comparison of NOx and soot.
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Figure 8. ISFC for engine.
Figure 8. ISFC for engine.
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Figure 9. Fuel ITE.
Figure 9. Fuel ITE.
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Figure 10. ICP Change for Test Fuel Under Different Loads: (a) 100%; (b) 75%; (c) 25%.
Figure 10. ICP Change for Test Fuel Under Different Loads: (a) 100%; (b) 75%; (c) 25%.
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Figure 11. HRR at Different Loads: (a) 100%; (b) 75%; (c) 25%.
Figure 11. HRR at Different Loads: (a) 100%; (b) 75%; (c) 25%.
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Figure 12. ICT at Different Loads: (a) 100%; (b) 75%; (c) 25%.
Figure 12. ICT at Different Loads: (a) 100%; (b) 75%; (c) 25%.
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Figure 13. ICT Cloud.
Figure 13. ICT Cloud.
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Figure 14. NOx Emission.
Figure 14. NOx Emission.
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Figure 15. Soot Emission.
Figure 15. Soot Emission.
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Figure 16. HC Emission.
Figure 16. HC Emission.
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Figure 17. CO Emission.
Figure 17. CO Emission.
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Table 1. Device parameters.
Table 1. Device parameters.
CodeMeasured QuantityContent/Measurement RangeAccuracyUnitUncertainty (%)
PPressure0–25±0.01MPa±0.5
CCO emission0–10±0.03% vol±0.32
EExhaust gas temperature0–1000±1% (FS)°C±0.25
BBrake power-0.03kw±0.03
NNOx emission0–5000±10ppm±0.53
SSoot emission0–9±0.1FSN±2.8
HHC emission0–20,000±10ppm±0.11
AAir flow mass0–33,300±1% (FS)g/min±0.5
ESEngine speed1–2000±0.2% (FS)rpm±0.24
FFuel flow measurement0.5–100±0.04L/h±0.5
Table 2. Main Engine Parameters.
Table 2. Main Engine Parameters.
Performance ParameterMeasureMeasurement
Engine type-Four-cylinder, turbocharged, water cooling
Cylinder count-4
Nozzle opening sizemm0.26
Bore and stroke dimensionsmm190 × 210
Conrodm0.410
Revolutions speedrpm2000
Injection nozzles-8
Power ratingkW220
Table 3. Fuel compositions.
Table 3. Fuel compositions.
No.Fuel NameComposition
1.D100100% diesel
2.D70B25BU570% diesel + 25% biodiesel + 5%N-butanol
3.D70B20BU1070% diesel + 20% biodiesel + 10% N-butanol
4.D70B10BU2070% diesel + 10% biodiesel + 20% N-butanol
5.D70B25E570% diesel + 25% biodiesel + 5% Ethanol
6.D70B20E1070% diesel + 20% biodiesel + 10% Ethanol
7.D70B10E2070% diesel + 10% biodiesel + 20% Ethanol
8.D70B3070% diesel + 30% biodiesel
Table 4. Fuel properties.
Table 4. Fuel properties.
PropertyBiodiesel [35]EthanolDieseln-Butanol [11]
Density (g/mL, at 293.15 K)0.8710.7860.835–0.8370.81
Evaporation heat (kJ/kg)300840260585.6
Cetane number (CN)53645–5125
Lower Heating Value (LHV)(J/g)37,50028,40042,50030,630
Viscousness (mm2/s, at 293.15 K)5.281.22.722.22
Air–fuel ratio12.5914.311.21
Boiling temperature (°C)240–34078.3210–235118
Oxygen volume fraction (%)10.834.80.021.6
Table 5. Mixed fuel characteristics.
Table 5. Mixed fuel characteristics.
BlendOxygen Volume Fraction (%)Density (g/mL, at 293.15 K)CNStoichiometric Air–Fuel RatioEvaporation Heat (kJ/kg)Viscosity (mm2/s, at 20 °C)LHV (J/g)
D10000.83648.014.302602.72042,500
D70B303.240.84749.513.762723.48841,000
D70B10E208.040.84840.113.063802.67239,180
D70B20E105.640.84744.813.413263.08040,090
D70B25E54.440.84747.1213.592993.28440,545
D70B10Bu205.40.83443.913.503292.87639,626
D70B20Bu104.320.84046.713.633003.18240,313
D70B25Bu53.780.84348.113.702863.33540,657
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Mao, C.; Wei, J.; Lan, W.; Ukaew, A. The Effect of Bioalcohol Additives on Biofuel Diesel Engines. Fire 2024, 7, 404. https://doi.org/10.3390/fire7110404

AMA Style

Mao C, Wei J, Lan W, Ukaew A. The Effect of Bioalcohol Additives on Biofuel Diesel Engines. Fire. 2024; 7(11):404. https://doi.org/10.3390/fire7110404

Chicago/Turabian Style

Mao, Chengfang, Jiewen Wei, Wangsheng Lan, and Ananchai Ukaew. 2024. "The Effect of Bioalcohol Additives on Biofuel Diesel Engines" Fire 7, no. 11: 404. https://doi.org/10.3390/fire7110404

APA Style

Mao, C., Wei, J., Lan, W., & Ukaew, A. (2024). The Effect of Bioalcohol Additives on Biofuel Diesel Engines. Fire, 7(11), 404. https://doi.org/10.3390/fire7110404

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