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Combustible dust may result in a catastrophic dust explosion with much larger accident consequences than gas explosions. In this study, porous materials are explored as a promising solution for mitigating explosions. This study focussed on the investigation of aluminium powder explosion in the influence of ceramic foam, with and without coating with non-precious nickel nanopowders. The microscopic properties and structural characteristics of the ceramic foam were analyzed using X-ray spectroscopy, X-ray diffractometry, and scanning electron microscopy. The findings revealed that the nickel-coated ceramic foams are non-uniform and almost spherical in shape, with obvious agglomerations of metallic-silica present on the strut structure. Compared to non-coated ceramic, it can be said that nickel-coated ceramic foams demonstrate a significant reduction in maximum overpressure by approximately 10%. This suggests that the interconnected micro-network structure of the nickel-ceramic walls aids in quenching the flame of the aluminium dust explosion and hence, suppressing the overpressure. [ABSTRACT FROM AUTHOR]

Accidental release of hydrocarbons can result in jet fires which have the potential to escalate accidental events to catastrophes. Jet fire can impinge on nearby equipment surface or a pasive firewall to make the fire plume temperature and the radiant heat flux complex. The present work experimentally investigated the flame characteristic of free horizontal jet fires and the impingement effect using propane as fuel, with different nozzle diameter, and exit velocity. To analyse the effect of flowrate to jet flame condition, the flow rates range between 30 and 600 g/min were employed with horizontal separation distance from the main source to target was at 0.8-m and 1.2-m. The results show that, the incremenet of flame features are faster for free release than impinging release. The presence of object downstream affect the flame profiles at some point. Thus, new correlations were proposed for the prediction of projected flame length and trajcetory length. [ABSTRACT FROM AUTHOR]

This paper presents a survey assessing factors contributing to the public acceptance of hydrogen as a fuel for vehicles in Malaysia. For the survey, a set of questionnaires was prepared in Google Forms and distributed to respondents through social media (WhatsApp, Facebook, Messenger, and Telegram). The survey was conducted during the movement order control in Malaysia due to the global pandemic, and the responses were collected from November to December 2021. One hundred seventy-six local respondents voluntarily participated in the survey. The responses were analysed using non-parametric statistical tests in the Statistical Package for the Social Sciences (SPSS). The highest number of respondents from the 18–25 age group is 101 (57.39 per cent), followed by 26–35 (26.7 per cent) and 36–45 (7.95 per cent). The statistical analysis of the survey shows that socio-demographics is a factor influencing public acceptance. The Spearman correlation test shows a positive correlation between Malaysia's environmental awareness and the potential to use a hydrogen-powered car; hence, there is a good chance of Malaysian acceptance of using hydrogen as fuel. Safety and public perception of hydrogen-powered cars also indicate a positive correlation, where the R- values for all questions are more than 0.5, indicating that safety is a factor that shapes public acceptance. Although the number of samples does not represent the population, it provides a reasonable basis to examine the influencing factors of public acceptance of hydrogen as a fuel for vehicles. [ABSTRACT FROM AUTHOR]

Gas explosions in obstructed vessels have been investigated for many years. However, the flame acceleration mechanism of enriched-hydrogen fuels with diluents in the piping system has received little systematic study in the literature. This particular study aimed to analyse the flame front mechanism of hydrogen-diluents/air explosion inside the pipe by considering the influence of tee junction distance from the ignition points. The tests were performed using H 2 /diluents-air at different concentrations and ignition positions, in two different tee junction pipe configurations. From the results, the worst case of explosion severity was found in 95% H 2 –2.5% Ar–2.5% N 2 /air for all ignition positions. In general, if ignition happened at the tee junction, the overpressure and rate of pressure rise profiles showed almost a similar trend on both configurations. Similar trend was also observed for the flame flow characteristic analysis. Overall, it was clearly demonstrated that a shorter distance between ignition point and obstacles resulted in higher explosion severity. [ABSTRACT FROM AUTHOR]

