Bibliometric analysis, physical properties, and experimental evaluation of additives-diesel ternary blends

doi:10.21203/rs.3.rs-3329638/v1

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Bibliometric analysis, physical properties, and experimental evaluation of additives-diesel ternary blends

https://doi.org/10.21203/rs.3.rs-3329638/v1

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published 18 Dec, 2023

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Petroleum fuel availability faces a significant challenge in today's world, primarily due to its heightened demand and overreliance on imports. The rapid pace of urbanization, intertwined with factors like air quality, economic considerations, and fuel availability, has ignited a growing awareness of the pressing need for a cleaner environment and the search for alternative fuel sources. As global emissions limits continue to rise, there is a collective pursuit of improved fuels that can seamlessly integrate with compression ignition engines. A comprehensive bibliometric analysis further underscores the escalating worldwide research efforts in this critical domain. According to the existing literature, nitromethane and 2-ethoxy ethyl acetate have demonstrated superior physical and combustion properties compared to other additives. To explore their potential, a meticulous performance and emission analysis was conducted using a single-cylinder, 4-stroke VCR CI engine, employing varying proportions of 2-ethoxy ethyl acetate and a constant 2% blend of nitromethane, with EEA concentrations ranging from 5%, 10%, to 15% (v/v). This research delved into the influence of these diverse fuel blends on the performance of CI engines and exhaust characteristics within a compression ratio spectrum spanning from 17 to 20. The experimental findings revealed that ternary blends, although having a marginal impact on engine performance, exhibited lower emissions compared to pure diesel. The pinnacle of this investigation emerged with the EEA5NM2D93 blend, which yielded optimal results in terms of both performance and emission characteristics.

2-Ethoxy ethyl acetate

Nitromethane

Diesel

Performance

Emissions

Due to the rising global population and corresponding rise in energy demand, environmental pollution may become a problem. On the contrary, it is obvious that fuels which are fossil-based as a source of enduring energy are limited. The urging for oil-based fuels (i.e., fossil fuels) has risen considerably as a result of globalization. Crude oil currently provides 12.2 x 109 tonnes of worldwide annual energy consumption. By 2035, this energy consumption will have increased to 1.75 x 109 tonnes of crude oil (Soudagar et al., 2020). Due to depletion of fuel reserves, the globe will face a future fuel scarcity (Mujtaba et al., 2021). In order to meet energy demand, the transportation industry used half of all fossil fuels (Marikatti et al., 2020). Transportation sector is the backbone of oil use and it will be responsible for 50% of greenhouse gas emissions by 2030 (Ahmed et al., 2020).

In addition to economic issues, the excessive use of fossil fuels has led to persistent environmental problem like climate catastrophe and global warming. The major source of energy in various forms is combustion of fuels. Reciprocating engines have higher stability and dependability. So it is often used in the agriculture and transportation field. Due to the accelerated rate of urbanization, large scale use of engines, poor air quality index, economy and scarcity of fossil fuels, it is necessary to protect the environment and look for alternative energy sources (Jhalani et al., 2022). Diesel engines have a better thermal efficiency than spark ignition engines. However, using a CI engine comes with two main risks. One is linked to concerns about the engine's exhaust emissions to the environment, while the other is linked to the viability of fossil fuels. CI engines produce a variety of toxic substances, including carbon monoxide (CO), unburned hydrocarbons (UHC), particulate matter (PM), nitrogen oxides (NOx), and others (Kumar et al., 2020a).

The development of clean alternative fuels for engines and the control of engine emissions (such as NOx, smoke, etc.) are two issues that many researchers around the world are working to tackle at the same time. According to recent study in the ignition of fuels in diesel engines, BTE and BSFC can be improvised by allowing the fuel to mix-up with more oxygen atoms, resulting in superior ignition and reduced smoke level, CO, and UHC emissions (Zhang et al., 2023).

