Particulates, unregulated and regulated emissions and catalytic converter efficiency evaluation of methanol (M15) fuelled BS-VI compliant light-duty spark-ignition engine.

Methanol adaptation in the transport sector is being encouraged worldwide. Methanol, a high-octane fuel, is emerging as a strong fuel candidate for powering spark-ignition (SI) engines and it can be indigenously produced from low-value agricultural biomass waste and high-ash coal. This study investigated particulates and unregulated and regulated emissions from M15 (15 % v/v methanol, 82 % v/v gasoline, 3 % v/v propanol) fueled Bharat Stage-VI (BS-VI) 2020 compliant light-duty SI engine equipped with a multipoint port fuel injection system and compared it with baseline gasoline fueled engine. The catalytic conversion efficiency for controlling regulated and unregulated emission species are also discussed for both test fuels. The experimental results showed a reduction in carbonaceous emissions from M15 fueled engine. Hydrocarbons (HC), carbon monoxide (CO) and particulate emissions reduced, while oxides of nitrogen (NOx) emissions were comparable to baseline gasoline-fueled engine. The catalytic conversion of CO emission was higher for M15 but lower for HC and NOx emissions. Various unregulated trace emission components such as formaldehyde, acetaldehyde, methane, ethene and propene reduced with methanol addition to gasoline. Considerable reductions in benzene and toluene trace emissions were observed for M15, but methanol and ethane trace emissions were higher. The catalytic conversion of all unregulated trace emission components was comparable for both test fuels except alcohols, where M15 exhibited increased trace emission values. The study reflected that M15 could easily replace gasoline in BS-VI-compliant light-duty SI transportation engines. However, verification of all regulatory emission compliances, diagnostics and durability compliances need be ascertained before large-scale implemetation.

Characterisation of particulates and trace metals emitted by a dimethyl ether-fuelled genset engine prototype.

Diesel-fuelled CI engines are the primary sources of particulate matter (PM) emissions which harm human health and the urban environment. Elevated PM emission levels can cause respiratory diseases and deteriorate urban air quality and atmospheric visibility. DME, a carbon-neutral and oxygenated fuel, is fast merging as a strong alternative to diesel to reduce PM emissions. The absence of a direct carbon-carbon bond in the molecular structure of DME improves combustion and reduces PM emissions to negligible levels. DME and baseline diesel are experimentally evaluated in a single-cylinder CI genset engine prototype to find the particulate number-size, surface area-size and mass-size distributions. In addition, total particulate number (TPN), total particulate mass (TPM), count mean diameter (CMD) of particulates, particulate morphology and trace metals were assessed. DME genset engine emitted higher numbers of smaller diameter particles, with lower surface area and mass distribution than baseline diesel. For DME, total PM mass emission and CMD of particulates were lower due to particles being finer. Morphological analysis of particulates showed the presence of larger particles from diesel and less bunched agglomerates of nucleation mode particles from the DME genset engine prototype. The trace metal analysis of particulates showed higher presence of trace metals such as Si, Ca, and Na in DME-fuelled engine than in diesel. As an alternative to diesel, DME can reduce PM emissions from genset engines, significantly enhance urban air quality, and minimise the threat of respiratory diseases.

Electrifying passenger road transport in India requires near-term electricity grid decarbonisation.

Battery-electric vehicles (BEV) have emerged as a favoured technology solution to mitigate transport greenhouse gas (GHG) emissions in many non-Annex 1 countries, including India. GHG mitigation potentials of electric 4-wheelers in India depend critically on when and where they are charged: 40% reduction in the north-eastern states and more than 15% increase in the eastern/western regions today, with higher overall GHGs emitted when charged overnight and in the summer. Self-charging gasoline-electric hybrids can lead to 33% GHG reductions, though they haven't been fully considered a mitigation option in India. Electric 2-wheelers can already enable a 20% reduction in GHG emissions given their small battery size and superior efficiency. India's electrification plan demands up to 125GWh of annual battery capacities by 2030, nearly 10% of projected worldwide productions. India requires a phased electrification with a near-term focus on 2-wheelers and a clear trajectory to phase-out coal-power for an organised mobility transition.

