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Article

Effect of Plasto-Oil Blended with Diesel Fuel on the Performance and Emission Characteristics of Partly Premixed Charge Compression Ignition Engines with and without Exhaust Gas Recirculation (EGR)

by
Krishna Moorthy Rajendran
1,
Deepak Kumar
1,
Bhawna Yadav Lamba
2,
Praveen Kumar Ghodke
3,
Amit Kumar Sharma
4,
Leonidas Matsakas
5 and
Alok Patel
5,*
1
Centre for Alternate Energy Research, Department of Mechanical Engineering, School of Engineering, University of Petroleum and Energy Studies, Dehradun 248007, India
2
Applied Sciences Clusters, School of Engineering, University of Petroleum and Energy Studies, Dehradun 248007, India
3
Department of Chemical Engineering, National Institute of Technology Calicut, Kozhikode 673601, India
4
Center for Alternate Energy Research (CAER), Department of Chemistry, Applied Sciences Clusters, University of Petroleum and Energy Studies (UPES), Dehradun 248007, India
5
Biochemical Process Engineering, Division of Chemical Engineering, Department of Civil, Environmental, and Natural Resources Engineering, Luleå University of Technology, SE-971 87 Luleå, Sweden
*
Author to whom correspondence should be addressed.
Energies 2023, 16(9), 3750; https://doi.org/10.3390/en16093750
Submission received: 23 February 2023 / Revised: 14 April 2023 / Accepted: 21 April 2023 / Published: 27 April 2023
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Abstract

:
Municipal mixed plastic waste (MMPW) recycling is an innovative way to turn environmental waste into energy fuels. In the present study, a thermochemical process was applied to depolymerize MMPW to produce hydrocarbon fuels known as plasto-oil. The obtained plasto-oil was blended with conventional diesel to test the performance of the PCCI-mode single-cylinder, four-stroke, direct-injection diesel engine. The PCCI combustion mixture was tested with 15% and 30% fuel vapor to ensure homogeneity with and without exhaust gas recirculation. The modified engine findings were compared to a standard conventional engine. At higher loads, PCCI combustion showed reduced emission of carbon monoxide and nitrogen oxides. While the thermal braking efficiency was marginally reduced at all engine loads while using the blends. The results showed that with and without 10% exhaust gas recirculation, an increase in air mix reduced NOx emissions; however, in the case of smoke emissions, an opposite trend was observed. A blend of plasto-oils also decreased CO and unburned hydrocarbon (HC) emissions at higher loads. In conclusion, it was shown that plasto-oils combined with conventional diesel fuel outperformed diesel fuel alone.

