Engine Emission Characteristics Research Articles

Effects of hydrogen enrichment on the performance and emission characteristics of a diesel engine with the addition of Syzygium cumini (Jamun) biodiesel

ABSTRACT Biofuel made from Syzygium cumini, often known as Jamun, has the potential to be a low-cost, sustainable, and emission-free alternative. In this work, we experimentally explore the performance of a compression ignition (CI) engine that burns a blend of hydrogen and biodiesel. Hydrogen is pumped into the air intake manifold by means of a hydrogen gaseous supplement that, when exposed to atmospheric conditions, co-combusts with a pilot flame ignited by Jamun oil. To investigate the impact of hydrogen supplementation on performance and exhaust emission, a variety of hydrogen–Jamun fuel mixture proportions are provided to the engine. The research demonstrates that adding hydrogen improves the thermal efficiency (5%) of diesel engines whereas lowering specific energy fuel consumption (4%) at fixed Jamun flow rates. The gas emission data demonstrates that when hydrogen (HC) emission (12%) supplements decreases, NOx emission (10%) increases somewhat but opacity (8%) increases significantly. The experiment demonstrates that hydrogen and Jamun duel fuel in compression ignition engines burn smoothly.

Hydrogen enrichment in methanol SI engine at varying injection timing during compression stroke

This study investigates the effect of hydrogen enrichment in a direct-injected methanol-fuelled SI engine, with combustion and emission performance analysed by varying the methanol injection timing from 150° to 60° CA bTDC. A three-dimensional computational fluid dynamic model of the hydrogen-enriched methanol engine was developed to predict the engine performance, in-cylinder, and emission characteristics. The numerical model was solved using three-dimensional Reynolds-Averaged Navier Stokes, the RNG k-epsilon model for turbulence, the O'Rourke and Amsden sub-model for heat transfer, the extended Zeldovich mechanism for nitric oxide emissions, and the Hiroyasu-NSC model for soot emissions. The results indicated that retarding the injection timing resulted in a decrease in the indicated specific CO and soot emissions along with a rise in the indicated specific NOx emissions. Furthermore, hydrogen enrichment with methanol enhanced the hydroxyl radical concentration, reduced the combustion duration, reduced also the indicated specific CO and soot emissions while increasing the indicated specific NOx emissions. The study indicates that hydrogen enrichment could extend the late injection timing limit of methanol by enhancing fuel-air mixing, which improves and controls the combustion process more effectively.

Experimental and simulation study on lean combustion characteristics of passive pre-combustion chamber ignition boosted GDI engine

In order to verify the potential application of passive pre-combustion chamber technology in commercial GDI engines, the efficiency characteristics, combustion characteristics (CA50, Knock Index and COV) and emission characteristics of a pre-combustion chamber ignition engine in a boosted environment were studied by three-stage injection strategy to form a lean burn environment (λ = 1.3). A 3D simulation model of pre-combustion chamber ignition engine is established. Combined with the engine bench test results, the process of intake, mixture formation, combustion and emission generation under different working conditions is simulated by simulation method. The development process of TKE (turbulent kinetic energy), air-fuel ratio, temperature and combustion emissions in the main/pre-combustor is studied. It is found that under high load conditions in boosted pre-combustion chamber engine, the average knock index can be controlled between 2 and 3.4 bar, and the COV can be controlled between 3% and 3.5%. The indicated thermal efficiency reaches over 40% within the load range of IMEP from 10 to 14 bar. When the load increases, NOx and soot emissions show a downward trend, the HC and CO emissions slight increase. The pre-combustion chamber engine exhibits a tumble intake pattern around the cylinder axis perpendicular to the cylinder axis. The TKE reaches its maximum value 20 CAD before the top dead center and then rapidly decreases. The use of a three-injection strategy can form a uniform stratified mixture at the ignition moment. The fuel air equivalence ratio in the ignition area of the pre-combustion chamber is 0.8–0.9, slightly higher than the average fuel air equivalence ratio of 0.75.