Based on recent developments, hydrogen-based combustion systems have received wide attention, mainly due to increasing awareness of enduring environmental pollutants and restricted access to fossil fuel usage. In the relevant literature, there are evidences of the possibilities on the partial or total replacement of hydrocarbon fuels with hydrogen in power plants and vehicle engines. However, some challenging issues particularly on hydrogen storage are remained to be resolved. This paper reviews and comments on addressing the effectiveness of hydrogen-enrichment on the engines and burners׳ performance includes the chemical kinetic analysis, the flame propagation structures and the effects of inhibitors on global burning velocity of hydrogen–hydrocarbon mixtures in different combustion bombs, chambers and vessels. It is recommended that future researches should aim towards the different application of hydrogen–hydrocarbon i.e. transportation and clean energy carrier. [ABSTRACT FROM AUTHOR]

Hydrogen is a promising fuel for the future. In recent years it has been successfully utilised in industries, particularly in refineries and petrochemicals. In previous studies, the effect of inhibitors on hydrogen explosion behaviour has been investigated in different systems, yet only scarce data are available. Therefore, experimental study is carried out to investigate the effects of argon, nitrogen and carbon dioxide on hydrogen/air explosion in a branched pipe configuration. The fuel/air mixtures were ignited at three different ignition positions, A, B and D. The results show that, when ignited at the furthest distance (position A), the tee junction area is most vulnerable to the critical pressure impact of gas explosion. However, no similar trend was observed at the other ignition positions. In addition, mixtures with the compositions 95% H 2 –2.5% Ar–2.5% N 2 /air, 95% H 2 –5% N 2 /air, H 2 /air and 95% H 2 –5% Ar/air showed higher risks due to the higher diffusivity ratio and the associated rate of pressure rise. This phenomenon is highlighted in the discussion part of this paper. The results show that mixtures with CO 2 lead to lower severity than other compositions (∼50% reduction), as the average recorded maximum flame speed for this particular mixture was lower at all of the ignition points. This suggests that the effectiveness of the inhibitors should be in the order of Ar < N 2 < CO 2 . [ABSTRACT FROM AUTHOR]

Dust explosion is considered as a serious threat for the industry that use or handle combustible materials as it may lead towards a significant economic loss in terms of damage to the facilities and suspension of activities, severe workplace injuries and fatalities. The rapid pressure developed during a dust explosion can be mitigated by venting. The present work explored the effects of venting on the explosion of different mixing weight ratios of aluminium and silver powder mixtures. The explosion characteristics of aluminium-silver mixtures were assessed in a 0.0012 m3 confined and vented cylindrical vessel. It was found that the application of 0.1 bar static burst pressure (Pstat) venting membrane gives one tenth reduction on explosion pressure and maximum rate of pressure rise for 70:30 and 50:50 mixing weight ratios of aluminiumsilver mixtures explosion, respectively. This finding suggests that besides the venting application effect, the oxidation reaction of aluminium could be disrupted due to the presence of silver powder in the metal mixtures which results in lower heat transfer and reduction of the mass burning rate, hence, lessen flame speeds and explosion severity. However, the venting effectiveness is reduced when the Pstat increases. In order to assess the applicability of the dust explosion venting standard; NFPA 68 and EN 14491, the experimental results were compared with the calculated values according to the standards. The comparative results show that, both NFPA 68 and EN 14491 give underestimated values for explosion venting as compared with the experimental results. [ABSTRACT FROM AUTHOR]