1. Introduction

The tertiary conversion of mixed municipal waste plastics into fuel fulfills the energy requirements of the industrial, transportation, and agricultural sectors. Recycling plastic waste to produce fuels faces substantial segregation challenges. While single-use plastic wastes with recognizable physiochemical features have less processing complication. Nevertheless, one practical strategy for recycling and reusing plastic is the collection of waste made up of single-use plastics [1,2]. Thermochemically, polyolefins are broken down into smaller particles using the pyrolysis process. As a result of the pyrolysis process, polymers are converted into a wide variety of hydrocarbons that exist in both liquid and gaseous forms. The conversion of solid waste into liquid or gaseous form depends on the residence time, temperature, and heating rate of process.
The liquid product of the pyrolysis process is known as pyrolysis oil, here, plasto-oil [3]. Biomass pyrolysis oil has many limitations. Enhancing pyrolysis oil requires a hydrotreating or hydrogenation process. In the literature, we found that different biomass can produce pyrolysis oil using the pyrolysis process. The obtained pyrolysis can hydrotreat to yield usable hydrocarbon fuels. It also found that producing hydrotreated oils is possible from palm oils and animal fats [2]. On the other hand, tire and plastic waste also yield hydrocarbon fuel using the pyrolysis process.
Many studies have found that pyrolysis oil from plastic/tires can be blended with conventional oil to address the fuel crisis. The observation indicated that up to 35% of tire pyrolysis oil might be blended with diesel fuel, allowing the test engine to operate without modification. While increased HC, SO2, CO, and smoke emissions are major disadvantages of blending pyrolysis oil with diesel [4,5].
The plastic waste pyrolysis process produces hydrogen, methane, and acetylene as non-condensable gas, while aromatics and olefins as condensable liquid fuel [3]. Chemical analysis found that high yields of gasoline range hydrocarbons (C8–C12) and aromatic content (up to 95.85 wt.%) were found in the oil product. At the same time, light hydrocarbons (C3–C4) reached 5 wt.% of the total weight. Many catalysts have been applied to enhance the chemical composition of pyrolysis oil. Aromatic molecules predominated as a result of the pyrolysis process over HZSM-5. Thus, waste plastics can be recycled into plasto-oil, used in various industries, such as agriculture, the automobile industry, and the manufacturing sector. A significant advancement was observed in the automobile industry using pyrolysis oil produced from plastic waste [4,5].
The plasto-oils can fuel compression ignition engines as compared to regular petroleum products. Compression ignition engines are preferred power plants due to their drivability and thermal efficiency. Despite their benefits, engines produce enormous amounts of NOx and smoke that affect human health [6,7]. Thermal braking efficiency was lower than diesel fuel at all load conditions, and engine load increased exhaust gas temperature. The same was observed with blends of plasto-oil in conventional engines. At the same time, plasto-oils in CI engines reduce carbon-based pollutants while NOx emissions increase [8,9]. Diesel fuel outperforms gasoline at full load. Additionally, plasto-oil increases heat losses and decreases engine thermal brake efficiency [10,11].
In another study, exhaust gas temperature (EGT) was fueled with neat plasto-oil at various injection timings, with increased EGR rates ranging from 10% to 30%. The results observed that EGT was raised due to the recirculated exhaust gas having a high specific heat [12]. Other studies were performed using a combination of emulsified bio-solution, palm biodiesel, and diesel. Chen et al. [13] demonstrated that the blends were beneficial to the environment by lowering emissions of polycyclic aromatic hydrocarbon (PAH) and particulate matter (PM) from diesel engines. In addition, the blends were shown to save money and conserve energy. An oxygenated additive may boost nitrogen dioxide (NO2) emissions and combustion efficiency while simultaneously reducing fuel consumption rate, brake-specific fuel consumption, PM, and CO emissions [14]. The same was observed in many works of literature [15,16].
Elumalai et al. assessed the impact of n-pentanol% on the performance, combustion, and emission characteristics of a PCCI engine running on pyrolyzed tires waste oil [17]. Furthermore, CuO/ZnO (CZ) nanoparticles were added to the fuel blend to provide extra oxygen for improved combustion. The fuel blend for this experiment was made by combining 20% waste tire pyrolysis oil with 80% diesel fuel containing 50 ppm CZ nanoparticles, and n-pentanol was sprayed into the intake manifold in various amounts, namely 10%, 20%, and 30%. As a result of the PCCI dual-fuel mode, PTO20CuZnO50P10 was determined to be the optimum choice since it significantly reduced emission parameters such as oxides of nitrogen (NOx), carbon monoxide (CO), hydrocarbon (HC), and others. In another study, plasto-oil was replaced with blended bio-diesel in a diesel engine to observe increasement in thermal brake efficiency. Senthilkumar et al. [18] tested Jatropha biodiesel with a plasto-oil blend in diesel engines. It was observed that carbon-containing gases as emissions are decreased while oxides of nitrogen increase along with exhaust temperatures [19,20]. Morphological studies of diesel-fueled HCCI engines were studied to assess particulate matter emissions and the effect of EGR rates. It was observed that as the exhaust gas recirculation increased at lower engine loads, quartz filter paper accumulated more particulate matter compared to higher engine loads. At the same time, PCCI engines produce less NOx and smoke emissions. Alternatively, selective catalytic reduction may reduce atmospheric HC and CO [21,22]. The most important aspect affecting PCCI combustion is the fuel mix, temperature, pressure, and ignition rate [23]. However, PCCI combustion’s most essential criterion is fuel adaptability. Many researchers have examined different fuels’ effects on the cylinder combustion process. In the present study, a wide variety of fuels are used to enhance the PCCI’s working range and manage its ignition phase [24,25].
Most of the analysis seems flawed, even though diesel and internal combustion engines have been subjected to a great deal of scrutiny for their emissions. IC engines can produce critical emissions, indicating that the levels of pollutants flowing out of the exhaust are lower than those in the air around the vehicle. The fact that DPFs produce a large amount of particulate matter has been well-known since they were first used commercially. Air pollution has lately reached the point where it may be considered a significant problem on a global scale [26]. Air pollution increased due to the usage of automobiles. The only option to solve the issue is to lower emissions produced by gasoline-powered automobiles, which now make up the overwhelming majority of vehicles on the road [27,28].
Despite automobiles’ usefulness, they are detrimental to human health since they produce large amounts of smoke and nitrogen oxides (NOx). Finding a replacement fuel for diesel engines is crucial in light of increasingly stringent pollution regulations and the diminishing supply of petroleum-based fuels [29,30]. Minimizing emissions and fuel consumption with an efficient fuel injection system is possible [31]. Therefore, the primary focus of the investigation is on the beneficial properties of plasto-oils produced by MMPWs, specifically in the context of an analysis of the engine characteristics of the PCCI engine. In comparison, the engine performance, combustion, and emission characteristics were examined across a wide range of engine loads while using EGR and MMPW-produced fuels without EGR.

