Browse Topic: Carbon monoxide

Items (2,289)

Experimental Investigation of Diesel, Aqueous Ammonia, and Compressed Natural Gas Mixtures on Performance and Emissions in a Compression Ignition Engine

04-19-03-0011

5/30/2026

Abstract This study investigates and evaluates systematically the combustion, performance, and emissions characteristics of heavy-duty diesel engines fueled by diesel–ammonia–compressed natural gas triple blends. While dual-fuel systems are well-documented, the interactive effects of ammonia and CNG within a single compression ignition (CI) engine remain largely unexplored. Experiments were conducted on a 300 Nm, 660 rpm diesel engine by testing pure diesel, diesel–ammonia blends (10–20 wt.% aqueous ammonia), and triple-fuel mixtures containing 10% of the total energy from compressed natural gas. Pure diesel was first tested to provide baseline data, and subsequently blends were tested for a comparative study. The primary contribution of this work is the identification of a synergistic effect of the fuel triple blends on engine performance and emissions. Results indicate that all fuel blends improve thermal efficiency and reduce fuel consumption compared to conventional diesel. The blend containing 20% aqueous ammonia, 80% diesel, and 10% of the total fuel energy supplied by compressed natural gas achieved the highest thermal efficiency of 39.7% (7% higher than diesel) and the lowest brake specific fuel consumption of 211.22 g/kWh. Furthermore, emissions analysis revealed that carbon dioxide and nitrogen oxide emissions were significantly reduced with this triple blend. The blend decreased carbon dioxide by 26.6% and nitrogen oxide emissions by 32.1%, while hydrocarbon emissions were also lowered by up to 29.2%. Carbon monoxide emissions increased slightly for the triple blends, reaching a maximum value of 3.9028 g/kWh for the A20D80CNG10 mixture, compared to diesel operation. The slight increase in carbon monoxide emissions for triple blends highlights a trade-off in emission behavior. These findings address the combined utilization of diesel–ammonia–compressed natural gas triple-fuel mixtures in heavy-duty engines, demonstrating that strategic blending can simultaneously improve efficiency while mitigating environmental impact. Graphical Abstract

Sinkala, Happy, Sarıtaş, Mehmet, Kül, Volkan Sabri, Akansu, Selahaddin Orhan, Ünalan, Sebahattin

Effect of Burning Biomass Fuel Cyclohexanol on Diesel Engine Performance

2026-99-1708

5/22/2026

Against the backdrop of growing global demands for energy sustainability and stricter emission regulations for diesel engines, this study investigates the performance implications of incorporating cyclohexanol—a renewable oxygenated fuel—into diesel fuel blends. Using a marine medium-speed diesel engine as the experimental platform, the research systematically evaluates engine performance and emission characteristics across a range of cyclohexanol-diesel blend ratios under low, medium, and high load conditions. Experimental findings reveal multifaceted effects of cyclohexanol blending on engine operation. Combustion of the blended fuels enhances the engine’s dynamic performance, particularly under medium and high loads, where the maximum in-cylinder burst pressure exhibits a noticeable increase. This improvement is attributed to cyclohexanol’s oxygen-carrying capacity, which promotes more vigorous and sustained combustion reactions. In terms of emissions, increasing the proportion of cyclohexanol in the fuel blend leads to significant reductions in soot and carbon monoxide (CO) emissions, reflecting the cleaner-burning properties of the oxygenated component. However, this is accompanied by an uptick in nitrogen oxide (NOx) emissions, likely due to the elevated combustion temperatures generated by the more efficient fuel oxidation process. From an economic perspective, cyclohexanol blending at consistent load levels induces a postponement in the crank angle at which peak heat release occurs during combustion. This temporal shift prolongs the effective combustion duration, enabling more complete fuel utilization within the cylinder. Consequently, fuel consumption rates decrease, and overall engine efficiency improves, highlighting the potential of cyclohexanol blends to enhance operational economy in marine propulsion systems. In summary, this study underscores the complex trade-offs associated with cyclohexanol-diesel blends: while they offer tangible benefits in power output, fuel efficiency, and reduced particulate emissions, managing the increase in NOx emissions remains a critical challenge. The results provide a foundational framework for advancing biofuel applications in marine engines, emphasizing the need for integrated emission control strategies to optimize the balance between performance and environmental sustainability.

Chen, Ke, Yang, Chenxi, Wang, Yibin, Fan, Jinyu, Liu, Yuchen, Ye, Zixiao, Huang, Jialiang

Effect of Exhaust Gas Components on Oxygen Storage Capacity Measurements of Automotive Catalysts

2026-01-0360

4/7/2026

Three-way catalytic converters (TWC) are one of the most popular methods to help reduce harmful tailpipe emissions emitted from internal combustion (IC) vehicles. To help improve conversion efficiency, TWCs can store and release oxygen via an oxygen storage capacity (OSC) mechanism. During engine control unit (ECU) calibration, on board OSC measurements are correlated to TWC and vehicle emissions to monitor emissions performance throughout the full useful life (FUL) of the vehicle. It is known that different test conditions, including temperature, space velocity and background gases in the exhaust stream affect OSC measurement, potentially altering the calculated OSC values and thus the perceived level of OSC and emissions preformance during operation. This study utilises an OMEGA test bench to complete OSC measurements on the full-scale automotive catalyst samples to quantify the effects of different background gases including carbon monoxide, hydrocarbons and nitric oxide on OSC measurements, concluding that all background gases studied affect measured OSC values. The study revealed that hydrocarbons had the largest effect on OSC measurement increasing OSC values by up to 50%. It was concluded that the increase in OSC measurement with injected hydrocarbons was due to the breakdown of hydrocarbons on the catalyst surface during rich periods of operation increasing the amount of oxygen required to fully oxidise the catalyst resulting in a larger perceived OSC measurement. During the initial ECU calibration original equipment manufacturers (OEM) should consider these effects on OSC measurement and understand how this will affect perceived OSC and vehicle emissions performance for FUL and onboard diagnostics (OBD) applications. This will help ensure emissions compliance and guide optimized catalyst and engine calibrations.

Mc Grane, Liam, Douglas, Roy, Irwin, Kurtis, Woods, Andrew, Elliott, Matthew, Istrate, Oana, Nockemann, Peter

BEV Incremental CO ₂ Emissions in a Ranked Order Electric Grid

2026-01-0424

4/7/2026

Battery Electric Vehicles (BEV) have been sold as ‘Zero Emissions Vehicles’ (ZEV) by governments to reduce transportation CO2. While they are not ZEV because they run on grid electricity, they could be ‘effectively ZEV’ if the incremental CO2 is ‘very small’. At the national level, this is estimated using following metrics: (1) Internal Combustion Engine Vehicle (ICEV) fuel consumption, from the total US gasoline consumption divided by the total fleet miles driven, 25 mpg or 350 g CO2/mi, (2) Strong Hybrid Electric Vehicles (HEV) about one third less, 240 g CO2/mi. (3) BEV energy consumption, using data from systematic on-road testing of a wide range of vehicles, estimated at 40 kWh/100 mi for a US sales mix. (4) Electricity marginal CO2: in a ranked order grid, zero-CO2 sources are prioritized and supplemented by fossil sources. IEA hourly data show that the US 48 contiguous states are self-contained, with zero-CO2 sources providing a third of total demand. The response to hourly demand changes comes largely from natural gas and coal power stations, with EPA data showing a combined marginal CO2 of 600 g CO2/kWh. On replacing an ICEV by a BEV, the reduction in gasoline use, - 350 g CO2/mi, is offset to two thirds by higher electricity consumption, 40 x 600 / 100 = + 240 g CO2/mi. BEV marginal CO2 is therefore similar to HEV, and not ‘much smaller’ than ICEV. This is because HEV engines and fossil power stations have similar efficiency and similar fuel CO2 intensity.

Phlips, Patrick

A Comparative Study of Combustion Stability Improvement via Prolonged Discharge Duration under Engine Idling Conditions

2026-01-0308

4/7/2026

Proper control over combustion and emission characteristics under engine idling conditions remains to be challenging, especially when engine block temperature is low. A specially designed common-coil pack was demonstrated to improve engine idling stability in previous SAE congress. In this paper, the progress on further development of the ignition system was reported with improved system stability and enhanced ignition performances. The impact of the prolonged discharge duration on the combustion stability was investigated on a turbocharged 4-cylinder production engine, with special attention to cylinder-by-cylinder variation under cold and hot engine block temperatures. It is observed that a prolonged discharge duration can reduce both cycle-to-cycle and cylinder-to-cylinder variations significantly. Especially under cold engine block temperature conditions, prolonged discharge duration together with advanced spark timing can increase engine load and reduce carbon monoxide emissions effectively. Then, the total energy consumption of the ignition system under various operation conditions were calculated and compared with the engine power gained by the ignition system.

Yu, Xiao, Jin, Long, Leblanc, Simon, Ting, David, Zheng, Ming

Reactivity Controlled Compression Ignition (RCCI) Combustion Engine Characteristics Fuelled with Diesel/Compressed Natural Gas (CNG) and Diesel/Methanol Fuel Pairs

2026-01-0319

4/7/2026

Ultra-low oxides of nitrogen (NOx) and particulate matter (PM) from reactivity-controlled compression ignition (RCCI) combustion have motivated researchers to explore more about low temperature combustion (LTC) engines. In this study, a comparative analysis of combustion, performance, and emission characteristics of RCCI combustion fuelled with diesel/compressed natural gas (CNG) and methanol/diesel fuel pairs has been carried out with respect to baseline compression ignition (CI) combustion. All experiments were performed in a constant speed engine at four different engine loads. For RCCI combustion experiments, a constant premixed ratio (rp= 0.50) and 15% exhaust gas recirculation (EGR) were used. The results exhibited a significant reduction in NOx emissions and relatively smoother RCCI combustion compared to baseline CI combustion. RCCI mode combustion resulted in relatively superior engine performance compared to baseline CI combustion, especially at higher engine loads. A comparison between the RCCI combustion fuelled with gaseous fuel (CNG) as a low reactivity fuel (LRF) and a liquid fuel (methanol) showed a slightly lower brake thermal efficiency (BTE) of CNG/diesel fuelled RCCI combustion compared to methanol/diesel fuelled RCCI combustion at low loads. As the load increased, the trend of BTE was reversed. The combustion characteristics of CNG/diesel fuelled RCCI combustion were found to be more stable compared to methanol/diesel fuelled RCCI combustion. The NOx emissions were lowest in methanol/diesel fuelled RCCI irrespective of engine load. At low load, methanol/diesel fuelled RCCI suffered from higher hydrocarbon (HC) and carbon monoxide (CO) emissions, while CNG/diesel fuelled RCCI maintained relatively lower HC and CO emissions.