According to bibliometric analysis with the keywords "diesel, biodiesel and additives" using VOSviewer software, it was observed that worldwide research in this area is continuously increasing. In the overlay display mode, Fig. 1 presents the bibliometric grid constructed based on the co-occurrence of author keywords. The threshold for keyword inclusion was set at a minimum of ten occurrences. Notably, among the various keywords, 'biodiesel' stands out as the most frequently appearing term, occurring 262 times. Table 1 provides a comprehensive overview of the top keywords, their respective occurrence frequencies, and the total link strength associated with each.

Table 1

Prominence of some top keywords in the context of research
S. No.	Keyword, occurrences and their total link strength
1	Biodiesel, waste cooking oil and transesterification emerges as the dominant keyword with a substantial 312 occurrences and a total link strength of 633.
2	Diesel engine and compression ignition engine follows closely with 250 occurrences and a link strength of 526.
3	Additives (Ethanol, n-butanol Butanol Methanol Diethyl ether and Biofuel) appears 248 times, accompanied by a link strength of 572.
4	Combustion and Combustion characteristics are another prominent term, appearing 193 times and garnering a link strength of 448.
5	Performance and engine performance exhibits a frequency of 247 occurrences, coupled with a link strength of 625.
6	Emissions, exhaust emissions and emission collectively appear 325 times with a link strength of 766, underlining their significance.
7	Diesel appears 46 times, accompanies by a link strength of 100.

The co-occurrence patterns and link strengths among these keywords are elucidated in Table 1. As evident from the table, the high frequency and link strength of 'biodiesel' and 'diesel engine' signify their central role in the research landscape, closely followed by 'additives', 'combustion' and 'performance'.

1.1 Use of additives

Since the emission norms have been revised for CI engines, the introduction of cleaner fuel is being encouraged more and more by the government. Numerous fuels, including oxygenated fuels like alcohols, are used as fuel additives with a different emphasis from regular diesel fuel in order to reduce engine exhaust emissions without altering engine parameters. A number of additives other than alcohol-oxygenated additives are available for blending with diesel (i.e. nitro paraffin, acetate, ether, etc.) and are capable of accelerating the combustion process or complete the combustion in engines by improving the cetane number, oxygen content, etc. and by reducing the delay period. As a result of the complete combustion of the fuel, the engine operates at high performance and low emissions (Kumar et al., 2019).

1.2 Nitromethane

Nitromethane (CH3-NO2) is an organic chemical that is mostly practiced in extractions, reaction medium solvents, and cleaning solvents in a variety of industrial appliances. It has the most basic organic nitro compound. Because nitromethane has a high oxygen content in its chemical structure, it is also regarded an oxygenated additive because it minimizes the quantity of oxygen required for complete combustion. It is a viscous, kind of a polar liquid with a low viscosity. Nitromethane is thermal sensitive and ignites quickly, almost instantly when brought into the combustion chamber, making it ideal for compression ignition engines. As a result, the blend's viscosity is reduced and its cetane index is elevated (Kumar et al., 2020b; Moghaddam and Moghaddam, 2014).

1.3 2-Ethoxy Ethyl Acetate

2-Ethoxy Ethyl Acetate is an organic chemical with the formula CH3-CH2-O-CH2-CH2-O2-C-CH3. It is a compound made up of ethoxy ethanol and acetic acid. It is a white liquid that is only slightly soluble in water (Rao et al., 2020; Senthil et al., 2011). The various combustion and physico–chemical properties of EEA, NM and Diesel are compared in Table 2.

Table 2

Properties of Oxygenated additives and Diesel (Kumar et al., 2018; Rao et al., 2020)
Particulars	EEA	NM	Diesel
Chemical Formula	C6H12O3	CH3NO2	C12H23
Cetane Number	61	NA	52
Density (kg/m3)-20°C	975	1139	828
Boiling Point (°C)	156	163	180–360
Viscosity	1.32	0.62	2.45
Auto ignition temperature (°C)	379	418	315
Calorific value (MJ/kg)	NA	11.4	42.8
Latent heat of vaporization (kJ/kg)	NA	561	250
Oxygen Content (%wt)	17	53	0

Nitromethane has a higher auto ignition temperature than EEA. EEA contains more oxygen than diesel, but less than nitromethane. Nitromethane has a far lower viscosity than diesel, and EEA has almost half the viscosity of diesel, yet it is easily soluble in diesel. It is also observed that EEA is having less auto ignition temperature, low consistency, and high cetane number. Nitromethane builds burning effectiveness on account of the great oxygen rate while EEA further develops the engine proficiency and cetane number of the mix and diminishes the ignition boundaries.