2. Materials and Methodology

2.1. Utilization of Municipal Mixed Plastic Waste (MMPW) for Plasto-Oil Production from

Lab-scale pyrolysis facility was set up at UPES Dehradun, India. Figure 1 illustrates the flow process of conversion of plastic waste into an alternative fuel named plasto-oil.
Raw materials, such as plastic bottles, polyethylene carry bags, bread packets, maggi covers and cups, spoons, plastic files and folders, pet bottles, and cable coverings, were collected, and segregated manually to remove unwanted materials, followed by cleaning the waste plastics. Moisture reduction was carried out with solar drying, followed by feeding to the pyrolysis plant.
The pyrolysis reactor was developed to be resistant to corrosion and high temperatures. Induced heat was used to supply heating, and a programmed temperature controller was connected to ensure the required temperature was maintained constantly. The reactor exit was connected to water-circulating cooling jackets so that the volatile byproducts of the pyrolysis may be condensed. Meanwhile, the bladder was attached to capture non-condensable gases, and GC-TCD was used to analyze gases.
The experiments were conducted under non-isothermal conditions. The reaction temperature was increased at a heating rate of 10 K min−1 from room temperature to the desired target temperature. The desired temperature was maintained under isothermal conditions for 30 min to ensure uniform temperature throughout the reactor. Before the process, 500 mL min−1 of nitrogen gas was initially used to purge the reactor to maintain an inert atmosphere. The volatiles produced during the pyrolysis process of plastic waste are cooled using the water-cooled condensers unit, as shown in Figure 2. The bladder was connected to collect non-condensable gases from the exhaust. The yield % of the end product was measured by taking the residual char, condensed liquid fuel, and the non-condensable gases quantity.

