Search Results (193)

This study investigates the fire behaviour of Battery Electric Vehicles (BEVs) and Internal Combustion Engine Vehicles (ICEVs) in confined environments such as underground parking facilities and tunnels. Using the Fire Dynamics Simulator (FDS), several scenarios were modelled to analyse the effects of ventilation and automatic suppression systems on fire growth, heat release, and smoke propagation. Three ventilation configurations—reduced, standard, and increased airflow—were evaluated to determine their influence on combustion dynamics and thermal development. Results show that BEV fires produce higher peak Heat Release Rates (up to 7 MW) and longer combustion durations than ICEVs, mainly due to self-sustained battery reactions. Increased ventilation enhances smoke removal but intensifies flames and radiant heat transfer, while limited airflow restricts combustion yet leads to hazardous smoke accumulation. The inclusion of a sprinkler system effectively reduced temperatures by over 60% within 100 s of activation, though residual heat in BEVs poses a risk of re-ignition. This underlines the need for tailored ventilation and suppression strategies in modern underground facilities to ensure safety in the transition toward electric mobility. Full article

This work examines the behaviour of a spark-ignition engine using oxy-fuel combustion, coupled with an oxygen production cycle based on a mixed ionic-electronic ceramic membrane. Through 1D-0D simulations, two compression ratios are studied: the original ratio of 9.6 and the optimised CR of 20, under various load levels and altitude conditions. The results show that operational limits exist at part-load conditions, where reducing the load without implementing additional control strategies may compromise system performance. It is observed that at low loads, the intake pressure can fall below atmospheric pressure, encouraging the presence of N₂ in the combustion process. Additionally, the engine can operate efficiently up to an altitude of 4000 m, although increasing boosting is required to maintain proper membrane conditions. These findings emphasise the importance of load control and the potential need for energy assistance under certain circumstances. Full article

This study provides a comparative thermochemical analysis of coconut husk, rice husk and mineral coal, assessing their potential for use in sustainable energy applications. Standardised proximate and ultimate analyses, thermogravimetric (TGA/DTG) evaluations and combustibility index measurements were performed under identical laboratory conditions to ensure consistent comparisons could be made. Coconut husk exhibited the lowest ignition temperature (320.88 °C) and the highest combustibility index (2.385). This indicates its suitability for rapid combustion and biochar production. Its low ash and sulphur content enhances its environmental performance. Rice husk demonstrated moderate thermal behaviour and a high ash yield owing to its elevated silica content, suggesting greater potential for non-energy applications, such as silica recovery and advanced materials production. Mineral coal displayed the highest carbon content and calorific value (24.38 MJ/kg), reflecting high energy density, but also a considerable sulphur content that raises environmental concerns. Unlike many studies that address these materials separately, this work provides a direct, side-by-side comparison under controlled conditions. This offers practical insights for selecting materials in energy systems. The results reinforce the potential of agro-industrial residues in cleaner energy strategies, while emphasising the need for emission control measures when using fossil fuels. Full article

Amine-based CO₂ absorption is a leading technology for post-combustion carbon capture, but solvent degradation remains a critical barrier to its long-term sustainability. Degradation reduces capture efficiency, increases solvent make-up costs, and generates environmentally harmful by-products, undermining the viability of carbon capture as a sustainable climate mitigation strategy. This study applies advanced machine learning techniques—Artificial Neural Networks (ANN), Random Forest (RF), XGBoost, and Adaptive Neuro-Fuzzy Inference Systems (ANFIS)—to predict thermal and oxidative degradation of amine solvents under varying operating conditions. Experimental datasets for piperazine-based mixtures and tertiary amines were used to train and validate predictive models with high statistical accuracy. The results demonstrate that machine learning can reliably forecast degradation behaviour, reducing dependence on resource-intensive experimental campaigns and enabling more sustainable CO₂ capture systems. By improving solvent stability assessment and process monitoring, this work contributes to the development of more resilient, cost-effective, and environmentally responsible carbon capture technologies, directly supporting global sustainability and climate change mitigation goals. Full article

