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An optically accessible solid fuel scramjet was used to investigate the supersonic combustion of varying polymethyl methacrylate solid fuel grain geometries. The rear wall angle of the flameholding cavity was varied (30, 60, 75, and 90°) and an alternative geometry (flush fuel grain) containing the addition of a backwards facing step to the front of a conventional fuel grain was explored. Optical diagnostics including high-speed shadowgraph, CH* chemiluminescence, and HD video were used to analyze flammability characteristics and determine quantitative regression rates for each geometry. The optical results were supplemented by static pressure traces along the length of the combustor for the duration of a test firing. All tests were conducted with Mach 2 inlet flow into the combustor at nominal inlet conditions of 12.9 atm and 900 °C. Shadowgraph imaging for both cold flow and combusting flow was used to characterize the varying flow fields associated with their respective geometries and their core flow oscillatory frequencies were preliminarily inspected. Chemiluminescence data reveals increased heat release in the downstream constant area and expansion sections of the flush fuel grains compared to conventional geometries. This heat release appears to correlate with increased time-averaged regression rates in these regions while the varying cavity angle fuel grains demonstrate differing magnitudes of maximum regression along the rear cavity wall and onset of the constant area section. In addition to increased overall regression rates, flush geometries increase the flameholding capabilities and demonstrate self-sustained burning at lower inlet temperatures than similar geometries designed without a flush section. • This manuscript documents a study on solid fuel scramjet combustion. • Geometries which have not previously been studied were considered. • The optical access of the combustor reveals new insight on the flowfield. [ABSTRACT FROM AUTHOR]

AbstractWastewater treatment plant sludge contains a high concentration of organic compounds that can be used to produce fuel viahydrothermal carbonization (HTC). This study investigated the combustion reactivity and kinetic parameters of hydrochars produced to understand the combustion behavior of the solid fuel derived from HTC. The hydrochar was produced at various temperatures ranging from 150 to 300 °C, reaction times ranging from 30 to 150 min, and solid loadings ranging from 10% to 30%. The combustion behavior of sewage sludge (SS) and hydrochar was evaluated using thermogravimetric analysis with a constant air flow rate (100 mL/min) and heating rate (10 °C/min) from ambient temperature to 900 °C. It was observed that the HTC temperature, reaction time, and solid loading influenced the combustion characteristics and kinetics of the hydrochar. Additionally, the hydrochar exhibited higher ignition and burnout temperatures and a lower peak temperature than SS, indicating superior performance and reactivity in combustion. The combustion kinetic analysis also revealed that the hydrochar had a range of lower activation energy (29.12–41.60 kJ/mol) than SS (52.95 kJ/mol). Therefore, hydrochar derived from SS has the potential to be used as a substrate for solid fuel production for future renewable energy sources. [ABSTRACT FROM AUTHOR]

In this work, we investigate the properties and stability of the combustion waves propagating in a system of layered solid fuel material in which the neighbouring fuel sheets can recuperate heat via thermal electromagnetic radiation. The analysis is undertaken within the flame sheet model, which allows to determine the combustion wave speed and structure and derive the dispersion relation characterising the stability of the reaction front. The proper choice of parameters leads to superadiabatic combustion temperature and significant increase of the combustion wave speed. In addition, the stable steady regimes of combustion can be substantially extended in the space of parameters. Such an enhancement of stability and ability to control the characteristics of the combustion wave propagation can be very attractive for the combustion synthesis of new layered materials, similarly to the chemical furnace technology proposed earlier. [ABSTRACT FROM AUTHOR]

