This study presents detailed experimental investigations of the impact of methanol-gasoline blends on regulated and unregulated gaseous species, particulate characteristics and soot morphology. The test fuels included methanol blends, namely, M15 (15% methanol and 85% gasoline by volume) and M20 (20% methanol and 80% gasoline by volume), along with baseline gasoline (G100). In this study, a single-cylinder, port-fuel-injection, spark-ignition genset engine was operated at 3300 rpm under varying load conditions. Regulated emissions were measured using a raw exhaust gas analyser, while unregulated species were quantified using Fourier-transform infrared spectroscopy. Particle size distribution was analysed using an engine exhaust particle sizer, and soot morphology was examined using field-emission scanning electron microscopy. The results show that methanol blends reduced CO and NO emissions, while HC emissions increased slightly. Most unregulated emissions, including formaldehyde, methane, acetylene, ethylene, benzene, formic acid, and n-octane, were lower with methanol blends. At the same time, a few species remained comparable to baseline gasoline under certain engine operating conditions. In terms of particulate emissions, M15 and M20 demonstrated lower particle number, mass, and surface area distributions, indicating suppressed soot formation. Morphology analysis further revealed that methanol blends produced smaller, less agglomerated, and structurally refined soot particles compared to baseline gasoline.

Methanol is a potential alternative fuel that reduces particulate emissions in the engine exhaust. This experimental study compared particulate matter (PM) emissions from a dual-fuelled genset engine and a baseline diesel-fuelled genset engine. In this experimental investigation, different fractions of methanol were used to displace mineral diesel on an energy basis in the dual-fuel combustion mode. The experiments were conducted using the Genset engine at a fixed speed of 1500 rpm and varying engine loads. Results showed that PM emissions were lower for dual-fuel combustion than for baseline diesel combustion. The particulate number-size distribution was higher in baseline diesel combustion. One key observation of this study was lower emissions of nanoparticles, nucleation-mode particles, and accumulation-mode particles from the dual-fuel engine compared to the baseline diesel engine. PM morphology investigations revealed that the baseline diesel engine emitted more agglomerated soot. The concentrations of trace metals in the PM were nearly similar for dual-fuel and baseline diesel combustion, which was another important observation of this study. The parametric characterisation of engine exhaust emissions showed the elimination of PM-NOx trade-off in dual-fuel mode. The maximum reductions in NOx, particulate mass, and particulate number were ∼79%, ∼62%, and ∼84%, respectively, for the methanol-diesel-fueled engine compared to baseline diesel. Soot reduction was ∼89% for the methanol-diesel-fueled engine. Soot, particulate mass, particulate number, and NOx emissions were lower from the dual-fuel engine, and methanol emerged as a superior alternative fuel for compression-ignition engines.

Many alternative solutions have emerged in the automotive and transportation sectors to address the need for sustainable solutions. This development has significantly impacted India. Policies and initiatives have been implemented to ensure energy security and achieve sustainability goals. To this end, ethanol-blended petrol (EBP), compressed biogas (CBG), compressed natural gas (CNG), and battery-electric vehicles (BEVs) are being promoted in India. This study aims to provide a comprehensive assessment of technologies through a cradle-to-grave (CTG) approach, which covers all stages, including vehicle manufacturing, fuel production, operation, and lifetime emissions. This study also presents a techno-economic assessment (TEA) for foreign-brand multi-utility vehicles (MUVs) with engine capacities ranging from 1.0 to 2.4 L or similar weight ranges for parity. A sensitivity analysis of various scenarios was also conducted to gain a complete understanding. The well-to-pump (WTP) emissions of a single CBG-IC engine vehicle (-70 g CO2-eq/km) offsets the emissions of two E10-IC engine vehicles (30 g CO2-eq/km) and represent a critical step towards achieving net-zero. Considering a vehicle life-span of 200,000 km in 10 years, the Greenhouse gas (GHG) emissions from CBG-IC engine vehicles (ICEVs) were 23 gCO2-eq/km, lower than BEV, E10-ICEV and CNG-ICEV by 87, 85 and 88 %, respectively. Economically, CBG-ICEV exhibited the lowest Total Cost of Ownership (TCO) among all powertrain options considered in this study.