Impacts of novel calotropis gigantea seed biodiesel usage as a fuel substitute along with various metal-oxide nanoparticles on the DICI engine characteristics

Calotropis gigantea, commonly known as Indian milkweed, is a prevalent plant in Asia. It typically thrives in open and unused areas, often considered a weed. This plant produces flowers and fruits consistently throughout the year, exhibiting a continuous flowering and fruiting cycle. This research investigated the viability of Calotropis gigantea seed oil as a potential source intended for biodiesel manufacturing. The oil was obtained from Calotropis gigantea seeds using hexane extraction in the Soxhlet apparatus. The seeds were determined to contain 33.3 wt% of oil content. The process of biodiesel production involved conducting a transesterification reaction. Further, the produced biodiesel was blended with pure diesel and three different nanoparticles, Titanium dioxide (TiO2), Chromium oxide (Cr2O3), and Silicon dioxide (SiO2), to evaluate combustion performance, and emission characteristics of a single-cylinder diesel engine under various load conditions. Incorporating Cr2O3 nanoparticles into the CGSB20 biodiesel blend yielded significant improvements in BTE, coupled with BSFC reduction. Specifically, in the CGSB20+Cr2O3 fuel mixture, BTE increased notably by 31.2%, reaching a value of 0.33 g/kWh for BSFC. Similarly, for the CGSB20+SiO2 and CGSB20+TiO2 blends, BTE experienced enhancements of 29.2% and 28.1%, respectively, while BSFC values were lowered to 0.37 and 0.4 g/kWh. Furthermore, the unchanging dispersal of nanoparticles within the CGSB20 blend exhibited extraordinary cylinder pressure and HRR values, reaching 77 bar and 34.2 J/CA, respectively. The CGSB20+ Cr2O3 blend yielded favorable emissions outcomes. Specifically, CO, NOx, UHC, and smoke emissions were approximately 4.5 g/kWh, 725 ppm, 0.11 g/kWh, and 23.6%, respectively.

Effect of ignition timing and hydrogen injection phase on HDI engine combustion and NOx emissions

ABSTRACT In order to improve the ITE and reduce NOx emissions in direct-injected hydrogen (HDI) engines under at medium and high loads, the effects of IT and hydrogen injection phase on the combustion and NOx emission characteristics of the HDI engine at high rpm and medium load were investigated numerically. The base engine is a four-cylinder turbocharged direct-injected gasoline (GDI) engine, which is modified into a HDI engine with direct-injected hydrogen fuel. The simulation is performed using GT-Power software. The operating condition of HDI engine is set to 5500 rpm and 50% load. Firstly, IT is optimized, and then based on the IT optimization results, the hydrogen injection phase is optimized. The results show that as the IT is advanced, the maximum pressure rise rate (MPRR) shows a gradual increasing trend, while the combustion intensity and the indicated thermal efficiency (ITE) increases firstly and then decreases, and the former reaches a maximum value at 25° CA BTDC, while the latter reaches a maximum value of 40.5% at 18°CA BTDC. In addition, the nitrogen oxide (NOx) emissions decrease as the IT is delayed. Based on 18°CA BTDC of IT, the results indicated that the later the moment of hydrogen injection, the higher the MPRR, resulting in the greater the knock intensity. The ITE is less affected by the hydrogen injection phase. When the hydrogen injection phase is delayed, NOx emissions increase slightly.

An experimental investigation of the impacts of titanium dioxide (TiO2) and ethanol on performance and emission characteristics on diesel engines run with castor Biodiesel ethanol blended fuel