Saikia, Bhargav, Kant, Akshay, Gupta, Abhishek, Singh, Akhilendra Pratap

Comparison of Ammonia Emission Characteristics Between Different Gasoline Vehicles Equipped with Three-Way Catalysts

2026-01-0374

4/7/2026

In recent years, the tightening of vehicle emission regulations has led to a decreasing trend in regulated pollutants such as NOₓ and CO. However, the emission of ammonia (NH₃), which is unintentionally generated during the purification process in three-way catalyst of gasoline vehicles, has become a growing concern. NH₃ emissions from vehicles can serve as a precursor to PM2.5 and have been reported to cause local roadside pollution. Therefore, there is a growing need for on-road testing to identify conditions under which NH₃ is likely to be emitted. Furthermore, since engine control strategies vary among vehicle types, it is desirable to consider differences in emission behavior across different models. In this study, on-road NH₃ emissions were measured for multiple vehicle models with different powertrains, and the effects of engine behaviors and engine operating duration across vehicles on NH₃ emissions were investigated. To analyze differences in NH₃ emission behavior among vehicle types, conventional gasoline vehicles and series-type hybrid vehicles were employed. Additionally, vehicle control parameters were obtained via an OBD (On-Board Diagnostics) interface unit and utilized for analysis. The analysis revealed that, for the conventional gasoline vehicles, aggressive accelerator pedal control induced rapid fluctuations in engine speed, which in turn led to NH₃ emissions. In contrast, for the series-type hybrid vehicles, NH₃ emissions were primarily observed when the engine started under specific conditions, whereas differences in driver behavior had only a minor direct impact on NH₃ emissions. In addition, longer engine operating durations resulted in higher emission levels. A common characteristic observed across both vehicle types was that NH₃ emissions were elevated during periods corresponding to CO emissions, which serve as precursors to NH₃ formation.

Ashizawa, Keigo, Fukunaga, Chisato, Gao, Tianyi, Sato, Susumu

New Graphite-Based Catalyst in Biodiesel Production

04-19-02-0009

3/20/2026

Climate change and the depletion of fossil fuels have increased the need for renewable energy sources such as biodiesel. Biodiesel is an environmentally friendly fuel derived from various vegetable oils through a process known as transesterification. In this study, a new graphite-based heterogeneous catalyst was developed by modifying it Na2CO3, K2CO3, Al2O3 and was used for biodiesel production from linseed, cottonseed, sunflower, olive oils. Catalyst activity gradually decreased from 90.0 to 76.7% for cottonseed oil, from 93.0 to 76.0% for olive oil, from 95.0 to 77.0% for sunflower oil, and from 89.0 to 69.0% for linseed oil after the fourth operation. The fuel properties of the obtained biodiesel samples were investigated and the most favorable characteristics of cottonseed oil–based biodiesel were found to be d 4 20 = 0.8448, ν 40 = 3.3820, flash point of 93°C. Based on the X-ray broad peaks at 22.8° and 26.4°, we can note that after the four-time reaction cycle, the structure of the catalyst was destroyed to expanded and pure graphite with the loss of catalytic activity. Additionally, the influence of the amount of oleic, linoleic, linolenic, and saturated acyl groups in oil samples on exploitation properties was investigated by NMR spectroscopy.

Mamedov, Ibrahim, Mamedova, Gulben, Mamedova, Yegana

Composite Current Collectors and Aramid Separator Enabled Safer High-Nickel Batteries

2026-01-7032

2/27/2026

The requirement on high energy density Li-ion batteries demands high energy chemistry system, this rise concerns on batteries’ safety issue. Battery non-active components, including current collectors and separator play important role in improving battery safety. Composite current collectors, which are consisted of a polymer layer between two plated thin metal layers, are widely treated as a solution to reduce safety concerns caused by high nickel layered cathode materials, e.g. LiNi1-x-yCoxMnyO2, LiNi1-x-yCoxAlyO2 and LiNi1-x-y-zCoxMnyAlzO2 with Ni content higher than 0.8. In the meantime, composite current collectors can reduce most weight of current collectors and improve the cell’s gravimetric energy density without replacing cathode or anode materials. Moreover, high thermal stable separator could effectively prevent internal short circuit for it melts in higher temperature. In this work, we came up with a cell design which contains composite current collectors as positive/negative current collector and high thermal stable separator with aramid coating layers. This design improved separator breaking point by 84 °C while reduced current collector melting point by 900 °C, thereby it makes current collector shrinks earlier than separator break, this avoids internal short circuit by detaching cathode and anode coating layer when the separator is still in place. The design was applied in high nickel LiNi0.91Co0.03Mn0.05Al0.01O2 cathode and graphite anode chemistry system with a thick coated electrode (4 mAh cm-2, 21 mg cm-2 per coating side). Pouch cell with 5 Ah nominal capacity was fabricated in this cell design. The electrochemical benefits and drawbacks by adopting positive or negative current collectors or both were evaluated, including the affection in cycling stability, cell resistance and rate performance. Nail penetration and thermal ramping was also adopted to evaluate the safety benefit of the design. The cell shows comparable electrochemical performance and improved cell safety after composite current collector and high thermal stable separator adoption.

Liu, Jingyuan, Lu, Yong, Liu, Haijing

Fracture Analysis of Polycrystalline NCM Electrode Particles under External Pressure with Varying Pressurized Coverage

2026-01-7016

2/27/2026

Nickel-rich cathode materials (LiNi1−x−yCoxMnyO2, NCM) are regarded as one of the most promising cathode candidates for solid-state batteries (SSBs) due to their high energy density and low cost. However, during electrochemical cycling, continuous lithium-ion insertion/extraction generates diffusion-induced stress (DIS) that fractures particles and accelerates capacity fade. Furthermore, NCM particles are subjected to external pressure during manufacturing, and inherent process non-uniformities result in varying pressurized coverage (defined as the ratio of covered area of active materials with solid-state electrolytes), which significantly influence particle cracking behavior. Based on chemo-mechanical coupling models, extensive work have investigated particle cracking behavior during charge-discharge processes. While limited research addressing crack evolution under concurrent electrochemical loading and external pressure. Thus, we developed a chemo-mechanical coupling model with globally embedded cohesive elements within polycrystalline NCM (PC-NCM) particles to simulate fracture behavior during single charge-discharge cycles. The effects of external pressure, charge/discharge C-rate and pressurized coverage are evaluated. Simulations demonstrate that external pressure significantly mitigates particle cracking. Notably, this crack-suppression effect intensifies with reduced pressurized coverage. This work provides critical insights into fracture mechanisms of NCM cathodes materials, offering fundamental guidance for electrode design optimization.

Wang, Jingjie, Chen, Ying, Yao, Zhiheng, Luan, Weiling, Chen, Haofeng

Enhancing Combustion, Performance and Emission Profiles Using Kapok Methyl Ester Blends with Hydrogen

2026-28-0058

2/12/2026

This study investigates the potential of using a dual green alternative fuel combination, the one is hydrogen fuel and another one is biodiesel for enhancing the Performance, combustion and emission profile of a compression ignition engine. The kapok oil biodiesel was blended with Diesel in proportions of 20% (K20) and 40% (K40) by volume. The hydrogen gas was supplied at a constant flow of 4 liter per minute (LPM). The experimental fuels are neat diesel D100, K20 (80% Diesel and 20 % kapok methyl ester), K40 (60% Diesel + 40 % Kapok methyl ester), K20 + H4L (K20 with 4 LPM hydrogen) and K40+H4L (K40 with 4 LPM hydrogen). These test blends are investigated in a single cylinder direct injection CI engine under 0% to 100% load conditions at a fixed speed of 1500 rpm combustion, and emissions characteristic were evaluated and compared with base fuel. The outcomes indicated that the use of B20 and B40 blends without hydrogen led to reduced BTE because of their lower cetane number and calorific value. Additionally, higher viscosity of the blends resulted in increased BFSC. However, the introduction of hydrogen and the K20H fuel blend demonstrated notable emission improvements compared to conventional diesel, achieving reductions of 9–11% in unburned hydrocarbons, 5.3% in carbon monoxide, and approximately 8% in nitrogen oxides (NOₓ). These findings highlight the potential of K20H as a cleaner alternative fuel.

Anbarasan, B, M, Kumaresan, Balamurugan, S, Rajesh, Munnusamy

Miner’s Safety Bot: An ESP32-Based Autonomous Mobile Mine Safety Monitoring System

2026-28-0116

2/12/2026

Mining operations are important to industrial growth, but they expose the mining workers to risk including hazardous gases, elevated ambient temperatures, and dynamic structural instabilities within underground environments. Safety systems in the past, typically based on fixed sensor networks or manual patrols, fall short in accurate hazard detection amidst shifting mine conditions. The proposed project Miner's Safety Bot advanced this paradigm by leveraging an ESP 32 microcontroller as a mobile platform that integrates gas sensing, thermal monitoring, visual inspection and autonomous obstacle avoidance. The system incorporates MQ7 semiconductor gas sensor to monitor real time carbon monoxide (CO), offering detection range from 5 to 2000 ppm with accuracy of 5 ppm. Temperature and humidity are monitored through DHT11 digital sensor, calibrated to ensure reliability across the harsh microclimates in mines. Navigation and autonomous movement are enabled by Ultrasonic Sensor (HC-SR04) with 3 mm accuracy level for obstacle detection, that is integrated into mobile chassis which is driven by L298N dual H-bridge motor drivers. The bot's orientation and sensor field of view are controlled by a servo motor. For visual inspection, ESP32-CAM module streams real time visuals from mine. Wireless data transmission uses the ESP32's inbuilt Wi-Fi to link sensor outputs to the Blynk IoT platform, that enables to monitor data remotely.

D, Suchitra, D, Anitha, Muthukumaran, Balasubramaniam, Mohanraj, Siddharth, Subash Chandra Bose, Rohan

Development of a CNG-Diesel Dual Fuel Tractor with Mechanical Fuel Injection System

2026-26-0114

1/16/2026

Identification of renewable and sustainable energy solutions remains a key focus area for the engine designers of the modern world. An avenue of research and development is being vastly dedicated to propelling engines using alternate fuels. The chemistry of these alternate fuels is in general much simpler than fossil fuels, like diesel and gasoline. One such promising and easily available alternate fuel is compressed natural gas (CNG). In this work, a 3-cylinder, 3-liter naturally aspirated air-cooled diesel engine from the off-highway tractor application is converted into a CNG Diesel Dual fuel (CNG-DDF) engine. Part throttle performance test shows the higher NMHC and CO emissions in CNG-DDF mode which have been controlled by an oxidation catalyst in C1 8-mode emission test. A comparative performance shows that the thermal efficiency is up to 2% lower with CNG-DDF with respect to diesel. However, it has shown the benefit of 44% in Particulate Matter, while retaining the same NOx + NMHC levels as the baseline diesel engine. The cycle average CO emission has been found to increase by 6%. Average exhaust gas temperature has been found to be lower by up-to 54°C with CNG-DDF. To control the particulate and HC levels of the baseline NA engine, the CNG injection has been confined from 20% to 85% engine loads, across all engine speeds. The peak firing pressure and in-cylinder temperature are lower by ~3% and ~7%, and the SoC got retarded by max 4°CA with CNG-DDF which is in-agreement with drop in thermal efficiency. The outcome from the engine dyno level testing has been successfully validated through the tractor testing.