According to literature reviews, ternary blends with higher oxygen content, increased cetane number, and better combustion properties are preferable to binary blends. Based on the literature survey, have selected 2-Ethoxy Ethyl Acetate and Nitromethane as the experimental additives to use in CI engine.

2.1 Engine set up

The engine used for this test is a single-cylinder, four-stroke, DI water-cooled, compression ignition engine. The engine may be manually or self-starting, and it is usually equipped with a centrifugal speed controller. Specifications for the engine are shown in reference Table 3. Figure 2 show the layout of the experimental test setup.

Table 3

Engine setup’s specifications
Equipment	Specification
Engine	4-stroke, single cylinder, water cooled, steady 1500 rpm Diesel Engine, 3.75 kW, 660 CC
Load Capacity(Nm)	Load cell Transducer, Torque Reso. : 0.01 kg–m, Range: 0–6.00 kgm, radius: 0.16 m
Dynamometer	RPM: 1500 rpm − 2200 rpm, 3.75 kW Rating of torque
Measurement of Temp (Five channel indicator)	RTD Sensor (Pt 100), Reso. : 0.1°C ,Range: 0–400°C
Exhaust Gas analyzer	AVL-DIGAS-444N, NOx gas- Electrochemical, Range 0-5000 PPM, Resolution 1ppm
Smoke Analyzer	AVL-437C, Range 0-99.99 m-1, Resolution 0.01

2.2 Blend preparation

Very first task of the study is to prepare the blend with no adulteration. For experimentation work four test fuel blends, pure diesel, EEA5NM2D93 (5% EEA, 2% NM and 93% Diesel), EEA10NM2D88 (10% EEA, 2% NM and 88% Diesel) and EEA15NM2D83 (15% EEA, 2% NM and 83% Diesel) were conditioned to analyze in a variable compression ratio diesel engine. The whole study was performed at a steady speed of 1500 revolutions per minute of engine, with a load ranging from 0 to 4, 8, 12, and 16 kg using 100% diesel and different D-EEA-NM mixtures. The experiments are carried out in various stages of CRs (17 to 20).

The various results of performance and exhaust emission with different concentrations of EEA-NM-Diesel fuel blends with different load (0 to 100%) and different CRs (17, 18, 19, 20) of engine are as shown in Figs. 3.1–3.6.

3.1 Brake specific fuel consumption (BSFC)

Figure 3.1 below illustrates the relationship between brake specific fuel consumption and brake power across various compression ratios (CRs) and fuel blends. As brake power increases, there is a noticeable decline in BSFC, as evident from the graph. The inclusion of EEA in the EEA-NM-Diesel blend results in a decrease in its heat content, leading to higher fuel consumption compared to pure diesel for achieving the same engine output torque. However, it is worth noting that among all the blends, the EEA5NM2D93 blend at CR 19 exhibits the most favorable BSFC performance. Although there isn't a significant improvement in BSFC observed throughout the experiment, it approaches the efficiency of pure diesel.

3.2 Brake thermal efficiency (BTE)

Figure 3.2 illustrates the relationship between Brake Thermal Efficiency (BTE) and Brake Power (BP). The curve depicted in the graph reveals a noteworthy trend: BTE exhibits a consistent improvement as engine BP increases. This phenomenon can be attributed to the advantageous properties of EEA, notably its high oxygen content, which enhances ignition efficiency and promotes more thorough fuel combustion (Kumar et al., 2020c).