Investigating the impact of ethanol and TiO2 on the performance and emission characteristics of diesel engines running on a blend of ethanol and castor biodiesel is the primary goal of this study. The nanoparticles of ethanol, biodiesel, and TiO2 diesel fuel were combined at several concentrations. Diesel, B10, B20, B30, B10E10T, B20E10T, B30E10T, B10E20T, B20E20T, and B30E20T were among the various fuels that were investigated. The physiochemical properties of all the sample fuels were assessed, including density, pour point, cloud point, fire point, flash point, and kinematic viscosity. Following this, other engine performance indicators, such as torque, power, and fuel-consumption, were examined. Studies were also carried out on the properties of emissions, including CO, CO2, HC, and NO. Peak braking power and engine torque were found for each fuel under investigation at around 2750 and 2500 rpm, respectively. The addition reduced the brake-specific fuel consumption for B10E20T by 7.41 % while increasing the braking engine's torque and power by 8.64 and 3.86 %, respectively, in compared to blends without the TiO2 additions. When compared to diesel, the exhaust emission data without the addition of TiO2 revealed a decrease in CO and HC emissions but an increase in CO2 and NO emissions. On the other hand, using ethanol blend reduced NO emissions. According to the overall findings, diesel engine performance, combustion characteristics, and exhaust gas emissions were enhanced averagely by 7.43 % when a certain ratio of ethanol, biodiesel, and TiO2 additives (B10E20 + 50 ppm) was used.

An experimental investigation on performance, emission and combustion characteristics of IC engine using liquid fuel produced through catalytic co-pyrolysis of pressed oil cake and mixed plastics with the addition of nanoparticles

The study focuses on using a combination of diesel and a liquid fuel derived from the co-pyrolysis of pressed neem cake (PNC) and mixed waste plastics (MWP) containing waste polyethylene terephthalate (PET) and low density polyethylene (LDPE) in equal amounts with the help of cupric oxide (CuO) catalyst. The engine analysis was carried out using diesel and five different blends of co-pyrolysis oil with diesel in proportions of 20 % (20 % pyrolysis oil + 80 % diesel = PD20), 40 % (PD40), 50 % (PD50) and 100 % pyrolysis oil (PD100), respectively. Initially, the co-pyrolysis oil was produced using PNC and MWP in a ratio of 1:2 under different operating temperatures between 350 °C and 650 °C. The process temperature was optimized to yield maximum liquid oil, and the characterization study was performed. In addition to that, CeO2 nanoadditives were used to improve the properties of PD20 fuel. Different dosages of nanoadditives were blended with PD20 to prepare PD20@25 (PD20 + 25 ppm CeO2), PD20@50, PD20@75, and PD20@100. The objective of the study is to assess the performance, emission, and combustion characteristics of a diesel engine utilizing co-pyrolysis oil-diesel blend by including the nanoadditives. The analysis was carried out on a single-cylinder water-cooled diesel engine mounted with an eddy current dynamometer. The experiments demonstrated that the combination of PD20 and 50 ppm CeO2 resulted in a 6 % increase in thermal efficiency when compared to other blended fuels and diesel. When compared to all fuels, the PD20@50 produced a higher decrease in CO and HC emissions by roughly 30 and 6.2 %, respectively. The combustion analysis showed that the heat release rate (HRR) and maximum cylinder pressure were also found to have improved by adding nanoparticles.

Assessment of performance and emission characteristics of CI engine using tyre pyrolysis oil and biodiesel blends by nano additives: An experimental study

In the current study, the diesel engine performance, emission, and combustion have been investigated using tyre pyrolysis oil (TPO) and biodiesel blended with nano-additives. The effect of the blending ratio on fuel combustion and emission was evaluated. The tyre pyrolysis oil was derived from scrap tyres through the pyrolysis process and biodiesel was synthesized from used cooking oil (UCO) through the transesterification process. Moringa oleifera-derived strontium oxide (SrO) nanoparticles were mixed into the fuel to provide extra oxygen for better combustion. Three blended fuels were formulated as: a) 5 % biodiesel and 95 % TPO containing 50 ppm SrO nanoparticles (B5TPO95SrO50), b) 10 % biodiesel and 90 % TPO containing 100 ppm SrO nanoparticles (B10TPO90SrO100), c) 50 % TPO and 50 % biodiesel without nano-additives (B50TPO50). Among the blended fuels, B10TPO90SrO100 showed the best brake thermal efficiency at 31.4 % and a brake-specific fuel consumption of 0.21 kg/kWh at full load. The B5TPO95SrO50 blended fuel showed reduced emission parameters such as unburned hydrocarbon (HC), carbon monoxide (CO), and oxides of nitrogen (NOx) by 2.05 %, 8.30 %, and 18.00 %, respectively, as compared to the conventional diesel engine at an optimum engine load (27.9 Nm). Hence, waste tyre oil and UCO biodiesel blended with biogenic SrO nano additive can be considered a promising fuel for a sustainable environment.