Choudhary, Vasu, Mukherjee, Nalini, Kumar, Sanjeev, Tripathi, Ayush, Nene, Devendra

Replacing Diesel Engines with CNG Engines – Impact on Emissions, Based on Chassis Dynamometer Tests of Medium and Heavy-Duty Buses

2026-26-0127

1/16/2026

This paper compares carbon dioxide, carbon monoxide, methane, and oxides of nitrogen emissions from medium and heavy-duty buses using diesel, diesel-hybrid, and CNG powertrains. Comparisons are made using results from chassis dynamometer-based tests with driving cycles intended to simulate a wide range of operating conditions. Tail pipe emissions are measured by diluting the vehicle’s exhaust in a full-scale dilution tunnel by mixing with conditioned air. Samples are drawn through probes of raw exhaust, diluted exhaust and measured using laboratory grade emission analyzers. Fuel consumption of diesel is measured using a weighing scale, while a gas flow meter is used for measuring CNG consumption. Experimental data from 19 buses tested on a chassis dynamometer over the last 8 years has been analyzed and a comparison of results from similar buses with the differently fueled powertrains is presented. Based on these test results, it is shown that replacing diesel engines with CNG engines does not significantly reduce the emissions of carbon dioxide, while it increases carbon monoxide and methane emissions, reduces oxides of nitrogen emissions, and does not substantially help to reduce global warming.

Iyer, Suresh

Development of above 500 kW Diesel Engine & After Treatment System to Meet CPCB-IV+ Emission Norms

2026-26-0234

1/16/2026

The CPCB-IV+ emission compliance for genset application is applicable with effect from 1st July 2023 as per as per GSR 804(E). The CPCB-II to CPCB-IV+ changeover in very stringent in emission front by almost 90 % emission reduction. It’s a significant advancement in environmentally sustainable powertrain technology. To meet the CPCB-IV+ Emission, combustion development & ATS technology plays an important role. First is the base engine need to optimize enough with combustion & associated parts. Second is the after treatment system which will carry the battle further to the engine emission with minimum margin of 10 % engineering target. This paper present the systematic approach followed to meet CPCB-IV+ emission norms for upgradation of 21 litre TCIC engine for the power range (56 < P ≤ 560). Here the challenge to avoid major changes in the existing CPCB-II FIE recipe & meet the CPCB-IV+ emission with ECU calibration & ATS system calibration with its potential. Here interesting parts unique communication architecture built with genset controller in leading role due to time line constraints. The engine integrates with advanced combustion strategies, improved fuel injections systems, and robust after treatment technology including DOC, DPF & SCR system to significantly reduce NOX, PM, HC & CO Emission. Phase-I (Base engine Calibration): - Baseline engine optimization with existing CPCB-II recipe & ECU calibration feature. Here we have used the 1600 bar rail pressure potential along with optimized fuel timing. The pilot & post injection strategy plays vital role to meet the targeted base engine emission. Phase-II (ATS system selection & its calibration): - To meet the CPCB-IV+ emission norms, stringent limits of NOX, PM introduces in India for genset application. For achieving this a highly optimized after treatment system (ATS) comprising DOC, DPF, SCR, and ASC is essential however our strict target is to avoid the DPF. These strategies collectively help to meet the CPCB-IV+ emission targets with optimum engine performance & fuel economy with potential of ATS architecture and a structured calibration methodology. The DOC enables rapid HC/CO oxidation, while the SCR system, controlled via open-loop urea dosing, achieves >95% NOx conversion. The ASC prevents ammonia slip beyond 10 ppm, ensuring exhaust pipe compliance. This project completed within very low stipulated time month effectively. Phase-III (OBD): - The OBD part of CPCB-IV+ contains the following Check on Torque Reduction & Shutdown Strategy Components wise diagnostic calibration on first proto Report on final diagnostic calibration Phase-IV (Engine Consistency & TA Certification):- Emission consistency trial.

Rane, Vikas, Jagtap, Shailesh, Gothekar, Sanjeev, Pawar, Narendra V, Khedkar, Prasad, Kagade, Samadhan, Kendre, Mahadev, G Bhat, Prasanna, Thipse, S

A Thermoelectric System for Emission Control Optimization in Two-Wheeler Automotive Applications

2026-26-0218

1/16/2026

Environmental pollution is one of the growing concerns of our society. As vehicle emissions are a major contributor to air pollution, emission control is a primary goal of the Automotive industry. Vehicle emissions are higher due to improper combustion, which leads to toxic gases being generated from the exhaust system. Unburnt fuel is one of the leading causes of toxic pollutants such as Carbon Monoxide, Nitric Oxides (NOx) and Hydrocarbons. The catalytic converter converts these gases into less toxic substances such as Carbon Dioxide, Nitrogen, and water vapor. The catalytic converter performs efficiently after reaching its “Light Off” temperature, after which the catalyst becomes active. Hence, elevated temperature of the exhaust gases aids in efficient conversion. Presently, the gases from the exhaust system are approximately at a temperature of 300°C-600°C. This paper outlines the concept of a Peltier (Thermoelectric) Module - based system, which helps maintain the high temperature of the exhaust gases prior to entering the catalytic converter. Peltier Modules are thermoelectric devices well-known for their usage in heating/cooling applications. The proposed system includes a chamber in which the Peltier Module is embedded. As the gases flow through the chamber, the embedded Peltier Module, which is powered by the battery, increases the temperature inside the chamber. Therefore, with this concept, the components required to heat the catalytic converter could be potentially reduced, since the exhaust gases will be maintained at the targeted temperature required for better emission control. Moreover, the Peltier Module is also known to be used for electricity generation. Consequently, by generating electricity through heat utilization on the surface of the chamber, we provide an added benefit of this proposed concept. This can be achieved by mounting the Peltier Module on the hot surface of the chamber. The other side of the Peltier Module is exposed to ambient air and thereby a potential difference is created through the Seebeck Effect.

Venkateshwaran, Aishwarya, Soodlu, Shashikiran, M, Mathaiyan

Improving Late Pilot Injection Strategy in Dual-Fuel Diesel/Methane Engines through Supercharging and Hydrogen Enrichment

03-18-08-0049

12/24/2025

In this study, a novel dual-fuel combustion strategy is investigated, employing late pilot injection in diesel–methane engines to improve performance and reduce emissions. The engine was first tested with conventional diesel and methane, exploring a wide range of pilot injection timings, injection pressures, and intake boost pressures. Subsequently, experiments were repeated using a methane/hydrogen blend to assess the influence of hydrogen addition. Results show that, when using only methane, delayed pilot injections have minimal effects on engine performance. In naturally aspirated operation, unburned hydrocarbons and carbon monoxide are reduced, while in supercharged conditions, emissions increase; however, they remain within acceptable limits. Nitrogen oxides and particulate matter reach their lowest levels with delayed injection. Introducing hydrogen reduces engine performance and hydrocarbons and carbon monoxide emissions; notably, it suppresses the typical nitrogen oxides increase associated with hydrogen, while also lowering particulate matter. These findings demonstrate that combining late pilot injections with hydrogen addition and supercharging is a promising strategy for improving dual-fuel engine efficiency and emissions, offering a potential pathway toward cleaner combustion.

Carlucci, Antonio Paolo, Strafella, Luciano, Ficarella, Antonio

Letter from the Guest Editors

04-19-01-0001

12/10/2025

Letter from the Guest Editors

Assanis, Dimitris, Cho, Seokwon, Lawler, Benjamin, Pintor, Dario Lopez

Effect of Fuel Injection Strategies on Performance, Combustion, and Emission Characteristics of Diesel–Diethyl Ether–Fueled Compression Ignition Engine

03-18-07-0043

11/20/2025

This experimental study compared a blend of diesel–DEE (DEE 40% v/v in diesel) with baseline diesel. This experimental study assesses different fuel injection strategies for controlling the in-cylinder charge stratification, such as single, double, and triple injections. The peak in-cylinder pressure under the partially premixed combustion mode was higher than conventional diesel combustion. Higher in-cylinder pressure with increasing dwell time was observed under triple injections. Retarding pilot injections increased the peak in-cylinder pressure. Conventional diesel combustion mode exhibited the highest brake thermal efficiency and lowest emissions with all injection strategies. A longer dwell time of 12° CA showed higher brake thermal efficiency, nitric oxide, and carbon monoxide emissions, whereas hydrocarbon emissions were lower compared to a shorter dwell time of 6° CA. Hydrocarbon and carbon monoxide emissions increased, but nitric oxide and brake thermal efficiency were reduced by advancing pilot injections. The diesel–DEE blend exhibited slightly lower brake thermal efficiency than baseline diesel at all injection strategies, except for the conventional diesel combustion mode. Diesel–DEE blend exhibited higher hydrocarbon and carbon monoxide emissions than baseline diesel, but nitric oxide emissions were lower.

Sonawane, Utkarsha, Agarwal, Avinash Kumar

Performance and Emission Characteristics of Diesel Engines Fueled with Watermelon Seed Oil Biodiesel Enhanced with Ferrous Oxide Nanoparticles

2025-28-0218

11/6/2025

A large number of research studies have raised global concerns about the rapid depletion of traditional energy sources like petroleum. These fuels, being largely non-renewable, are being consumed at a rate much faster than they can be replenished. This growing imbalance between demand and supply has led to fears that, in the near future, the world could face a serious energy crisis if alternative sources are not developed and adopted in time. The use of alternative fuels plays an important role in lowering harmful emissions, including those that contribute to ozone formation and other toxic pollutants. It is a well-established scientific understanding that the continued combustion of fossil fuels is a key driver of global atmospheric warming. As environmental awareness grows, many individuals across the globe believe that shifting toward cleaner and more sustainable fuel sources is essential for protecting and improving the health of our planet. Extensive research is being conducted to evaluate the compatibility of various alternative fuels—such as rubber seed oil, melon seed oil, sunflower oil, jatropha oil, and waste cooking oil—for use in internal combustion (IC) engines. In light of this, the current study focuses on assessing the feasibility of using watermelon seed oil as a potential alternative fuel. Through the process of transesterification, watermelon seed oil was converted into biodiesel. The study involved testing pure diesel and its blends with biodiesel—namely B10, B20, and B30—to analyze and compare their performance, emission levels, and combustion behavior within a diesel engine setup. Test results indicated that the use of biodiesel led to an increase in brake specific fuel consumption (BSFC) and a slight reduction in brake thermal efficiency (BTE), primarily due to its lower calorific value. Although there was a moderate rise in nitrogen oxides (NOx) and carbon monoxide (CO) emissions, the use of biodiesel and its blends effectively reduced hydrocarbon (HC) and carbon dioxide (CO₂) emissions. Furthermore, combustion analysis revealed that, compared to conventional diesel, biodiesel blends resulted in reduced peak cylinder pressure and a lower heat release rate during the combustion process.