A cleaner route of biodiesel production from waste frying oil using novel potassium tin oxide catalyst: A smart liquid-waste management.

The valorization of waste frying oil (WFO) to biodiesel has been carried out via solid base catalyzed transesterification reaction. A novel potassium tin oxide (KSO) catalyst was synthesized via polymer precursor auto combustion method. The catalyst showed the best physicochemical properties when it was calcined at 800 °C. Using KSO 800 catalyst, the highest FAME conversion (99.5%) of WFO found at moderated reaction condition within very short time (35 min); moreover, no leaching of K-species was observed in reusability test upto 5th cycle. Kinetics proved that the above catalytic reaction followed pseudo-first-order kinetics and the rate of the reaction was doubled with increasing 10 °C reaction temperature. The reaction activation energy, enthalpy of activation, entropy of activation, and Gibb's free energy of activation of the reaction were found to be 66.52 kJ/mol, 62.95 kJ/mol, -74.07 J/mol/K and 88 kJ/mol respectively. Evaluation of the green parameters revealed that KSO 800 catalyzed transesterification process approached a cleaner route with excellent efficacy in terms of turnover frequency and yield. KSO 800 helped to produce high quality biodiesel from WFO adopting faster and greener reaction pathway. Thus, KSO 800 was considered as a potential and green catalyst for transforming waste oil into biofuel.

Particulate characteristics of low-temperature combustion (PCCI and RCCI) strategies in single cylinder research engine for developing sustainable and cleaner transportation solution.

In this experimental study, particulate matter (PM) characterizations of different low-temperature combustion (LTC) strategies have been compared with conventional compression ignition (CI) combustion for finding out a sustainable and cleaner transport solution. LTC strategies included premixed charge compression ignition (PCCI) and reactivity-controlled compression ignition (RCCI) combustion. Particulate sampling and characterization were carried out in a single-cylinder diesel engine. All engine tests were performed at 1, 2, 3, 4 bar brake mean effective pressure (BMEP) at 1500 rpm. CI and PCCI combustion experiments were performed using mineral diesel as the test fuel. However, mineral diesel and methanol were used as high reactivity fuel (HRF) and low reactivity fuel (LRF), respectively in the RCCI combustion strategy. For all combustion strategies, fuel injection pressure (FIP) was kept constant at 500 bar. However, the number of injections and start of injection (SoI) timings were varied to optimize the engine performance. Results showed that the RCCI combustion strategy emitted a relatively lower concentration of particles than the other two strategies (PCCI and CI). A relatively higher number concentration of accumulation mode particles (AMP) compared to nucleation mode particles (NMP) in the exhaust of the RCCI combustion strategy was an important finding of this study. Number-size and mass-size distributions of particles emitted from different strategies also exhibited the dominant concentration of particles in the CI combustion strategy. PM bound trace metal analysis was yet another critical aspect of this study, which showed that both RCCI and PCCI strategies emitted a relatively lower concentration of trace metals than the conventional CI combustion strategy. Parametric analysis of different PM characteristics and NOx-PM trade-off analysis also demonstrated the importance of LTC strategies over the conventional CI combustion strategy. Overall, this study demonstrated that all LTC strategies could be used for PM and NOx reduction; however, the RCCI combustion strategy was more dominant in NOx and PM reduction, in addition to having an excellent capability of using alternative fuel in the quest for developing sustainable transport solution.

Toxicity of exhaust particulates and gaseous emissions from gasohol (ethanol blended gasoline)-fuelled spark ignition engines.