2.2. Engine Test Setup and Experiment Methodology

A PCCI engine was keep through its paces under a variety of load conditions while utilizing two distinct diesel-blended plasto-oil vapors (1.15% plasto-oil blended with 85% Diesel, 2.30% plasto-oil blended with 70% Diesel), 10% exhaust gas recirculation (EGR), and without EGR. In the beginning, the conventional engine was operated in PCCI mode. In the first step, Diesel-plasto-oil blends were prepared by blending plasto-oil in diesel at proportion of 15:85 (15% plasto-oil and 85% diesel) and 30:70 (30% plasto-oil and 70% diesel) then poured into fuel tank which connected with common rail injections into intake manifold through fuel pump. Table 1 shows plasto-oil fuel characteristics properties as per ASTM.
Figure 3A,B shows a CI engine adapted to function in PCCI mode coupled to a water-cooled eddy current dynamometer for the experiments. Its eddy current dynamometer was used to measure the engine load and change. Table 2 lists engine specs. A direct injection diesel engine (compression ignition: CI engine) with 3.7 kW at 1500 rpm and engine loads of 20%, 40%, 60%, 80%, and 100% was tested. We collected performance, pollution, and ignition data to assess the engine’s performance. Single-cylinder engines may be easier to inspect. Complexity grows with engine cylinder count.
The fuel injection timing was maintained at 23° BTDC throughout the testing, and the exhaust gas temperature was measured between the exhaust gas manifold and before the EGR.
In addition, to monitor any temperature increases that may occur within the engine, there are four temperature sensors, two of which are located at the intake of cooling water and the other two at the exhaust. It was necessary to alter the intake manifold to accommodate the water-cooled EGR. During the combustion process, reducing intake charge and in-cylinder temperatures was the primary objective of the water-cooled EGR system. The quantity of EGR recycled was regulated mechanically.
Throughout, the engine RPM was held constant. Therefore, the only factor at play was the amount of work being carried out by the engine. Thus, the EGR flow rate can be kept constant at 10% via mechanical means, regardless of variations in engine load. The calorimeter, which included temperature sensors at its beginning and finish to measure the temperature differences of the exhaust gases, was also connected to the exhaust gas pipe. PCCI mode’s vapor flow rate obliged the engine to run in conventional mode at all engine loads. The data gathering system captured each engine load’s volumetric fuel flow rates. The mass basis was used to calculate the engine’s fuel consumption.
In contrast to 15% and 30% of the recorded flow rate, which were manually decided, the fuel flow rate was set for the specified load. The input flow rate for diesel blended plasto-oil at each engine load was calculated manually. The estimated volumetric flow rate value was measured using a digital scale and a timer, then converted to the equivalent mass flow rate flow. The technique was repeated for each engine load and vapor % necessary. The regulator of the engine adjusted minor differences. After making any adjustments, we let the engine rest for two to three minutes before compiling the final data.
The exhaust gas analyzer with NDIR technology was used to monitor engine tailpipe pollutants such as hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides. A smoke meter was attached to the test engine to collect data from the exhaust. Measurement accuracy and uncertainty of instruments have been present in supplementary file as Table S1.

3. Results and Discussion

3.1. The Impact of Various Plasto-Oils (15% and 30%) Blended with Diesel Vapour on Engine Performance

To examine the performance (Brake thermal efficiency and sspecific fuel combustion) and emissions (CO, HC, NOx and smoke) of a diesel engine fueled with diesel-plasto-oil, the engine was run at different loads using the following four possible parametric conditions under PCCI operation:
  • 30% fuel vapor (diesel blended with 30% plasto-oil) with EGR;
  • 30% fuel vapor (diesel blended with 30% plasto-oil) without EGR;
  • 15% fuel vapor (diesel blended with 15% plasto-oil) with EGR;
  • 15% fuel vapor (diesel blended with 15% plasto-oil) without EGR.
It was observed that the conventional engine could be converted into PCCI mode by injecting diesel vapor through the air intake manifold. As stated above, the engine was run under four different conditions in PCCI mode, i.e., 30% and 15% diesel–plasto-oil vapor with and without EGR. The obtained results are discussed below.

3.2. Brake Thermal Efficiency

The results of Brake thermal efficiency of diesel engines run on different fuel vapor percentages, with and without exhaust gas recirculation, are shown in Figure 4. The experiment outcomes showed that, in the absence of EGR, the brake thermal efficiency declined by 2.50% with 15% fuel vapor and by 3.25% with 30% fuel vapor. Similarly, the brake thermal efficiency was decreased by 8–10% with EGR as the fuel vapor increased and the engine was operating at maximum load. The main reason for decreasing the efficiency was that it diluted the oxygen in the charge stream to lower NOx emissions.
Other reasons observed were external mixing with fuel vapor, air–fuel homogeneity, combustion conditions, and charged mixture quality. The diesel blended plasto-oil vapor, EGR, and air induction into the combustion chamber were only allowed through the intake manifold. Increasing the fuel vapor induction rate to 30% reduced charge generation airflow and BTE for optimal combustion. It was found that 30% diesel blended plasto-oil vapor with EGR induction drastically restricted air intake, resulting in insufficient charge for combustion and significant brake power losses. The intake manifold absorbed fuel vapor from the outside, which may have condensed due to the temperature difference between intake air fluids and diesel vapor with plasto- oil. Since PCCI combustion used less fuel to charge, the brake thermal efficiency was also found to be decreased [32].

3.3. Specific Fuel Combustion

As shown in Figure 5, the fuel consumption of the test engine was found to decrease with increasing load for both 15% and 30% plasto-oil vapor with and without EGR. For example, when the engine utilized 30% fuel vapor (plasto-oil blended diesel fuel) with EGR, the specific fuel consumption (sfc) decreased from 426 g/kWh at 20% load to 308 g/kWh at 100% load. Similarly, in the case of 15% fuel vapor with EGR, the sfc decreased from 435 g/kWh at 20% load to 320 g/kWh when operating at full load.