The main objective of the current work is to investigate the influence of catalyst to biomass ratio (by weight%) on the catalytic upgrading of sugarcane bagasse derived pyrolysis vapours over cerium (Ce) loaded Hydrogen exchanged Zeolite Socony Mobil-5 (HZSM-5) catalyst via in-situ fixed bed reactor. The temperature of pyrolysis was kept at 500 °C for all investigated samples. The HZSM-5 catalyst was used as a support with 1 wt% of Ce as promoter loaded via incipient wetness impregnation method. The biomass sample was fixed at 2 g, while the catalyst mass loading was loaded according to the catalyst to biomass ratio which are 0.5:1.0, 1.0:1.0, 1.5:1.0, and 2.0:1.0. For comparison, the non-catalytic and biomass catalytic over HZSM-5 catalyst was also pyrolyzed at the same operating conditions. The results show that the yields of pyrolysis oil and coke were significantly influenced by the use of Ce/HZSM-5 catalyst at various catalyst to biomass ratio than the catalytic pyrolysis over HZSM-5, in which generate higher pyrolysis oil yield (58.0–68.0 wt%) and lower coke yield (2.9–4.1%). The increasing loading of mass in Ce/HZSM-5 catalyst has additional effect with respect to C 6 –C 8 hydrocarbon contents in pyrolysis oil than the catalytic samples over the HZSM-5 catalyst. Among the tested catalyst to biomass ratio, the catalyst to biomass ratio of 1.5:1 has demonstrated to be the potential candidates in the catalytic upgrading of sugarcane bagasse derived oxygenated pyrolysis vapours into higher content of C 6 –C 8 hydrocarbons (2.45%) in pyrolysis oil with lower coke yield (3.2%) over Ce/HZSM-5 catalyst. The bi-functional Ce/HZSM-5 catalyst was more effective in suppressing the coke formation in comparison to HZSM-5 catalyst at all investigated catalyst to biomass ratios and this was attributed to the synergistic effect of Ce on HZSM-5 support. [ABSTRACT FROM AUTHOR]

The main objective of the present work is to study the effect of Nickel-Cerium/Alumina multifunctional catalyst (Ni-Ce/Al 2 O 3 ) mass loading on pyrolysis of coconut copra and rice husk via thermogravimetric analysis. The sample is pyrolyzed from 30 °C up to 700 °C at a constant heating rate of 10 °C/min in nitrogen environment flowing at 150 mL/min. The multifunctional catalyst (Ni-Ce/Al 2 O 3 ) was prepared via incipient wet impregnation method. Pyrolysis feedstocks were prepared based on biomass to catalyst mass loading ratio. The TG-DTG curve shows that the presences of catalyst significantly affect the devolatilization rate of biomass. Among TGA-pyrolyzed coconut copra samples, the CC-3 (1:0.15) has achieved the highest mass loss (83.3%). For rice husk, the non-catalytic sample has attained the highest mass loss of volatile matter (48.7%). In addition, the kinetic characteristics of non-catalytic and catalytic pyrolysis of biomass were also studied and calculated by employing the Coats-Redfern integral method. The CC-1 has lower activation energy (53.10 kJ/mol) than that of catalytic sample particularly CC-3 (79.28 kJ/mol). The presence of a catalyst on rice husk is able to reduce the activation energy of non-catalytic rice husk sample from 49.78 to 45.24 kJ/mol. [ABSTRACT FROM AUTHOR]