This study provides a comprehensive analysis of lemon peel (LP) combustion behaviour using combined physicochemical characterization and non-isothermal thermogravimetric kinetics. To achieve this, LP was characterized for its proximate and ultimate composition, with its structure analysed via FTIR, XRD, and SEM. Thermogravimetric analysis (TGA) was then performed at high heating rates (20–80 K min⁻¹) to investigate combustion stages, and kinetic and thermodynamic parameters were determined using six model-free and one model-fitting method. The results revealed a high heating value (23.02 MJ kg⁻¹) and high volatile matter (73.2 wt%), establishing LP’s significant energy potential. TGA displayed four distinct decomposition stages corresponding to dehydration, pectin/hemicellulose, cellulose, and lignin/char combustion. Kinetic analysis yielded activation energies that varied with conversion, peaking at approximately 304 kJ mol⁻¹, and a three-dimensional diffusion (D3) mechanism was identified as the rate-limiting step. In conclusion, while its high energy content and low nitrogen (1.26 wt%) and sulphur (0.20 wt%) content make LP an attractive low-emission biofuel, its viability is challenged by a high potassium concentration in the ash (34.8 wt% K₂O), posing a severe risk of slagging. This study provides the comprehensive combustion kinetic data for LP at high heating rates, which is essential for designing appropriate energy conversion technologies and ash management strategies. Full article

This study examined engine combustion characteristics of the plastic diesel produced through pyrolysis of waste plastics as an eco-friendly source of engine fuel. We extensively measured and compared the key fuel properties based on various diesel fuel standards. Distillation and hydrotreatment processes were used to improve the quality of the pyrolysis oil, resulting in distilled plastic diesel (DPD) and hydrotreated plastic diesel (HPD). DPD and HPD were blended at 10:90 and 20:80 (vol%) ratios with commercial diesel, resulting in fuel blends termed as DPD10, DPD20, HPD10, and HPD20, respectively, to analyse their engine combustion characteristics. A full-scale 4-cylinder, 4-stroke diesel engine was used in this study. There are virtually no studies available in the literature where engine combustion characteristics have been tested with both distilled and hydrotreated plastic pyrolytic oil. This study comprehensively investigated the combustion behaviours of all four fuel blends under full-load conditions and at an engine operating speed of 1500 rpm, except engine exhaust gas temperature which was measured at varying engine speeds from 1200 rpm to 2400 rpm at an interval of 300 rpm. The study found notable differences in engine combustion characteristics between the commercial diesel and plastic diesel blends under identical operating conditions. The HPD blends had higher exhaust gas temperatures (EGTs) than the DPD blends, particularly at lower blend ratios, whereas the DPD10 and HPD10 blends had higher peak cylinder pressures than DPD20 and HPD20. The HPD10 blend exhibited the highest heat release rate (HRR) of 120.41 J/°CA. The engine combustion characteristics using a full-scale engine with distilled and hydrotreated plastic diesel and their comparison are not fully studied in the literature yet. Full article

Hydrogen-fuelled internal combustion engines (H₂ICEs) generate water vapour that can condense in the sump and form water-in-oil emulsions, altering lubricant performance. This study measures the viscosity–temperature behaviour, copper corrosivity, and boundary tribology of three commercial oils—synthetic (5W-40), semi-synthetic (10W-40), and mineral (15W-40)—emulsified with 5–40 wt% water and tested in both freshly emulsified and aged (3 months; clarified oil layer) states. In fresh emulsions, viscosity rose with water fraction. At 25 ^∘C and 40 wt%, the increase was 44.4% (5W-40), 78.7% (10W-40), and 81.2% (15W-40) versus the neat oils. Ageing drove viscosities toward the baseline, with the strongest effect observed for 15W-40, indicating destabilisation. The Vogel–Fulcher–Tammann (VFT) model was fitted to all datasets (RMSE < 5%). A VFT-based screening map uses two ratios at the friction test temperature: $R_{\eta }=\eta /{\eta }_{\mathrm{neat}}$ (relative film-forming tendency) and $R_s=S/S_{\mathrm{neat}}$ with $S=B/{(T-T_0)}^2$ (thermal-thinning sensitivity). A Preferred regime, $R_{\eta }\ge 1.25$ and $R_s\le 0.95$, is correlated with lower friction, smaller wear scars, and copper rating 1a, with most aged conditions migrated out of this regime. Under boundary conditions, 5–10 wt% water generally reduced friction, whereas higher fractions and ageing increased friction and wear. Synthetic oil (5W-40) showed the most robust response. Full article