This study investigates global entrainment and spatially resolved liquid-phase mixture fraction distribution in dense non-evaporative liquid sprays. The measurements are done using two techniques: diffused back illumination to study macroscopic spray development and global gas entrainment, and one-phase structured illumination planar imaging with laser-induced fluorescence to suppress multiple scattering and obtain a corrected spatial distribution of mixture fraction. Diesel and naphtha are selected as liquids to enable the study of liquid property effects. The effects of injection pressure (500-1000 bars) and ambient pressure (10-40 bars) were also studied. Penetration length and spray cone angle are modeled using existing semi-empirical models. Global entrainment scaled linearly with a non-dimensional axial distance incorporating liquid and ambient density. The centerline mixture fraction profiles collapse across all operating conditions, following an inverse-power-law relation with the non-dimensional axial distance. The radial mixture fraction distribution consistently followed a Gaussian distribution across all operating conditions. These results provide experimentally grounded reduced-order correlations linking spray morphology, operating conditions, liquid properties, and the local mixture fraction distribution, suitable for the validation and development of dense spray models.

With gasoline direct injection, fuel injection parameters should be optimally tuned since they are critical in determining the fuel-air mixing and the charge quality during combustion. Fuel injection timing and pressure are two critical parameters examined in this study to investigate their combined impact on fuel-air mixture characteristics. The study aims to investigate the effect of these fuel injection parameters on varying spark timings and engine speeds. The results were analyzed for the engine's combustion, performance, and emissions characteristics. The experiments were conducted on a 500-cc, single-cylinder, wall-guided gasoline direct injection engine. All the tests were performed with a fixed fuel injection quantity of similar to 22 mg. Three fuel injection pressures of 100, 150, and 200 bar, and three fuel injection timings, indicating different stages of the intake stroke, were considered for the experiments, namely early intake (315 deg bTDC), mid-intake (270 deg bTDC), and late-intake (225 deg bTDC) injection timing. For an early fuel injection timing (315 deg bTDC), the degree of complete combustion was maximized, resulting in the shortest combustion duration. A fuel injection pressure of 100 bar was found to be suitable for early injection at all engine speeds. Mid-intake injection timing (270 deg bTDC) showed deteriorated combustion at all engine speeds and injection pressures. Late injection timing (225 deg bTDC) resulted in the lowest ignition delay and early pressure rise due to spray-generated turbulence. Higher engine speeds of 1500 and 2000 rpm, along with higher fuel injection pressure, enhanced the combustion for late injection; however, cyclic variations increased. Hydrocarbons and carbon monoxide emissions also increased with late fuel injection timing. Spark advance of similar to 28 deg bTDC showed the maximum indicated mean effective pressure with superior combustion stability. Overall, a fuel injection timing of 315 deg bTDC with 100 bar fuel injection pressure resulted in the highest thermal efficiency and lower carbon monoxide and hydrocarbon emissions at all engine speeds. However, nitric oxide emissions were significantly higher for these parameters.

Diesel engines are highly efficient and proven workshorse for heavy-duty automotive applications globally. However, they face challenges in controlling particulate matter emissions. Gasoline compression ignition technology simultaneously controls engine-out particulate matter and nitrogen oxide emissions. This study employed gasoline compression ignition technology using a 70:30 % (v/v) gasoline-diesel blend (G70) as a low-reactivity test fuel and an optimised fuel injection strategy. An open electronic control unit operated the engine in gasoline compression ignition mode. Tests were performed at different engine speeds (1500-2500 rev/min) and loads (5 and 10-bar brake mean effective pressure). The engine was also operated using a stock electronic control unit in baseline conventional diesel combustion mode. Particle numbers and soot mass were measured for all test cases. Soot morphology and nano-structures were analysed using scanning and transmission electron microscopy. Raman spectroscopy was used to investigate the soot particle's graphene layer. Trace metal elements and polycyclic aromatic hydrocarbons in the soot were assessed using inductively coupled plasma-mass spectrometry and gas chromatography-mass spectrometry. The results concluded that gasoline compression ignition emitted a lower PM mass than the baseline diesel. Diesel soot showed larger primary particles and compact aggregates, whereas chain-like soot aggregates were seen in the G70 soot. The primary particle diameter increased with engine speed but decreased with engine load. Twenty-seven trace elements and 13 polycyclic aromatic hydrocarbons were detected in the soot sample, accounting for similar to 6.64-8.85 % (w/w) of the particulate matter mass.