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Hydrothermal carbonization (HTC) is a promising technology for the conversion of waste biomass into an energy-dense coal-like product known as hydrochar. This study evaluated the application of HTC to generate a renewable solid fuel resource from hazardous oily sludge. The influence of process parameters on the energy characteristics of hydrochar was investigated. A design matrix of 20 experimental HTC runs was used as input for response surface methodology (RSM). The central point for this HTC operation was at a temperature of 200°C, with a duration of 75 min and a concentration of 5.5%. The higher heating value (HHV) increased from 18.18 to 28.7 MJ/kg. A linear correlation was derived between yield and HHV. The influence of process parameters on energy densification and energetic retention properties revealed that energy storage properties were enhanced. In total, 66.6%–80% of energy was retained in hydrochar. The enhancement of the fuel characteristics of hydrochar was demonstrated by the elevated fuel ratio of 0.31 obtained at a temperature of 250°C, thereby indicating the improvement brought about by the HTC process. The quantification of energy losses due to convection and radiation yielded 309 and 1,854 kJ/h, respectively. Maximizing the efficiency of internal heat sources is crucial to conserving energy and reducing costs in HTC. Practical Applications: The activities of the oil industry have several impacts on the environment due to the large amounts of oily waste generated. Oily sludge is a prevalent hazardous waste generated in the petroleum industry, and effectively treating it remains a key challenge for the petroleum and petrochemical sectors. Hydrothermal carbonization is an important thermochemical conversion process that can be used as an energy-efficient alternative to enhance the dewaterability of sludge and meanwhile to convert sludge into high-value-added products, such as clean biofuel, organic fertilizers, and precursors of functional materials. Optimizing the process conditions is essential to successfully implement the HTC processing of oily sludge in real field conditions. In this study, waste oily sludge was converted to an energy-rich product, namely, hydrochar. For this, the study investigated the hydrochar characteristics for hydrothermal conditions including a reaction temperature of 175°C–250°C, a reaction time of 30–120 min, and a solid load of 3%–8%. The study also found that the majority of energy loss occurred during the cooling process and therefore suggests that this process might be operated as a continuous process rather than a batch process. [ABSTRACT FROM AUTHOR]

Biomass briquetting is gradually emerging as a means of sustainable energy production. The interest in briquetting has been occasioned by the continuous rise in the cost of energy coupled with the need to harness efficient and affordable alternatives. Briquettes are produced through various means, ranging from a simple low-pressured technique to a high-pressured technique. This, including the large-scale availability of biomass materials in many regions of the world, has made the process practicable and affordable. The technology has gained acceptance across the scientific community as it is a means of attaining a circular and green economy especially as it helps to curtail deforestation. Briquetting has advanced and now incorporates the blending of biomass with animal and municipal wastes such as dung, microalgae, plastics, sludge, and food waste. This paper reviewed recent literature spanning over a decade on the technical aspects of biomass briquetting to establish the current state of research. It contains a brief on renewable energy with a focus on biomass energy, as well as the impact of solid fuels on households and the environment. It reviewed briquettes and briquetting technology by highlighting key processes and quality parameters. The paper also reports the economic aspects of various briquetting technology to assess their viability and also reports the combustion process to evaluate the extent of toxic gas emissions and their impact on coal-based power plants. To this end, an overview of recent studies was made followed by a highlight of recent advancements in briquetting technology. [ABSTRACT FROM AUTHOR]

The problem of organic and non-economic LDPE plastic waste, which is abundant in the Singkawang City landfill, is accompanied by the reduced availability of coal as a fuel for steam power plants. Therefore, this study utilizes organic and plastic waste as biomass fuel that can be used in steam power plants using the co-firing method. This research aims to identify the characteristics, analyze the optimal composition based on SNI 8966:2021, and examine the influence of solid fuel composition. The research method used four composition variations: 100:0%, 95:5%, 85:15%, and 75:25. The best average water content, volatile matter, ash, fixed carbon, and calorific value were 4%, 60.67%, 11.33%, 2.67%, and 5,374.29 Kcal/kg, respectively. The characteristics of the solid fuel comply with SNI 8966:2021, except for the fixed carbon content. Based on the Kruskal-Wallis test, the fuel compositions for the characteristics of water content, volatile matter, ash, and calorific value are significantly different, with values of 0.035, 0.056, 0.041, and 0.016. Based on Spearman rank correlation analysis, water and ash contents decreased as the percentage of plastic increased, with correlation coefficients of -0.753 and -0.302. Meanwhile, the calorific value and volatile matter increased, with correlation coefficients of 0.811 and 0.972.

