Fuels, Volume 5, Issue 3 (September 2024) – 6 articles

This study aims to analyze the influence of adding Aeroshell 500 oil on physicochemical properties. It was found that the oil’s kinematic viscosity is much higher than that of diesel and Jet A, with a higher density and flash point as well. Elemental analysis revealed a higher carbon content and lower hydrogen content in Aeroshell oil compared to Jet A and diesel, with lower calorific power. Adding 5% oil increases the mixture viscosity, flash point, and density; decreases the calorific power; and increases the carbon content for both diesel and Jet A. In the second part, mathematical models determined the combustion temperatures for Jet A, diesel, Jet A plus 5% Aeroshell 500 oil, and diesel plus 5% Aeroshell 500 oil, based on an air excess from one to five. Elemental analysis determined the oxygen and air quantities for these mixtures and stoichiometric combustion reaction for CO₂ and H₂O. Regarding the CO₂ quantity, adding 5% Aeroshell 500 to Jet A increases it from 3.143 kg to 3.159 kg for each kilogram of mixture burned in the stoichiometric reaction. Similarly, adding the oil to diesel in a 5% proportion increases the CO₂ quantity from 3.175 to 3.190 in the stoichiometric reaction. Through experimentation with the Jet Cat P80 microturbine engine across four operating regimes, it was observed that the combustion chamber temperature and fuel flow rate are lower when using diesel with a 5% addition of Aeroshell 500 oil compared to Jet A with the same additive. However, the thrust is slightly higher with diesel + 5% Aeroshell 500 oil. Moreover, the specific fuel consumption is higher in regimes one and two for diesel + 5% Aeroshell 500 oil compared to Jet A + 5% Aeroshell 500 oil, while the differences are negligible in regimes three and four. At maximum operating conditions, the excess air was determined from the measured values, comparing the combustion chamber temperature with the calculated value, with a 7% error, extrapolating the results for the scenario when oil is not used. Also, during the testing campaign, the concentrations of CO and SO₂ in the exhaust gas jet were measured, with higher concentrations of CO and SO₂ observed for diesel compared to Jet A. Full article

Large-scale subsurface hydrogen storage is critical for transitioning towards renewable, economically viable, and emission-free energy technologies. Although preliminary studies on geochemical interactions between different minerals, aqueous ions, and other dissolved gasses with H₂ have helped partially quantify the degree of hydrogen loss in the subsurface, the long-term changes in abiotic hydrogen–brine–rock interactions are still not well understood due to variable rates of mineral dissolution/precipitation and redox transformations under different conditions of reservoirs. One of the potentially understudied aspects of these complex geochemical interactions is the role of iron on the redox interactions and subsequent impact on long-term (100 years) hydrogen cycling. The theoretical modeling conducted in this study indicates that the evolution of secondary iron-bearing minerals, such as siderite and magnetite, produced after H₂-induced reductive dissolution of primary Fe³⁺-bearing phases can result in different degrees of hydrogen loss. Low dissolved Fe²⁺ activity (<10⁻⁴) in the formation water can govern the transformation of secondary siderite to magnetite within 100 years, eventually accelerating the H₂ consumption through reductive dissolution. Quantitative modeling demonstrates that such secondary iron mineral transformations need to be studied to understand the long-term behavior of hydrogen in storage sites. Full article

The water hyacinth (WH), also known as Eichhornia crassipes, is Bangladesh’s fast-growing and rapidly expanding sustainable aquatic bioenergy feedstock. The WH, as an energy crop, has been harnessed as a phytoremediation agent to purify contaminated water and produce fuel and environmentally friendly products. A country’s economy relies on the availability of raw materials for energy production, cleaning life-supporting abiotic resources for consumption, and the innovation of cost-effective, eco-friendly products. The present study focuses on a three-in-one nexus using the WH to purify polluted water, the (post-purification) biomass to produce clean energy fuels (biogas and bioethanol), and for the manufacture of daily-use products. The ability of the WH, an aquatic macrophyte, to act as a phytoremediator to improve the quality of eutrophic lake water in a laboratory setting was investigated. Water samples were collected from four lakes surrounding the urban community in Dhaka, Bangladesh. The potential to remove salts and solutes and improve the physio-chemical properties of water, including pH, dissolved oxygen (DO), electrical conductivity (EC), total dissolved solids (TDSs), turbidity, and NaCl concentration, were assessed. During the aquatic macrophyte treatment, a 100% WH survival rate was shown, with no visible toxicity symptoms observed in the biomass. The WH improved water quality after one week, as determined by a significant decrease in turbidity, EC, NaCl, and TDSs, and improved pH and DO levels. Here, we establish the WH’s proficiency in removing nutrients/solutes and improving water quality. In addition, we discuss the utilization of this invasive aquatic biomass to produce energy after remediation of water including cost-effective and eco-friendly products to incur daily life with environmental and socioeconomic benefits in Bangladesh. Full article