3.4. Exhaust Gas Temperature

The variations in exhaust gas temperature (EGT) with varying engine loads (i.e., 20%, 40%, 60%, 80%, and 100%) are shown in Figure 6. The main observations are that the combustion rate, temperature, and pressure increase when the engine is operated at higher loads. It was observed that as the engine load increased, the exhaust gas temperature rose. The engine’s maximum EGT temperature was reached at 307 °C while it was running at full engine load, in PCCI mode, with 15% fuel vapor, and no EGR. The main reasons identified may be the interaction between the temperature of the cylinder and the geometry.
When using the primary standard (no EGR) for comparison, EGT drops by 9% for 15% fuel vapor induction and 23% for 30% for fuel vapor induction. On the other hand, when using EGR as the primary benchmark for comparison. EGT drops by 29% and 32%, for 15% and 30% fuel vapor induction, respectively. The lean A–F charge, which causes a cooler combustion temperature, was crucial in reducing EGT in PCCI mode. The intake air’s phase change, caused by its temperature, prohibits it from participating in combustion. As EGR dilutes the charge, the outcome is a low charge density.

3.5. Volumetric Efficiency

Figure 7 illustrates the range of volumetric efficiencies an engine can achieve under various load conditions. According to the observation, there was a decrease in volumetric efficiency with an increase in EGR. While a conventional engine operated in its suction stroke, the intake manifold was only open to air circulation, which was not in the case of PCCI conditions. Following the compression stroke, fuel was delivered into the combustion chamber while the charge was formed. Due to the intake, air that filled the manifold had high volumetric efficiency, but due to the area’s size, it only had a small charge mixing span. The combustion process does not use the intake air entirely due to the shorter mixing period.
As a result, a significant amount of air was wasted throughout the process. The intake airflow rate in the manifold was obstructed due to the increased occupancy brought on by recirculated exhaust gas and the volume in the manifold that was filled with fuel vapor while in the PCCI, which lowers volumetric efficiency. Contrarily, pre-mixing begins at the start of the suction stroke and continues until the start of the combustion stroke. In contrast to the traditional method, which results in excess air and raises NOx emissions, this allowed for a longer time for producing a homogeneous charge and fully utilizing the available air. It has been shown that at 30% fuel vapor induction, with and without EGR, the volumetric efficiency decreased by 10% and 23%, respectively. Furthermore, it was shown that when the amount of fuel vapor induction were 15% and 30%, the volumetric efficiency decreased by 9% and 16%. Because of this, the impact of EGR was substantially more significant than the impact of gasoline vapor on the engine’s drop in volumetric efficiency.

3.6. Hydrocarbon Emissions

Diesel vapor causes fluctuations in the air–vapor ratio and inefficient combustion because it promotes homogeneity but decreases volumetric efficiency. As the engine load rises, air–vapor ratios achieve ideal combustion conditions. In general, when engine loads rose, HC emissions followed declining patterns. A high fuel-vapor-to-intake-air ratio and improper combustion, which increases HC and CO, are caused by the EGR cutting off more air than is necessary when the engine is running at low engine loads.
In conventional engines, lean mixture generation results in early lean flame blowout zone development and considerable HC emissions at low engine loads [33]. Figure 8 depicts the variation in HC emissions across all engine loads. The patterns showed that both emissions, which were highest at low load, were caused by incomplete combustion. Compared to a conventional engine running at a low engine load, 15% fuel vapor with 10% EGR induction increased HC emissions by 1.63 g/kW h, while 15% fuel vapor without EGR induction increased them by 1.55. However, 30% fuel vapor with 10% EGR and without EGR induction resulted in an increase in HC emissions of 0.58 g/kW h and 0.67 g/kW h, respectively.