Aluminum (Al) holds a pivotal role in augmenting the energetic potential of solid fuel formulations. Its incorporation can notably amplify the energy yield upon combustion. Nevertheless, challenges such as ignition delay and incomplete combustion have hindered its optimal utilization. In the context of hybrid rocket propulsion, where reignition and high regression rates are sought, a promising solution lies in harnessing the potential of metal-fluoropolymer combinations. This paper explores the influence of polytetrafluoroethylene (PTFE) and Viton fluoropolymer additives on the combustion and regression rates of hydroxyl‑terminated polybutadiene (HTPB)-based solid fuels loaded with nano-aluminum (nAl). To comprehensively address these objectives, binary composites of nAl-PTFE and nAl-Viton were prepared using high-energy ball-milling, and the resulting mixtures were incorporated into hydroxyl‑terminated polybutadiene (HTPB)-based fuel through a vacuum-casting technique. The ignition and combustion characteristics of the solid fuels, as well as the post-combustion products, were examined using an opposed flow burner setup to gain insights into their oxidation and combustion mechanisms. The findings demonstrate that the inclusion of PTFE and Viton in nAl has a positive impact on the ignition delay time, combustion behavior, and regression rates of the solid fuels. The HTPB-nAl-PTFE(S3) sample exhibited the shortest ignition delay time of 108 ms, outperforming the other tested samples (S1: 227 ms, S2: 182 ms, S4: 122 ms). Furthermore, the addition of nAl to pure HTPB resulted in an average regression rate of 0.3–0.6 mm/s for HTPB-nAl (S2), representing a two fold improvement compared to pure HTPB-based samples. Compared to the baseline HTPB fuel, HTPB-nAl-PTFE(S3) demonstrated a significant increase in regression rate by approximately 178%, while HTPB-nAl-Viton(S4) exhibited an increased regression rate of 122%. These results highlight the positive influence of fluoropolymers on combustion behavior, ultimately enhancing the overall performance of the fuel. Additionally, the study observed gas-phase reactions during the combustion process, including the reaction between nano-aluminum (nAl) and fluoride, the intermediate product of Al oxidation, and the decomposition products of fluoride. These reactions resulted in the faster fracture of the alumina (Al2O3) shell, leading to improved heat release and regression rate performance.

Although current EU regulations, such as EU Directive 2015/1189 on the eco-design of solid fuel boilers and Directive 2015/1188, in accordance with the Machinery Directive 2006/42/EC, require manufacturers to meet specific emission requirements for CE marking, the routine and regular onsite testing of household heating appliances is still not mandatory in many EU countries. This research endeavour addressed this gap by evaluating the effectiveness of the Bacharach method as a rapid and cost-effective tool for assessing flue gas quality, particularly in terms of particulate matter mass concentration. This study also compared the results of the Bacharach method with those obtained from two commercially available portable analysers. The research outcomes demonstrate that the Bacharach method, in combination with an innovative evaluation approach, offers a viable solution, enabling the swift and economical assessment of flue gas quality with the primary objective of determining the boiler class according to the limits specified by standard EN 303-5 under operating conditions. The modified Bacharach method for measuring TSP in solid fuel-fired boilers provides qualitatively similar results to the commercially used SM500 and STM225 instruments. The modified Bacharach methodology was primarily developed for comparison to the boiler class 3 limit (i.e., 125 and 150 mg/m3). The study revealed that the modified Bacharach method, when applied to biomass-based boilers, exhibited higher accuracies in the case of classification into classes 3 and 4, whereas fossil fuel-based boilers demonstrated higher accuracy in the case of class 5 limits. [ABSTRACT FROM AUTHOR]

The physical characteristics of solid biofuel under combustion in a Rijke tube installation have been studied. A decrease in the flame temperature and an increase in the heat flux density on the tube wall on the occurrence of vibrating combustion were detected. To study vibrating combustion under conditions close to practical use in power plants, experiments were carried out on a "container–tube" type installation. The optimal parameters of the installation for the implementation of vibrating combustion of solid biofuels were obtained. A theoretical model of the development of sound disturbances of a combustion wave has been developed and its influence on heat transfer characteristics has been elucidated. An empirical-theoretical relationship has been obtained for calculating heat transfer in a Rijke tube during vibrating combustion. A model is proposed for calculating the amplitude of disturbances for instabilities in "container–tube" installations. [ABSTRACT FROM AUTHOR]