Dimethyl ether (DME) is an excellent alternative fuel for compression ignition (CI) engines, reducing dependency on fossil fuels and improving IC engine performance with minimal exhaust emissions. DME’s physical and chemical properties differ significantly from those of mineral diesel. The lower viscosity and lubricity of DME result in issues such as frequent fuel leakages and increased engine wear. Understanding air–fuel mixture formation is crucial for exploring the physics behind the advantages offered by DME combustion. Therefore, a comprehensive understanding of spray development, fuel atomisation, combustion, emissions, and performance characteristics must be investigated under engine-like conditions. Optimising various components and operating parameters is also required for improving the engine performance. However, utilising DME as fuel for the engine requires significant modifications to the engine parts, and tuning them to optimum conditions is rather challenging. Using numerical modelling techniques offers advantages over the experiments for studying combustion of DME-fuelled engines. This review article provides a brief discussion of the thermodynamic properties of DME, and highlighting their importance in accurately predicting performance and emissions through simulation studies. Detailed chemical kinetic reactions of DME combustion under conditions similar to those in a real engine are discussed to understand the formation of combustion and emission species. The optimisation of engine component design and fuel injection system for DME is also studied using modelling and simulation tools. The 1D models of diesel engines are successfully applied to DME to predict spray penetration, spray area, and injection rate, as well as to establish a design rule for the optimum injection angle at advanced fuel injection timings. The optimum maximum in-cylinder temperature range for low NOx, CO and HC was 2100 to 2300 K.

Internal combustion (IC) engines have been the heart of the transport sector and many stationary applications for over a century. However, they suffer from carcinogenic emissions, particularly particulate matter, which adversely affect the human health and the environment. Worldwide emission norms are increasingly becoming more and more stringent to control the on-road PM emissions. Over the past decades, our understanding of particulate formation in the engines has helped reduce such emissions to a great extent to comply with the prevailing emission norms. The ever-stringent emission level warrants new measurement and analytical methods addressing measurement sensitivity and specificity issues. This review paper starts with a detailed analysis of particulate formation phenomena to better understand the effect of different parameters, including fuel compositions and structure. Particulate matter composition and structure are discussed in this paper under the following sections. Finally, critical insights have been provided on particulate sampling and characterisation techniques, methodology, and the respective instruments to address the current and future challenges for PM emission quantification and characterisation.

In recent years, the global imperative to mitigate emissions from the transportation sector has intensified, driven by escalating concerns regarding air quality degradation and climate change. In addition to the other pollutants released by vehicles, particulate matter (PM) is a significant public health concern. With over 150 years of IC engine development, introducing low-carbon fuels such as methanol has unlocked previously unexplored potential. Methanol is a carbon-neutral, and oxygenated fuel. The absence of a direct carbon-carbon bond significantly reduces the PM emissions. In this study, methanol and baseline diesel are compared experimentally in a specifically developed single-cylinder CI engine to evaluate the engine emissions based on particulate number-size, surface-area-size, and mass-size distributions. Furthermore, total particulate number (TPN), total particulate mass (TPM), particulate count mean diameter (CMD), particulate morphology, and trace metal analysis were performed. The developed methanol-fueled CI engine emitted lower nano-particles (NP), nucleation mode particles (NMP), and accumulation mode particles (AMP), which were attributed to lower CMD and total PM mass emissions. Soot Morphology showed the presence of larger particulates from diesel and nearly negligible particulates from methanol-fuelled engine. Trace metal analysis of the particulates showed higher levels of Na, Mg, Al, K, and Ca from methanol-fueled engines than baseline diesel-fueled engines. The experimental evidence in this research concludes that methanol can significantly reduce PM emissions from CI engines.

