International Journal of Energy Research

Volume 2025, Issue 1 5787065

Research Article

Open Access

Eco-Friendly Additives: Performance and Emissions Analysis of a Diesel Engine With Jojoba Methyl Ester and CNT Blends

Muhammad Sarfraz Ali,

Corresponding Author

Muhammad Sarfraz Ali

[email protected]

orcid.org/0000-0003-2731-7465

Department of Mechanical Engineering , Swedish College of Engineering and Technology , Rahim Yar Khan , 64200 , Pakistan , swedishryk.edu.pk

Department of Mechanical Engineering , University of Engineering and Technology , Lahore , 54890 , Pakistan , uet.edu.pk

Search for more papers by this author

Asad Naeem Shah,

Asad Naeem Shah

Department of Mechanical Engineering , University of Engineering and Technology , Lahore , 54890 , Pakistan , uet.edu.pk

Search for more papers by this author

Sadia Saleem,

Sadia Saleem

orcid.org/0009-0007-0302-6408

Institute of Computer Science and Information Technology , The Women University , Multan , 60000 , Pakistan , wum.edu.pk

Search for more papers by this author

Ali Azam,

Ali Azam

orcid.org/0000-0002-0175-3966

School of Mechanical Engineering , Southwest Jiaotong University , Chengdu , 610031 , China , swjtu.edu.cn

Search for more papers by this author

Ammar Ahmed,

Ammar Ahmed

orcid.org/0000-0002-8978-5638

School of Mechanical Engineering , Southwest Jiaotong University , Chengdu , 610031 , China , swjtu.edu.cn

Search for more papers by this author

Zafar Abbas,

Zafar Abbas

orcid.org/0000-0002-2639-308X

Department of Mechanical Engineering , Pakistan Institute of Engineering and Technology , Multan , 60000 , Pakistan

Search for more papers by this author

Shanawar Hamid,

Shanawar Hamid

orcid.org/0000-0002-2827-0585

Department of Civil Engineering , Swedish College of Engineering and Technology , Rahim Yar Khan , 64200 , Pakistan , swedishryk.edu.pk

Search for more papers by this author

Eustache Hakizimana,

Corresponding Author

Eustache Hakizimana

[email protected]

orcid.org/0000-0003-0627-4259

Department of Mechanical and Energy Engineering , University of Rwanda , Kigali , Rwanda , ur.ac.rw

Search for more papers by this author

Muhammad Sarfraz Ali,

Corresponding Author

Muhammad Sarfraz Ali

[email protected]

orcid.org/0000-0003-2731-7465

Department of Mechanical Engineering , Swedish College of Engineering and Technology , Rahim Yar Khan , 64200 , Pakistan , swedishryk.edu.pk

Department of Mechanical Engineering , University of Engineering and Technology , Lahore , 54890 , Pakistan , uet.edu.pk

Search for more papers by this author

Asad Naeem Shah,

Asad Naeem Shah

Department of Mechanical Engineering , University of Engineering and Technology , Lahore , 54890 , Pakistan , uet.edu.pk

Search for more papers by this author

Sadia Saleem,

Sadia Saleem

orcid.org/0009-0007-0302-6408

Institute of Computer Science and Information Technology , The Women University , Multan , 60000 , Pakistan , wum.edu.pk

Search for more papers by this author

Ali Azam,

Ali Azam

orcid.org/0000-0002-0175-3966

School of Mechanical Engineering , Southwest Jiaotong University , Chengdu , 610031 , China , swjtu.edu.cn

Search for more papers by this author

Ammar Ahmed,

Ammar Ahmed

orcid.org/0000-0002-8978-5638

School of Mechanical Engineering , Southwest Jiaotong University , Chengdu , 610031 , China , swjtu.edu.cn

Search for more papers by this author

Zafar Abbas,

Zafar Abbas

orcid.org/0000-0002-2639-308X

Department of Mechanical Engineering , Pakistan Institute of Engineering and Technology , Multan , 60000 , Pakistan

Search for more papers by this author

Shanawar Hamid,

Shanawar Hamid

orcid.org/0000-0002-2827-0585

Department of Civil Engineering , Swedish College of Engineering and Technology , Rahim Yar Khan , 64200 , Pakistan , swedishryk.edu.pk

Search for more papers by this author

Eustache Hakizimana,

Corresponding Author

Eustache Hakizimana

[email protected]

orcid.org/0000-0003-0627-4259

Department of Mechanical and Energy Engineering , University of Rwanda , Kigali , Rwanda , ur.ac.rw

Search for more papers by this author

First published: 21 February 2025

https://doi.org/10.1155/er/5787065

Citations: 1

Academic Editor: Muhammad Shahbaz

Share a link

Email
Wechat
Bluesky

Abstract

Diesel engines have extensive use in vehicles, power plants, and agriculture, but they pose significant challenges due to both regulated and unregulated emissions. As fossil fuel supplies diminish and pollution levels increase, it has become crucial to shift from conventional fuels to biodiesel and alternative additives. This experimental study investigates the emission and performance characteristics of a water-cooled, three-cylinder, four-stroke compression ignition engine operating on blends of Jojoba methyl ester (JME) combined with additives such as carbon nanotube (CNT). JME was mixed with pure diesel in concentrations of 5% and 15% by volume, creating blends referred to as J5 and J15. CNT was added to these blends at a concentration of 20, 40, and 60 ppm. Emission and performance metrics were evaluated across engine speeds varying from 1200 to 2200 rpm. The findings revealed significant improvements, with brake thermal efficiency (BTE), brake power (BP), and torque increasing by 6.7%, 3.8%, and 3.8% respectively. A 2.6% reduction in brake-specific fuel consumption (bsfc) was observed at 1600 rpm with the J5CNT60 blend. The introduction of Jojoba biodiesel into neat diesel resulted in reductions of 12.8%, 14.56%, 15.25%, and 7.27% in nitrogen oxide (NO_x), carbon monoxide (CO), carbon dioxide (CO₂), and unburned hydrocarbon (UHC) emissions, respectively. Although Jojoba biodiesel resulted in a slight increase in smoke opacity (SO) emissions by less than 1%, the addition of CNT led to a 2% decrease in SO emissions at 2000 rpm.

Summary

•
Biodiesel and carbon nanotube (CNT) were fueled to study the emission and performance of the diesel engine.
•
The compression ignition (CI) engine fueled with CNT improved the performance parameters.
•
Biodiesel reduced carbon dioxide (CO₂), carbon monoxide (CO), and unburned hydrocarbon (UHC) emissions by 15.25%, 14.56%, and 7.27%, respectively.
•
CNT increased nitrogen oxide (NO_x), CO₂, and CO emissions by 19.50%, 8.13%, and 7.80%, respectively.

1. Introduction

Diesel engines are highly effective for power generation, agricultural applications, and transportation due to their durability, simplicity, and availability in a wide range of sizes. They also offer superior brake thermal efficiency (BTE) compared to petrol engines in automotive applications [1, 2]. Burning fossil fuels releases a significant amount of hazardous gases into the environment, contributing to pollution, including acid rain, global warming, smog, and the greenhouse effect [3]. Cardiovascular and respiratory diseases are linked to compression ignition (CI) engine emissions, which include carbon monoxide (CO), nitrogen oxide (NO_x), unburned hydrocarbon (UHC), particulate matter (PM), soot, and various toxic ketones and aldehydes [4, 5]. Given the depletion of petroleum reserves and the ongoing rise in environmental hazards, there is an urgent need to explore renewable and eco-friendly fuel alternatives.

A comprehensive literature review presents three established techniques for enhancing CI engine performance and reducing harmful emissions: (i) improvement in engine design [6], (ii) fuel adjustment or preprocessing [7], and (iii) engine exhaust after-treatment or postprocessing [8]. Table 1 presents earlier studies demonstrating the use of these techniques. The combustion characteristics of traditional petroleum-based fuels can be enhanced by incorporating small amounts of nonmetallic or metallic additives or by mixing in minor quantities of biodiesel during the fuel preparation or modification process [25]. Biodiesel can be produced through the transesterification process using various common oils, including those derived from fish, cardoon, Salvia macrosiphon, rapeseed, brassica, Calophyllum inophyllum, castor, cottonseed, rice bran, neem, sunflower, corn, soybean, hazelnut, karanja, moringa, turpentine, palm, canola, and jatropha. The additional oxygen in biodiesel promotes smoother combustion, enhancing performance and reducing emissions [26]. The oxygen in biodiesel enhances combustion by promoting the oxidation of carbon and hydrogen molecules, resulting in more complete fuel burning. This reduces emissions like CO and UHC, improves energy release, and ensures smoother combustion, even in suboptimal air–fuel mixing conditions. One advantage of using biodiesel is its physicochemical properties, which closely resemble those of pure diesel, enabling its use in CI engines without requiring modifications. Adding metallic nano additives to fuel provides a practical and cost-effective approach to reducing emissions, improving engine performance, and increasing combustion efficiency. These additives are mixed with diesel in small amounts and have minimal impact on the fuel’s physical and chemical properties [27]. Nanomaterials regulate emissions by improving combustion efficiency through their high surface area and catalytic properties, which promote complete fuel oxidation. They enhance engine performance by increasing energy release, reducing friction, and improving thermal and combustion characteristics.

Table 1. Performance enhancement and emissions control methods for diesel engines.

Methodology	Reference	Adjustment type	Engine performance				Emission parameters
Methodology	Reference	Adjustment type	BMEP	BTE	bsfc	EGT	NO_x	Smoke	PM	HC	CO
Engine design improvement	[9]	Retreated SOI	—	↓	↑	—	—	—	—	—	—
	—	Advanced SOI	—	↑	↓	—	↑	—	↓	↓	—
	—	FIP 1000 bars	↑	↓	↑	↑	↑	—	↓	↑	↑
	—	FIP 500 bars	↓	↑	↓	↓	↓	—	—	↓	↓
	[10]	TIP	—	↑	↓	↑	↑	↓	—	↓	↓

Fuel adjustment or preprocessing	[11]	D + GO	—	—	↓	↓	↓	—	—	—	—
	[12]	D + Ag + CNT (120 mg)^a	↑	↑	↓	↑	↑	—	—	↓	↓
	[13]	D + water emulsions	—	—	—	↓	↓	—	↓	—	—
	[14]	D + carbon black	—	—	—	↓	↓	↑	—	↑	↑
	[15]	D + Ce₂O₃ + lemongrass oil	—	↑	↑	↑	↑	↓	—	↑	↑
	[16]	D + Ti₂O₃ (80 ppm/l)^a	—	↑	↑	↑	↑	—	—	↓	↓
	[17]	D + CuO (50 mg)^a	↑	↑	↑	↓	↓	—	—	↓	↓
	—	D + Al₂O₃ (50 mg)^a	↑	↑	↑	↓	↓	—	—	↓	↓
	[18]	D90B10 + Al₂O₃ (90 mg)^a	↑	↑	↓	↑	↑	—	—	↓	↓
	[19]	D + FPC	—	↑	↓	—	—	↓	—	—	—
	[20]	D90TO10	—	↑	↑	↑	↑	—	—	↓	↑
	—	D80TO20	—	↓	↓	↑	↑	—	—	↓	↑
	—	D70TO30^a	—	↑	↑	↑	↑	—	—	↑	↓
	—	D60TO40	—	↓	↑	↑	↑	—	—	↑	↑
	—	D50TO50	—	↓	↓	↑	↑	—	—	↑	↑
	[21]	DWSA20	—	↑	↓	—	—	↓	—	↓	↓
	—	DWSA15	—	↑	↓	—	—	↓	—	↓	↓
	—	DWSA10^a	—	↑	↓	—	—	↓	—	↓	↓
	—	DWSA5	—	↑	↓	—	—	↓	—	↓	↓
	[22]	Mn + D100 (16 mg)	—	—	↓	↓	↓	—	↓	—	↓
	—	Mn + D100 (12 mg)^a	—	—	↓	↓	↓	—	↓	—	↓
	—	Mn + D100 (8 mg)	—	—	↓	↓	↓	—	↓	—	↓
	—	Mn + D100 (4 mg)	—	—	↓	↓	↓	—	↓	—	↓
	[1]	Graphite	—	↑	↓	—	↑	—	—	—	↑

Exhaust after-treatment or postprocessing	[23]	EGR and EEVO	—	—	↑	↓	↓	—	↑	—	—
Exhaust after-treatment or postprocessing	[24]	Combination of DPF, SCR, EGR	—	—	—	—	↓	↓	—	↓	↓

Note: Upward arrows indicate an increase, while downward arrows indicate a decrease in efficiency and emission parameters.
Abbreviations: BMEP, brake mean effective pressure; bsfc, brake-specific fuel consumption; BTE, brake thermal efficiency; CNT, carbon nanotube; CO, carbon monoxide; EEVO, early exhaust valve opening; EGT, exhaust gas temperature; HC, hydrocarbon; NO_x, nitrogen oxide; PM, particulate matter; SOI, start of injection timing.
^aIndicates optimum concentration of fuel additives.