Agricultural residues such as maize byproducts and discarded cocopeat substrates are abundant but underutilised biomass resources. Improving their fuel quality requires densification, such as pelletisation, combined with thermochemical upgrading. In this study, pellets were prepared by blending cocopeat and maize residues at weight ratios of 9:1, 7:3, and 5:5, followed by torrefaction at 220, 250, and 280 °C. Their fuel characteristics were evaluated through mass yield, elemental and proximate analyses, chemical composition, calorific value, combustion indices, and grindability. Results showed that increasing maize residue content reduced ash and fuel ratio but increased volatile matter, while cocopeat-rich pellets provided higher fixed carbon and lignin contents, improving thermal stability. Torrefaction significantly enhanced calorific value (up to 21.83 MJ/kg) and grindability, while increasing aromaticity. However, higher torrefaction severity decreased the combustibility index but improved volatile ignitability, indicating a trade-off between ignition behaviour and stable combustion. An optimal balance was observed at 250 °C, where energy yield and combustion performance were maximised. This study demonstrates the feasibility of valorising discarded cocopeat substrates, blended with maize residues, into renewable solid fuels, and provides practical guidance for optimising blending ratios and torrefaction conditions in waste-to-energy applications. Full article

In developing countries, indoor air pollution in rural areas is often attributed to the use of solid biomass fuels for cooking. Such fuels generate particulate matter (PM), carbon monoxide (CO), carbon dioxide (CO₂), polyaromatic hydrocarbons (PAHs), and volatile organic compounds (VOCs). PM created from biomass combustion is a pollutant particularly damaging to health. This rigorous study employed a personal sampling device and multi-stage cascade impactor to collect airborne PM (including PM_2.5) and deposited ash from 20 real-world kitchen microenvironments. A robust analysis of the PM was undertaken using a range of morphological, physical, and chemical techniques, the results of which were then compared to a controlled burn experiment. Results revealed that airborne PM was predominantly carbon (~85%), with the OC/EC ratio varying between 1.17 and 11.5. Particles were primarily spherical nanoparticles (50–100 nm) capable of deep penetration into the human respiratory tract (HRT). This is the first systematic characterisation of biomass cooking emissions in authentic rural kitchen settings, linking particle morphology, chemistry and toxicology at health-relevant scales. Toxic heavy metals like Cr, Pb, Cd, Zn, and Hg were detected in PM, while ash was dominated by crustal elements such as Ca, Mg and P. VOCs comprised benzene derivatives, esters, ethers, ketones, tetramethysilanes (TMS), and nitrogen-, phosphorus- and sulphur-containing compounds. This research showcases a unique collection technique that gathered particles indicative of their potential for penetration and deposition in the HRT. Impact stems from the close link between the physico-chemical properties of particle emissions and their environmental and epidemiological effects. By providing a critical evidence base for exposure modelling, risk assessment and clean cooking interventions, this study delivers internationally significant insights. Our methodological innovation, capturing respirable nanoparticles under real-world conditions, offers a transferable framework for indoor air quality research across low- and middle-income countries. The findings therefore advance both fundamental understanding of combustion-derived nanoparticle behaviour and practical knowledge to inform public health, environmental policy, and the UN Sustainable Development Goals. Full article