Gas hydrate formation poses a significant challenge in offshore oil and gas production, particularly during cold restarts after extended shut–ins, which can lead to pipeline blockages. Although steady–state models have traditionally been used to predict hydrate formation under continuous production conditions, these models are often inadequate for transient operations due to issues like near–zero fluid flow shear affecting the viscosity calculations of hydrate slurries. This study introduces novel conceptual models for dispersed water–in–crude oil systems specifically designed for cold restart scenarios. The models are supported by direct observations and various experimental approaches, including bottle tests, rheometer measurements, micromechanical force apparatus, and rocking cell studies, which elucidate the underlying mechanisms of hydrate formation. Additionally, this work introduces a modeling approach to represent conceptual pictures, incorporating particle settling and yield stress, to determine whether the system will plug or not upon restart. Validation is provided through transient large–scale flowloop tests, confirming the plugging mechanisms outlined. This comprehensive approach offers insights into conditions that may safely prevent or potentially lead to blockages in the fully dispersed system during field restarts, thereby enhancing the understanding and management of gas hydrate risks in offshore oil and gas operations. Full article

This paper aims to study the performance of solar collectors of various sizes under different weather conditions in different Japanese cities, i.e., Kofu City, Nagoya City and Yamagata City. The heat generated by the solar collector was used to conduct a biogas dry reforming reactor for producing H₂ to feed a solid oxide fuel cell (SOFC). This study revealed that the output temperature of a solar collector T_fb in April and July was higher than that in January and October irrespective of city. The optimum length of the absorber (dx) of the collector was 4 m irrespective of city. It was clarified that the T_fb in Yamagata City in January and October, i.e., winter and autumn, is lower than that in Kofu City and especially Nagoya City, which is strongly influenced by the tendency of solar intensity (I), not the velocity of the surrounding air (u_a). On the other hand, the T_fb is almost the same in April and July, i.e., spring and summer, irrespective of city. The amount of produced H₂ via the biogas dry reforming reactor and the power generated by the SOFC using H₂ in spring and summer were higher compared to the other seasons irrespective of city. This study revealed that the highest available household number per month was 4.7, according to the investigation in this study. Full article

Scientific studies on the impact of wood species on solid fuel production, performance, and sustainability are grossly inadequate. The knowledge of this is imperative as users of solid fuels are increasing rapidly, especially in Africa. On this note, it becomes necessary to explore measures that will improve its efficiency and sustainability as an energy source. This study investigates some properties of selected wood species used as an energy source in Nigeria and their pelleting potential. Nine samples were characterized and assessed for suitability of pelleting following four wood pellet quality standards. The properties investigated are physical (moisture content and density) and thermochemical (calorific value, ash content, volatile matter, fixed carbon, and ultimate properties (carbon, nitrogen, hydrogen, oxygen, sulfur, arsenic, cadmium, and lead)). These were selected because they are among the most important pellet parameters contained in the quality standards. The findings revealed a net calorific value between 10.61 MJ.kg⁻¹ for Tectona grandis and 18.44 MJ.kg⁻¹ for Eucalyptus cam. The ash content, volatile matter, and fixed carbon contents of the samples range between 2.1 and 24.4%, 65.94 and 87.77%, and 3.51 and 18.63%, respectively. Anogeissus leiocarpus was found to be the species with the best rating score in terms of fuel properties, while Vitellaria paradoxa was the lowest. However, in terms of conformity with the four wood pellet standards, Khaya senegalensis, Parkia biglobosa, and Eucalyptus cam., having presented density, calorific value, sulfur, arsenic, cadmium, and lead within the limits of the wood pellet quality standards, were considered the best wood species in terms of fuel suitability and pelleting potential. The findings therefore suggest that not all wood species are suitable as fuel. Thus, for species that do not meet the standard wood pellet requirements, alternatives such as the use of biomass blends, additives, or process adjustments can be employed to adapt the quality to the standards or by using the fuels in improved cookstoves. Full article