Moreover, EEA's excellent volatility contributes to improved fuel-air mixing prior to ignition, further enhancing combustion effectiveness within the engine. Consequently, BTE demonstrates a mixed response with varying proportions of EEA. Notably, the blend EEA5NM2D93, particularly at CR19, yields the highest BTE among all the blends, particularly under full load conditions, showcasing its superior performance in comparison to the other blends.

3.3 Hydrocarbon (HC)

Figure 3.3 depicts a graph that illustrates the relationship between HC emissions in parts per million (ppm) and engine Brake Power (BP) for various blends across different Compression Ratios. It becomes evident from the graph that as the proportion of EEA in the blends increases, there is a notable reduction in hydrocarbon emissions. Specifically, blend EEA10NM2D88 demonstrates the lowest HC emissions percentage among the tested blends.

However, it's worth noting that when the EEA content exceeds 10%, there is an observable increase in HC emissions, indicating a non-linear relationship between EEA concentration and HC emissions.

3.4 Carbon monoxide (CO)

Figure 3.4 provides a visual representation of the relationship between carbon monoxide emissions and engine Brake Power (BP). As the percentage of EEA in the EEA-NM-Diesel blend increases, there is a concurrent rise in the oxygen content within the blend. This heightened oxygen content plays a vital role in facilitating the complete combustion of the fuel, resulting in a significant reduction in CO emissions.

Notably, among all the blends tested under various CRs and full load conditions, blend EEA10NM2D88 consistently stands out by yielding the lowest CO emission values. This underscores the blend's effectiveness in minimizing CO emissions across different operational scenarios.

3.5 Oxides of nitrogen (NOx)

Figure 3.5 presents a graphical representation of the relationship between NOx emissions and engine Brake Power (BP) for various blends under different Compression Ratios. Across all engine load conditions, it becomes evident that NOx emissions are notably higher in the case of EEA-NM-Diesel blends when compared to pure Diesel blends.

It is worth highlighting that EEA's presence has a pronounced influence on NOx emissions, particularly at high engine loads. EEA is responsible for increasing the combustion temperature. This reflects the higher % of NOx emissions for the inclusion of EEA in the fuel blends.

3.6 Smoke emissions

Figure 3.6 illustrates the relationship between smoke emissions and engine Brake Power. In general, the pattern of smoke emissions closely mirrors that of carbon monoxide emissions. Smoke emissions consist of suspended particles and are typically associated with conditions of oxygen deficiency.

The chart clearly illustrates a consistent reduction in smoke emissions when EEA is introduced into the EEA-NM-Diesel blends. This reduction can be attributed to the higher oxygen content and lower carbon content found in these blends. As a result, an increase in oxygen content leads to a decrease in smoke emissions. Consequently, engines operating on EEA-NM-Diesel blends tend to produce less smoke, as supported by Nayyar et al. (2020). Remarkably, among the various blends tested, EEA15NM2D83 stands out by exhibiting the lowest level of smoke emissions. This blend demonstrates its effectiveness in minimizing smoke emissions, particularly at CR20 under full load conditions.

In this study, a diesel engine was operated under varying loads and compression ratios (CRs) using ternary fuel blends (EEA-NM-D), and its performance and emission characteristics were meticulously recorded. The engine was run under standard operating conditions, comparing the results between pure diesel and different ternary blends, namely EEA5NM2D93, EEA10NM2D88, and EEA15NM2D83. The findings were then scrutinized against those obtained with pure diesel to determine the most favorable blend. Based on a comprehensive analysis of the experimental results, the following conclusions can be drawn:

BTE for the EEA5NM2D93 blend demonstrated remarkably similar performance to pure diesel. BTE exhibited improvement with both increasing compression ratios and loads. Notably, the EEA5NM2D93 blend achieved an exceptional BTE of 39.89% at a compression ratio of 19 under full load conditions, compared to other blends.