Meso-scale combustors face persistent challenges in sustaining stable combustion and efficient heat transfer due to high surface-to-volume ratios and attendant heat losses. In contrast, larger outlet diameters exhibit weaker recirculation and more diffused temperature zones, resulting in reduced combustion efficiency and thermal confinement. The behavior of non-premixed flames in meso-scale combustor has been investigated through a comprehensive numerical study, utilizing computational fluid dynamics (CFD) under stoichiometric natural gas (methane)–air conditions; three outlet configurations (6 mm, 8 mm, and 10 mm) were analysed to evaluate their impact on temperature behaviour, vortex flow, swirl intensity, and central recirculation zone (CRZ) formation. Among the tested geometries, the 6 mm outlet produced the most robust central recirculation, intensifying reactant entrainment and mixing and yielding a sharply localised high-temperature core approaching 1880 K. The study highlights the critical role of geometric parameters in governing heat release distribution, with the 6 mm configuration achieving the highest exhaust temperature (920 K) and peak wall temperature (1020 K), making it particularly suitable for thermoelectric generator (TEG) integration. These findings underscore the interplay between combustor geometry, flow dynamics, and heat transfer mechanisms in meso-scale systems, providing valuable insights for optimizing portable power generation devices. Full article

Background: Exposure to indoor air pollution (IAP), including particulate matter of size 2.5 µm/m³ (PM_2.5) and carbon monoxide (CO) resulting from the combustion of biomass fuels in homes, is an important risk factor associated with growth and developmental delays in neonates. We investigated the association between exposure to HAP and adverse birth outcomes in a birth cohort study of 594 pregnant females in Sri Lanka. Methods: Pregnant females between the ages of 18 and 40 years were enrolled in their first trimester and followed until delivery. Baseline assessments of fuel used for cooking were used to categorize the females into high-exposure (wood and kerosene) or low-exposure (liquid petroleum gas and electricity) groups. Indoor air quality measurements of PM_2.5 (n = 303) and CO (n = 258) were conducted in a subgroup of households. The outcomes at birth included the neonates’ appearance, pulse, grimace, activity, respiration (APGAR) score, Brazelton Neonatal Behavioural Assessment Scale (BNBAS) score, and birth weight. Linear and logistic regressions were used to evaluate the association between household air pollution (HAP) and birth outcomes. Results: Of the 526 neonates assessed at delivery, 55.7% were born to mothers with high HAP exposure and 44.3% with low HAP exposure, respectively. The results of the linear regression found an inverse association between higher exposure to HAP and birthweight in the adjusted and unadjusted models; the birth weight of children in the high-exposure group was lower by 107 g compared to that of the low-exposure group after adjusting for other variables (β = −106.8; 95% confidence intervals: −197.6, −16.0). Exposure status was not associated with birth length, gestational age, or the APGAR score; however, the BNBAS motor score was significantly lower in the neonates of the high-exposure group (6.41 vs. 6.55, p = 0.04), though it was not significant when adjusted for other variables. No correlation was found between the measured indoor PM_2.5 levels and birth weight, birth length, gestational age, APGAR score, or BNBAS score. Conclusions: Exposure to IAP due to emissions from combustion products from biomass fuels adversely affects birth weight. These effects may be more pronounced in vulnerable populations in settings where primary healthcare for pregnant women is limited. Full article

This review article provides an overview of the use of hydrogen and tyre pyrolysis oil as fuels for homogeneous charge compression ignition (HCCI) engines. It discusses their properties, the ways they are produced and their sustainability, which is of particular importance in the present moment. Both fuels have certain advantages but also throw up many challenges, which complicate their application in HCCI engines. The paper scrutinises engine performance with hydrogen and tyre pyrolysis oil, respectively, and compares the fuels’ emissions, a crucial focus from an environmental perspective. It also surveys related technologies that have recently emerged, their effects and environmental impacts, and the rules and regulations that are starting to become established in these areas. Furthermore, it provides a comparative discussion of various engine performance data in terms of combustion behaviour, emission levels, fuel economy and potential costs or savings in real terms. The analysis reveals significant research gaps, and recommendations are provided as to areas for future study. The paper argues that hydrogen and tyre pyrolysis oil might sometimes be used together or in complementary ways to benefit HCCI engine performance. The importance of life-cycle assessment is noted, acknowledging also the requirements of the circular economy. The major findings are summarised with some comments on future perspectives for the use of sustainable fuels in HCCI engines. This review article provides a helpful reference for researchers working in this area and for policymakers concerned with establishing relevant legal frameworks, as well as for companies in the sustainable transport sector. Full article