In the last couple of decades, blending of oxygenated additives with gasoline has been advocated to reduce dependence on fossil fuels and to reduce hazardous health effects of gaseous emissions and particulate matter (PM) emitted by internal combustion (IC) engines in the transport sector worldwide. The primary objective of this research was to carry out a comparative analysis of exhaust PM emitted by gasohol (gasoline blended with 10% ethanol, v/v)-fulled spark ignition (SI) engine with that of baseline gasoline-fuelled SI engine. To assess the PM toxicity, physical, chemical and biological characterizations of PM were carried out using the state-of-the-art instruments and techniques. Measurements of regulated and unregulated gaseous species were also carried out at part/full loads. The results showed that the gasohol-fuelled engine emitted relatively lower concentrations of unregulated gaseous species such as sulfur dioxide (SO2), isocyanic acid (HNCO), etc. Physical characterization of exhaust particles revealed that the gasohol-fuelled engine emitted a significantly lower number of particles compared to the gasoline-fuelled engine. The presence of harmful polycyclic aromatic hydrocarbons (PAHs) and higher trace metal concentrations in PM emitted from the gasoline-fuelled engine was another important finding of this study. Biological characterizations showed that PM emitted from the gasohol-fuelled engine were less cytotoxic and had lower reactive oxygen species (ROS) generation potential. Mutagenicity of PM emitted from the gasohol-fuelled engine was also lower compared to that from the gasoline-fuelled engine. Overall, this study demonstrated that utilization of gasohol in SI engines led to the reduction in emissions, and lowering of PM toxicity, in addition to partial replacement of fossil fuels with renewable fuels.

Mutagenicity and Cytotoxicity of Particulate Matter Emitted from Biodiesel-Fueled Engines.

Biodiesel engines produce several intermediate species, which can potentially harm the human health. The concentration of these species and their health risk potential varies depending on engine technology, fuel, and engine operating condition. In this study, experiments were performed on a large number of engines having different configurations (emissions norms/fuel used), which were operated at part load/full load using B20 (20% v/v biodiesel blended with mineral diesel) and mineral diesel. Experiments included measurement of gaseous emissions, and physical, chemical, and biological characterization of exhaust particulate matter (PM). Chemical characterization of PM was carried out for detecting polycyclic aromatic hydrocarbons (PAH's) and PM bound trace metals. The biological toxicity associated with PM was assessed using human embryonic kidney 293T cells (HEK 293T). The mutagenic potential of the PM was tested at three different concentrations (500, 100, and 50 µg/mL) using two different  Salmonella strains, TA98 and TA100, with and without liver S9 metabolic enzyme fraction. PM samples exhibited cytotoxic effect on HEK 293T cells (IC50 < 100 µg/mL) and there was significant potential for reactive oxygen species (ROS) generation. Comparison of different engines showed that modern engines (Euro-III and Euro-IV compliant) produced relatively cleaner exhaust compared to older engines (Euro-II compliant). Biodiesel-fueled engines emitted lower number of particles compared to diesel-fueled engines. However, chemical characterization revealed that biodiesel-fueled engines exhaust PM contained several harmful PAHs and trace metals, which affected the biological activity of these PM, as reflected in the biological investigations. Mutagenicity and cytotoxicity of PM from biodiesel-fueled engines were relatively higher compared to their diesel counterparts, indicating the need for exhaust gas after-treatment.

Performance evaluation of a biodiesel fuelled transportation engine retrofitted with a non-noble metal catalysed diesel oxidation catalyst for controlling unregulated emissions.