Spark-ignition engines fuelled by Compressed Natural Gas (CNG) are popular for low engine-out emissions and high fuel economy. However, it suffers from reduced maximum power output due to a loss in volumetric efficiency. Introducing CNG in the port in dual-fuel mode in a gasoline direct injection (GDI) engine can harness the advantage of maintaining the engine power output while reducing carbon emissions. This study investigated three different premix ratios of CNG (25 %, 50 %, and 75 %) based on energy supply at different engine load and speed conditions to understand the engine characteristics in dual-fuel mode. The remaining combustion energy was supplied by direct injection of gasoline. The results were examined through a detailed analysis of combustion, performance, and emissions characteristics for the dual-fuel engine operations. They were compared with baseline GDI and CNG-only port-injection operations. The regression analysis was also performed to investigate the influence of control parameters on engine characteristics. The addition of CNG showed different effects on gasoline combustion, depending on the engine's torque output. Under low engine load conditions, improvement in CNG/gasoline dual-fuel combustion was observed with an increase in CNG mass flow rate, mainly characterised by the early combustion stage. However, in the full-load regime, the later combustion phase was delayed, thereby extending the combustion duration in CNG/gasoline dual-fuel combustion. Experimental ignition delay and combustion duration results were predicted well with the correlations provided in the literature. CNG premixing beyond 50 % enhanced the brake thermal efficiency of the engine. Significant reductions in carbon-based emissions, including carbon monoxide (CO), hydrocarbons (HC), and smoke opacity, were observed with a 50 % CNG ratio (C50G50). The regression analysis revealed that ignition delay had a significant influence on HC emissions, while the C/H ratio primarily affected smoke emissions. The oxides of nitrogen (NOx) emissions did not show considerable variations compared to baseline GDI, except at low load and speed conditions. Overall, C50G50 demonstrated optimal results in maintaining engine performance while achieving significant emissions reduction across all engine operating conditions.

The physicochemical properties of test fuels, ambient conditions, and fuel injection strategies strongly influence the spray characteristics. This study experimentally investigated the macroscopic spray characteristics of diethyl ether-diesel blend under a double-split injection strategy. Diesel-diethyl ether blend (DEE40, 40 % diethyl ether in diesel, v/v) spray penetrated faster in the initial stage of spray evolution and exhibited a higher spray penetration rate. However, the liquid penetration length of the spray was comparable to or lower in the later stages of the spray evolution. Diethyl ether spray had a lower density. Hence, a higher injection velocity for DEE40 spray was observed at the start of the injection. However, far-field velocity completely depends on spray droplets' further breakup and evaporation. Diesel-diethyl ether blends exhibited stronger cavitation inside the injector, improving the spray atomisation compared to baseline diesel. In the far field, the higher vapour pressure of diethyl ether enhanced fuel droplet evaporation with the spray evolution. The liquid spray area also showed similar trends to the liquid penetration length for both test fuels. DEE40 spray not only showed higher axial penetration but also radial spread. However, rapid atomisation and evaporation of DEE40 showed a sudden reduction in liquid penetration length and spray area. The fuel injection pressure of 1200 bar had a higher liquid penetration length than 700 bar for both test fuels due to higher spray momentum. A split injection with a dwell time of 0.15 ms showed higher spray penetration than a single injection case. The immediate push from the second injection pulse accelerated the momentum of the entire fuel spray. In addition, too short dwell time promoted droplet collision and coalescence, increasing the liquid penetration length. The longer dwell time of 0.45 ms and DEE40 spray showed the formation of finer droplets and a lower liquid spray area due to the superior evaporation of these finer droplets.

Conventional diesel-fuelled vehicles have been widely used for decades in the transport sector. The exhaustible nature of crude oil-based fuels and the irreparable damage caused by fossil-fueled powered vehicles have led to the urgency of adopting cleaner engine technologies and green biofuels. A four-carbon chain alcohol, namely butanol (C4H10O), is an emerging fuel that can partially replace baseline diesel by forming butanol-diesel blends. Butanol is completely soluble in diesel, thus eliminating the need for a co-solvent, which is not the case for methanol and ethanol. This experimental study aims to investigate the combustion, performance, emission characteristics, and cyclic variations for three different butanol-diesel blends. Three n-butanol-diesel blended fuels (But10, But20, But30) were prepared, and the baseline diesel was used as the reference fuel. At low loads, But20 (1.67 % at 1.14 and 3.5 % at 2.28 bar BMEP) and But30 (7.8 % at 1.14 and 8.5 % at 2.28 bar BMEP) exhibited higher brake thermal efficiency, but But10 (7.8 % at 1.14 and 1.17 % at 2.28 bar BMEP) exhibited lower brake thermal efficiency than the baseline diesel. All butanol-diesel blends exhibited higher brake thermal efficiency than the baseline diesel at the rest of the test loads. At 5.71 bar BMEP, similar to 13.6 % higher brake thermal efficiency was observed for But30 than baseline diesel. The exhaust gas temperature of butanol-diesel blends was more than the baseline diesel for all engine test loads. At 4.57 bar BMEP, the highest (similar to 13.47 %) exhaust temperature was observed for But20 than for the baseline diesel. However, the exhaust gas temperature decreased with the increase in the percentage of butanol in the butanol-diesel blends. Also, butanol-diesel blends consumed comparable and lower energy to produce diesel-equivalent torque/ power output at low and high loads, respectively. Butanol-diesel-fueled engines generated higher in-cylinder pressure and heat release rates than baseline diesel. A higher rate of pressure rise than baseline diesel was observed using butanol-diesel blends. The butanol-diesel blends showed lower cyclic variations than baseline diesel. Compared to baseline diesel, CO emissions were reduced for But10 (similar to 63.2 % at 5.71 bar BMEP) and But30 (similar to 58.4 % at 5.71 bar BMEP). Nitrogen Oxides were higher at low loads, comparable at mid loads, and lower at high loads for butanol-diesel blends than baseline diesel. Smoke opacity was lower for butanol-diesel blends than baseline diesel. But10 showed higher smoke opacity reduction compared to baseline diesel. However, hydrocarbon emissions were significantly higher for butanol-diesel blends than baseline diesel.