This study investigated the thermomechanical behaviour of the nozzle of a GTM 400MOD miniature turbojet engine during combustion of aviation kerosene and co-combustion of kerosene with hydrogen. Numerical analysis was based on experiments conducted on a dedicated test rig at engine speeds ranging from 31,630 rpm to 65,830 rpm, providing data on the temperature and dynamic pressure at the nozzle outlet. These data served as input to numerical analyses using the ANSYS Fluent, Steady-State Thermal, and Static Structural modules to evaluate exhaust gas flow, temperature distribution, and stress and strain states. The paper performed a basic analysis with additional simplifications, and an extended analysis that took into account, among other things, thermal radiation in the flow. The results of the basic analysis show that, at comparable thrust levels, co-firing and pure kerosene combustion yield similar nozzle temperature distributions, with maximum wall temperatures ranging from 978 K to 1090 K, which remain below the allowable limit of 1193 K (920 °C). Maximum stresses reached approximately 261 MPa, close to but not exceeding the yield strength of 316 stainless steel. Maximum nozzle deformation did not exceed 0.8 mm. Small dynamic pressure fluctuations were observed; For example, at 31,630 rpm, co-firing increased the maximum dynamic pressure from 1.56 × 104 Pa to 1.63 × 104 Pa, while at 47,110 rpm, it decreased from 4.05 × 104 Pa to 3.89 × 104 Pa. The extended analysis yielded similar values for the nozzle temperature and pressure distributions. Stress and strain increased by more than 76% and 78%, respectively, compared to the baseline analysis. The results confirm that hydrogen co-firing does not significantly alter the nozzle thermomechanical loads, suggesting that this emission-free fuel can be used without negatively impacting the nozzle’s structural integrity under the tested conditions. The methodology, combining targeted experimental measurements with coupled CFD and FEM simulations, provides a reliable framework for assessing material safety margins in alternative fuel applications in small turbojet engines. Full article

The thermal properties and flammability of rigid polyurethane foams (RPUFs) containing various flame retardants, including solid (melamine, expanded graphite (EG), Exolit OP 935, ammonium polyphosphate (APP)) and liquid (Roflam B7, Roflam PLO) types, added at 30 wt.% and 60 wt.% by weight have been evaluated. Thermogravimetric analysis (TGA) demonstrated enhanced thermal stability, with the maximum 10% weight loss temperature (292 °C, +34 °C vs. reference) observed for foams containing 60 wt.% Exolit OP 935 and APP. The limiting oxygen index (LOI) test demonstrated the optimal performance for 30 wt.% APP and melamine (26.4 vol.% vs. 18.7 vol.% reference). In the UL-94 test, Exolit OP 935 and APP achieved a V-0 rating. The 60 wt.% Exolit with an EG blend also demonstrated a substantial reduction in heat release rate. These findings underscore the cooperative effects of hybrid flame retardants, thereby supporting their utilization in fire-safe RPUFs for construction and transport. Full article

A thorough understanding of fuel behaviour is essential for designing and operating thermochemical systems. Thermogravimetric analysis (TGA) is among the most widely used fuel characterization methods, offering parameters like reactivity and ignition temperature, and enabling comprehensive fuel behaviour assessment through combined indices. This study critically examines the applicability of TGA-based indices for predicting coal performance in industrial processes such as gasification and combustion, where devolatilization, ignition, and burnout stages are key. TGA-derived data are compared with results from established methods, including drop tube furnace (DTF), pulse ignition (PI), and entrained flow reactor (EFR) tests. Findings indicate that the Volatile Matter Release Index (D₂) effectively predicts DTF behaviour (R² = 0.938, max residuals: 4.1 pp), proving useful for fast devolatilization analysis. The Flammability Index (C₁) and Ignition Index (C₃) correlate well with PI results (R² = 0.927 and 0.931, max residuals: 53.3a °C), making them reliable ignition indicators. While TGA tools showed limited accuracy in burnout prediction, the proposed Modified Burnout Characteristic Index (B_1′) achieved reasonable performance (R² = 0.734, max residuals: 0.062%∙°C⁻¹). Overall, selected TGA-based indices offer strong predictive potential for key thermochemical conversion stages. Full article