3.7. Carbon Monoxide Emissions

The early generation of the lean flame blowout zone, which causes significant CO emissions at low engine loads, is caused by lean mixture production in a conventional engine, as observed in the literature [34]. Figure 9 depicts the fluctuation in CO emissions at constant engine speed under various engine loads. It was brought on by incomplete combustion, which generated both pollutants, while an engine ran at a low load. When the engine run at a low load, 10% EGR induction increased CO emissions by 6.4 g/kW h, while 15% fuel vapor without EGR induction increased CO emissions by 5.5 g/kW h. Utilizing 30% fuel vapor with 10% EGR reduced CO emissions by 1.16 g/kW h, whereas utilizing no EGR resulted in a 1.05 g/kW h reduction.

3.8. NOx Emissions

Figure 10 illustrates how NOx emissions steadily decreased for 30% and 15% of FV with and without EGR test periods as engine load increased from 20 to 100%. The conventional engine loses velocity due to fuel atomization and insufficient mixing, which restricts charge output. When diesel and air are combined, NOx forms at the point of contact [34]. In contrast to conventional induction, which produces distinct layers, fuel vapor induction at a low load generates a uniform charge. During partial PCCI, diesel fuel injection diminishes due to vapor induction. Vapor induction, the primary cause of heterogeneity, increased, lowering the air available for fuel injection.
Additionally, raising the vapor percentage offsets the loss of direct injection and reduced NOx emissions; however, injecting fuel in an environment with insufficient air may have resulted in increased HC and CO emissions. With 15% fuel vapor induction and no EGR, the reduction in NOx emissions from low to high engine load was 27%, and with 30% fuel vapor induction, it was 40%. EGR combined with fuel vapor induction can further reduce NOx emissions from low engine load to high engine load by 38 and 38%, respectively, for 15% and 30% fuel vapor induction. When the engine operated at lower load conditions, the fuel–air ratio that produced the most effective utilization of fuel and air in conventional engines was attained. Contrarily, the heterogeneity of directly injected diesel resulted in a portion of the fuel being converted into a temperature and pressure-raising agent, which had no detrimental effects on the combustion process. A brief burst of combustion occurred in the combustion chamber, where the fuel pockets have developed, as the compression process proceeds. More than 152 °C is reached [21]. Nitrogen oxide, or NOx, developed due to the high temperatures and pressures from the compression stroke and the combustion pressure.
The partial PCCI engine provides a longer premixing interval for air and fuel vapor than the regular PCCI engine, leading to a more uniform charge generation and less excess air due to a decrease in volumetric efficiency. It helps stop nitrogen from reacting since there were fewer free radicals. EGR can help improve engine performance by reducing too much oxygen in the combustion chamber. The unburned hydrocarbons and carbon monoxide in the exhaust gas interact with the oxygen in the intake air, preventing the nitrogen from utilizing it and reducing NOx emissions.

3.9. Smoke Emission

During the experiment, an increase in smoke opacity was seen in the exhaust stream. It is the result of using EGR and producing a rich combination of the air–fuel mixture. With increasing load, the A–F ratio decreases while Smoke emissions increase. For all engine loads, Figure 11 shows an increase in smoke opacity with increasing load. The engine produced more smoke at higher loads due to the denser mixture, which also caused a buildup of soot, unburned hydrocarbons, and partially burned gases in the exhaust.
The smoke is opaque due to the lack of air to ignite the fuel. When using EGR and a low engine load, smoke opacity was decreased by about 24% and 29%, respectively, for 15% and 30% fuel vapor. When the engine was operated at a high load with a 15% and 30% fuel vapor mix, the visible smoke decreased by about 18% and 23%, respectively. Compared to a traditional engine, the premixing of a uniform air–vapor mixture lowers opacity by preventing the creation of rich mixture pockets. Some places may not have enough oxygen to oxidize the rich mixture’s fuel completely. As a result, incomplete combustion produces an enormous amount of needless intermediate components, primarily soot, which increases the opacity of the smoke. In a partial PCCI situation, the air–vapor mixture is lean without additional fuel over much of the combustion chamber. Because there is less soot in the exhaust than there would be with better combustion, the smoke is less opaque. Since HC and CO tend to make the mixture rich by reusing unburned hydrocarbons or removing necessary oxygen from the real A–F mixture, applying 10%, EGR did not reduce smoke opacity during part-load operation.