Recent advances in the application of zero- or low-carbon fuels, e.g., hydrogen and methane, for internal combustion engines have achieved carbon reduction and decarbonization, making them environmentally friendly alternatives. The macroscopic and microscopic jet and combustion characteristics could make practical combustion devices for hydrogen-enriched natural gas possible. However, experimental research on this topic has been rare and is critical for developing and validating numerical models. Therefore, a proper orthogonal decomposition (POD) methodology was developed: deep learning based on time-series prediction—recurrent neural network, long short-term memory (LSTM), and gated recurrent unit (GRU); and hybrid models—convolutional neural network (CNN)-LSTM, and CNN-GRU. It enhances prediction accuracy, making prediction possible under different working conditions. The flow field prediction performance was compared with validated numerical simulation data. A numerical simulation was performed using 0.8-MPa initial injection pressure, 300- and 353-K initial ambient temperatures, 0.1-, 0.4-, and 0.8-MPa pressures, and 10HCNG, 20HCNG, and 40HCNG hydrogen-enriched natural gases to investigate the dynamic flow field. The CNN-GRU model predicted the velocity and pressure fields excellently, while LSTM exhibited in predicting the turbulence kinetic energy field. However, the overall deviation of CNN-LSTM network predictions for turbulence kinetic energy flow field values tended to increase. The performance of POD, time-series prediction, and hybrid prediction models in reconstructing flow field dynamics is described in detail. The results show that hybrid prediction models are suitable for constructing pressure, velocity, and turbulence kinetic energy to reconstruct jet flow dynamics under various working conditions.

Abstract Methanol has attracted the attention of policymakers and researchers looking for a variety of electro-fuels (E-Fuels) to displace conventional fuels. Vehicle manufacturers have assessed the technical feasibility of operating methanol-fueled engines with minor modifications. This investigation evaluated a port-fuel-injected spark ignition engine with M15 (15% v/v Methanol, 3% v/v Isopropyl alcohol, and 82% v/v Gasoline). A comparative analysis of engine performance, combustion, and raw engine emissions was performed for M0 and M15 in a modern Bharat Stage-VI (BS-VI) emission-compliant engine. Experimental results revealed that the overall in-cylinder pressure of M15 improved compared to M0. Also, the heat release rate and the rate of pressure rise were comparable to those of M0. The crank angle positions at which the maximum in-cylinder pressure, rate of pressure rise, and heat release rate occurred were similar for M15 with respect to M0 across all test speeds. The start of combustion and combustion phasing showed mixed trends, i.e., advanced or retarded, depending on engine speed. Combustion duration extended for M15 fueling vis-à-vis M0. Exhaust gas temperature showed a random trend for M15 compared to M0. M15 exhibited a higher brake thermal efficiency than M0. The M15-fueled engine emitted lower hydrocarbon emissions than the M0 engine. Carbon monoxide decreased for M15 vis-à-vis baseline gasoline. Nitric oxide decreased and increased during low-medium and high engine speeds, respectively, for M15 with respect to M0. M15 emitted higher formaldehyde, isocyanic acid, and 1,3-butadiene than M0. Other unregulated species, such as propene, ethylene, acetylene, benzene, toluene, ethane, and methane, showed a mixed trend for M15 compared to M0. The M15-fueled engine emitted concentrations of sulfur dioxide similar to those of M0.