G, Manikandan, Subbaiyan, Gunasekharan, Saminathan, Sathiskumar, T, Karthi, S, Gokul, J, Sanmuganathan

Effects of Intake-Air Heating on a Light-Duty CNG-Diesel Reactivity-Controlled Compression Ignition Engine

2025-32-0003

11/3/2025

Reactivity controlled compression ignition (RCCI) is a promising low-temperature combustion strategy that offers high thermal efficiency with reduced nitrogen oxides (NOx) and soot emissions. However, at low loads, RCCI operation often suffers from incomplete combustion, leading to elevated partial combustion products, such as, unburned total hydrocarbons (THC) and carbon monoxide (CO) emissions. Intake-air heating is a potential strategy to address these issues by enhancing fuel reactivity and promoting more complete combustion. In this study, the effects of intake-air heating (from ambient to ~95°C) on performance, combustion, and emissions were experimentally investigated in a light-duty diesel engine operated in compressed natural gas (CNG)-diesel RCCI mode. Experiments were conducted at low and intermediate loads at various engine speeds. A single injection strategy was employed for low-load, while a double-injection strategy was used at intermediate-load operating condition s. CO and THC emissions were significantly reduced at low loads with intake-air heating, but at intermediate-loads no significant reductions in CO and THC emissions were observed. However, NOx emissions increased and combustion stability improved with intake-air heating at all the investigated operating conditions. Furthermore, increased intake-air temperature at low-load high-speed operation with single injection strategy resulted in significant combustion oscillations due to end-gas auto-ignition. The presence of oscillations was confirmed by a fast Fourier transform (FFT) analysis of the in-cylinder pressure that revealed significant resonance in the first circumferential mode at higher intake temperatures. Furthermore, with intake-air heating, an increase in the energy substitution by CNG from 50% to 70%, and a marginal increase in EGR from 45 to 55%, improved the THC-NOx trade-off in RCCI operation.

Navaneethakrishnan, P., Sarangi, Asish K, Suman, Abhishek, Sreedhara, Seshadri, Singh, Arvind Kumar

Quasi-Dimensional Simulation of a Turbulent Jet Ignition Combustion in High-Performance High-Speed Motorcycle Engine

2025-32-0002

11/3/2025

High-performance and high-revving Internal Combustion Engines (ICEs) are central to the motorbike driving experience. To achieve these peculiar characteristics, rich combustion strategies are often used to improve combustion performance, resulting in incomplete combustion leading to high unburned Hydro-Carbon (uHC) and Carbon Monoxide (CO) emissions. Turbulent Jet Ignition (TJI) combustion could replace standard Spark Ignition (SI) systems to improve combustion efficiency and reduce emissions with minimal modification to existing configurations. Extensive experimental and numerical analyses are needed to develop and understand the complex phenomena that characterize TJI combustion, using considerable time and resources. To address this, reduced-order models are used to accelerate the research and development processes by simplifying the analysis of complex combustion phenomena. This paper presents an enhanced reduced-order model initially developed for SI engines and later extended to include TJI combustion. Phenomenological sub-models were incorporated to capture the characteristics of TJI combustion, like flame development and enhanced turbulence. This model was applied to simulate high-speed, high-performance motorcycle ICEs at different engine speeds and loads and was validated against experimental and Three-Dimensional Computational Fluid Dynamics (3D CFD) results. Both SI and TJI conditions were analyzed, the latter characterized by a passive Pre-Chamber (PC). Using the same initial conditions as for 3D CFD simulations, the model demonstrated a high degree of accuracy in reproducing experimental and computational results, both quantitatively and qualitatively, across a wide range of operating conditions. A single set of tuning constants was applied successfully for all scenarios, highlighting the model’s robustness and versatility. This work underscores the potential of reduced-order modeling to advance the development of high-performance, low-emission combustion systems.

Ballerini, Alberto, D'Errico, Gianluca, Nodi, Alessandro, Buttitta, Marco, Marmorini, Luca

First Investigation of Ducted Fuel Injection on a Retrofitted Heavy-Duty Multi-Cylinder Production Engine

04-19-01-0005

10/22/2025

Ducted fuel injection (DFI) was tested for the first time on a production multi-cylinder engine. Design-of-experiments (DoE) testing was carried out for DFI with a baseline ultra-low sulfur diesel (ULSD) fuel as well as three fuels with lower lifecycle carbon dioxide (CO2) emissions: renewable diesel, neat biodiesel (from soy), and a 50/50 blend by volume of biodiesel with renewable diesel denoted B50R50. For all fuels tested, DFI enabled simultaneous reductions of engine-out emissions of soot and nitrogen oxides (NOx) with late injection timings. DoE data were used to develop individual calibrations for steady-state testing with each fuel using the ISO 8178 eight-mode off-road test cycle. Over the ISO 8178 test, DFI with a five-duct configuration and B50R50 fuel reduced soot and NOx by 87% and 42%, respectively, relative to the production engine calibration. Soot reductions generally decreased with increasing engine load. Hydrocarbon and carbon monoxide emissions tended to increase with DFI but were not excessive over the ISO 8178 test. Brake-specific energy consumption generally increased with DFI due to the use of retarded injection timings and exhaust-gas recirculation to achieve the desired NOx reductions but was less than or equal to that for conventional diesel combustion with ULSD at a similar NOx level. Significant deposits were encountered on one cylinder when running at idle with the ULSD fuel only, but this was mitigated by replacing the corresponding fuel injector (which showed deformation at the exits of two of its orifices) and using a fuel detergent additive in subsequent testing. In all, the engine was successfully operated for over 300 hours in the DFI configuration. Research areas for improved DFI implementation are identified.

Ogren, Ryan M., Baumgard, Kirby J., Radhakrishna, Vishnu, Kempin, Robert C., Mueller, Charles J.

Biodiesel Characterization and Prediction Using ANN Modeling along with the Assessment of Performance and Emission Behavior of Fuel Sources— Gossypium hirsutum and Stoechospermum marginatum —Used in Direct Injection CI Engine

2025-01-5071

10/16/2025

The demand for alternate fuel continues to grow steadily, while energy sources are being researched and explored every year. Considering the energy demand and fuel cost this research was initiated to identify better sources for fuel production. Also the emission released into the atmosphere causes significant influence in the global market in terms of pollution, which was also a prime motive toward this research analysis. A green biodiesel, fatty acid alkyl ester, has attracted much attention as an environmentally friendly diesel fuel. This is due to several advantages, especially that fatty acid alkyl ester is renewable, biodegradable, and has less toxic properties as a fuel. In this article, cottonseed (Gossypium hirsutum) biodiesel and algal (Stoechospermum marginatum) biodiesel was prepared with a yield of 94% and 85%, respectively. Single-stage transesterification was performed since the free fatty acid percentage was within the limit. The performance characteristics in terms of brake thermal efficiency and brake specific fuel consumption, algal biodiesel performed better in comparison with cottonseed biodiesel, and its values were closer to standard diesel fuel. The maximum BTE of ABD100 was noticed to be 36.2% and optimized BSFC was 17 kg/kW-h for ABD100. The emission characteristic analysis stated that biodiesel detailed lower CO emission than diesel fuel, at high loads UBHC were lower for biodiesel than diesel fuel, up to 6% and 18% difference. NOx emission was higher for biodiesel, which may be due to better combustion and the diesel fuel produced higher smoke emission, whereas biodiesel depicted lower emission values. Comparatively, algal biodiesel was found to be better, which showcased lower ignition delay and better engine emissions.

Godwin, John J., Hariram, V., Muthiya, Solomon Jenoris, Sambandam, Padmanabhan, Prathik, S. J., Santhosh, K., Baskar, S., Boopathi, D.

Optimization of CI Engine Operation with DME on an FTP Cycle

2025-01-0394

10/7/2025

Fuels that can be produced in a sustainable manner are of high interest because they can provide an essential step toward net zero emissions vehicles. This study examines the combustion of one such fuel, Dimethyl Ether (DME), in a compression ignition, 4-cylinder, 2.2L engine. Testing was conducted using the Federal Test Procedure (FTP) certification cycle from the US Environmental Protection Agency (EPA). Different sets of calibration maps were designed to target low-NOx (30-50ppm) by using high EGR and intake throttle and high-NOx (approximately 1000ppm) using no EGR. An intermediate, mid-NOx calibration was also evaluated. Varying calibration approaches yielded total integrated engine out emissions ranging from 118 to 145gCO2/km, all below the 191gCO2/km from the baseline diesel. The corresponding NOx+UHC and CO emissions were also evaluated. The mid-NOx calibration was overall more favorable, as it met TIER 3-Bin 20 emissions requirements with the current efficiencies of the base engine diesel aftertreatment system. This paper reviews the transient behavior with three different calibrations, noting the effect of air-to-fuel ratios where the engine combustion efficiency deteriorates. It also highlights the impact of improved air and fuel controls, and the application of real time combustion feedback to enhance the combustion stability of the engine and the reduction of CO2 emissions. The paper explores the impact of renewable DME, and its carbon index, on the CO2 emissions for the low-NOx calibration. While a 5% renewable DME content can reduce the CO2 to the target level, the fuel consumption remains high due to the poor combustion efficiency and corresponding high HC and CO during transient operation.

De Ojeda, William, Wu, Simon (Haibao), Harrison, Christopher, Hall, Carrie, Arslan, Elaheh, Pulpeiro Gonzalez, Jorge

Computational Fluid-Dynamics Analysis of the Effect of Ethanol-Air Mixture Supply in a Heavy-Duty Engine

2025-24-0029

9/7/2025

As part of the Bio-FiRE-for-EVer research project aiming to propose a solution for off-grid charging stations based on the adoption of a reciprocating engine, this study investigated the combustion development and pollutant emissions of an 8.7 l six-cylinder heavy-duty PFI internal combustion engine fueled by ethanol. The reference experimental case features critical issues in the formation of the air-fuel, mainly due to the slow evaporation rate of the alcohol fuel inside the intake manifold via a single point injection, providing a non-uniform and averagely rich (λ=0.89) reactant mixture inside the cylinders. For this purpose, an in-depth analysis of the in-cylinder phenomena is performed by using a CFD solver for the reacting flow. A geometry of the cylinder system complete with intake and exhaust ducts is created for calculations with the three-dimensional Ansys FORTE code. The inclusion of the inlet duct in the computational domain allows the experiencing of several setups of the mixture. Indeed, due to the uncertainties on the complete vaporization of ethanol, experimental data allowed a preliminary validation of the CFD based predictions by considering the presence of liquid fuel fraction (30%) in the inlet duct. After the model calibration, firstly, a more favorable air-fuel ratio condition of λ=1 is examined and then, two alternative solutions are proposed to optimize the engine performance via a multipoint injection upstream of the intake valves but still considering a rich mixture. Based on the results it is demonstrated that the presence of liquid represents a more realistic condition achieving outputs closer to the experimental measurements. The adjustment of air-fuel ratio to a stoichiometric value by only enhancing the amount of air leads to significant improvements in terms of mechanical outputs and CO emissions. Besides, an optimized injection setup can overcome the maldistribution of fuel among cylinders, its incomplete oxidation and reduce the percentage of fuel that remains liquid forming a film on the duct’s wall.