4. Conclusions

The result recommended employing retrofitting technologies, such as air mixture homogeneity, which lowered NOx, smoke, HC, and CO emissions from standard diesel engines using a mixture of plasto-oil. The external mixture production strategy can be used cost-effectively with a standard engine with only minor intake manifold changes. Cooled EGR controlled up to 10% of PCCI combustion. The PCCI engine’s EGR postponed combustion. PCCI engines have low-pressure, early burnout. The study found that under intermediate and higher loads, the test engine’s thermal braking efficiency using plasto-oils decreased. At all load activities, the engine’s efficiency with plasto-oils was almost as good as diesel fuel when operating in an unknown environment. Plasto-oils, which omitted nitrogen oxides, created more carbon-based pollutants at intermediate and higher loads than diesel fuel. Activities with lower loads revealed minimal variation in the pollutants. High loads resulted in lower in-cylinder combustion chamber temperatures, which decreased nitrogen oxide emissions.
Diesel PCCI combustion at 30% and 15% fuel vapor induction may perform better with exhaust gas recirculation. At the full load (100%), HC, CO, NOx, and smoke emissions were 0.585 g/kW h, 1.16 g/kW h, 4.96 g/kW h, and 50%, respectively, with 30% fuel vapor and 10% EGR. At the full load (100%), HC, CO, NOx, and smoke emissions were 0.692 g/kW h, 0.95 g/kW h, 5.46 g/kW h, and 53%, respectively, with 15% fuel vapor and 10% EGR. So, as per the findings, 30% plasto-oil blended with diesel is more efficient for HC, NOx, and smoke emissions reductions compared with 15% plasto-oil blended with diesel. While NOx and smoke emissions dropped, HC and CO emissions rose, supporting earlier findings. The PCCI engine releases less NOx and smoke, per a recent study. Comparing PCCI’s operation to conventional diesel and engine operation using plasto-oils, we can see that it was functioning with improved performance and emissions. Engine performance and emissions were enhanced using plasto-oil from municipal mixed plastic waste recovery and recycling; technologies used after exhaust gas emissions, such as selective catalytic reduction, can lower HC and CO emissions. In the future, diesel engines might be replaced by PCCI technology with less than 10% EGR and SCR technology.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/en16093750/s1, Table S1: Measurement accuracy and uncertainty.

Author Contributions

Conceptualization, K.M.R., A.K.S. and P.K.G.; methodology, K.M.R., D.K., A.K.S. and P.K.G.; validation, K.M.R., A.K.S., P.K.G., B.Y.L., A.P. and L.M.; formal analysis, K.M.R. and P.K.G.; investigation, K.M.R., D.K., P.K.G. and A.K.S.; resources, K.M.R., A.K.S. and B.Y.L.; data curation, K.M.R. and P.K.G.; writing—original draft preparation, K.M.R., A.K.S. and P.K.G.; writing—review and editing, K.M.R., A.K.S., A.P., P.K.G. and L.M.; visualization, K.M.R., A.P. and L.M.; supervision, A.P. and L.M.; project administration, K.M.R., A.K.S. and P.K.G.; funding acquisition, P.K.G. All authors have read and agreed to the published version of the manuscript.

Funding

This work is funded and supported by the Science and Engineering Research Board (SERB), DST, New Delhi—110 070 (Project file No. ECR/2017/000185).

Data Availability Statement

Not applicable.

Acknowledgments

This research is dedicated to the late chancellor S. J. Chopra, UPES. The authors are very thankful to Ram Sharma (VC) and D. K. Avasthi (Dean, R & D) for providing continued support and for providing analysis facilities in UPES, Bidholi campus, Dehradun, UK, India. We also thank the Central Instrumentation Centre (CIC), R & D, UPES, for FTIR and GC−MS analysis.

Conflicts of Interest

The authors declare no conflict of interest.

Nomenclature

A–FAir–fuel ratio
BTEbrake thermal efficiency, %
CAcrank angle
CCCombustion chamber
CIcompression ignition
CMCarbon monoxide
DIDirect injection
EGRExhaust gas recirculation
EGTExhaust gas temperature
FVFuel vapor
GC-TCDGas Chromatography-Thermal Conductivity Detector
HCHydrocarbon
HZSM-5H form of Zeolite Socony Mobil 5
MMPWMunicipal Mixed Plastic Waste
NOxOxides of Nitrogen
PCCIPartially premixed charge compression ignition
SCRSelective Catalytic Reduction
WPOWaste Plasto-oil