The addition of nanoparticles to biodiesel–diesel blends has emerged as a promising strategy to enhance engine performance and reduce emissions. Jojoba methyl ester (JME) has been investigated as a biodiesel feedstock due to its low chemical reactivity, availability, and sustainable cultivation in nonarable lands. However, its high viscosity and lower calorific value often lead to reduced engine performance and increased emissions. To overcome these limitations, researchers have explored multiwalled carbon nanotubes (MWCNTs) as fuel additives. Studies have demonstrated that MWCNTs improve fuel properties by increasing thermal conductivity, promoting complete combustion, and reducing ignition delay, leading to enhanced engine efficiency and lower emissions of NO_x, CO, and UHCs. The catalytic effects of MWCNTs, coupled with their high surface area-to-volume ratio, make them effective in improving combustion and minimizing PM emissions [28].

The integration of nanomaterials into biodiesel blends has gained significant attention for improving engine performance and reducing harmful emissions. Recent investigations by Venkatesan et al. [29] have explored the use of jojoba biodiesel, derived through a base-catalyzed transesterification process, in combination with diesel, n-butanol, and MWCNTs. MWCNTs, prepared as a stable aqueous nanosolution with the Tween 80 surfactant, demonstrated significant potential in enhancing combustion efficiency and emissions reduction. Experimental studies utilizing a 5.2 kW diesel engine showed that optimized blends improved BTE by 8.87%, rate of heat release (ROHR) by 32.21%, and in-cylinder pressure by 11.27%. Concurrently, key emissions like UHCs, CO, carbon dioxide (CO₂), and smoke were reduced by 10.23%, 26.25%, 14.17%, and 17.52%, respectively. These findings highlight the catalytic role of MWCNTs in promoting complete combustion, shortening ignition delays, and improving the overall thermal and environmental performance of diesel engines.

Particles containing nuclei modes emitted from CI engines during combustion are harmful to the human body. These particles can adversely affect the lungs, bronchi, stomach, and vascular tissues [30, 31]. Various methods have been utilized to reduce soot and NO_x emissions simultaneously to comply with diesel engine emission standards. Recent studies suggest that biodiesel can significantly decrease emissions of CO₂, CO, smoke opacity (SO), and UHCs from diesel engines. While biodiesel may cause a slight increase in NO_x emissions, this can be managed by modifying the fuel injection timing [32]. Jojoba oil is a relatively lesser-known renewable resource that shows promise for cultivation in hot climates compared to other alternatives. Numerous studies suggest that nonedible jojoba oil has potential as a fuel for CI engines [33]. Jojoba was first cultivated in the Sonoran Desert in the Southern United States and Africa.

Jagtap, Pawar, and Lahane [34] suggested employing the EGR framework to lower NO_x and CO₂ emissions from the CI engine, finding a reduction of 9.8% in NO_x and 7.2% in CO₂ emissions. Malmgren et al. [35] analyzed diesel engine emissions and recommended the use of a diesel particulate filter combined with a diesel oxidation catalyst to lower PM and NO_x emissions from diesel exhaust. These changes resulted in reductions of 5.6% in NO_x emissions and 2.3% in PM emissions. Senthil, Paramasivam, and Rajendran [36] proposed a technique to increase the NO_x/NO₂ ratio in diesel engines by using H₂ and optimizing ignition for improved after-treatment performance. The researchers observed a notable decrease in several emission parameters.

Tayari, Abedi, and Rahi [37] explored the use of fuel additives and fuel processing technology to reduce particulate emissions from medium-speed, large-scale CI engines. They tested various concentrations of isopropanol as fuel additives. There was a significant reduction in NO_x emissions when they added isopropanol to the pure diesel with 20% EGR. A detailed examination of diesel engine emissions, including NO_x, UHC, and particulate size distributions, was conducted by Clenci et al. [38]. The study reported a 3.1% decrease in UHC emissions and a 4.4% decrease in NO_x. Tosun and Özcanlı [39] examined the performance, combustion, and emissions of a CI engine using two modified fuels: soybean biodiesel blends and alumina (Al₂O₃) biodiesel blends with nano additives. Their findings showed an increase in cylinder pressure alongside a higher heat release rate, with combustion being more complete compared to pure diesel fuel. They observed significant emission reductions, including a 35% decrease in sulfur dioxide (SO₂), a 60% reduction in UHC, an 80% drop in CO, and a 70% reduction in NO_x. The grooves on pistons in hydraulic pumps can stabilize pistons and influence efficiency. Earlier studies investigated leakage and friction dynamics, groove designs, and effects on pressure and flow [40].

Bi et al. [41] examined how carbon nanotube (CNT) and Schleicher oleosa biodiesel affect diesel engine performance. Their experiments involved various concentrations of CNT (40, 80, and 1200 ppm) mixed with B10 and B20 biodiesel. The findings revealed an 8.21% improvement in BTE and reductions of 27.49% in NO_x, 29.41% in SO, 65.7% in CO, and 44.98% in hydrocarbon (HC) levels. Additionally, there was a notable increase in brake power (BP) and torque, along with a 7.12% decrease in brake-specific fuel consumption (bsfc) when blending biodiesel and CNT with pure diesel. Gad, Abdel Aziz, and Kayed [42] explored the effects of graphene quantum dot nanoparticles and ethanol biodiesel on a CI engine’s performance and emissions. Their study used an ethanol blend with 30 ppm graphene quantum dot nanoparticles, tested at various engine speeds under constant load. Results showed increases of 12.42% in torque and 28.18% in power, along with reductions of 29.54% in CO, 31.12% in HC, and 14.35% in bsfc, compared to pure diesel. The impact of blending biodiesel with pure diesel on engine performance and emissions has been thoroughly investigated by Hojati and Shirneshan [43]. Their works examined the impact of compression ratio and biodiesel blends on combustion characteristics, thermal efficiency, and emissions. Their study further builds upon these findings by utilizing a thermodynamic zero-dimensional model to predict engine parameters for various biodiesel–diesel blends and compression ratios. Barsari and Shirneshan [44] explored the tribological behavior of biodiesel blends derived from sunflower and soybean oils using a four-ball wear testing machine. It highlighted how increased biodiesel concentration improves lubrication and reduces wear at lower rotational speeds, while higher speeds lead to degradation due to oxidation and reduced viscosity.

The use of CNT in internal combustion (IC) engines, as fuel additives or in structural components, raises concerns about nanometer-sized particle emissions. These emissions stem from incomplete combustion of CNT-containing fuels and thermal degradation at high temperatures. Ultrafine particles (<100 nm) formed during combustion are especially harmful due to their ability to penetrate the respiratory system, posing health, and environmental risks. Sridhara and Satapathy [45] reported increased ultrafine particulate emissions from CNT-based fuels in diesel engines, while Rodoshi Khan and Bin Rashid [46] found that high temperatures cause CNT fragmentation, releasing nanoscale particles. Mitigation strategies include optimized diesel and gasoline particulate filters with improved pore structures. CNT-specific catalysts, such as cerium oxide (CeO₂) and platinum-based systems, enhance the oxidation of CNT and byproducts. Emerging methods like plasma-assisted oxidation and electrostatic precipitators also show potential for managing CNT-derived nanoparticle emissions effectively, though they require further development.

Polycyclic aromatic hydrocarbons (PAHs) are hazardous organic compounds formed during incomplete fuel combustion. Known for their carcinogenic, mutagenic, and teratogenic effects, PAHs pose significant environmental and health risks due to their persistence and bioaccumulation. Reducing PAH emissions from engines is essential for meeting environmental regulations and safeguarding health. Biodiesel, a renewable fuel, shows promise in reducing PAH emissions compared to conventional diesel. Its higher oxygen content improves combustion efficiency and limits incomplete combustion products. Studies reveal biodiesel’s advantages: Arias et al. [47] reported lower PAH emissions with biodiesel blends, attributing this to their lower aromatic content. Arias, Molina, and Agudelo [48] observed significant PAH reductions with waste cooking oil biodiesel. Nanoparticle fuel additives, such as CeO₂, aluminum oxide (Al₂O₃), and CNT, further enhance combustion and minimize PAH formation. Yusuf, Inambao, and Ampah [49] showed CeO₂ nanoparticles in biodiesel reduce gaseous and particulate PAHs via improved oxidation.

Recent studies have highlighted the potential of MWCNTs as additives in biodiesel blends to enhance engine performance and reduce emissions. Pullagura et al. [50] investigated the combination of jojoba biodiesel, diesel, and n-butanol with MWCNTs as fuel additives, demonstrating significant improvements in BTE and reductions in UHCs and CO emissions. Similarly, Sulochana et al. [51] examined biodiesel–diesel blends with MWCNTs, reporting enhanced combustion characteristics, increased thermal efficiency, and lower PM emissions. Çılğın [52] explored the effects of CNT and biodiesel blends on diesel engine performance, observing notable reductions in NO_x, SO, and fuel consumption while improving BP and torque. Despite these advancements, gaps remain in optimizing the blending ratios of JME and MWCNTs for maximizing performance and minimizing emissions.

The reviewed literature demonstrates that while numerous studies have explored the impact of biodiesel and nanoparticle additives, critical gaps remain in the detailed characterization of optimal blending ratios and the combined effects of JME and MWCNTs on diesel engine performance and emissions. This study fills these gaps by determining optimal concentrations. Through systematic experimentation, we established optimal concentrations of JME (5% and 15% by volume) and MWCNTs (20, 40, and 60 ppm), providing a clearer understanding of blending ratios for maximizing performance and minimizing emissions. Also, this study evaluates the combined use of JME biodiesel and MWCNTs, showing synergistic effects in improving BTE (up to 6.72%) and reducing bsfc (by 2.65%) compared to pure diesel. The flowchart of the current experimental study is shown in Figure 1. The findings of this study provide new insights into the operational behavior of CI engines, including variations in torque, BP, and specific emission parameters such as CO, CO₂, UHC, and NO_x, across engine speeds ranging from 1200 to 2200 rpm. For example, the J5CNT60 blend showed the greatest overall performance improvements, while the J15 blend resulted in the most significant reductions in emissions. These advancements set the foundation for future research and policy development in the use of biodiesel and nanoparticle blends as sustainable fuel alternatives.