De Robbio, Roberta, Cameretti, Maria Cristina, Palomba, Marco, Tuccillo, Raffaele

Analysis of Combustion Characteristics and Performance of a Multi-Cylinder Engine Operating on Syngas/Diesel in Dual-Fuel Mode

2025-24-0042

9/7/2025

Despite improvements in internal combustion engine efficiency, fossil fuel reliance remains a challenge for sustainable energy. Syngas, a hydrogen-carbon monoxide mixture produced from gasification, typically of carbon-based feedstocks, offers a viable transitional fuel due to its compatibility with existing combustion technologies and reduced emissions. However, its low ignition propensity elevated intake temperatures or pressures, a limitation that can be overcome through diesel pilot injection in dual-fuel engine configurations. This study extends prior single-cylinder research to a 1.6 L four-cylinder HCCI engine operating in dual-fuel mode, resembling a Reactivity Controlled Compression Ignition (RCCI) engine. The analysis focuses on cylinder-to-cylinder combustion variation, thermal efficiency, and pollutant emissions, with particular emphasis on the influence of diesel pilot injection timing. Experimental evaluations are conducted across a range of injection timing and Syngas flow rates (100 to 160 L/min). Key metrics include ignition delay, heat release rate, maximum pressure rise rate, coefficient of variation of indicated mean effective pressure, and pollutant emissions. Results indicate that diesel pilot injection timing significantly affects combustion phasing, heat release dynamics, and overall engine efficiency. Advancing or retarding the injection timing alters ignition delay and heat release characteristics, with optimal settings improving Syngas utilization and reducing particulate emissions. These findings highlight the importance of injection strategy optimization for realizing the full potential of Syngas in multi-cylinder engines, supporting their integration into cleaner and more efficient propulsion systems.

El Younsi, Laila, Nelson-Gruel, Dominique

Exploring the Emission Spectrum of Pure Hydrogen Combustion in Spark Ignition Engines: A Comprehensive Experimental Study

2025-24-0051

9/7/2025

Hydrogen internal combustion engines (H2ICE) have shown enormous potential for zero-carbon emissions, aligning with the European zero-carbon targets in 2050. Adopting hydrogen as a zero-carbon fuel offers a time- and cost-effective approach to directly replacing carbon-based and fossil fuel-powered ICEs. The study aims to provide comprehensive data on the H2ICE engine during steady-state operations of a single-cylinder spark ignition engine with a direct hydrogen injection system. It focuses on emissions, including carbon monoxide (CO) and unburnt hydrocarbons (HC), utilising ultra-fast analysers positioned close to the exhaust valves to minimise signal delay. Particulate matter (PM) emissions are also measured to evaluate the potential for zero-carbon emissions from the H2ICE. Additionally, NO and NO2 emissions are analysed against air-fuel ratios (AFR) to estimate combustion temperature and NOx mechanisms. Water vapour and oxygen emissions are captured to assess their quantities under different loads and to verify the actual Lambda compared to the wideband O2 sensor. The study's main findings show that by looking at the averaged data, the averaged CO2 and HC emissions were less than 0.02% over mid-load of 10 bar IMEP at 2000 rpm and a lambda value of 2.75. However, examining cycle peak values near the exhaust valve opening reveals small spikes under 100 ppm, which have been correlated with PM emissions data to confirm carbon emissions resulting from lubricant induction. These emissions exhibit distinct characteristics, particularly during periods of higher coefficient of variation (COV), and are captured during abnormal combustion events. This suggests increased piston acceleration leads to greater lubricant entry into the combustion chamber. Additionally, an impressive water vapour peak value of 42.7% of the exhaust volume at lambda 1 indicates great potential for adopting EGR and water injection.

Mohamed, Mohamed, Zaman, Zayne, Wang, Xinyan, Zhao, Hua, Hall, Jonathan

Numerical Study of Mixing, Combustion and NOx Emissions in a DI High Performance Hydrogen Engine Operated at Stoichiometry

2025-24-0010

9/7/2025

The roadmap towards carbon neutrality by 2050 makes necessary drastic reduction of road vehicle tailpipe carbon emissions. One viable approach to reach the abatement of carbon monoxide and dioxide is to fuel internal combustion engines (ICEs) with hydrogen. The burning of a hydrogen-air mixture inside the combustion chamber reduces to minimal amount the production of carbon emissions and particulate matter that are only produced by the presence of lubricant oil. However, the high temperatures reached by the end-gases promote the formation of nitrogen oxides. In high-performance ICEs, the pursuit for high-specific power by means of the adoption of stoichiometric mixtures is hindered by the need to reduce NOx - as this pollutant drastically drops when moving towards ultra-lean mixtures. The paper aims to present a CFD-3D framework to simulate the full engine-cycle of a high-performance Spark-Ignited (SI) Direct-Injection (DI) ICE fuelled at stoichiometric conditions. The methodology is validated thanks to experimental data collected at part-load condition (2000 rpm and 4.5 IMEPH) changing the injection timing and at full-load operation (6000 rpm and 24 bar IMEPH). The experimental measurements of nitrogen oxides at the part load conditions are compared with the outcome of the CFD. In particular, the most delayed injection case is compared with the most advanced one to give an overview of the effect of the stratification of the mixture in the formation of the analysed pollutants. Furthermore, the validated model is employed to predict amount of NOx generated in the most demanding condition (6000 rpm) to better understand the influence of temperature, pressure and mixture composition on the NOx production pathways.

Baudone, Antonio Denny, Marini, Alessandro, Sfriso, Stefano, Falcinelli, Francesco, Mortellaro, Fabio, Tonelli, Roberto, Breda, Sebastiano

Experimental Investigations on the Effects of Injector Orientation in a Diesel-Gasoline-Fuelled Premixed Charge Compression Ignition Engine

2025-24-0043

9/7/2025

Premixed Charge Compression Ignition (PCCI) presents a promising alternative to conventional diesel combustion (CDC), offering significant reductions in pollutant emissions by lowering local in-cylinder temperatures and enhancing fuel-air mixing. However, a significant challenge in implementing PCCI is controlling the start of combustion, especially given its narrow operating load range. This is primarily due to early ignition and knocking combustion at higher loads when using high-reactivity diesel fuel, which limits the practical applicability of PCCI mode in diesel engines. In the present study, experimental investigations are carried out on a light-duty diesel engine operating in PCCI mode using two fuel blends: 10% (D90G10) and 20% (D80G20) gasoline mixed with diesel on a volume basis. To facilitate combustion control and emission reduction, exhaust gas recirculation (EGR) and water vapor are used as charge diluents. A common rail direct injection (CRDi) system replaces the conventional mechanical fuel injection system, and the engine's compression ratio is reduced from 17.5 to 15 to enable PCCI operation. Initial parametric studies revealed that early direct injection combined with high injection pressure limited the PCCI operating load range to 30% of the rated load when using diesel fuel. However, incorporating EGR with diesel extended this load range to 60%, albeit with increased unburnt hydrocarbon (HC) and carbon monoxide (CO) emissions. To address these challenges, the engine's cylinder head was modified to accommodate a vertically oriented injector, and diesel was replaced with diesel–gasoline blends. Experiments were then conducted using the modified cylinder head at a constant engine speed of 1500 rpm, under varying load conditions and injection timing, to analyze the effects of injector orientation and fuel blends in combination with EGR and water vapor as charge diluent. The results indicate that the diesel–gasoline blends increase ignition delay and enhance fuel-air mixing time between the end of fuel injection and the start of combustion. Specifically, with the G20D80 blend and combined EGR and water vapor dilution, the engine's operating load range was extended to 74% of the rated load. Compared to the CDC, emissions of NOx and soot were significantly reduced. Additionally, HC and CO emissions were reduced by 11.2% and 43.2% at 60% loads, and smoke was reduced by 57.6%, compared to the baseline PCCI, using EGR and water vapor as charge diluents with D80G20 fuel blends.

Ranjan, Ashish Pratap, Krishnasamy, Anand

Mid-IR Laser Extinction Measurements of Formaldehyde Emissions in a Methanol Mixing-Controlled Compression Ignition Engine

2025-24-0034

9/7/2025

As energy security and sustainability becomes important, the role of alternative fuels, particularly methanol, is becoming increasingly significant. While the feasibility of methanol as a substitute for diesel fuel has been explored, understanding of emissions from methanol-fueled compression-ignition engines remains limited, even though these engines are known to emit formaldehyde (CH2O) due to methanol’s chemical structure and oxidation pathways. In this study, a quantitatively measurable mid-IR laser-based extinction methodology was employed to understand CH2O formation in a methanol mixing-controlled compression ignition (MCCI) engine. Stable methanol MCCI combustion was achieved with the addition of 5%vol 2-ethylhexly nitrate (EHN) and by using a triple injection strategy (pilot + pilot + main), and CH2O emissions were measured with high temporal resolution by laser extinction while sweeping the injection timing. In addition, the injection strategy was systematically varied by enabling and disabling different injection events to investigate the effect of pilot and main injections on CH2O formation. Injection timing sweeps revealed that CH2O emissions did not monotonically increase with retarded injection, as carbon monoxide did. This decoupling suggests that CH2O formation is not governed solely by global combustion inefficiencies but is instead tied to localized mixture conditions and oxidation pathways. Cycles with elevated CH2O emissions featured minimal low-temperature heat release of pilot injections and, subsequently, more retarded combustion phasing. This indicates that combustion quality of pilot injections strongly affect engine-out emissions, and suggests that overly lean mixtures created by pilot injections promote CH2O formation when later exposed to high-temperature heat release (HTHR). Injection strategy modulation showed that the absence of HTHR results in minimal CH2O emissions, even when large amount of fuel were injected, emphasizing HTHR’s role in initiating methanol oxidation and CH2O formation. In contrast, strategies promoting lean mixtures followed by HTHR led to higher CH2O emissions due to incomplete oxidations. Additionally, acetaldehyde (CH3CHO) emissions were consistently detected. Chemical kinetic simulations revealed that CH3CHO forms through unimolecular decomposition of EHN-derived intermediates or secondary reactions between methanol and species derived from EHN oxidation like C2H5O2. These results offer new insight into the oxidation behavior of methanol under MCCI conditions and highlight the role of thermal and chemical stratification in pollutant formation.