Experimental investigation of performance, emission, and combustion characteristics of a diesel engine using blends of waste cooking oil-ethanol biodiesel with MWCNT nanoparticles

In this study, blends of 5 % and 10 % ethanol with waste cooking oil biodiesel are mixed with Multi-Walled Carbon Nanotubes (MWCNT) at a concentration of 30 ppm. MWCNTs, known for their high surface area and unique properties, are added to potentially enhance combustion efficiency and reduce emissions. These blends are then tested in a diesel engine to evaluate their performance, emission and combustion characteristics using Design of experiment technique. After conducting various experiments and analyses, the blend of 20 % biodiesel, 10 % ethanol, and 30 ppm MWCNT was identified as the most optimal due to its favorable engine characteristics. Brake Thermal Efficiency (BTE) was increased from 3.1 % to 3.4 % with the addition of MWCNTs, indicating enhanced fuel efficiency. Moreover, average Fuel Consumption is decreased from 2.2 % to 2.5 %, suggesting improved fuel utilization. Using MWCNT 30 ppm in B20 ethanol blends (MWCNT 30 ppm B20+E10) resulted in 35 % reduction in nitrogen oxide (NOx) emissions, 37 % reduction in CO emissions and 39 % reduction in HC emissions. Hence MWCNTs demonstrated effectiveness in mitigating harmful exhaust emissions The optimized values for all parameters fall within acceptable ranges, indicated successful optimization using Response surface methodology. Additionally, statistical analysis reveals that the machine learning- XGBoost model outperformed all other advanced machine learning models across all tested metrics, including MSE, MAE, and R-square.

Development of Free Fatty Acid (FFA) monitoring device for evaluation of oil samples used for biodiesel production

Diversion of oil sources for biodiesel production has been gaining importance to meet the environmental concerns and energy demand. The free fatty acid (FFA) content of the feedstock is a significant factor in biodiesel production. The FFA values determine the complexity of the biodiesel production. Until date, an experimental procedure has been used to determine the FFA concentration of an oil source; this method is dependent on titration, which is a laborious process involving significant volumes of chemicals. Hence, in the present study, an attempt was made to develop a device for the identification of FFA of the oils. Waste cooking oil samples subjected to wide range of cooking conditions like cooking time, temperature, type of food are collected from different food outlets. Subsequently, the composition of oil samples and the variation in their quality were analysed using gas chromatography flame ionization detector (GC – FID). Biodiesel is prepared from the oil samples through transesterification and the impact of FFA and their respective methyl esters in the quality and properties have been investigated. The properties of biodiesel were determined as per ASTM standards. The study was further extended to correlate the properties of biodiesel with the composition of the oil from which it was derived. The analysis evidently proved the dependence of biodiesel properties on the FFA percentage and the composition of the oil. The results have been further substantiated with the performance and emission characteristics of internal combustion engine fuelled with the prepared biodiesel samples.

Optimization of water and 1-pentanol concentrations in biodiesel-diesel blends for enhanced engine performance and environmental sustainability

This study focuses on optimizing the concentrations of water and 1-pentanol in biodiesel-diesel blends derived from Gossypium hirsutum (cottonseed) oil to enhance engine performance and reduce environmental impact. Biodiesel from cottonseed oil (COB) was produced via transesterification, followed by an analysis of its elemental and chemical composition, and physicochemical properties. Using a Box-Behnken design matrix, the volume concentrations of COB (10-30%), water (5-15%), and 1-pentanol (5-20%) in diesel fuel were varied to optimize engine performance and emission characteristics. ANOVA was employed to evaluate the influence of these parameters on key output responses. The results demonstrated that COB possesses favorable elemental and chemical properties, and the optimal concentrations of COB, water, and 1-pentanol were identified as 14.7%, 9.9%, and 11.2%, respectively. ANOVA findings revealed that COB had the maximum influence on brake specific fuel consumption (93.4%), nitrogen oxides (55.3%), carbon monoxide (78.5%), and carbon dioxide (97.1%), while 1-pentanol significantly influenced brake thermal efficiency (38.9%) and hydrocarbon emissions (70%). Confirmation experiments validated these optimizations, showing substantial improvements in both performance and emissions. The study concludes that integrating water and 1-pentanol into COB blends can reduce fossil fuel consumption by approximately 35%, while enhancing energy efficiency and minimizing environmental impact.