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Energies 16 03750 g001 550
Figure 1. Schematic flow process diagram of plastic waste to alternate fuel.
Figure 1. Schematic flow process diagram of plastic waste to alternate fuel.
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Figure 2. Three-stage condensing system for liquid hydrocarbon production through pyrolysis.
Figure 2. Three-stage condensing system for liquid hydrocarbon production through pyrolysis.
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Figure 3. (A) Engine experimental test setup. (B) Engine experimental test setup schematic diagram.
Figure 3. (A) Engine experimental test setup. (B) Engine experimental test setup schematic diagram.
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Figure 4. Brake thermal efficiency variation concerning engine load.
Figure 4. Brake thermal efficiency variation concerning engine load.
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Figure 5. Specific fuel consumption variation concerning engine load.
Figure 5. Specific fuel consumption variation concerning engine load.
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Figure 6. Exhaust gas temperature variation concerning engine load.
Figure 6. Exhaust gas temperature variation concerning engine load.
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Figure 7. Volumetric efficiency variation concerning engine load.
Figure 7. Volumetric efficiency variation concerning engine load.
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Figure 8. Hydrocarbon emission variation concerning engine load.
Figure 8. Hydrocarbon emission variation concerning engine load.
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Figure 9. Carbon monoxide emission variation concerning engine load.
Figure 9. Carbon monoxide emission variation concerning engine load.
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Figure 10. NOX emission variation concerning engine load.
Figure 10. NOX emission variation concerning engine load.
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Figure 11. Smoke emission variation concerning engine load.
Figure 11. Smoke emission variation concerning engine load.
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Table
Table 1. Plasto-oil fuel characteristics properties (ASTM standards).
Table 1. Plasto-oil fuel characteristics properties (ASTM standards).
Fuel PropertiesPlasto-Oil
AppearanceDark brown
Moisture (% v/v) (ASTM D95)2.4
API gravity @ 60 °F (ASTM D287)39.6
Density @15 °C g/cc (ASTM D4052-16)0.816
Kinematic viscosity @ 40 °C (cSt) (ASTM D445)2.34
Gross heat of combustion (MJ/kg) (ASTM D240-17)42.58
Conradson carbon residue (% wt) (ASTM D189)0.4
Ash (% wt) (ASTM D482)0.013
Pour point (°C) (ASTM D97)18
Flash point (°C) (ASTM D93)35
Cetane number (ASTM-D613)35.34
Table
Table 2. Technical parameters for the Compression ignition (CI) engine under test.
Table 2. Technical parameters for the Compression ignition (CI) engine under test.
ParameterSpecifications
Engine typeCompression ignition
Engine cooling typeWater-cooled
Number of cylinders1
Stroke/Bore110 mm/87.5 mm
Specific fuel consumption265 g/kWh
Output power3.7 kW at 1500 rpm
Stroke volume0.533 L
Compression ratio 16.5:1
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Rajendran, K.M.; Kumar, D.; Lamba, B.Y.; Ghodke, P.K.; Sharma, A.K.; Matsakas, L.; Patel, A. Effect of Plasto-Oil Blended with Diesel Fuel on the Performance and Emission Characteristics of Partly Premixed Charge Compression Ignition Engines with and without Exhaust Gas Recirculation (EGR). Energies 2023, 16, 3750. https://doi.org/10.3390/en16093750

AMA Style

Rajendran KM, Kumar D, Lamba BY, Ghodke PK, Sharma AK, Matsakas L, Patel A. Effect of Plasto-Oil Blended with Diesel Fuel on the Performance and Emission Characteristics of Partly Premixed Charge Compression Ignition Engines with and without Exhaust Gas Recirculation (EGR). Energies. 2023; 16(9):3750. https://doi.org/10.3390/en16093750

Chicago/Turabian Style

Rajendran, Krishna Moorthy, Deepak Kumar, Bhawna Yadav Lamba, Praveen Kumar Ghodke, Amit Kumar Sharma, Leonidas Matsakas, and Alok Patel. 2023. "Effect of Plasto-Oil Blended with Diesel Fuel on the Performance and Emission Characteristics of Partly Premixed Charge Compression Ignition Engines with and without Exhaust Gas Recirculation (EGR)" Energies 16, no. 9: 3750. https://doi.org/10.3390/en16093750

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