Details are in the caption following the image — **Figure 1**
Open in figure viewer PowerPoint

Flowchart of the current experimental study.

2. Materials and Methods

2.1. JME and CNT Nanoparticles

The MWCNT, with a purity of 90%–95%, an inner diameter of 2–4 nm, and an outer diameter of 8 nm, was sourced from Soochow Hengqiu Graphene Technology Co., Ltd., China. The JME was supplied by Pakistan State Oil (PSO). Figure 2 displays images of JME and CNT, including scanning electron microscope (SEM) images of the nanoparticles.

2.2. Experimental Setup

The experimental study was carried out on a test bench, as shown in Figure 3, with the schematic diagram provided in Figure 4. Details of the experimental setup are presented in Table 2. During the diesel engine tests, atmospheric pressure was kept at 101.325 kPa and ambient temperature at 22°C. To analyze the regulated gaseous emissions of the CI engine, an AVL smoke meter and Ditest were utilized. Specifications of the equipment used in this study are listed in Table 3.

Table 2. Specifications of the diesel engine used for experiments.

Parameter	Specifications
Type	Diesel T 3.1524
Maximum torque	212 Nm
Maximum engine speed	2250 rpm
Maximum brake power	60 hp
Number of cylinders	3
Injection	Direct
Capacity	2.5 l
Bore	91.4 mm
Stroke	127 mm
Compression ratio	15.5 : 1
Aspiration	Turbo
Cooling	Water
Air cleaner type	Oil bath
Fuel filter	Dual, high capacity
Exhaust	Horizontal
Certified by	BS AU 141a (1971)

Table 3. Specification of the apparatus used for the experiments.

Testbed	Single phase 220 V AC supply, Tokyo Meter Co. Limited
Dynamometer	An electrobraking (eddy current), water-cooled dynamometer having a 500 Nm load capacity
Emission analyzer	An AVL smoke-meter 415SE for FSN and SC, An AVL DITEST CDS 440 for NO_x, HC, and CO with A recognition limit of 0.02 mg/m³ (SC)/0.002 (FSN)

2.3. Nanoadditives and Fuel Preparation

JME at concentrations of 5% and 15% was mixed with pure diesel. The chemical prospects of pure diesel are detailed in Table 4. The experimental design, which includes various concentrations of JME and MWCNT, is outlined in Table 5.

Table 4. Properties of pure diesel.

Parameters	Pure diesel	Investigative standard
Viscosity, cSt (@ 40°C)	3.775	ASTM D445
Flashpoint (°C)	76	ASTM D93
Pour point (°C)	−18	ASTM D97
Density, g/ml (25°C)	849.2	ASTM D1298
Cetane index	51	ASTM D613

Table 5. Design of experiments.

Number of experiment	Diesel (%)	JME concentration (percentage by volume)	MWCNT concentrations (mg/l)	Fuel nomenclature
1	100	—	—	D
2	95	5	—	J5
3	85	15	—	J15
4	95	5	20	J5CNT20
5	95	5	40	J5CNT40
6	95	5	60	J5CNT60
7	85	15	20	J15CNT20
8	85	15	40	J15CNT40
9	85	15	60	J15CNT60

2.4. Experimental Methodology

The current experimental study was conducted at various engine speeds, ranging from 1200 to 2200 rpm in increments of 200 rpm. The engine operated under full load conditions. Each experiment investigated emissions, fuel consumption, load, and speed. To clear any leftover fuel blends from previous tests, the engine was operated for 10 min before each new test.

2.5. Uncertainty Analysis

To verify the accuracy of the calculated characteristics, it is crucial to evaluate the related uncertainty. The uncertainty analysis was conducted using Equation (1), which calculates the combined uncertainty based on the propagation of individual measurement uncertainties. This approach is derived from standard uncertainty analysis methodology as outlined by Mubarak, Shaija, and Suchithra [53] in their study. Uncertainty represents the range of variability in repeated measurements and differs from accuracy, which describes the closeness of a measurement to the true value:

(1)

where Y is a variable that represents uncertainties in X_i and Y that differ on X_i; ω_Y, and ω_Xi, respectively. Table 6 provides the accuracies and uncertainties associated with parameters such as engine speed, bsfc, power, and torque. According to Equation (1), the total percentage uncertainty for the experiments conducted on the diesel engine is 3.1%:

Table 6. Measuring ranges, accuracies, and uncertainty in the measurements.

Parameter	Measuring ranges	Accuracies	Uncertainty (%)
Speed	0–7000 rpm	±2 rpm	±0.5
Torque	0–200 Nm	±0.2 Nm	±1
Power	0–110 kW	±0.5 kW	±1
BTE	—	—	±1
SFC	—	—	±2
Temperatures	0–1000°C	±1°C	±0.1
NO_x	0–2500 ppm	±5 ppm	±1
CO	0–8000 ppm	±8 ppm	±1
CO₂	0–21 vol. %	±0.2 vol. %	±1
O₂	0–21 vol. %	±0.1 vol. %	±1

3. Results and Discussions

An in-depth analysis of the experimental findings is provided. The subsections address key performance metrics such as torque, BP, BTE, and specific fuel consumption. Additionally, it evaluates emission characteristics, including CO, CO₂, UHCs, NO_x, and SO.

3.1. Analysis of Torque Variation and Enhancement

Figure 5a shows how JME biodiesel and CNT affect engine torque at different speeds. The peak torque was achieved with the J5CNT60 fuel blend at 1400 rpm. At higher speeds, the engine cylinder does not fill during the intake stroke, leading to reduced torque despite the inlet valve being fully open [54]. This is due to the short duration of air intake and increased cylinder pressure, which diminishes combustion pressure. Consequently, the engine torque was lower than expected due to the higher momentum of the moving engine components.

The maximum increase in torque was observed to be 3.84% with the J5CNT60 fuel blend at 1400 rpm, whereas the J5 and J15 fuel blends exhibited the lowest torque values. The decrease in engine power for the J5 and J15 blends is due to the lower energy content of JME. Typically, biodiesel produces less torque compared to pure diesel at all tested speeds. These findings are consistent with previous studies; for example, Ghodke and Suryawanshi [55] demonstrated a maximum torque increase of 16.16% at 2500 rpm in their experimental study. Another study reported a 5% increase in torque when using the B100 fuel blend at an engine speed of 1600 rpm [54]. Additionally, Heidari-Maleni et al. [56] found a 0.34% increase in torque.

As the percentage of biodiesel increases, the fuel’s density and viscosity also rise, leading to a decline in spray characteristics. In the engine cylinder, the larger droplet diameter and higher viscosity of the injected fuel hinder the compressed air’s ability to penetrate effectively, leading to inadequate atomization. Compared to pure diesel, engine torque significantly improves when CNTs are added to the pure diesel. As the concentration of CNT increases, torque continues to rise. This improvement is attributed to the engine cylinder combusting more fuel and achieving better combustion quality. As a result, torque and piston force rise due to the increased average pressure.

Figure 5b demonstrates the typical changes in torque for various fuel blends. For the blends J5CNT20, J5CNT40, J5CNT60, J15CNT20, J15CNT40, and J15CNT60, the average torque increases by 0.69%, 1.83%, 2.25%, 1.29%, 1.72%, and 1.86%, respectively. In contrast, the average torque with the J5 and J15 fuel blends decreases by 0.36% and 0.48%, respectively.

3.2. BP

Figure 6a illustrates the impact of JME biodiesel and CNT on the BP of an engine running on neat diesel. There is a notable increase in BP across various engine speeds, ranging from 1200 to 2200 rpm. However, previous studies have shown that power tends to stabilize or decrease slightly at engine speeds between 2300 and 2900 rpm. Estimating fuel quality at higher engine speeds is challenging due to incomplete combustion [57]. For optimal performance, the best speed range is between 1700 and 2200 rpm. The behavior of engine power with fuel blends mirrors that of the torque.

The highest BP was noted with the J5CNT60, J5CNT40, and J15CNT60 fuel blends. In contrast, the J5 and J15 blends, along with neat diesel fuel, exhibited the lowest BP. The greatest increase in BP, 3.84%, was achieved with the J5CNT60 fuel blend at 1400 rpm. An increase in BP was observed with higher concentrations of CNT in the fuel blends, suggesting better fuel ignition in the engine’s combustion chamber and more efficient energy conversion. Aliana-Nasharuddin et al. [58] also reported a 4.91% improvement in BP with the inclusion of CNT.

Figure 6b illustrates the changes in the engine’s average BP across various fuel blends. The average BP for the fuel blends J5CNT20, J5CNT40, J5CNT60, J15CNT20, J15CNT40, and J15CNT60 showed increases of 0.69%, 1.84%, 2.17%, 1.38%, 1.75%, and 1.97%, respectively. In contrast, the average BP for the J5 and J15 fuel blends decreased by 0.36% and 0.38%, respectively.

3.3. BTE

Figure 7a shows how BTE varies with different fuel blends at various engine speeds. At an engine speed of 1400 rpm, the J5CNT20 fuel blend improved BTE by 6.72% compared to neat diesel. Fuel blends with lower concentrations of biodiesel and higher concentrations of CNT exhibit improved BTE due to enhanced combustion properties. CNTs contain a higher amount of oxygen in their chemical structure, which facilitates more complete combustion within the engine cylinder. This enhanced burning of the fuel can result in improved BTE. Previous research has highlighted that key parameters, such as the viscosity and exhaust gas temperature (EGT) of biodiesel, negatively impact combustion efficiency inside the engine cylinder [59].

The results show that incorporating biodiesel into pure diesel fuel resulted in a reduction in BTE, aligning with the findings of a previous study by Shirneshan et al. [60]. Previous studies have shown a reduction in maximum BTE by 1.38%–1.54% when 20% biodiesel was added to B50 fuel blends [61]. Additionally, it was noted that the percentage continued to rise with the increased addition of biodiesel. CNTs possess higher calorific values than pure diesel. Nevertheless, the heating values of biodiesel are lower compared to those of pure diesel fuels.

Figure 7b shows the variations in the average BTE for each fuel blend. The average BTE increased by 1.88%, 0.96%, and 1.28% with the J5CNT20, J5CNT40, and J5CNT60 blends, respectively. In contrast, the average BTE decreased by 1.37%, 3.22%, 1.06%, 0.19%, and 0.79% with the J5, J15, J15CNT20, J15CNT40, and J15CNT60 blends, respectively.

3.4. bsfc

Figure 8a illustrates the variation in bsfc with engine speed. Generally, as engine speed increases, bsfc tends to rise because the engine needs more power strokes to complete within a given time at higher RPMs. For all the blends investigated, the lowest bsfc values were observed at engine speeds of 1200 and 1400 rpm. For neat diesel, the minimum bsfc recorded was 241.378 g/kWh, whereas, with the biodiesel and CNT fuel blends, the lowest bsfc observed was 238.785 g/kWh with the J5CNT60 fuel blend. The J5CNT60 blend achieved a maximum reduction in bsfc of 2.65% compared to neat diesel at an engine speed of 1600 rpm.