In present study, engine exhaust was sampled for measurement and analysis of unregulated emissions from a four cylinder transportation diesel engine using a state-of-the-art FTIR (Fourier transform infrared spectroscopy) emission analyzer. Test fuels used were Karanja biodiesel blend (B20) and baseline mineral diesel. Real-time emission measurements were performed for raw exhaust as well as exhaust sampled downstream of the two in-house prepared non-noble metal based diesel oxidation catalysts (DOCs) and a baseline commercial DOC based on noble metals. Two prepared non-noble metal based DOCs were based on Co-Ce mixed oxide and Lanthanum based perovskite catalysts. Perovskite based DOC performed superior compared to Co-Ce mixed oxide catalyst based DOC. Commercial noble metal based DOC was found to be the most effective in reducing unregulated hydrocarbon emissions in the engine exhaust, followed by the two in-house prepared non-noble metal based DOCs.

Effectiveness of non-noble metal based diesel oxidation catalysts on particle number emissions from diesel and biodiesel exhaust.

Two new formulations of non-noble metal based diesel oxidation catalysts based on CoCe based mixed oxide (DOC2) and perovskite catalysts (DOC3) were prepared and retrofitted in a 4-cylinder diesel engine fueled by diesel and Karanja biodiesel blend (KB20). In this study, their effectiveness in reducing raw exhaust particulate emissions vis-à-vis a commercial diesel oxidation catalyst (DOC1) was evaluated. Emission characteristics such as particle number-size distribution, mass-size distribution, and surface area-size distribution, total particle number concentration and count mean diameter as a function of engine load at constant engine speed were evaluated. Variations in total particle number concentration as a function of engine speed were also determined. The prepared DOCs and the commercial DOC showed varying degrees of performance as a function of engine operating conditions. Overall, effectiveness of the prepared DOC's appeared to be more fuel specific. For diesel exhaust, overall performance of DOC1 was more effective compared to both prepared DOCs, with DOC2 being superior to DOC3. In case of KB20 exhaust, the overall performance of DOC2 was either more effective or nearly comparable to DOC1, while DOC3 being not so effective. This showed that the DOCs based on CoCe based mixed oxide catalysts have potential to replace commercial noble metal based DOC's, especially in engines fueled by biodiesel.

Assessment of toxic potential of primary and secondary particulates/aerosols from biodiesel vis-à-vis mineral diesel fuelled engine.

Toxicity of engine out emissions from primary and secondary aerosols has been a major cause of concern for human health and environmental impact. This study aims to evaluate comparative toxicity of nanoparticles emitted from a modern common rail direct injection engine (CRDI) fuelled with biodiesel blend (B20) vis-à-vis mineral diesel. The toxicity and potential health hazards of exhaust particles were assessed using various parameters such as nanoparticle size and number distribution, surface area distribution, elemental and organic carbon content and polycyclic aromatic hydrocarbons adsorbed onto the particle surfaces, followed by toxic equivalent factor assessment. It was found that biodiesel particulate toxicity was considerably lower in comparison to mineral diesel.

Development of surface functionalized activated carbon fiber for control of NO and particulate matter.

This study investigates the development and potential application of activated carbon fibers (ACF) functionalized with ammonia for control of NO and particulate matter (PM) in diesel engine exhaust. A tubular reactor packed with ACF was used to experimentally study the oxidation of NO at room temperature. Tests were conducted at ACF functionalized with three aqueous ammonia concentrations (3, 5, 10 M), three basic reagents (ammonia, pyridine, amine) and three NO concentrations (100, 300, 500 ppm). After offline investigation, the ACF-packed tubular reactor was installed downstream of the engine's exhaust to ascertain the PM capturing efficiency of ACF. The experimental conditions for PM removal included three weights of ACF (2, 3.5, 4.5 g), three engine loads (0, 25, 50 Nm) and three temperatures (150, 300, 450 degrees C). The maximum 70% conversion for NO was obtained at NO concentration of 300 ppm for ACF functionalized with 5M ammonia, whereas maximum 90% reduction in PM was observed at engine load of 25 Nm and 450 degrees C. The study shows significant potential for the ACF based filters in capturing both homogeneous and heterogeneous pollutants emitted from automobiles. Our previously developed transport model incorporating the mechanism for the oxidation of NO was also used to explain the experimental data.