The understanding of biogas explosion characteristics is needed to describe the severity of the explosion. Biogas is a flammable gas and will explode when ignited. This study reports the experimental results on biogas explosion characteristics in a standard 20-L spherical vessel under quiescent conditions using electric spark (10 J) as an ignition source. Computational Fluid Dynamic (CFD) code FLame ACcelaration Simulator (FLACs) was used to simulate the biogas explosion based on the experimental case study. The dependence of explosion characteristics such as explosion pressure (Pmax), rate of pressure rise (dP/dt), and deflagration index (KG), on biogas concentration and carbon dioxide, CO2 composition is demonstrated. The data allow for the evaluation of the potential severity of biogas explosion, which in turn helps engineers design the explosion mitigation and prevention device related to this gas. The experimental data reported from this study concluded that Pmax = 8–8.50 bar, the dP/dt = 100–400 bar/ms and the KG = 32.7–121 bar m/ms were recorded at equivalence ratio, (ER) = 1.2 with CO2 composition in the biogas = 30% vol/vol. It was found that the severity of the biogas explosion increased proportionally with the biogas concentration. On the contrary, the explosive intensity was weakened by increasing the CO2 concentration due to the physical effects of CO2 and thermal instability. This study also recorded that the biogas explosion was categorized under hazard level = St-3 indicating a catastrophic explosion. These data are important for preventing and mitigating the biogas explosion. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Catalytic of oxygenated pyrolysis vapours over the newly synthesized Nickel-Cerium/HZSM-5. • The addition of nickel and cerium on HZSM-5 had suppressed coke contents than HZSM-5. • The NC2 catalyst produced the highest yield of pyrolysis oil (60.50 wt.%). • The NC3 catalyst has attained the highest contents of C 6 – C 8 hydrocarbons (8.82%) in pyrolysis oil. Abstract The main objective of the present work is to investigate the influence of nickel to cerium ratio on Hydrogen exchanged Zeolite Socony Mobil-5 (HZSM-5) towards the catalytic upgrading of sugarcane bagasse derived oxygenated pyrolysis vapours into C 6 – C 8 hydrocarbons in pyrolysis oil via in-situ fixed bed reactor. The pyrolysis reaction temperature and catalyst to biomass mass ratio were kept constant at 500 °C and 1:1 respectively for all the investigated samples. The HZSM-5 was used as a support at 94 wt.%, while the balance 6 wt.% was impregnated with various weight of nickel and cerium as promoters based on the nickel to cerium ratios via incipient wetness impregnation method. The nickel to cerium ratios are as follows: 1:5 (NC1), 2:4 (NC2), 3:3 (NC3), 4:2 (NC4), and 5:1 (NC5). The results show that all the metal modified HZSM-5 catalysts had greatly suppressed the formation of coke contents (9.0–10.5 wt.%) compared to the HZSM-5 catalyst (NC0) (15.1 wt.%). The highest pyrolysis oil yield (60.5 wt.%) was achieved by NC2 catalyst. Among the tested nickel to cerium ratios, the NC3 catalyst has demonstrated to be the potential candidates in the catalytic upgrading of sugarcane bagasse derived oxygenated pyrolysis vapours into higher contents of C 6 – C 8 hydrocarbons in pyrolysis oil (8.82%). [ABSTRACT FROM AUTHOR]

The production of pure silver nanoparticles (Ag-NPs) with unique properties remains a challenge even today. In the present study, the synthesis of silver nanoparticles (Ag-NPs) from natural pullulan (PL) was carried out using a radiation-induced method. It is known that pullulan is regarded as a microbial polysaccharide, which renders it suitable to act as a reducing and stabilizing agent during the production of Ag-NPs. Pullulan-assisted synthesis under gamma irradiation was successfully developed to obtain Ag-NPs, which was characterized by UV-Vis, XRD, TEM, and Zeta potential analysis. Pullulan was used as a stabilizer and template for the growth of silver nanoparticles, while gamma radiation was modified to be selective to reduce silver ions. The formation of Ag-NPs was confirmed using UV–Vis spectra by showing a surface plasmon resonance (SPR) band in the region of 410–420 nm. As observed by TEM images, it can be said that by increasing the radiation dose, the particle size decreases, resulting in a mean diameter of Ag-NPs ranging from 40.97 to 3.98 nm. The XRD analysis confirmed that silver metal structures with a face-centered cubic (FCC) crystal were present, while TEM images showed a spherical shape with smooth edges. XRD also demonstrated that increasing the dose of gamma radiation increases the crystallinity at a high purity of Ag-NPs. As examined by zeta potential, the synthesized Ag-NP/PL was negatively charged with high stability. Ag-NP/PL was then analysed for antimicrobial activity against Staphylococcus aureus, and it was found that it had high antibacterial activity. It is found that the adoption of radiation doses results in a stable and green reduction process for silver nanoparticles. [ABSTRACT FROM AUTHOR]