Abstract The advanced compression ignition and lean-burn capabilities of a gasoline compression ignition (GCI) engine result in higher thermal efficiency, making it a promising choice for next-generation vehicles. Studies show that gasoline-diesel blend fuelled GCI engines produce lower nitrogen oxides and soot emissions. There is significant interest in the automotive industry in using GCI combustion engines for heavy-duty vehicles; however, this combustion mode needs to be better understood through experimental and simulation studies. Simulation helps understand the in-cylinder fluid flow and combustion dynamics of experimental results. This work aims to model GCI combustion over a range of engine speeds (1500–2500 rpm) and to validate the model against experimental results at a 5-bar brake mean effective pressure (BMEP) engine load. A triple-injection strategy, exhaust gas recirculation (EGR), and preheated intake air were employed to achieve GCI combustion in the test engine. The effect of a narrow-angle injector was investigated to control the wall impingement of the test fuel. The simulation results revealed that the fuel parcels from pilot injections caused wall wetting, while others were trapped in the squish regions. Most fuel droplets evaporated before the combustion onset, supporting the concept of partially premixed combustion. The narrow injection angle of the fuel spray directed more fuel into the piston bowl, reducing combustion efficiency.

Rapidly depleting petroleum reserves are a significant concern for the energy sector, especially transportation, which primarily relies on petroleum-derived fuels. Alternative fuels are one solution to address these issues in the transportation sector. Primary alcohols (such as methanol, ethanol, and butanol) are renewable and potential alternative fuels for internal combustion (IC) engines. Methanol and ethanol, which have a higher octane number than gasoline, can be used directly in the spark-ignited (SI) engines. However, alcohol-fueled compression ignition (CI) engines require modifications to the engine hardware and advanced combustion technology. Alcohol-fueled engines also reduce the particulate matter (PM) and nitrogen oxide (NOx) emissions. This review paper discusses the production and properties of various alcohols, as well as the technologies available for utilising primary alcohols as fuels in the transportation sector. The combustion, performance, and emission characterisation of alcohol-fueled engines are discussed. PM emissions and their health and environmental impacts are also included in this review paper. Finally, the cost estimation of different alcohol applications in SI and CI engines is discussed, followed by an overview of the way forward for alcohol as a future transportation fuel and its commercialisation potential.

Predicting the transient penetration of the liquid phase is critical for optimising fuel-air mixing and preventing wall wetting in modern combustion systems. This study performs a comprehensive meta-analysis of 17 test fuels—including diesel, n-dodecane, and n-heptane—to evaluate the universality of spray correlations published between 1998 and 2025. We demonstrate that foundational heat-transfer-based models (the Higgins-Siebers lineage), when refined with specific thermodynamic adjustments, provide the most robust fit across all fuels and conditions to date. The equation avoids the tendency to overfit or to produce dimensionally non-homogeneous equations that are valid only for specific experiments.A core contribution of this work is the development of a generalised transient model for liquid-phase penetration (S_L). This model tracks the liquid phase as it follows the vapour-phase penetration through distinct regimes: growth is governed by the spray breakup time (t_b), and a transition to a steady-state liquid length (LL) occurs. We propose a unifying expression, S_L=d_e∙max(8, min(40, LL⁄d_e, S_L⁄d_e)), which effectively bounds penetration between the breakup length and a characteristic maximum of ∼ 40 equivalent diameters. The model is shown to be valid for almost all known test fuels under typical operating conditions, with a predictive accuracy of ±16%, making it a reliable tool for engine designers. This study reconciles the scatter in the historical literature by quantitatively comparing diagnostic discrepancies among Mie scattering, DBI, shadowgraphy, and X-ray radiography. We map the parametric sensitivities of the limiting liquid length, illustrating how fuel properties (boiling point, latent heat, and specific heat) and ambient conditions (density and temperature) shift the evaporation boundaries. This work provides a definitive framework for standardising transient liquid spray behaviour, suitable for both analytical design and CFD validation.