Performance and Emission Characteristics of VCR Engine Fueled with TYRE Oil and Cotton Seed Oil Blends

Performance and Emission Characteristics of VCR Engine Fueled with TYRE Oil and Cotton Seed Oil Blends

Assessing performance variability in a dual-fuel diesel engine using diesel and biogas: an experimental study across different compression ratios

The increasing concerns about energy security and environmental sustainability have intensified the search for alternative fuels. This study investigates the performance and emission characteristics of a dual-fuel diesel engine utilizing purified biogas and diesel across various compression ratios. A single-cylinder, direct-injection, water-cooled, variable compression ratio diesel engine was adapted to operate in dual-fuel mode, running experiments at compression ratios of 12, 14, 16, 18, and 20 with a constant injection timing of 23° before top dead center under different load conditions. The study reveals a peak brake thermal efficiency of 33.25% at a compression ratio of 20, demonstrating the potential of biogas as a viable alternative fuel. Notably, while carbon monoxide and hydrocarbon emissions decreased with higher compression ratios, nitrogen oxide emissions increased, highlighting a trade-off in emission characteristics. This work contributes to the understanding of biogas utilization in diesel engines, offering insights into optimizing engine performance and emissions through compression ratio adjustments. The findings can inform future developments in sustainable energy solutions.

Investigating Engine Performance and Emission Characteristics of a CI Engine Fueled with Waste Fried Oil Blend Containing Butanol, Alumina, and Silver Nanoparticles

Investigating Engine Performance and Emission Characteristics of a CI Engine Fueled with Waste Fried Oil Blend Containing Butanol, Alumina, and Silver Nanoparticles

Exploring novel porphyrin photocatalyst for the conversion of frying oil to biodiesel: A step for globular economy

The current protocol addresses the outcomes on the photo-transesterification of frying sunflower oil (FSO) catalysed by porphyrin comprising sulphonic acid functionalized pyridinium ionic liquid (PcSAFPyIL). A novel photocatalyst was synthesized and confirmed by 1H and 13C NMR, Powder XRD, FT-IR, XPS, and fluorescence emission spectrophotometry. The energy band gap (1.85 eV) was determined by cyclic voltammetry, Hammett acidity (H0 = 0.217) by UV–visible spectrophotometer and metal free nature by powder XRD and XPS. The photocatalytic activity of PcSAFPyIL in the visible region was confirmed by reflecting intense Soret band (421 nm) and four Q bands (515, 554, 591 and 647 nm). This may be due to inherent aromatic characters and conjugation with chromophore groups at meso-position of porphyrin ring. The obtained photocatalyst was scrutinized for the photo-transesterification of FSO in a lab-made photoreactor. The ideal reaction parameters were found to be 20 mg photocatalyst quantity with 1:12 (FSO: ROH) under exposure of 2 x 5 W LED at room temperature, to afford 90 % biodiesel in 24 h. Moreover, the formation of biodiesel was confirmed by (1H, 13C) NMR, FT-IR, DEPT-135, and GC–MS. Further, stability, heterogeneous nature and the gram scale reaction PcSAFPyIL was also efficiently accomplished using the optimized photocatalytic conditions. Additionally, the physicochemical properties of the biodiesel fuel B15 (15 % blended with marketed diesel) and pure marketed diesel are consistent. Moreover, the engine performance and emission characteristics of B15 such as brake-specific fuel consumption (BSFC), break thermal efficiency (BTE) found comparable and better than commercial diesel.