The data indicate that an increase in the biodiesel proportion in fuel blends leads to a rise in bsfc. This is due to biodiesel’s lower heating value, which necessitates burning more fuel in the engine. Furthermore, the density and viscosity of the fuel have a significant impact on BSFC. Biodiesel blends often experience poorer spray and atomization characteristics in the combustion zones, which diminishes combustion quality and efficiency compared to pure diesel. As a result, bsfc values are higher for biodiesel blends than for neat diesel. However, incorporating CNT results in a reduction in BSFC, as CNTs have higher heating values that lower the required fuel quantity. Mansoury, Jafarmadar, and Kousheshi [62] observed similar results in their research, noting a 2.39% reduction in bsfc for DA50 fuel blends.

Figure 8b demonstrates how the average bsfc of the engine varies with different fuel blends. The average bsfc decreased by 0.77%, 1.17%, 1.77%, 0.67%, 0.98%, and 0.79% for the fuel blends J5CNT20, J5CNT40, J5CNT60, J15CNT20, J15CNT40, and J15CNT60, respectively. Conversely, with the J5 and J15 fuel blends, the average bsfc increased by 0.17% and 0.40%, respectively.

3.5. CO Emissions

Figure 9a shows how CO emissions change with engine speed, with the lowest CO emissions recorded at 1600 rpm. The minimum CO values for the various fuels were as follows: diesel (0.078%), J5 (0.071%), J15 (0.065%), J5CNT20 (0.074%), J5CNT40 (0.079%), J5CNT60 (0.082%), J15CNT20 (0.075%), J15CNT40 (0.079%), and J15CNT60 (0.81%). The lowest CO emissions of 17.28% were recorded for the J15 fuel blend at an engine speed of 1800 rpm, while the highest increase, at 10.37%, was noted with the J5CNT60 fuel blend at 2200 rpm. Yilmaz, Vigil, and Donaldson [63] reported similar findings, noting a reduction in CO emissions from the CI engine.

Blending biodiesel with pure diesel reduces CO emissions due to increased oxygen availability, which improves combustion efficiency. The additional oxygen from biodiesel allows for a more complete conversion of carbon atoms into CO₂. Biodiesel’s lower stoichiometric air–fuel ratio means it needs less oxygen for combustion, resulting in higher EGT compared to pure diesel. Moreover, the high cetane number of biodiesel further lowers CO emissions.

However, adding more CNT to J5 and J15 blends leads to increased CO emissions. This rise is primarily due to inadequate oxygen in the engine cylinder, which causes incomplete combustion of the fuel. Additionally, incorporating CNT into the fuel decreases the EGT.

Figure 9b demonstrates the variation in average CO emissions from the engine across different fuel blends. The average CO emissions decreased by 7.36%, 14.56%, 3.07%, 5.97%, and 2.48% with the fuel blends J5, J15, J5CNT20, J15CNT20, and J15CNT40, respectively. Conversely, the average CO emissions increased by 1.32%, 7.81%, and 3.04% with the J5CNT40, J5CNT60, and J15CNT60 fuel blends, respectively.

3.6. CO₂ Emissions

Figure 10a shows CO₂ emissions for different fuel blends, with the peak emissions occurring at 1600 rpm. For Diesel, J5, and J15, the maximum CO₂ emissions were 6.08%, 5.63%, and 5.39%, respectively, at 2200 rpm. In comparison, the highest CO₂ emissions for blends with J5CNT20, J5CNT40, J5CNT60, J15CNT20, J15CNT40, and J15CNT60 were 5.81%, 6.17%, 6.65%, 5.69%, 5.94%, and 6.47%, respectively, at the same speed. All fuel blends exhibited a similar trend. Fuels with added biodiesel typically produce lower CO₂ emissions than pure diesel. The highest reduction in CO₂ emissions, at 20.86%, was observed for J5 at 1600 rpm. The reduced CO₂ emissions for J5 and J15 suggest that the fuel underwent more complete combustion within the engine’s cylinder. The largest increase in CO₂ emissions was 9.31% with the J5CNT60 blend at 2200 rpm.

As the number of nanoparticles of CNT in the J5 and J15 fuel blends increases, the carbon content rises, leading to higher CO₂ emissions. This increase in CO₂ emissions is primarily due to insufficient oxygen in the engine cylinder, which causes incomplete combustion of the fuel. Additionally, the calorific value of the fuel blends has a significant impact on CO₂ emissions. These observations align with findings from Razzaq et al. [61], who reported a 9.88% rise in CO₂ emissions with the addition of CNT to pure diesel fuel.

Figure 10b shows the changes in average CO₂ emissions across all fuel blends. The average CO emissions decreased by 9.75%, 15.26%, 4.12%, 7.96%, and 5.10% for the fuel blends J5, J15, J5CNT20, J15CNT20, and J15CNT40, respectively. In contrast, the average CO₂ emissions increased by 0.12%, 8.14%, and 4.15% for the fuel blends J5CNT40, J5CNT60, and J15CNT60, respectively.

3.7. UHC Emissions

Figure 11a illustrates how UHC emissions vary with engine speed. The lowest UHC emissions were observed at 2200 rpm. A notable reduction of 10.12% in UHC emissions was achieved with the J15 fuel blend at 1800 rpm. In contrast, the highest increase in UHC emissions, 23.52%, occurred when using the J15CNT60 fuel blend at 2200 rpm.

The decrease in UHC emissions with biodiesel-blended fuel is due to the earlier ignition of biodiesel and the extended duration for complete combustion. Research by Mohammed et al. [59] shows a 26.6% reduction in UHC emissions with the addition of biodiesel to the fuel, compared to using only pure diesel. Figure 11b illustrates the variation in average UHC emissions for the CI engine. The average UHC emissions decreased by 3.19% with the J5 and 7.28% with the J15 fuel blends. However, UHC emissions increased with the J5CNT20, J5CNT40, J5CNT60, J15CNT20, J15CNT40, and J15CNT60 fuel blends by 0.91%, 9.55%, 22.73%, 8.64%, 22.73%, and 35.00%, respectively.

3.8. NO_x Emissions

Figure 12a illustrates the variation in NO_x emissions at various engine speeds. The NO_x emissions decreased by 12.84% with the J15 fuel blend at 2200 rpm. Conversely, the highest increase in NO_x emissions, recorded at 24.06%, was observed with the J5CNT60 fuel blend at 1400 rpm. Kashyap, Das, and Kalita [64] reported similar findings in their research.

As the percentage of biodiesel increased from 5% to 15%, NO_x emissions also rose. This increase in NO_x emissions is influenced by reasons such as combustion chamber temperature, ignition delay, pressure, and the duration of the combustion process. The elevated oxygen content in biodiesel promotes more complete combustion. Furthermore, fuel blends with biodiesel exhibit more complex bsfc compared to neat diesel, leading to higher NO_x levels in the exhaust gases.

Figure 12b illustrates the changes in average NO_x emissions across various fuel blends. The average NO_x emissions were reduced by 5.00% with the J5 blend and by 9.73% with the J15 blend. In contrast, the NO_x emissions increased by 5.30%, 13.39%, and 19.51% with the J5CNT20, J5CNT40, and J5CNT60 fuel blends, respectively, and by 1.73%, 9.17%, and 15.72% with the J15CNT20, J15CNT40, and J15CNT60 fuel blends, respectively.

3.9. SO

Figure 13a illustrates the impact of CNT and biodiesel on SO at various engine speeds. PM, the most complex of diesel engine emissions, consists of carbonaceous particulates or soot and the less concentrated, cooler exhaust gases that form the PM. As engine speed increases, SO decreases rapidly, the highest SO emissions were observed at 1200 rpm, while at 2200 rpm, the SO for pure diesel was recorded at 32.93%.

When biodiesel is added to pure diesel for J5 and J15 fuel blends, the SO, relative to the power produced, increases compared to pure diesel. For the J5 and J15 fuel blends, the SO was measured at 32.81% and 32.94%, respectively. Adding CNT to J5 and J15 blends reduced the SO compared to blends without CNT. Among the blends, the SO was highest with the J15 blend and lowest with the J5CNT60 blend. The greatest reduction in SO was 1.90% with the J15CNT60 blend at 2000 rpm, while the maximum increase was 0.80% at 1200 rpm.

Figure 13b shows the changes in average SO across various fuel blends. The average SO increases by 0.11% and 0.44% for the J5 and J15 fuel blends, respectively. In contrast, the SO decreases by 0.20%, 0.64%, 1.00%, 0.04%, 0.38%, and 0.78% for the J5CNT20, J5CNT40, J5CNT60, J15CNT20, J15CNT40, and J15CNT60 fuel blends, respectively. The notable reduction in SO can be attributed to the lowered viscosity resulting from the addition of CNT. Additionally, diesel particulate filters can greatly mitigate the respiratory health risks associated with PM emissions.

4. Statistical Evaluation of Experimental Results for Diesel Engines

The statistical analyses were conducted using Minitab 20.1.3 software, calculating p-values and F-values to evaluate the significance of the results at a 95% confidence level. It assesses how JME and CNT influence diesel engine performance metrics, such as BP, torque, BTE, and emission factors including CO, CO₂, UHCs, NO_x, and SO. For each attribute, p-values and F-values were calculated from various experimental data. The F-values exceeded 0.05, and the p-values were below 0.05. This indicates that, at a significance level of 0.05 (or a 95% confidence level), the differences between the data sets are substantial. Table 7 provides a comparison of p-values and F-values for various fuel blends, neat diesel, and the average values of bsfc, BTE, BP, and torque. The significant differences observed at a 95% confidence level indicate that the fuel additives substantially disturb engine performance parameters.

Table 7. Statistical evaluations of the engine performance for all fuel blends compared to pure diesel.

Fuel blends	BTE (%)			bsfc (g/kWh)			BP (kW)			Torque (Nm)
Fuel blends	Δ (mean values)	p value	F value	Δ (mean values)	p value	F value	Δ (mean values)	p value	F value	Δ (mean values)	p value	F value
J5	1.095	0.0056	6.951	−9.785	0.0019	206.38	2.683	0.0051	385.90	4.653	0.035	5.659
J15	0.917	0.0042	6.286	−8.163	0.0008	251.67	2.262	0.0042	528.68	2.438	0.041	2.135
J5CNT20	1.359	0.0061	5.934	−10.867	0.0015	238.90	3.084	0.0039	589.23	5.950	0.028	2.958
J5CNT40	1.650	0.0057	5.357	−12.264	0.0012	229.52	3.407	0.0024	421.52	6.264	0.052	3.504
J5CNT60	1.908	0.0049	5.650	−13.960	0.0016	235.68	3.895	0.0046	510.08	6.759	0.015	4.918
J15CNT20	1.164	0.0064	6.028	−9.978	0.0014	250.28	2.680	0.0059	575.38	3.658	0.062	4.237
J15CNT40	1.597	0.0039	5.706	−10.861	0.0017	276.60	2.858	0.0048	681.06	5.365	0.054	3.902
J15CNT60	1.706	0.0047	5.392	−11.709	0.0011	247.09	3.354	0.0063	652.84	6.068	0.046	3.172

Abbreviations: BP, brake power; bsfc, brake-specific fuel consumption; BTE, brake thermal efficiency.