The Indian automobile market faces challenges in adopting energy-efficient and cleaner technologies. A scientific, data-based approach is essential to capture end users’ real perceptions of the overall benefits of energy, environment, and economic audit. A comprehensive evaluation of policies on electricity grid decarbonisation and the promotion of vehicle technology via financial subsidies is essential to track the right direction for sustainable technology development. This study uses lifecycle assessment and the total cost of ownership method to evaluate the current policies and technologies development for the Indian vehicle market. The lifecycle analysis compared energy and fossil fuel consumption, toxic emissions, and the costs of different vehicle technologies and renewable electricity generation targets for the Indian market. This study conducts various sensitivity analyses to understand the effect of renewable electricity generation sources. A sensitivity analysis of the total cost of ownership for vehicles was conducted across parameters, including battery replacement prices, annual distance travelled, initial purchase price, and energy prices. During the lifecycle inventory analysis, it was found that the net electricity generated in Pan-India differs significantly from the total installed capacity. The targeted share of renewable electricity generation by 2030 may not be achieved at the current rate of renewable electricity installations. Over the entire lifecycle of battery electric vehicles, human toxic and ecotoxic emissions, such as particulate matter, sulphur, and nitrogen oxide, were higher than those of comparable hybrid electric and internal combustion engine vehicles. Analysis showed that the most economical powertrain options were internal combustion engines, followed by hybrid vehicles. An increased share of renewable energy would help reduce emissions from battery-electric vehicles. The results suggest that HEVs are also a suitable solution for the light motor vehicle sector in terms of energy and emissions. Moreover, as the policy shifts from the promotional to the mature phase, the cost to the end user could be lower for hybrid powertrains. The study results provide recommendations to policymakers to achieve the energy and emissions targets listed in the policy recommendation table.

Globally, regulatory bodies strictly govern atmospheric pollutants to achieve net-zero emissions. Electrofuels (Efuels), such as methanol, dimethyl ether, hydrogen, and ammonia, are gaining attention from both the non-road and on-road segments. Developing and developed countries are betting on methanol to achieve a net-zero future. Methanol is primarily recommended as fuel for spark-ignition engines but is also being explored for use in compression-ignition engines. Phase separation of methanol in diesel creates hurdles for using methanol-diesel blends in commercial vehicles. It can be resolved by finding an appropriate co-solvent. Due to their phasestability-enhancing properties, 1-dodecanol and iso-butanol were unique solutions for providing stable methanol-diesel blends. Combining methanol-diesel-iso-butanol for lower methanol concentration and methanoldiesel-iso-butanol-1-dodecanol for higher methanol concentration offers a stable and homogeneous fuel mixture. This study evaluated the engine performance, emissions, and combustion characteristics using MBD5 (5 % (v/v) methanol, 5 % (v/v) iso-butanol, and 90 % (v/v) diesel) and MBD10 (10 % (v/v) methanol, 6 % (v/v) iso-butanol and 2.5 % (v/v) 1-dodecanol, 81.5 % (v/v) diesel) at constant engine speeds of 1200 rpm and varying load conditions (no load, 1.14, 2.28, 3.43, 4.57 and 5.71 bar BMEP). The engine's "cyclic" variations were assessed and compared with the baseline diesel. MBD5 and MBD10 produced higher in-cylinder pressure than baseline diesel at tested engine loads. MBD exhibited a similar heat release rate to diesel at low and mid-load conditions. MBD5 and MBD10 exhibited higher heat release rates at higher loads than baseline diesel. The coefficient of variations of IMEP was significantly lower for methanol-diesel blends at low and mid loads. Overall, MBD5 and MBD10 exhibited lower and comparable cyclic variations to baseline diesel. Brake-specific energy consumption was either comparable or slightly lower for methanol-diesel blends with respect to baseline diesel at different engine loads. MBD5 and MBD10 produced slightly higher hydrocarbons, comparable nitrogen oxides, and lower carbon monoxide mass emissions than baseline diesel.

Primary alcohols are being advocated for decarbonising transport by policymakers worldwide. The alcohol family comprises many primary alcohols, such as methanol, ethanol, and butanol, which could be blended with conventional diesel for powering compression ignition engines without substantial hardware modifications. Ethanol-diesel blends can be a viable fuel option. This study prepared stable ethanol-diesel blends (EBD5, EBD10) using novel co-solvents: iso-butanol and 1-dodecanol. Comparative analysis indicated that ethanol-diesel blends improved engine performance, combustion, and emission characteristics, especially at higher loads. EBD5 emerged as the optimum fuel blend in reducing cyclic variations vis-a`-vis baseline diesel and EBD10. This study demonstrated that ethanol-diesel blends were stabilised using iso-butanol and 1-dodecanol as co-solvents, improving the engines' performance in off-road applications.