Lee, Sanguk, Lopez Pintor, Dario, Narayanan, Abhinandhan

A Life Cycle Assessment of Potential Pathways to Increase Sustainable Aviation Fuel Yields through CO ₂ Upgrading Co-located with Corn Ethanol Production

13-06-03-0023

9/4/2025

Alcohol-to-jet (ATJ) upcycling of ethanol to sustainable aviation fuel (SAF) is an attractive emerging pathway for SAF production, especially in the US Midwest with large-scale corn ethanol production. Only 39% of the corn carbon is converted to ethanol, 20% is emitted as CO2. Capturing the CO2 to produce additional ethanol or SAF directly can increase the carbon yield. To guide technology selection, this work used life cycle assessment for several CO2-to-SAF production pathways. Additionally, improvements for corn ethanol production were explored by replacing natural gas burners with heat pumps for corn drying, which reduced the carbon intensity of corn ethanol by nearly 16%. But subsequent upgrading of the ethanol to SAF is only 4.5–20% better than conventional aviation fuel. By contrast, CO2-based alternative routes to SAF fared better, reducing carbon intensities between 83% and 90%. Gas fermentation of CO2 to ethanol with subsequent ATJ upcycling to SAF was contrasted to Fischer–Tropsch conversion of CO2 to SAF. Both streams require CO2 conversion to CO, which can be produced using reverse water–gas shift or solid oxide electrolyzer cells. The Fischer–Tropsch synthesis shows a higher reduction in carbon intensity (up to 90%) compared to ATJ (up to 84.4%). For other impact categories, such as ozone depletion, ecotoxicity, and the like, the differences are of similar magnitude. Capturing CO2 locally at the bioethanol factory and converting that CO2 to ethanol might overall be preferable with a fermentation process that is quite like bioethanol production compared to Fischer–Tropsch synthesis for which products require a new transportation infrastructure. The aviation fuel yield from ATJ can reach 90%, higher than the 50–70% yield from Fischer–Tropsch synthesis, with gasoline and diesel fuel as major by-products for which markets will shrink in the future. Overall, ATJ appears to be the best choice for CO2-to-SAF using the synergy with corn ethanol factories for quick launch.

McCord, Stephen, Talsma, Sam, Bouchard, Jessey, Zavaleta, Victor Gordillo, He, Xin, Sick, Volker

Ethanol Fuel as Enabler for High-Efficiency and Low-Soot Combustion in Dual-Fuel and Blend Modes

03-18-04-0028

7/16/2025

Global climate initiatives and government regulations are driving the demand for zero-carbon tailpipe emission vehicles. To ensure a sustainable transition, rapid action strategies are essential. In this context, renewable fuels can reduce lifecycle CO2 emissions and enable low-soot and NOx emissions. This study examines the effects of renewable ethanol in dual-fuel (DF) and blend fueling modes in a compression ignition (CI) engine. The novelty of this research lies in comparing different combustion modes using the same engine test rig. The methodology was designed to evaluate the characteristics of various injection modes and identify the inherent features that define their application ranges. The investigation was conducted on a single-cylinder engine equipped with state-of-the-art combustion technology. The results indicate that the maximum allowable ethanol concentration is 30% in blend mode, due to blend stability and regulatory standards, and 70% in DF mode, due to combustion stability and emission concerns. DF mode produces higher THC and CO emissions compared to blend or conventional diesel combustion (CDC) modes. However, ethanol consistently reduces smoke formation across all engine test conditions and fueling modes. At ultra-low-NOx levels (0.5 g/kWh), smoke emissions remain below 0.5 FSN. At the highest ethanol fraction in DF mode (70%), smoke emissions decrease to very low levels (−0.1 FSN), with improvements in thermal efficiency and CO2 emissions. DF mode requires specific injection control strategies to mitigate THC and CO emissions. In blend mode, the highest ethanol fraction (30%) results in CO2 and soot reductions, with CO and THC emissions comparable to CDC.

Belgiorno, Giacomo, Ianniello, Roberto, Di Blasio, Gabriele

Experimental Investigations on the Effects of Injector Design and Operating Parameters on PCCI Combustion in a Light-Duty Diesel Engine

03-18-04-0026

7/9/2025

Due to increasingly stringent emission regulations, advanced combustion strategies, such as premixed charge compression ignition (PCCI), have emerged promising solutions for achieving low NOx and soot emissions. However, challenges such as increased unburned hydrocarbon (HC), carbon monoxide (CO) emissions, and a restricted engine operating load range remain unsolved. Since conventional diesel engines are not inherently designed for PCCI operation, re-optimizing engine parameters is essential. The primary objective of this work is to investigate the influence of injector orientation and nozzle spray angle on combustion parameters, performance, and emissions in a PCCI diesel engine. Initial parametric studies revealed that early direct injection combined with high fuel injection pressure limited the PCCI load range to 30% and 60% of the rated capacity with diesel, without and with EGR, respectively, accompanied by higher HC and CO emissions. To address these limitations, the injector orientation is modified from inclined to vertical, increasing the offset from 5 to 9 mm and employing symmetric spray angles along the z-axis. The experiments were conducted at a constant engine speed of 1500 rpm with varying load conditions at optimized timing in PCCI mode to investigate the effect of injector orientation, offset, and spray angle. The results demonstrate two positive aspects: first, the load range extended from 30% to 40% of the rated load with diesel, with improved engine brake thermal efficiency and reduced NOx emission up to 85.6% compared to conventional diesel combustion (CDC). Second, while using the EGR, the load range extends from 60% to 62.5%, achieving up to 96% NOx reduction compared to CDC. Although HC and soot increased significantly, a notable decrease in HC was observed at higher loads compared to lower load conditions. According to this study, injector orientation and nozzle spray angle variation are effective strategies for enhancing the performance and extending the operating load range of PCCI engines.

Ranjan, Ashish Pratap, Krishnasamy, Anand

Life Cycle Assessment of Hydrogen Generation through Steam Methane Reforming: A Focus on Co-Product Allocation between Steam and Electricity

2025-01-0181

6/16/2025

This research presents a numerical analysis of the environmental impacts associated with using hot steam as a co-product in hydrogen production through Steam Methane Reforming (SMR) of renewable gas sources. As hydrogen production technology advances rapidly, reducing emissions and addressing environmental concerns, particularly greenhouse gas (GHG) emissions, have become essential. This study examines the SMR process with a focus on the environmental effects of utilizing hot steam as a co-product for electricity generation or facility heating. The analysis evaluates renewable feedstocks, including landfill gas, animal waste, food waste, and wastewater sludge, to determine their viability for sustainable hydrogen production. Key pollutants, such as carbon monoxide and nitrogen oxides, along with GHGs, are assessed to identify the most environmentally advantageous feedstock options. This work aims to provide insights to promote sustainable hydrogen production practices.

Rosyadi, Ahmad Adib, Lim, Ocktaeck

Assessing the Performance of a Modified Fuel Injection System–Equipped Dimethyl Ether-Fueled Genset/Tractor Engine

04-18-03-0014

5/21/2025

Ethers are emerging as suitable mineral diesel replacements. A customized mechanical fuel injection system was used to investigate the dimethyl ether–fueled genset/tractor, and ~75% rated engine load was achieved over diesel. The in-cylinder pressure rise rate was about half for the dimethyl ether engine. However, the lower pressure generated in the high-pressure dimethyl ether line reduced brake thermal efficiency for the dimethyl ether engine. Dimethyl ether engines emitted lower nitrogen oxide emissions than baseline diesel except at higher loads and reduced nozzle opening pressure. Carbon monoxide emissions increased due to prolonged and incomplete combustion at higher loads with reduced nozzle opening pressure. Blowby gas leakage was lower for dimethyl ether than for baseline diesel engines. Overall, the genset/tractor engine could perform satisfactorily using a customized fuel injection system and will help achieve carbon neutrality from the various sectors using this technology.

Agarwal, Avinash Kumar, Pal, Manojit, Valera, Hardikk

Experimental Investigation of Carbon Nanotube Additives Effect on Performance and Emission of a High-Injection Pressure Common Rail Diesel Engine

03-18-03-0020

5/16/2025

Due to the continuous decrease in fossil fuel resources, and drawbacks of some biofuel properties, in addition to restricted environmental concerns, it becomes a vital manner to innovate some approaches for energy saving and emission reduction. One of the promising approaches is to enhance the fuel properties via adding nanoparticles. Carbon nanotubes (CNTs) blended with biofuels get extensive investigations by researchers using conventional diesel engines at relatively limited operating regimes. The objective of this work is to extend these studies using diesel fuel, rather than biofuels, on a high-injection pressure (1400–1600 bar) common rail diesel engine at wide operating conditions and higher CNT concentrations. Experimental results show an increase in peak pressure up to 24.46% than pure diesel when using 100 ppm CNTs concentration. Also, BSFC has decreased by 33.19%, and BTE increased by 54.2% compared to pure diesel fuel at high speeds and loads. NOx and CO2 emissions raised by 24.3% and 23.3%, respectively, while CO emission decreased by 23.68%. These results could be a motivation for extra investigations for CNTs using smaller sizes, lower than 10 Nm, at wider engine regimes and particle concentrations.

Moaayet, Sayed, Neseem, Waleed Mohamed, Amin, Mohamed Ibrahim, Shahin, Motasem Abdelbaky

Study on the Optimal Pre-Chamber Geometry for Active Pre-Chamber Gas Engines

2024-32-0023

4/18/2025

In a pre-chamber engine, fuel in the main-chamber is ignited and combusted by the combustion gas injected from the pre-chamber. Therefore, further fuel dilution is possible and thermal efficiency can be also improved. However, adding a pre-chamber to an engine increases the number of design parameters which have a significant impact on the main combustion and the exhaust gas. Then, in this study, the optimum geometry of the pre-chamber in an active pre-chamber gas engine was investigated. The considered parameters were the volume of pre-chamber, the diameter of a nozzle hole, and the number of nozzle holes. 18 types of pre-chambers with different geometries were prepared. Using these pre-chambers, engine experiments under steady conditions were conducted while changing the conditions such as engine speeds, mean indicated pressure and air excess ratio. Based on the experimental data, neural network models were constructed that predict thermal efficiency, NOx and CO emissions from the pre-chamber geometries and the engine operation conditions. Employing these models as objective function, the optimal geometry of the pre-chamber is obtained as Pareto solutions. The availability of this method to determine the optimal geometry of pre-chamber was proved since the general trade-off relationship between thermal efficiency and NOx was shown.