Multiple linear regression models were developed to quantify the relationship between the independent variables (biodiesel concentration, CNT concentration, engine speed) and dependent variables (performance metrics and emissions). The models showed that engine speed and CNT concentration had the strongest effects on BP, torque, and BTE, while biodiesel percentage also contributed, especially in emission reductions. Standardized regression coefficients were calculated to rank the influence of each independent variable. Engine speed and CNT concentration were the most influential factors, followed by biodiesel percentage. Interaction terms revealed a synergistic effect between biodiesel and CNTs, enhancing performance more than either factor alone.

Table 8 shows the emission values for UHC, NO_x, CO₂, CO, and SO of the diesel engine, which vary significantly between fuel-additive treated blends and pure diesel (D). Regarding SO, fuel blends with CNT exhibit a distinct pattern compared to those treated with JME. The symbol ∆ (mean values) represents the variation between the average values of each characteristic for pure diesel (D) and other fuel blends. Negative or positive values indicate that the parameters for pure diesel (D) were either higher or lower than those for the other blends. The significant differences observed are validated by p-values below 0.05 and high F-values.

Table 8. Statistical evaluations of the engine emissions for all the fuel blends compared to pure diesel.

Fuel blends	CO (%)			CO₂ (%)			UHC (ppm)			NO_x (ppm)			Smoke (%)
Fuel blends	Δ (mean values)	p value	F value	Δ (mean values)	p value	F value	Δ (mean values)	p value	F value	Δ (mean values)	p value	F value	Δ (mean values)	p value	F value
J5	1.927	0.0101	8.208	6.208	0.0075	42.393	19.815	0.054	103.123	13.695	0.0107	19.726	−0.652	0.0046	5.750
J15	1.358	0.0092	7.543	5.724	0.0066	67.683	15.640	0.06	128.413	11.058	0.0084	45.016	−0.808	0.0051	5.085
J5CNT20	2.163	0.0089	7.191	6.598	0.0063	54.913	23.908	0.047	115.643	14.250	0.0100	32.246	−0.184	0.0029	4.733
J5CNT40	2.492	0.0074	6.614	6.905	0.0048	45.533	28.162	0.071	106.263	16.957	0.0081	22.866	0.681	0.0018	4.156
J5CNT60	2.908	0.0096	6.907	7.516	0.0070	51.693	32.509	0.042	112.423	19.360	0.0095	29.026	1.806	0.0048	4.449
J15CNT20	1.705	0.0109	7.285	6.127	0.0083	66.293	20.952	0.089	127.023	13.067	0.0123	43.626	0.171	0.0046	4.827
J15CNT40	2.068	0.0098	6.963	6.591	0.0072	92.613	25.830	0.081	153.343	16.194	0.0087	69.946	0.580	0.0060	4.505
J15CNT60	2.519	0.0113	6.649	6.991	0.0087	63.103	29.058	0.073	123.833	17.992	0.0110	40.436	1.197	0.0067	4.191

Abbreviations: CO, carbon monoxide; CO₂, carbon dioxide; NO_x, nitrogen oxide; UHC, unburned hydrocarbon.

5. Fuel Conversion Efficiency and Energy Balance Between the Emissions and Performance Parameters of JME and CNT Blends

The fuel conversion efficiency (ηf) of a CI engine is defined as the ratio of the mechanical work generated by the engine to the energy content of the diesel fuel it consumes. This efficiency is evaluated for each fuel blend, as shown in Figure 14. It has been observed that CNT enhances fuel conversion efficiency more effectively with J5 fuel blends than with J15 blends. This improvement is due to a higher cetane index, a slight reduction in kinematic viscosity, and the superior performance of CNT when combined with lower concentrations of JME. Even J15CNT40 achieves a fuel conversion efficiency similar to that of J5CNT20. Generally, fuel conversion efficiency decreases at higher speeds due to increased fuel consumption but improves from lower to medium speeds.

In this study, a specific fuel blend was identified to achieve an optimal balance between engine emissions and performance. The most effective fuel blend was chosen based on its performance and emission characteristics. Figure 15 displays the maximum percentage variation in BTE, bsfc, BP, torque, CO₂, CO, UHC, NO_x, and SO across various fuel blends—J5CNT20, J5CNT40, J5CNT60, J15CNT20, J15CNT40, and J15CNT60—at engine speed from 1200 to 2200 rpm, with increments of 200 rpm. It is evident that BTE, BP, and torque increase while bsfc decreases with all fuel blends. The J5CNT60 fuel blend shows the greatest improvement in torque and reduction in bsfc. CO and SO are reduced with all fuel blends, with the lowest CO levels observed for J15CNT20. Additionally, CO₂, UHC, and NO_x levels increase with higher concentrations of CNT. The J15CNT60 blend gave the highest UHC emissions, while the J5CNT20 and J15CNT60 blends have the lowest and highest NO_x formation rates, respectively.

Figure 16 illustrates the percentage variations in average engine characteristics for pure diesel, J5 + CNT, and J15 + CNT fuel blends. Generally, the BP, torque, UHCs, and NO_x increase by 1.58%, 1.56%, 11.06%, and 12.72% with J5 + CNT blends, and by 1.62%, 1.69%, 22.12%, and 8.86% with J15 + CNT blends, respectively. The average bsfc decreases by 1.23% with J5 + CNT and by 0.80% with J15 + CNT blends. The percentage of average BTE increases by 1.36% with J5 + CNT and decreases by 0.67% with J15 + CNT blends. The average CO increases by 2.01% with J5 + CNT and decreases by 1.80% with J15 + CNT blends. Additionally, the proportion of average CO₂ decreases by 2.9% with J15 + CNT blends and increases by 1.37% with J5 + CNT blends. The average SO₂ decrease by 0.60% with J5 + CNT and by 0.39% with J15 + CNT blends. On average, J15 + CNT combinations produce 2.14%, 1.05%, and 16.4% more torque, BP, and UHC compared to J5 + CNT blends. The J15 + CNT blend results in reductions of 1.56%, 6.24%, 4.95%, 10.36%, 20.51%, and 2.38% in CO, BTE, bsfc, CO₂, NO_x, and smoke, respectively, compared to J5 + CNT blends. The effects of JME biodiesel and CNT on each characteristic considered in the study are summarized in Table 9.

Table 9. Comparison of all the fuel blends used in the current investigation.

Fuel blends	∆ Torque	∆ BP	∆ bsfc	∆ BTE	∆ CO	∆ CO₂	∆ UHC	∆ NO_x	∆ Smoke
J5CNT20	1.3% ↑	0.6% ↑	1.7% ↓	6.7% ↑	5.1% ↓	7.2% ↓	4.2% ↑	7.4% ↑	0.6% ↓
J5CNT40	2.6% ↑	2.2% ↑	1.6% ↓	2.0% ↑	2.3% ↓	1.5% ↑	10.6% ↑	16.7% ↑	1.5% ↓
J5CNT60	3.8% ↑	3.2% ↑	2.7% ↓	3.5% ↑	1.0% ↓	10.3% ↑	19.1% ↑	24.1% ↑	1.9% ↓
J15CNT20	2.5% ↑	1.3% ↑	1.2% ↓	2.8% ↑	10.9% ↓	11.5% ↓	10.6% ↑	3.1% ↑	0.7% ↓
J14CNT40	2.7% ↑	1.8% ↑	1.9% ↓	5.1% ↑	8.3% ↓	8.5% ↓	19.1% ↑	10.1% ↑	1.1% ↓
J15CNT60	3.1% ↑	2.3% ↑	2.3% ↓	4.6% ↑	1.6% ↓	2.1% ↑	27.6% ↑	21.9% ↑	1.5% ↓

Note: Upward arrows indicate an increase, while downward arrows indicate a decrease in efficiency and emission parameters.
Abbreviations: BP, brake power; bsfc, brake-specific fuel consumption; BTE, brake thermal efficiency; CO, carbon monoxide; CO₂, carbon dioxide; NO_x, nitrogen oxide; UHC, unburned hydrocarbon.

Given the previous discussion, the J5CNT60 emerges as the ideal fuel blend. According to the literature, CNT, despite being a carbon-based substance, can pose several health risks even in minimal amounts. In contrast, biodiesel derived from JME is nontoxic and environmentally friendly. Nanoparticles are frequently employed in industrial applications such as warmers, steam boilers, combustion turbines, and IC engines (both compression and spark ignition) to enhance engine performance while reducing fuel consumption [65]. Even a slight reduction in fuel combustion can result in significant fuel savings in large-scale processing sectors and power plants, notably improving vehicle mileage and fuel efficiency in public transportation. Furthermore, a slight decrease in emissions is an added benefit.

6. Cost Analysis

In 2024, the cost of CNT in recent research conducted in Pakistan, including importation, shipping, and customs, is approximately $250 per kilogram. Biodiesel supplied by PSO in Pakistan costs about $3 per liter. Fuel blends are prepared by mixing 20, 40, and 60 mg/l of CNT with pure diesel. Biodiesel is added at concentrations of 5% and 15% to pure diesel to create the fuel blends. The cost for fuel blends containing 5% biodiesel and varying concentrations of CNT is $0.020, $0.025, and $0.030 per liter, respectively. For fuel blends with 15% biodiesel and different concentrations of CNT, the costs are $0.50, $0.55, and $0.60 per liter, respectively. In Pakistan, the price of diesel is around $0.96 per liter. When adding 5% biodiesel and the mentioned concentrations of CNT to pure diesel, the price increases by 2.04%, 2.53%, and 3.03%, respectively. Similarly, the price increases by 4.95%, 5.41%, and 5.88% when the same concentrations of CNT are combined with 15% biodiesel. Using CNT with 5% and 15% biodiesel concentrations can reduce bsfc by up to 2.64% and 2.28%, respectively. A comparison of fuel blends at different prices of CNT is shown in Figure 15. Due to the high cost of CNT from importation, shipping, and customs fees, large-scale use in commercial diesel is currently uneconomical in Pakistan. However, if these nanoparticle additives were produced domestically, their cost could be reduced by ~30%. In the United States, where nanoparticles cost around $130 per kilogram, using them as additives is more financially feasible. Additional advantages, including lower exhaust emissions and bsfc, can be assessed to advocate for the use of these nanoparticle additives.

7. Comparison With Previous Studies

This study demonstrates that the combination of JME biodiesel and CNT improves both engine performance and emissions as demonstrated in Figures 16 and 17. The addition of JME biodiesel significantly reduced emissions of NO_x, CO, CO₂, and UHCs, with reductions of up to 12.84% for NO_x and 10.12% for UHC. CNT enhanced combustion efficiency, leading to improvements in BP, torque, and BTE, with the J5CNT60 blend showing a 3.84% increase in torque and a 6.72% improvement in BTE. At higher CNT concentrations, CO₂ and NO_x emissions increased, but CO and SO were reduced.

Compared to previous studies, the JME-CNT blends in this study offer a balanced approach, achieving both performance gains and emission reductions, particularly in CO and SO, as detailed in Table 10. This confirms the potential of JME-CNT blends as a sustainable and efficient alternative to conventional fuels.

Table 10. Comparison of the effects of carbon nanotubes and jojoba methyl ester fuel blends on diesel engine performance and emissions with findings from previous studies using various nanoparticle additives.