BSFC for the blended fuel was slightly higher compared to pure diesel, particularly as compression ratios and loads increased. The lowest BSFC recorded was 0.205 kg/kW-hr with the EEA5NM2D93 blend at a compression ratio of 20 during full load operation.

NOx emissions from the blended fuel were somewhat elevated across all compression ratios and load conditions. NOx levels increased with higher compression ratios and loads. The EEA5NM2D93 blend exhibited the lowest NOx emissions, measuring 26 PPM at a compression ratio of 17 under zero load conditions. Even at peak load, the NOx emissions from EEA5NM2D93 were lower than those of other blends, registering at 266.

The percentage of smoke emitted from the blended fuel was notably lower than that of pure diesel combustion. Moreover, an inverse relationship was observed between smoke percentage and compression ratio. The EEA5NM2D93 blend achieved the lowest smoke percentage, at 6.5, at a compression ratio of 20 under medium load conditions. Furthermore, under full load conditions, a significant reduction in smoke emissions was observed with the EEA15NM2D83 blend at a compression ratio of 20.

HC and CO emissions exhibited a similar trend as smoke emissions, with emissions decreasing substantially as compression ratios increased. The lowest recorded emissions for HC and CO were 3 ppm and 0.02 ppm, achieved with the EEA5NM2D93 and EEA10NM2D88 blend respectively at a compression ratio of 20 under full load conditions.

The study focuses on optimizing ternary fuel blends, exploring advanced technologies, addressing emissions challenges, and considering their practical application in evolving energy and environmental demands. This will contribute to the development of cleaner and more sustainable solutions for the transportation sector.

Abbreviations
BP	Brake power	kg	Kilogram
BSFC	Brake specific fuel consumption	kJ	Kilojoules
BTE	Brake thermal efficiency	MEA	2–Methoxy ethyl acetate
CI	Compression ignition	NM	Nitromethane
CO	Carbon monoxide	NOx	Nitrogen oxides
CO2	Carbon dioxide	ppm	Parts per million
CR	Compression ratio	rpm	Revolutions per minute
EEA	2–Ethoxy ethyl acetate	UHC	Unburnt hydrocarbon
HC	Hydrocarbon	VCR	Variable compression ratio

Acknowledgement

The authors extend their heartfelt appreciation to the administration of Swami Keshvanand Institute of Technology, Management, and Gramothan, Jaipur, for their invaluable support in facilitating the research.

Ethical Approval

The authors hereby approves that principles of ethical and professional conduct have been followed in the work.

Consent to Participate

The present research does not involve any human or animal participation.

Consent to Publish

The authors and the responsible authorities at the institute/organization where this work has been carried out give their explicit consent to submit and publish the work in ESPR, if found suitable.

Author Contributions

All the authors have contributed to the conception, design, writing and experimental work performed to prepare this article. Material preparation, data collection and analysis were performed by Chandan Kumar and Mukesh Kumar. The first draft of the manuscript was written by Chandan Kumar and Sumit Sharma. All authors commented on previous versions of the manuscript. All authors have read and approved the final manuscript.

Funding

The authors declare that no funds, grants, or financial support were received during the preparation of this manuscript.

Competing Interests

The authors have no relevant financial or non-financial interests to disclose.

Availability of data and materials

Not Applicable

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published 18 Dec, 2023

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You are reading this latest preprint version

Bibliometric analysis, physical properties, and experimental evaluation of additives-diesel ternary blends

Status:

Journal Publication

Version 1

Abstract

Figures

1. Introduction

1.1 Use of additives

1.2 Nitromethane

1.3 2-Ethoxy Ethyl Acetate

2. Experimental setup

2.1 Engine set up

2.2 Blend preparation

3. Results and discussions

3.1 Brake specific fuel consumption (BSFC)

3.2 Brake thermal efficiency (BTE)

3.3 Hydrocarbon (HC)

3.4 Carbon monoxide (CO)

3.5 Oxides of nitrogen (NOx)

3.6 Smoke emissions

4. Conclusions

Abbreviations

Declarations

References

Status:

Journal Publication

Version 1