Yasuda, Kotaro, Yamasaki, Yudai, Sako, Takahiro, Takashima, Yoshitane, Suzuki, Kenta

Decarbonization of Off-Road Engines by Methanol Mixing-Controlled Compression Ignition with Ignition Enhancer

2025-01-8411

4/1/2025

Methanol is one of the most promising fuels for the decarbonization of the off-road and transportation sectors. Although methanol is typically considered an alternative fuel for spark ignition engines, mixing-controlled compression ignition (MCCI) combustion is typically preferred in most off-road and medium-and heavy-duty applications due to its high reliability, durability and high-efficiency. In this paper, methanol MCCI combustion was enabled using ignition improvers and the potential benefits of this approach compared to conventional diesel combustion were investigated. Methanol was blended with 7%vol of 2-ethylhexyl nitrate (EHN) and experiments were performed in a single-cylinder production-like diesel engine with a displacement volume of 0.8315 L and a compression ratio of 16.5:1. The conditions of the ISO 8178 C1 regulatory cycle for off-road engines were tested, and performance and emissions over the cycle were calculated. Methanol MCCI shows 5.3% lower fuel consumption (in gallons of diesel equivalent) than conventional diesel combustion, resulting in a 20% reduction in operation costs. Smoke emissions are also very low, 97% lower than those of conventional diesel over the cycle, and a diesel particulate filter will not be required with methanol. CO emissions are higher than those of diesel and slightly higher than the legal limit, so an oxidation catalyst will be required with methanol. However, low load operation at rated speed accounts for 44.2% of the total CO emissions over the regulatory cycle, so optimization of this operating point is key to reduce CO and simplify the required aftertreatment. NOx emissions are higher than the legal limit for both methanol and diesel, so both technologies will require NOx aftertreatment, such as a selective catalyst reduction catalyst. In conclusion, the ultra-low soot, lower fuel consumption, lower operating cost, and retrofit potential of methanol MCCI indicate that this is a promising approach for decarbonization of the off-road sector.

Lee, Sanguk, Lopez Pintor, Dario, MacDonald, James, Narayanan, Abhinandhan, Chan, Adrian

Energy Conversion Efficacy of Neat Dimethyl Ether Combustion with Heat Release Characterization and Emission Analysis

2025-01-8417

4/1/2025

Dimethyl ether (DME) is widely regarded as a suitable energy source for compression ignition power systems because of its high reactivity. It has been widely reported that DME possesses a significantly low propensity to form soot, hindering the innate NOx-soot trade-off encountered with diesel fuel operation. Beyond the fuel-borne oxygen content of DME, its unique physical properties present a contrasting combustion behavior which may be advantageous to direct injection systems, especially concerning the mixing-controlled combustion mode. This work aims to detail the energy conversion efficacy of DME through heat release characterization and exhaust emission speciation. The tests were controlled within a single-cylinder research engine with an off-board high-pressure injection system to handle liquified DME up to 1000bar. To mitigate interference in fuel additives over the combustion behavior, the high-pressure fuel system specifically managed neat DME. The in-cylinder pressure was the indicator for combustion behavior, whereas exhaust emissions were sampled with infrared and mass spectroscopy for exhaust speciation. The in-cylinder combustion profile was aligned with the actual rate of injection to designate the characteristics between the injection and combustion events. Overall, the fuel-to-heat conversion efficiency is comparable, while the combustion efficiency is slightly greater owing to lower carbon monoxide emissions. Without injection-combustion overlap, i.e. low load and primarily premixed combustion, the heat release pattern of DME was like diesel. Under extended injection-combustion overlap, diesel finished injection up to CA50% of cumulative heat release whereas DME injection often finished up to ~CA80%. The end of the injection was followed by a fast and abrupt drop in heat release, e.g. the end of combustion. The application of exhaust gas dilution, however, altered the end of the combustion pattern and promote carbon monoxide emissions.

Leblanc, Simon, Cong, Binghao, Leach, Jace, Yu, Xiao, Reader, Graham, Zheng, Ming

Refining Control, Charging, and Battery Chemistry for CO ₂ e Savings in Heavy-Duty Off-Road Plug-In Series Hybrid

14-14-02-0009

2/27/2025

With current and future regulations continuing to drive reductions in carbon dioxide equivalent (CO2e) emissions in the on-road industry, the off-road industry is also likely to be regulated for fuel and CO2e savings. This work focuses on converting a heavy-duty off-road material handler from a conventional diesel powertrain to a plug-in series hybrid, achieving a 49% fuel reduction and 29% CO2e reduction via simulation. Control strategies were refined for energy savings, including a regenerative braking strategy to increase regenerative braking and a load-following hydraulic strategy to decrease electrical energy consumption. The load-following hydraulic control shuts off the hydraulic electric machine when it is not needed—an approach not previously seen in a load-sensing, pressure-compensated system. These strategies achieved a 24.1% fuel savings, resulting in total savings of 61% in fuel and 41% in CO2e in the plug-in series compared to the conventional machine. Beyond control strategies, this study evaluated battery chemistry and charging strategy refinements for total cost of ownership (TCO) and lifetime CO2e. LFP batteries emerged as the most cost-effective and least emitting due to their longer lifespan, which reduced replacement frequency. Charging comparisons showed that Level 2 charging (L2C) typically resulted in lower TCO but higher lifetime CO2e than DC fast charging (DCFC). DCFC costs were heavily influenced by local demand charges, and DCFC emissions were heavily influenced by local grid emissions.

Goodenough, Bryant, Czarnecki, Alexander, Robinette, Darrell, Worm, Jeremy, Subert, David, Kiefer, Dylan, Heath, Matthew, Brunet, Bob, Kisul, Robert, Latendresse, Phil, Westman, John, Black, Andrew

Experimental Investigation and Operating Characteristics of LHR Engine Using Pongamia Pinnata and Azadirachta Indica Biodiesel Blend with Industrial Waste Additive

2025-28-0039

2/7/2025

The huge energy demand and environmental anxiety have focused the interest on alternative fuels to the diesel engine. This suggested the worldwide search for renewable, less pollutant and agricultural-based alternative fuel. Also, attention is given to increasing the efficiency of a conventional diesel engine when running on alternative fuels. Non-edible oil derived from Pongamia pinnata and Azadirachta indica seed oil blends as an alternative fuel have been considered for this study. Using Copper oxide (5% w/w), the two oils were transesterified for 6 hours at a temperature of 75 °C and a methanol to oil ratio of 20:1. The biodiesel samples that were produced underwent FTIR and GC-MS analysis. The results indicated that the FAME conversion for the biodiesel derived from Azadirachta indica and Pongamia pinnata was 99.19% and 97.93%, respectively. Diesel engine combustion components, viz., the piston crown and liner, were coated with Aluminium titanate thermal barrier material. The objective of this study is to replace 10% of diesel fuel by volume with the direct blending of esterified vegetable oils in diesel engine operation. The concept of low heat rejection could improve the decrease in engine performance due to blending. The single-cylinder coated engine characteristics were examined for diesel-biofuel blends, and these results were compared to those of conventional diesel engine fuel operations. The studies study better performance and emission for the coated engine than the conventional engine in both diesel and vegetable oil blends. A significant reduction in hydrocarbon and carbon monoxide emissions was observed for both coated and uncoated engines, but NO emission was increased up to 9% for the coated engine.

R, Suresh, R, Ashwin, Uppuluri, Kiranbabu, T, MohanRaj

Impact of Hydrogen Enrichment on Performance and Emissions Characteristics of a Compression Ignition Engine Operated in Dual Fuel Mode with Karanja Oil Methyl Ester-Tire Pyrolysis Oil Blend

2025-28-0109

2/7/2025

The growing demand for fossil fuels and the search for alternatives have the potential to reduce emissions and enhance energy security. Karanja oil and tire pyrolysis oil (TPO) are identified as promising substitutes. This study examines the performance and emission characteristics of a 5.2 kW, 1500 rpm, four-stroke single-cylinder compression ignition engine. The engine was tested using diesel, the optimal combination of Karanja oil biodiesel (KOME) and TPO (50:50% volume ratio), and this KOME-TPO blend with hydrogen supplied in dual fuel mode at flow rates of 10 lpm, 20 lpm, and 30 lpm, designated as H10, H20, and H30, respectively. The results indicated that BTE for H30 was the highest, reaching 32.21% compared to 30.52% for diesel at 5.2 kW BP. BSEC for H30 was the lowest at 11.18 MJ/kWh, compared to 11.80 MJ/kWh for diesel at the same BP. Emission analysis showed that smoke and HC emissions were significantly lower for hydrogen-enriched blends. At 5.2 kW BP, HC emissions for H30 were 15 ppm compared to 32 ppm for diesel, and smoke emissions were 38% for H30 compared to 67% for diesel. However, NO emissions were higher for hydrogen-enriched blends, with 1535 ppm for H30 compared to 1245 ppm for diesel at 5.2 kW BP. CO emissions were also lower for H30, recorded at 0.07% vol compared to 0.08% vol for diesel. This study demonstrates that blending hydrogen with KOME-TPO can effectively reduce HC and smoke emissions while enhancing BTE and BSEC, although further optimization is needed to manage NOx emissions. These findings suggest that hydrogen-enriched biodiesel blends offer a promising alternative to conventional diesel fuel, supporting sustainable energy use and reduced environmental impact.

Duraisamy, Boopathi, Stanley Martin, Jerome, Chelladorai, Prabhu, Rajendran, Silambarasan, Marutholi, Mubarak, Madheswaran, Dinesh Kumar

Performance and Emission Analysis of a CI Engine Using Various Blends of Diesel and Prosopis Juliflora Seed Oil-Derived Biodiesel

2025-28-0129

2/7/2025

The rising demand for fossil fuels and the exploration of renewable energy sources from plants have gained significant attention due to their role in reducing emissions and enhancing energy security. Prosopis juliflora, abundantly available in India, offers a viable source for biodiesel production. This study investigates the performance and emission characteristics of a 5.2 kW, 1500 rpm, four-stroke single-cylinder compression ignition (CI) engine using blends of diesel, vegetable oil, and biodiesel derived from Prosopis juliflora seeds. The engine was tested with pure diesel, vegetable oil (PJO), biodiesel (B100), and biodiesel-diesel blends at 20%, 40%, 60%, and 80% by volume, designated as B20, B40, B60, and B80, respectively. Key performance metrics, including brake thermal efficiency (BTE) and brake specific energy consumption (BSEC), were measured, along with emissions such as carbon monoxide (CO), smoke, hydrocarbons (HC), and nitrogen oxides (NO). Results indicated that BTE for B20 was comparable to diesel, with values of 30.52% and 30.68%, respectively, at 5.2 kW. The BSEC for B20 was recorded at 11.79 MJ/kWh compared to 11.74 MJ/kWh for diesel. Emission analysis revealed that HC and smoke emissions were lower for all biodiesel blends compared to diesel. At 5.2 kW, HC emissions were 74 ppm for B20 versus 75 ppm for diesel, and smoke emissions were 67.7% for B20 compared to 69.1% for diesel. However, NO and CO emissions were slightly higher for biodiesel blends. This study suggests that Prosopis juliflora-derived biodiesel can effectively reduce HC and smoke emissions while maintaining performance, highlighting B20 as a promising alternative to conventional diesel fuel.