References	Additives used	Torque	BP	BTE	bsfc	CO	CO₂	UHC	NO_x	Smoke
Pure diesel	None	Baseline properties of pure diesel

[17]	Copper oxide	1% ↑	—	3.2% ↑	1.2% ↑	5% ↓	4.2% ↑	2.3% ↓	2% ↓	—
[18]	Ferrous picrate	—	—	3.4% ↑	2.1%	—	—	3.1% ↓	—	2.4% ↓
[19]	Aluminum oxide	—	5.4% ↑	5.4% ↑	10.6% ↑	3% ↓	1.6% ↓	1.7% ↓	43.6% ↑	—
[20]	Titanium oxide	—	—	1% ↑	2.1%	25% ↓	—	—	32% ↑	1.3% ↓
[22]	Manganese	14% ↑	12.9% ↑	—	8.2% ↓	12.4% ↓	7.2% ↑	—	18.7% ↑	—
[1]	Graphite	2.8% ↑	9.6% ↑	4.1% ↑	2.6% ↓	14.2% ↑	—	—	18.1% ↑	—
Present study	CNT	3.8% ↑	3.2% ↑	6.7% ↑	2.7% ↓	10.9% ↓	11.5%	19.1% ↑	21.9% ↑	1.9% ↓

Note: Upward arrows indicate an increase, while downward arrows indicate a decrease in efficiency and emission parameters.
Abbreviations: BP, brake power; bsfc, brake-specific fuel consumption; BTE, brake thermal efficiency; CO, carbon monoxide; CO₂, carbon dioxide; NO_x, nitrogen oxide; UHC, unburned hydrocarbon.

8. Conclusions

In the experimental study, a four-stroke, water-cooled, three-cylinder CI engine was utilized to examine how CNT and JME influence engine emissions and performance. JME was mixed with pure diesel at 5% and 15% concentrations, resulting in J5 and J15 blends. CNTs were incorporated into these blends at levels of 20, 40, and 60 ppm. An eddy-current dynamometer was used to evaluate performance metrics such as torque, BP, BTE, and bsfc. The engine operated under full load conditions across a speed range of 1200–2200 rpm, in 200 rpm intervals. CO₂, CO, NO_x, and UHCs were analyzed with the AVL DITEST, while SO was measured using a smoke meter.

The following results were obtained in this research:

•
The J5CNT60 fuel blend produced a 3.84% increase in maximum torque at an engine speed of 1400 rpm compared to pure diesel.
•
The J5CNT20 fuel blend achieved the highest BTE improvement of 6.72% at 1400 rpm.
•
When compared to pure diesel, the J5CNT60 fuel blend resulted in a maximum reduction of 2.65% in bsfc at 1600 rpm.
•
CO emissions were reduced by 17.28% at 1800 rpm using the J15 fuel blend, while the J5CNT60 blend caused a 10.37% increase in CO emissions at 2200 rpm.
•
The J5CNT60 fuel blend led to a maximum reduction of 20.86% in CO₂ emissions at 2200 rpm, but also showed a 9.31% increase in CO₂ emissions at the same speed.
•
The J15 fuel blend achieved a 10.12% reduction in UHCs emissions at 1800 rpm, while the J15CNT60 blend caused a 23.52% increase in UHC emissions at 2200 rpm.
•
NO_x emissions decreased by 12.84% at 2200 rpm with the J15 fuel blend, whereas the J5CNT60 blend resulted in the highest NO_x emissions increase of 24.06% at 1400 rpm.
•
Smoke emissions were reduced by 1.90% with the J15CNT60 fuel blend at 2000 rpm, while the highest increase in SO was 0.80% at 1200 rpm.
•
In summary, the J5CNT60 fuel blend showed the greatest performance enhancements, whereas the J15 fuel blend resulted in the most notable emission reductions. Consequently, J5CNT60 and J15 were found to be the most effective fuels in this study.

The J5CNT60 fuel blend, containing 5% JME and 60 ppm CNT, significantly improved engine performance, increasing torque by 3.84%, BTE by 6.72%, and reducing bsfc by 2.65%. Further studies should focus on optimizing fuel blends for different engine conditions, evaluating long-term engine durability, and assessing the economic feasibility of using CNTs on a larger scale.

A policy could be developed and implemented at both the national and international levels to support and promote the use of biodiesel and CNT blends with conventional diesel fuel. This approach would contribute to the sustainability of fuel reserves, reduce capital expenditures, and improve environmental cleanliness.

Nomenclature

ASTM:: American Society for Testing and Materials
BMEP:: Brake mean effective pressure
bsfc:: Brake-specific fuel consumption
BTE:: Brake thermal efficiency
CI:: Compression Ignition
CNT:: Carbon nanotubes
CO:: Carbon monoxide
CO₂:: Carbon dioxide
D:: Pure diesel
DAQ:: Data acquisition unit
EGT:: Exhaust gas temperature
EEVO:: Early exhaust valve opening
FIP:: Fuel injection pressure
FPC:: Ferrous picrate combustion catalyst
g:: Gram
J5:: 95% D + 5% JME
J5CNT20:: J5 + 20 ppm CNT
J5CNT40:: J5 + 40 ppm CNT
J5CNT60:: J5 + 60 ppm CNT
J15:: 85% D + 15% JME
J15CNT20:: J15 + 20 ppm CNT
J15CNT40:: J15 + 40 ppm CNT
J15CNT60:: J15 + 60 ppm CNT
JME:: Jojoba methyl ester
kW:: Kilowatt
kWh:: Kilowatt-hour
m³:: Cubic meter
mg:: Milligram
mm:: Millimeter
MWCNT:: Multiwalled carbon nanotubes
Nm:: Newton meter
NO_x:: Nitrogen oxide
°C:: Centigrade degree
ppm:: Parts per million
rpm:: Revolution per minute
SWCNT:: Single-walled carbon nanotubes
SO:: Smoke opacity
SOI:: Start of injection timing
TIP:: Turbulence inducer piston
UHCs:: Unburned hydrocarbons.

Conflicts of Interest

The authors declare no conflicts of interest.

Author Contributions

Muhammad Sarfraz Ali: conceptualization, methodology, software, formal analysis, writing–original draft. Asad Naeem Shah: supervision, writing–review and editing. Sadia Saleem: software, resources, writing–review and editing. Ammar Ahmad: investigation, resources, writing–review and editing, data curation. Ali Azam: investigation, validation, writing–review and editing. Zafar Abbas: validation, investigation. Shanawar Hamid: writing–review and editing, validation. Eustache Hakizimana: writing–review and editing. Sadia Saleem contributed equally to this work and should be listed as cofirst author.

Funding

No funding was received for this research.

Acknowledgments

The authors are pleased to acknowledge the valuable guidance and assistance from Engr. Muhammad Asif HSE Pakistan.

Open Research

Data Availability Statement

The research data supporting the findings of this study are not shared.