K-means clustering optimization of various quantum dots and nanoparticles-added biofuels for engine performance, emission, vibration, and noise characteristics

The utilization of biodiesel as a bio-lubricant, combined with various types of nanoparticles, and quantum dots presents an innovative approach towards enhancing the performance of diesel engines. In this study, biodiesel was blended with different nanoparticles to improve its lubricating properties, and the k-means clustering method was applied to identify the optimal nanoparticle that maximizes the performance of the diesel engine. The experiment involved synthesizing biodiesel-based lubricants infused with nanoparticles of varying compositions, including but not limited to carbon nanotubes, graphene oxide, and metal oxides. The successful implementation of the Entropy-k-means hybrid model facilitated the identification of the optimal bio-lubricant for diesel engines. The experimentation uncertainty came out to be 4 % which lies in an acceptable range. Additionally, a strong Pearson r correlation was observed between Brake Thermal Efficiency (BTE) and Sound, highlighting their interrelationship. Moreover, the prioritization analysis indicated that NOx obtained the highest priority at 0.45, contrasting with the lowest priority attributed to sound at 0.01. Furthermore, the clustering analysis conclusively identified magnetic bio-lubricant as the top-performing option with minimum centroidal distance of 1.2. The optimal outcomes are BTE (30.5 %), Brake Specific Fuel Consumption (191.5 g/kWh), NOx (88 ppm), CO (7.1 g/km), Vibration (68.5 Hz), and Sound (74.5 dB). The application of k-means clustering facilitated the identification of the most effective nanoparticle for enhancing engine performance, thereby contributing to the advancement of sustainable lubrication technologies in the automotive industry.

Effects of hydrogen volume fraction, air fuel ratio, and compression ratio on combustion and emission characteristics of an SI ammonia-hydrogen engine

An effective approach to reducing greenhouse gas emissions is to utilize low/zero carbon fuels. This study simulated the combustion of a marine spark ignition (SI) ammonia-hydrogen engine, focusing on the effects of hydrogen volume fraction (XH2), air fuel ratio (λ), and compression ratio (CR) on the combustion and emission characteristics. The pathways of nitrogen-based pollutants such as NH3, NO, and N2O were explained. The results show that increasing XH2 improves Pmax, heat release rate, thermal efficiency, and power. Regarding emission characteristics, when XH2 rises, NH3 emissions drop; NOx emissions remain almost constant at λ ≤ 1 (2100 ppm at λ = 1) and considerably increase at λ > 1, peaking at 5245 ppm. Moreover, as CR rises, the engine power and thermal efficiency increase, NOx emissions decrease by 10%, and N2O emissions are below 20 ppm. Furthermore, chemical kinetic analysis shows that NO comes from N and N2, diffuses from the flame front toward the center in the cylinder under λ = 1.2. And NO comes from HNO and is generated in the flame front and the center under λ = 0.9, respectively. N2O is produced by NH and NH2 and is only generated in the flame front.

Optimizing heat transfer predictions in HCNG engines: A novel model validation and comparative study via quasi-dimensional combustion modeling and artificial neural networks

Heat transfer from the walls of engine has a significant role on engine combustion, performance and emission characteristics. The study objectives to showcase the efficacy of the new model through an analysis by comparison with existing heat transfer models. New model is based on woschni model in which pressure and temperature is replaced by other fluid properties like density, thermal conductivity and dynamic viscosity. A series of experiments were conducted on a compressed natural gas internal combustion engine across varying hydrogen fractions, EGR ratios, engine speeds and different loads under stoichiometric conditions. The study demonstrates the efficacy of the proposed model by constantly achieving high prediction quality across a wide range of engine calibration coefficients by using Quasi-dimensional Combustion Model (QDCM) on MATLAB. Comparative analyses of new model with different heat transfer models were undertaken to validate the heat transfer rates with experimental results across a broad spectrum of operational conditions. It is observed that heat transfer rate is increased by increasing the engine load as 25%, 50%, 75% and 100% as 90.57J/deg, 130.12J/deg, 200.02J/deg, and 260.26J/deg with new model correspondingly. Heat transfer rate reduced by rise in engine speed with 1100 rpm, 1200 rpm, 1500 rpm and 1700 rpm is as 32.91 kW, 32.16 kW, 25.36 kW and 18.03 kW by new heat transfer model respectively. Artificial neural network (ANN) popular backpropagation algorithm is adopted to predict the heat transfer rate of HCNG engine, the five-input and one-output network structure are used. The values of correlation coefficient (R) and mean square error (MSE) were 0.99957 and 0.22667, 0.99998 and 0.010776, 0.99253 and 4.4762, 0.9961 and 1.2329, 0.99994 and 0.025108 for Woschni, New_Model, Chang, Sitkei and experimental respectively. This research work offers that ANN is a wise option for conventional modeling systems. In this way, the heat transfer rate of hydrogen-added CNG engines may be precisely predicted using ANN modeling.