Duraisamy, Boopathi, Stanley Martin, Jerome, Thiyagarajan, Prakash, Rajendran, Silambarasan, Marutholi, Mubarak, John, Godwin

Emission and Economic Characteristics of Diesel/PODE Blended Fuel in Actual Road Driving

2025-01-7115

1/31/2025

Diesel/Polymethoxy Dimethyl Ether (PODE) blend fuel can significantly reduce emissions from diesel engines. However, emission levels often vary due to high transients during real-world driving conditions. To evaluate the emission and economic performance of diesel/PODE blend fuel, this study analyzed the real-world driving behavior of heavy tractors using different blend ratios (0%, 20%, 30%) across urban, suburban, and expressway road sections, in compliance with the national VI emission standard. Based on Vehicle Specific Power (VSP) bins, the study compared carbon monoxide, carbon dioxide, nitrogen oxide, particulate matter, and fuel consumption rates between pure diesel and blended fuels, providing insights into their performance under varying driving conditions. In addition, specific emissions of pollutants, effective fuel consumption, and effective thermal efficiency for urban, suburban, and expressway sections, as well as for the entire test process, are analyzed to quantify the impact of PODE. The results show that adding PODE reduces CO and PN emissions while increasing NOx emissions, with the most significant reductions in CO and PN occurring under high power output conditions. In actual road driving, CO and PN emissions are highest in urban sections, while NOx specific emissions peak in expressway sections. Adding PODE increases the effective fuel consumption rate. At a 30% blending ratio, the average effective thermal efficiency is approximately 2% higher than that of pure diesel, with varying effects observed at a 20% blending ratio across different sections. These findings provide valuable insights for the further development of diesel/PODE blends and their application in heavy-duty engines by manufacturers.

Liu, He, Yang, Yajing, Farooq, Muhammad Shahid, Liu, Shenghua, Wei, Yanju

Effect of Injection Pressure and Equivalent Ratio on Combustion and Emissions of The Ammonia/Diesel Dual Fuel Engine

2025-01-7111

1/31/2025

In the context of low-carbon and zero-carbon development strategies, the transformation and upgrading of the energy structure is an inevitable trend. As a renewable fuel, ammonia has a high energy density. When ammonia is burned alone, the combustion speed is slow. The emissions of nitrogen oxides and unburned ammonia is high. Therefore, a suitable high-reactivity combustion aid fuel is required to improve the combustion characteristics of ammonia. Based on this background, this study converted a six-cylinder engine into a single-cylinder ammonia/diesel dual-fuel system, with diesel fuel as the base and a certain percentage of ammonia blended in. The impact of varying the injection pressure and equivalence ratio on engine combustion and emissions was examined. The results demonstrate that an appropriate increase in injection pressure can promote fuel-gas mixing and increase the indicated thermal efficiency (ITE). With regard to emissions, an increase in injection pressure has been observed to reduce unburned ammonia emissions and the equivalent greenhouse gases. An increase in the equivalence ratio results in the suppression of combustion within the engine cylinder, accompanied by a reduction in the peak of pressure curve and a delay in the phase corresponding to the peak. An increase in the equivalence ratio results in a longer ignition delay time and combustion duration. Indicated thermal efficiency and ammonia combustion efficiency show a tendency to increase first and then decrease. With regard to emissions, the combustion process is adversely affected by an increase in the equivalence ratio. It leads to an increase in total hydrocarbon and CO emissions. Unburned ammonia decreases. NOx emissions increase first and then decreases influenced by cylinder temperature.

Wang, Hu, Lv, Zhijie, Zhang, Shouzhen, Wang, Mingda, Yang, Rui, Yao, Mingfa

Effects of Injection Parameters On the Evaporation, Mixing, Combustion and Emission Characteristics of a Spark Ignition Methanol Engine

2025-01-7119

1/31/2025

The combustion performance test under different injection parameters was carried out on an inline 6-cylinder spark-ignition (SI) methanol engine, and the influence mechanism of injection parameters on methanol evaporation, mixing, combustion and emission was revealed through simulation. The results indicate that compared to the low-flow nozzle scheme (14*D0.26), when adopting the high-flow nozzle scheme (16*D0.30), the injection duration is shorter. The evaporation rate of methanol in the intake port is increased, the amount of methanol droplets and wall-attached liquid film in the cylinder is reduced, and the temperature in the cylinder is elevated. Moreover, the changes are more significant under high-load operating conditions. The change in the methanol charge rate during the intake process leads to a slightly higher inhomogeneity of the in-cylinder mixture. The relatively high temperature in the cylinder and the appropriate increase in the mixture concentration on the exhaust side are conducive to accelerating the combustion in the early and middle stages. The CA0-10 is shortened, and the CA50 is advanced, which improves the combustion performance under different loads. The brake thermal efficiency (BTE) is increased by 0.53% to 1.27%. Moreover, as the load increases, the increase in BTE becomes more significant. In terms of emission performance, adopting the 16*D0.26 nozzle scheme reduces the amount of methanol in the piston crevice, weakens the crevice effect, and reduces HC emissions by 56.3% to 68.5% under different loads. However, the relatively rich mixture in the combustion chamber on the exhaust side leads to an increase in CO emissions. In conclusion, adopting the high-flow nozzle scheme can lead to a relatively small increase in CO emissions while significantly reducing HC emissions, reducing the liquid film in the cylinder, and obtaining a relatively high BTE. Moreover, it is possible to adjust the injection phase more flexibly under high-load operating conditions.

Zhang, Zhi, Liu, Haifeng, Li, Yongzhi, Chang, Weide, Shu, Zanqiao, Ju, Chengyuan, Ratlamwala, Tahir Abdul Hussain, Yao, Mingfa

Exploring the Future of Sustainable Fuels: Experimental and Predictive Insights on Engine Performance and Emissions Using Algae Biodiesel Blends

2024-01-5250

1/28/2025

This study investigates the potential of biodiesel derived from Azolla algae as an alternative fuel for conventional diesel. The performance and emissions characteristics of various biodiesel blends were evaluated experimentally. The physicochemical properties of pure diesel (D100), and blends with Azolla biodiesel at 5% (BD5), 10% (BD10), 15% (BD15), 20% (BD20), and 100% (B100) were analyzed. It is observed that the amount of fuel consumed is higher at higher loads when fuel is blended with biodiesels. Hydrocarbon emissions were reduced with biodiesel blends at full load and the reduction is higher with increase in blend concentration. A significant difference of 85 ppm NOx was observed between BD20 and D100 at full load. CO emissions decreased with higher biodiesel concentrations, with BD20 resulted less CO emissions than D100, making BD20 a more environmentally viable fuel. Artificial neural networks (ANN) were employed for predictive modeling, achieving approximately 95% accuracy. Pearson’s correlation coefficients (0.9770 to 1.000) and root mean square errors (0.01048 to 0.0804) for all the output parameters indicate the model’s high efficiency and accuracy, closely matching experimental values.

Senthilkumar, D., Murugesan, Sivanesan, Bhadrinath, P., Shamitha, G., Adityasree, R.

Performance Analysis of Graphene-Coated Heat Pipe Heat Exchangers for Automobile Exhaust Cooling and Purification

2025-01-5006

1/23/2025

This research investigates the development of a heat pipe heat exchanger coated with graphene for cooling and purification of automobile exhausts. The heat exchanger directly affects the performance of the engine because proper heat dissipation and transfer can improve engine performance, reduce fuel consumption, and decrease the emission. Moreover, this effect is much more noticeable on coated heat pipes because of the enhanced thermal conductivity and mechanical properties of the graphene films. A heat null emitted by internal combustion engines was used in the experimental setup to test the thermal performance, cooling efficiency, and purification efficiency of the newly designed in-house exhaust simulation system where the new heat pipes were inserted. The results of the experiment show that the heat pipes have very high thermal performance as the efficiency of the heat pipes was calculated to be around 85%. Furthermore, the temperature decrease over the surfaces of the heat exchanger was measured at 350°C, which means 70% of the exhaust gas temperature was cooled. The purification efficiency of the heat pipes was approximately 70% for nitrogen oxides, particulate matter, carbon monoxide, and hydrocarbons, all which are harmful pollutants produced by internal combustion engines. Since these substances were reduced by about 70%, the results and the use of the graphene coats demonstrate the effectiveness and feasibility of such a heat pipe for emission reduction. Consequently, a graphene-coated heat pipe heat exchanger is recognized as a highly effective device for enhancing engine performance, reducing fuel consumption, and promoting more efficient transportation with lower emissions.

Karthigairajan, M., Seeniappan, Kaliappan, Balaji, N., Natrayan, L., Sheik, Salman Basha, Ravi, D.

Combustion of Hydrated Ethanol and Gasoline RON95 Ultra-High Pressure Direct Injection in Optical Access SI Engine

2024-36-0152

12/20/2024

High and ultra-high pressure direct injection (UHPDI) can enhance efficiency gains with flex-fuel engines operating on ethanol, gasoline, or their mixtures. This application aims to increase the engine’s compression ratio (CR), which uses low CR for gasoline due to the knocking phenomenon. This type of technology, involving injection pressures above 1000 bar, permits late fuel injection during the compression phase, preventing auto-ignition and allowing for higher compression ratios. UHPDI generates a highly turbulent spray with significant momentum, improving air-fuel mix preparation, and combustion, resulting in even greater benefits while minimizing particulate matter emissions. This study aims to develop ultra-high-pressure injection systems using gasoline RON95 and hydrated ethanol in a single-cylinder engine with optical access. Experimental tests will be conducted in an optically accessible spark ignition research engine, employing thermodynamic, optical, and emission results. In the present work, the spark plug was placed in the lateral, so the ignition and part of the flame propagate close to the cylinder wall, and it will exchange with greater heat to the wall than the flame portions that propagate towards the central region of the chamber. Therefore, the flame front propagates at different speeds; causing stretching and wrinkling that can lead to instabilities and cyclic variability. To address this issue, this work presents experimental results that, through the images post-processing of flames under a SOI (start of injection) sweep strategy in the compression phase to closer of the spark ignition, associating the non-uniform propagation velocity of the flame with the cyclic variability. The fuel impingement on the wall was critical in this scenario, which led to higher soot concentrations and diffusive flames for gasoline. It was found that the injection close to the spark plug enhances the heat release, and combustion stability, decreasing soot emissions. Total unburned hydrocarbons (THC), Nitrous oxides (NOx), aldehydes, and soot emissions decreased for end of injection events closer to the spark ignition. This trend opposes the increase observed in CO emissions.

Malheiro de Oliveira, Enrico R., Mendoza, Alexander Penaranda, Martelli, Andre Luiz, Dias, Fábio J., Weissinger, Frederico F., dos Santos, Leila Ribeiro, Lacava, Pedro Teixeira

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