References

1 Ahmed A., Shah A. N., and Azam A., et al.Environment-Friendly Novel Fuel Additives: Investigation of the Effects of Graphite Nanoparticles on Performance and Regulated Gaseous Emissions of CI Engine, Energy Conversion and Management. (2020) 211, https://doi.org/10.1016/j.enconman.2020.112748, 112748.
10.1016/j.enconman.2020.112748
CAS Web of Science® Google Scholar
2 Anandan S. and Ramaswamy M., Oil Economics, 2019, MJP Publisher.
Google Scholar
3 Lawan I., Zhou W., and Idris A. L., et al.Synthesis, Properties and Effects of a Multi-Functional Biodiesel Fuel Additive, Fuel Process, Fuel Processing Technology. (2020) 198, https://doi.org/10.1016/j.fuproc.2019.106228, 106228.
10.1016/j.fuproc.2019.106228
CAS Web of Science® Google Scholar
4 Rodrigues Teixeira A. C., Borges R. R., Machado P. G., Mouette D., and Dutra Ribeiro F. N., PM Emissions From Heavy-Duty Trucks and Their Impacts on Human Health, Atmos, Atmospheric Environment. (2020) 241, https://doi.org/10.1016/j.atmosenv.2020.117814, 117814.
10.1016/j.atmosenv.2020.117814
CAS Google Scholar
5 Azam A., Shah A. N., and Ali S., et al.Design, Fabrication and Implementation of HE-OBCU-EGR Emission Control Unit on CI Engine and Analysis of its Effects on Regulated Gaseous Engine Emissions, Journal of King Saud University—Engineering Sciences. (2021) 33, no. 1, 61–69, https://doi.org/10.1016/j.jksues.2019.10.002.
10.1016/j.jksues.2019.10.002
Google Scholar
6 Khanmohammadi M., Garmarudi A. B., Garmarudi A. B., and de la Guardia M., Characterization of Petroleum-Based Products by Infrared Spectroscopy and Chemometrics, TrAC Trends in Analytical Chemistry. (2012) 35, 135–149, https://doi.org/10.1016/j.trac.2011.12.006, 2-s2.0-84859728759.
10.1016/j.trac.2011.12.006
CAS Web of Science® Google Scholar
7 Hoang A. T., Nižetić S., and Ong H. C., et al.A Review on Application of Artificial Neural Network (ANN) for Performance and Emission Characteristics of Diesel Engine Fueled With Biodiesel-Based Fuels, Sustainable Energy Technologies and Assessments. (2021) 47, https://doi.org/10.1016/j.seta.2021.101416, 101416.
10.1016/j.seta.2021.101416
Web of Science® Google Scholar
8 Reşitoğlu İ. A., Altinişik K., and Keskin A., The Pollutant Emissions From Diesel-Engine Vehicles and Exhaust Aftertreatment Systems, Clean Technologies and Environmental Policy. (2015) 17, no. 1, 15–27, https://doi.org/10.1007/s10098-014-0793-9, 2-s2.0-84942120514.
10.1007/s10098-014-0793-9
CAS Web of Science® Google Scholar
9 Agarwal A. K., Srivastava D. K., Dhar A., Maurya R. K., Shukla P. C., and Singh A. P., Effect of Fuel Injection Timing and Pressure on Combustion, Emissions and Performance Characteristics of a Single Cylinder Diesel Engine, Fuel. (2013) 111, 374–383, https://doi.org/10.1016/j.fuel.2013.03.016, 2-s2.0-84879055764.
10.1016/j.fuel.2013.03.016
CAS Web of Science® Google Scholar
10 Isaac JoshuaRamesh Lalvani J., Parthasarathy M., Dhinesh B., and Annamalai K., Pooled Effect of Injection Pressure and Turbulence Inducer Piston on Performance, Combustion, and Emission Characteristics of a DI Diesel Engine Powered With Biodiesel Blend, Ecotoxicology and Environmental Safety. (2016) 134, 336–343, https://doi.org/10.1016/j.ecoenv.2015.08.020, 2-s2.0-84940118326.
10.1016/j.ecoenv.2015.08.020
CAS PubMed Google Scholar
11 Ooi J. B., Ismail H. M., Swamy V., Wang X., Swain A. K., and Rajanren J. R., Graphite Oxide Nanoparticle as a Diesel Fuel Additive for Cleaner Emissions and Lower Fuel Consumption, Energy & Fuels. (2016) 30, no. 2, 1341–1353, https://doi.org/10.1021/acs.energyfuels.5b02162, 2-s2.0-84959020471.
10.1021/acs.energyfuels.5b02162
CAS Web of Science® Google Scholar
12 Najafi G., Diesel Engine Combustion Characteristics Using Nano-Particles in Biodiesel-Diesel Blends, Fuel. (2018) 212, 668–678, https://doi.org/10.1016/j.fuel.2017.10.001, 2-s2.0-85031329334.
10.1016/j.fuel.2017.10.001
CAS Web of Science® Google Scholar
13 Vellaiyan S., Enhancement in Combustion, Performance, and Emission Characteristics of a Biodiesel-Fueled Diesel Engine by Using Water Emulsion and Nanoadditive, Renewable Energy. (2020) 145, 2108–2120, https://doi.org/10.1016/j.renene.2019.07.140.
10.1016/j.renene.2019.07.140
CAS Web of Science® Google Scholar
14 Wamankar A. K. and Murugan S., Combustion, Performance and Emission of a Diesel Engine Fuelled With Diesel Doped With Carbon Black, Energy. (2015) 86, 467–475, https://doi.org/10.1016/j.energy.2015.04.012, 2-s2.0-84931578437.
10.1016/j.energy.2015.04.012
CAS Web of Science® Google Scholar
15 Annamalai M., Dhinesh B., and Nanthagopal K., et al.An Assessment on Performance, Combustion and Emission Behavior of a Diesel Engine Powered by Ceria Nanoparticle Blended Emulsified Biofuel, Energy Conversion and Management. (2016) 123, 372–380, https://doi.org/10.1016/j.enconman.2016.06.062, 2-s2.0-84976438481.
10.1016/j.enconman.2016.06.062
CAS Web of Science® Google Scholar
16 D’Silva R., Binu K. G., and Bhat T., Performance and Emission Characteristics of a C.I. Engine Fuelled With Diesel and TiO₂ Nanoparticles as Fuel Additive, Materials Today: Proceedings. (2015) 2, no. 4-5, 3728–3735, https://doi.org/10.1016/j.matpr.2015.07.162, 2-s2.0-84947309939.
10.1016/j.matpr.2015.07.162
Google Scholar
17 Gumus S., Ozcan H., Ozbey M., and Topaloglu B., Aluminum Oxide and Copper Oxide Nanodiesel Fuel Properties and Usage in a Compression Ignition Engine, Fuel. (2016) 163, 80–87, https://doi.org/10.1016/j.fuel.2015.09.048, 2-s2.0-84942904045.
10.1016/j.fuel.2015.09.048
CAS Web of Science® Google Scholar
18 Hosseini S. H., Taghizadeh-Alisaraei A., Ghobadian B., and Abbaszadeh-Mayvan A., Effect of Added Alumina as Nano-Catalyst to Diesel-Biodiesel Blends on Performance and Emission Characteristics of CI Engine, Energy. (2017) 124, 543–552, https://doi.org/10.1016/j.energy.2017.02.109, 2-s2.0-85013751635.
10.1016/j.energy.2017.02.109
CAS Web of Science® Google Scholar
19 Zhu M., Ma Y., and Zhang D., An Experimental Study of the Effect of a Homogeneous Combustion Catalyst on Fuel Consumption and Smoke Emission in a Diesel Engine, Energy. (2011) 36, no. 10, 6004–6009, https://doi.org/10.1016/j.energy.2011.08.015, 2-s2.0-80053453110.
10.1016/j.energy.2011.08.015
CAS Web of Science® Google Scholar
20 Shahir V. K., Jawahar C. P., Vinod V., and Suresh P. R., Experimental Investigations on the Performance and Emission Characteristics of a Common Rail Direct Injection Engine Using Tyre Pyrolytic Biofuel, Journal of King Saud University - Engineering Sciences. (2020) 32, no. 1, 78–84, https://doi.org/10.1016/j.jksues.2018.05.004, 2-s2.0-85048404479.
10.1016/j.jksues.2018.05.004
Google Scholar
21 Hoseini S. S. and Sobati M. A., Performance and Emission Characteristics of a Diesel Engine Operating on Different Water in Diesel Emulsion Fuels: Optimization Using Response Surface Methodology (RSM), Frontiers in Energy. (2019) 13, no. 4, 636–657, https://doi.org/10.1007/s11708-019-0646-7.
10.1007/s11708-019-0646-7
Web of Science® Google Scholar
22 Çelik M., Solmaz H., and Serdar Yücesu H., Examination of the Effects of Organic Based Manganese Fuel Additive on Combustion and Engine Performance, Fuel Processing Technology. (2015) 139, 100–107, https://doi.org/10.1016/j.fuproc.2015.08.002, 2-s2.0-84946479955.
10.1016/j.fuproc.2015.08.002
CAS Web of Science® Google Scholar
23 Gosala D. B., Ramesh A. K., and Allen C. M., et al.Diesel Engine Aftertreatment Warm-up Through Early Exhaust Valve Opening and Internal Exhaust Gas Recirculation During Idle Operation, International Journal of Engine Research. (2018) 19, no. 7, 758–773, https://doi.org/10.1177/1468087417730240, 2-s2.0-85053671327.
10.1177/1468087417730240
CAS Web of Science® Google Scholar
24 Konstandopoulos A. G., Kostoglou M., Beatrice C., Di Blasio G., Imren A., and Denbratt I., Impact of Combination of EGR, SCR, and DPF Technologies for the Low-Emission Rail Diesel Engines, Emission Control Science and Technology. (2015) 1, no. 3, 213–225, https://doi.org/10.1007/s40825-015-0020-0, 2-s2.0-85010881732.
10.1007/s40825-015-0020-0
CAS Google Scholar
25 Elsharkawy E. A., Abou Al-Sood M. M., El-Fakharany M. K., and Ahmed M., Enhancing the Impact of Biodiesel Blend on Combustion, Emissions, and Performance of DI Diesel Engine, Arabian Journal for Science and Engineering. (2020) 45, no. 2, 1109–1123, https://doi.org/10.1007/s13369-019-04245-3.
10.1007/s13369-019-04245-3
CAS Web of Science® Google Scholar
26 Devarajan Y., Nagappan B., and Subbiah G., A Comprehensive Study on Emission and Performance Characteristics of a Diesel Engine Fueled With Nanoparticle-Blended Biodiesel, Environmental Science and Pollution Research. (2019) 26, no. 11, 10662–10672, https://doi.org/10.1007/s11356-019-04446-1, 2-s2.0-85061736895.
10.1007/s11356-019-04446-1
CAS PubMed Web of Science® Google Scholar
27 Roy S., Parsi P. K., and Kotha R. S., et al.Effective Utilisation of Waste Cooking Oil in a Single-Cylinder Diesel Engine Using Alumina Nanoparticles, Sustainable Energy & Fuels. (2020) 4, no. 2, 571–581, https://doi.org/10.1039/c9se00393b.
10.1039/C9SE00393B
CAS Web of Science® Google Scholar
28 El-Seesy A. I., Abdel-Rahman A. K., Bady M., and Ookawara S., Performance, Combustion, and Emission Characteristics of a Diesel Engine Fueled by Biodiesel-Diesel Mixtures With Multi-Walled Carbon Nanotubes Additives, Energy Conversion and Management. (2017) 135, 373–393, https://doi.org/10.1016/j.enconman.2016.12.090, 2-s2.0-85008402193.
10.1016/j.enconman.2016.12.090
CAS Web of Science® Google Scholar
29 Venkatesan H., Kumar V. Udhaya, Sivamani S., and Premkumar T. Micha, Evaluation of Combustion, Performance and Emission Characteristics of a Diesel Engine Fuelled With Diesel—Jojoba Biodiesel—n Butanol With Multi-Walled Carbon Nanotube as Fuel Additive, International Journal of Ambient Energy. (2023) 44, no. 1, 1748–1766, https://doi.org/10.1080/01430750.2023.2188256.
10.1080/01430750.2023.2188256
CAS Google Scholar
30 Grytting V. S., Chand P., Låg M., Øvrevik J., and Refsnes M., The pro-Inflammatory Effects of Combined Exposure to Diesel Exhaust Particles and Mineral Particles in Human Bronchial Epithelial Cells, Particle and Fibre Toxicology. (2022) 19, no. 1, 1–22, https://doi.org/10.1186/s12989-022-00455-0.
10.1186/s12989-022-00455-0
PubMed Web of Science® Google Scholar
31 Leikauf G. D., Kim S.-H., and Jang A.-S., Mechanisms of Ultrafine Particle-Induced Respiratory Health Effects, Experimental & Molecular Medicine. (2020) 52, no. 3, 329–337, https://doi.org/10.1038/s12276-020-0394-0.
10.1038/s12276-020-0394-0
CAS PubMed Web of Science® Google Scholar
32 Faber S. C., McNabb N. A., Ariel P., Aungst E. R., and McCullough S. D., Exposure Effects beyond the Epithelial Barrier: Transepithelial Induction of Oxidative Stress by Diesel Exhaust Particulates in Lung Fibroblasts in an Organotypic Human Airway Model, Toxicological Sciences. (2020) 177, no. 1, 140–155, https://doi.org/10.1093/toxsci/kfaa085.
10.1093/toxsci/kfaa085
CAS PubMed Web of Science® Google Scholar
33 Shaah M. A. H., Hossain M. S., and Allafi F. A. S., et al.A Review on Non-Edible Oil as a Potential Feedstock for Biodiesel: Physicochemical Properties and Production Technologies, RSC Advances. (2021) 11, no. 40, 25018–25037, https://doi.org/10.1039/D1RA04311K.
10.1039/D1RA04311K
PubMed Web of Science® Google Scholar