On the Influence of Engine Compression Ratio on Diesel Engine Performance and Emission Fueled with Biodiesel Extracted from Waste Cooking Oil

Despite the extensive research on biodiesels, further investigation is warranted on the impact of compression ratios on emissions and engine performance. This study addresses this gap by evaluating the effects of increasing the engine’s compression ratio on engine performance metrics—brake-specific fuel consumption (BSFC), power, torque, and exhaust gas temperature—and emissions—unburnt hydrocarbons (HCs), carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NOx), and oxygen (O2)—when fueled with a 20% blend of waste cooking oil biodiesel (WCB20) and petroleum diesel (PD) under various operating conditions. The viscosity of the prepared fuels was measured at 25 °C and 40 °C. Experiments were conducted on a single-cylinder diesel engine under wide-open throttle conditions at three different speeds (1400 rpm, 2000 rpm, and 2600 rpm) and two compression ratios (16:1 and 18:1). The results revealed that at a lower compression ratio, both WCB20 and petroleum diesel exhibited reduced BSFC compared to higher compression ratios. However, increasing the compression ratio from 16:1 to 18:1 significantly decreased HC emissions but increased CO2 and NOx emissions. Engine power increased with engine speed for both fuels and compression ratios, with WCB20 initially producing less power than diesel but surpassing it at higher compression ratios. WCB20 demonstrated improved combustion quality with lower unburnt hydrocarbons and carbon monoxide emissions due to its higher oxygen content, promoting complete combustion. This study provides critical insights into optimizing engine performance and emission characteristics by manipulating compression ratios and utilizing biodiesel blends, paving the way for more efficient and environmentally friendly diesel engine operations.

Investigation on NOx control of a CI engine through the collective effect of hydrogen and biodiesel blend at modified compression ratio

The main challenges with using biodiesel in CI engines are higher NOx emissions and reduced brake thermal efficiency. These biodiesel-related issues can be handled by concurrently introducing gaseous fuels along with primary fuel into CI engines. This study examines the effects of hydrogen in a dual fuel mode operation with diesel and Calophyllum inophyllum biodiesel blend (B20) at different compression ratios on the engine's performance, combustion, and emission characteristics. A single-cylinder, 4-stroke, variable compression ratio engine operating at 1500 rpm was used for the research. A standard compression ratio (SCR) of 17.5 and a modified compression ratio (MCR) of 15.5 at a constant hydrogen flow rate of 6 L per minute (lpm) were used with diesel and B 20. The addition of hydrogen with diesel and B20 resulted in higher cylinder pressure and heat release rate when compared to pure diesel and B20 operation. This resulted in a shorter delay period (by an average of 9.4 % and 7.1 %) with lower peak pressure than pure diesel and B20 operation. During the dual fuel mode of H2 with B 20 at a modified compression ratio, the maximum heat release rate was decreased and its occurrence was retarded. NOx, UBHC, and CO emissions of the engine were decreased significantly by an average of 20.8% 43.7, %, and 22 % respectively with 37.7 % increase in smoke opacity. The increase in NOx emission with the use of H2 with diesel was reduced by operating H2 with B20 and at a reduced compression ratio. This lower emission was achieved with a compromise of a marginal decrease in engine brake thermal efficiency.