34 Jagtap S. P., Pawar A. N., and Lahane S., Improving the usability of Biodiesel Blend in Low Heat Rejection Diesel Engine Through Combustion, Performance and Emission Analysis, Renewable Energy. (2020) 155, 628–644, https://doi.org/10.1016/j.renene.2020.03.115.
10.1016/j.renene.2020.03.115
CAS Web of Science® Google Scholar
35 Malmgren E., Brynolf S., Fridell E., Grahn M., and Andersson K., The Environmental Performance of a Fossil-Free Ship Propulsion System With Onboard Carbon Capture—a Life Cycle Assessment of the HyMethShip Concept, Sustainable Energy & Fuels. (2021) 5, no. 10, 2753–2770, https://doi.org/10.1039/D1SE00105A.
10.1039/D1SE00105A
CAS Web of Science® Google Scholar
36 Senthil R., Paramasivam C., and Rajendran S., Influence of Injection Pressure on Performance and Emission Characteristics of Nerium Methyl Ester Operated DI Diesel Engine, Applied Mechanics and Materials. (2014) 592–594, 1632–1637, https://doi.org/10.4028/www.scientific.net/AMM.592-594.1632, 2-s2.0-84904975422.
10.4028/www.scientific.net/AMM.592-594.1632
CAS Google Scholar
37 Tayari S., Abedi R., and Rahi A., Comparative Assessment of Engine Performance and Emissions Fueled With Three Different Biodiesel Generations, Renewable Energy. (2020) 147, 1058–1069, https://doi.org/10.1016/j.renene.2019.09.068.
10.1016/j.renene.2019.09.068
CAS Web of Science® Google Scholar
38 Clenci A., Berquez J., and Stoica R., et al.Experimental Investigation of the Effect of an Afterburner on the Light-Off Performance of an Exhaust After-Treatment System, Energy Reports. (2022) 8, 406–418, https://doi.org/10.1016/j.egyr.2022.07.025.
10.1016/j.egyr.2022.07.025
Web of Science® Google Scholar
39 Tosun E. and Özcanlı M., Hydrogen Enrichment Effects on Performance and Emission Characteristics of a Diesel Engine Operated With Diesel-Soybean Biodiesel Blends With Nanoparticle Addition, Engineering Science and Technology, an International Journal. (2021) 24, no. 3, 648–654, https://doi.org/10.1016/j.jestch.2020.12.022.
10.1016/j.jestch.2020.12.022
Web of Science® Google Scholar
40 Saheban Alahadi M. J., Shirneshan A., and Kolahdoozan M., Experimental Investigation of the Effect of Grooves Cut Over the Piston Surface on the Volumetric Efficiency of a Radial Hydraulic Piston Pump, International Journal of Fluid Power. (2017) 18, no. 3, 181–187, https://doi.org/10.1080/14399776.2017.1337440, 2-s2.0-85025806821.
10.1080/14399776.2017.1337440
Google Scholar
41 Bi Y., Wang P., and Luo L., et al.Analysis of Out-of-Round Deformation of a Dry Cylinder Liner of a Non-Road High-Pressure Common-Rail Diesel Engine Based on Multi-Field Coupling, Journal of the Brazilian Society of Mechanical Sciences and Engineering. (2021) 43, no. 1, 1–15, https://doi.org/10.1007/s40430-020-02737-0.
10.1007/s40430-020-02737-0
Web of Science® Google Scholar
42 Gad M. S., Abdel Aziz M. M., and Kayed H., Impact of Different Nano Additives on Performance, Combustion, Emissions and Exergetic Analysis of a Diesel Engine Using Waste Cooking Oil Biodiesel, Propulsion and Power Research. (2022) 11, no. 2, 209–223, https://doi.org/10.1016/j.jppr.2022.04.004.
10.1016/j.jppr.2022.04.004
Web of Science® Google Scholar
43 Hojati A. and Shirneshan A., Effect of Compression Ratio Variation and Waste Cooking Oil Methyl Ester on the Combustion and Emission Characteristics of an Engine, Energy & Environment. (2020) 31, no. 7, 1257–1280, https://doi.org/10.1177/0958305X19893045.
10.1177/0958305X19893045
CAS Web of Science® Google Scholar
44 Barsari M. A. N. and Shirneshan A., An Experimental Study of Friction and Wear Characteristics of Sunflower and Soybean Oil Methyl Ester Under the Steady-State Conditions by the Four-Ball Wear Testing Machine, Journal of Tribology. (2019) 141, no. 4, 10, https://doi.org/10.1115/1.4042390, 2-s2.0-85060788602, 044501.
10.1115/1.4042390
CAS Web of Science® Google Scholar
45 Sridhara V. and Satapathy L. N., Effect of Nanoparticles on Thermal Properties Enhancement in Different Oils—A Review, Critical Reviews in Solid State and Materials Sciences. (2015) 40, no. 6, 399–424, https://doi.org/10.1080/10408436.2015.1068159, 2-s2.0-84944072711.
10.1080/10408436.2015.1068159
CAS Web of Science® Google Scholar
46 Rodoshi Khan N. and Bin Rashid A., Carbon-Based Nanomaterials: A Paradigm Shift in Biofuel Synthesis and Processing for a Sustainable Energy Future, Energy Conversion and Management: X. (2024) 22, https://doi.org/10.1016/j.ecmx.2024.100590, 100590.
10.1016/j.ecmx.2024.100590
CAS Google Scholar
47 Arias S., Molina F., Palacio R., López D., and Agudelo J. R., Assessment of Carbonyl and PAH Emissions in an Automotive Diesel Engine Fueled With Butanol and Renewable Diesel Fuel Blends, Fuel. (2022) 316, https://doi.org/10.1016/j.fuel.2022.123290, 123290.
10.1016/j.fuel.2022.123290
CAS Web of Science® Google Scholar
48 Arias S., Molina F., and Agudelo J. R., Palm Oil Biodiesel: An Assessment of PAH Emissions, Oxidative Potential and Ecotoxicity of Particulate Matter, Journal of Environmental Sciences. (2021) 101, 326–338, https://doi.org/10.1016/j.jes.2020.08.022.
10.1016/j.jes.2020.08.022
CAS PubMed Google Scholar
49 Yusuf A. A., Inambao F. L., and Ampah J. D., The Effect of Biodiesel and CeO₂ Nanoparticle Blends on CRDI Diesel Engine: A Special Focus on Combustion, Particle Number, PM_2.5 Species, Organic Compound and Gaseous Emissions, Journal of King Saud University - Engineering Sciences. (2022) 16, https://doi.org/10.1016/j.jksues.2021.12.003.
10.1016/j.jksues.2021.12.003
Google Scholar
50 Pullagura G., Vanthala V. S. P., and Vadapalli S., et al.Enhancing Performance Characteristics of Biodiesel-Alcohol/Diesel Blends With Hydrogen and Graphene Nanoplatelets in a Diesel Engine, International Journal of Hydrogen Energy. (2024) 50, 1020–1034, https://doi.org/10.1016/j.ijhydene.2023.09.313.
10.1016/j.ijhydene.2023.09.313
CAS Web of Science® Google Scholar
51 Sulochana G., Prasad C. V., and Bhatti S. K., et al.Impact of Multi-Walled Carbon Nanotubes (MWCNTs) on Hybrid Biodiesel Blends for Cleaner Combustion in CI Engines, Energy. (2024) 303, https://doi.org/10.1016/j.energy.2024.131911, 131911.
10.1016/j.energy.2024.131911
CAS Web of Science® Google Scholar
52 Çılğın E., Investigation of the Effects of Single and Double-Walled Carbon Nanotube Utilization on Diesel Engine Combustion, Emissions, and Performance, Case Studies in Thermal Engineering. (2024) 57, no. January, https://doi.org/10.1016/j.csite.2024.104282, 104282.
10.1016/j.csite.2024.104282
Web of Science® Google Scholar
53 Mubarak M., Shaija A., and Suchithra T. V., Experimental Evaluation of Salvinia Molesta Oil Biodiesel/Diesel Blends Fuel on Combustion, Performance and Emission Analysis of Diesel Engine, Fuel. (2021) 287, https://doi.org/10.1016/j.fuel.2020.119526, 119526.
10.1016/j.fuel.2020.119526
CAS Web of Science® Google Scholar
54 Fridrichová K., Drápal L., Vopařil J., and Dlugoš J., Overview of the Potential and Limitations of Cylinder Deactivation, Renewable and Sustainable Energy Reviews. (2021) 146, https://doi.org/10.1016/j.rser.2021.111196, 111196.
10.1016/j.rser.2021.111196
CAS Web of Science® Google Scholar
55 Ghodke P. R. and Suryawanshi J. G., Investigation of Multi-Cylinder Diesel Engine to Meet Future Indian Emission Norms, Iranian Journal of Science and Technology Transactions of Mechanical Engineering. (2014) 38, no. M1, 239–252.
Web of Science® Google Scholar
56 Heidari-Maleni A., Mesri-Gundoshmian T., Jahanbakhshi A., Karimi B., and Ghobadian B., Novel Environmentally Friendly Fuel: The Effect of Adding Graphene Quantum Dot (GQD) Nanoparticles With Ethanol-Biodiesel Blends on the Performance and Emission Characteristics of a Diesel Engine, NanoImpact. (2021) 21, https://doi.org/10.1016/j.impact.2021.100294, 100294.
10.1016/j.impact.2021.100294
CAS PubMed Web of Science® Google Scholar
57 Sangeetha M., Boomadevi P., Khalifa A. S., Brindhadevi K., and Sekar M., Vibration, Acoustic and Emission Characteristics of the Chlorella Vulgaris Microalgae Oil in Compression Ignition Engine to Mitigate Environmental Pollution, Chemosphere. (2022) 293, https://doi.org/10.1016/j.chemosphere.2021.133475, 133475.
10.1016/j.chemosphere.2021.133475
CAS PubMed Web of Science® Google Scholar
58 Aliana-Nasharuddin N., Asikin-Mijan N., and Abdulkareem-Alsultan G., et al.Production of Green Diesel From Catalytic Deoxygenation of Chicken Fat Oil over a Series Binary Metal Oxide-Supported MWCNTs, RSC Advances. (2020) 10, no. 2, 626–642, https://doi.org/10.1039/C9RA08409F.
10.1039/C9RA08409F
CAS PubMed Web of Science® Google Scholar
59 Mohammed A. S., Atnaw S. M., Ramaya A. V., and Alemayehu G., A Comprehensive Review on the Effect of Ethers, Antioxidants, and Cetane Improver Additives on Biodiesel-Diesel Blend in CI Engine Performance and Emission Characteristics, Journal of the Energy Institute. (2023) 108, https://doi.org/10.1016/j.joei.2023.101227, 101227.
10.1016/j.joei.2023.101227
CAS Web of Science® Google Scholar
60 Shirneshan A. R., Almassi M., Ghobadian B., and Najafi G. H., Investigating the Effects of Biodiesel From Waste Cooking Oil and Engine Operating Conditions on the Diesel Engine Performance by Response Surface Methodology, Iranian Journal of Science and Technology Transactions of Mechanical Engineering. (2014) 38, no. M2, 289–301.
Web of Science® Google Scholar
61 Razzaq L., Mujtaba M. A., and Soudagar M. E. M., et al.Engine Performance and Emission Characteristics of Palm Biodiesel Blends With Graphene Oxide Nanoplatelets and Dimethyl Carbonate Additives, Journal of Environmental Management. (2021) 282, https://doi.org/10.1016/j.jenvman.2020.111917, 111917.
10.1016/j.jenvman.2020.111917
CAS PubMed Web of Science® Google Scholar
62 Mansoury M., Jafarmadar S., and Kousheshi N., Experimental Study of the Effects of Air-Injection, Injection Timing and Cooled EGR on the Combustion, Emissions and Performance of a Nature Aspirated Direct Injection Diesel Engine, Iranian Journal of Science and Technology Transactions of Mechanical Engineering. (2015) 39, no. M1, 147–152.
Web of Science® Google Scholar
63 Yilmaz N., Vigil F. M., and Donaldson B., Fuel Effects on PAH Formation, Toxicity and Regulated Pollutants: Detailed Comparison of Biodiesel Blends With Propanol, Butanol and Pentanol, Science of The Total Environment. (2022) 849, https://doi.org/10.1016/j.scitotenv.2022.157839, 157839.
10.1016/j.scitotenv.2022.157839
CAS PubMed Web of Science® Google Scholar
64 Kashyap D., Das S., and Kalita P., Exploring the Efficiency and Pollutant Emission of a Dual Fuel CI Engine Using Biodiesel and Producer Gas: An Optimization Approach Using Response Surface Methodology, Science of The Total Environment. (2021) 773, https://doi.org/10.1016/j.scitotenv.2021.145633, 145633.
10.1016/j.scitotenv.2021.145633
CAS PubMed Web of Science® Google Scholar
65 Mei D., Zuo L., Adu-Mensah D., Li X., and Yuan Y., Combustion Characteristics and Emissions of a Common Rail Diesel Engine Using Nanoparticle-Diesel Blends With Carbon Nanotube and Molybdenum Trioxide, Applied Thermal Engineering. (2019) 162, https://doi.org/10.1016/j.applthermaleng.2019.114238, 2-s2.0-85071127420, 114238.
10.1016/j.applthermaleng.2019.114238
CAS Web of Science® Google Scholar

Citing Literature

All articles

Eco-Friendly Additives: Performance and Emissions Analysis of a Diesel Engine With Jojoba Methyl Ester and CNT Blends

Abstract

1. Introduction