This paper describes a new active method of controlling the position of the burning surface of a solid fuel strand in an opposed-flow burner experiment. This method is designed to avoid biases to the combustion process introduced by retaining wires and to avoid experimental delays caused by wire failures. Regression rates are presented for hydroxyl-terminated polybutadiene fuel strands burning in various oxidizer streams. The active control method uses a control loop composed of a diode laser, a photodiode, and a stepper motor. For comparison, tests were also performed using the commonly used passive control method of spring-loading the fuel against a retaining wire. This active control method can only be used at high values of oxidizer mass flux; at low mass flux, soot accumulation obstructs the laser beam. In passive control tests, the retaining wire conducts heat from the flame into the fuel and increases regression rate. The presence of the wire also modifies the extinction limits of the flame. A model was developed for regression rate as a function of oxidizer mass flux, oxidizer composition, and retaining wire diameter. This model can be used to correct future regression rate data for the bias introduced by retaining wires. [ABSTRACT FROM AUTHOR]

The stalks left after harvesting corn, tomatoes, and tobacco have no further use and are usually burned on agricultural land. In our work samples of this waste were collected and pyrolyzed at 400 ℃ for 30 min in a nitrogen atmosphere. The solid residue (biochar) obtained by pyrolysis was analyzed, and the results were compared with widely used solid fuels such as wood, coal, coke and charcoal. The heat values of biochar from tomato, tobacco, corn ZP 6263, and corn BC 398 stalks were 24.12, 23.09, 26.24 and 25.78 MJ kg-1, respectively. These values are significantly higher than the heat value of wood, which is about 12.50 MJ kg-1. The ash content of biochar was 12-20 %, which is consistent with the ash content of solid fuels. No heavy metals were found in biochar samples. The results show that biochar obtained from the pyrolysis of agricultural waste, such as tomatoes, tobacco and corn stalks, has good potential for use as a solid fuel. [ABSTRACT FROM AUTHOR]

This study explores the hydrothermal carbonization (HTC) process applied to the exhausted chestnut produced by the tannin extraction industry, utilizing process water recirculation to enhance the efficiency and sustainability of the conversion process. Tannin extraction from wood typically involves hot water treatment, leaving behind residual wood biomass known as exhausted wood. These by-products maintain their renewable properties because they have only been exposed to hot water under a high pressure, which is unlikely to cause major alterations in their structural components. Hydrothermal treatment was carried out at temperatures of 220 °C and 270 °C for 1 h, with process water being recirculated four times. This investigation focused on analyzing the effects of recirculation on the yield and fuel properties of hydrochar, as well as characterizing the combustion behavior of the obtained hydrochar. The results indicated that recirculation of process water led to improvements in both the mass and energy yields of hydrochar. The mass yield of the hydrochar samples increased by 5–6%, and the ERE of the hydrochar samples increased by 5–8% compared to the HTC reference sample. However, alterations in the combustion characteristics were observed, including decreases in ignition temperature and combustion reactivity. The results indicate that, with PW recirculations, the combustion index decreased by about 14% and 18% for 220 °C and 270 °C, respectively. Overall, this research demonstrates the potential of utilizing HTC on chestnut tannin residue with process water recirculation to produce stable solid fuel and provides insights into the combustion behavior of the resulting hydrochar. [ABSTRACT FROM AUTHOR]

Combustion of biomass, including charcoal releases harmful pollutants that not merely contribute to household and outdoor air pollution, particularly in rural regions, but also imposes significant risks on human health. Due to the rising concerns on the increasing severity of environmental pollution, some countries have established benchmarks on pollutant emissions based on governmental health guidelines. In this paper, a numerical study of thermal performance and emissions was performed in a digital charcoal stove model using the commercial software ANSYS Fluent 2024 R1. The main objective of this study is to comprehend the effect of the variation of air inlet velocity on determining the optimum operating conditions. A 2D digital charcoal stove was constructed and non-premixed combustion model was employed for simulating the data. Variation of the amount of emissions was performed by changing the velocity of air inlet, (0.02-0.045m/s) while maintaining a constant fuel inlet velocity of 0.04m/s, under air and fuel temperatures (300 and 400K). The results showed a decreasing trend in maximum mass fraction of CO2 with increasing air inlet velocity up to 0.045m/s, then remained stable. Additionally, at an air inlet velocity of 0.02m/s, the stove achieved a maximum temperature of 1820K and the lowest CO/CO2 ratio, showing that this condition is optimal as it provided the highest combustion efficiency. [ABSTRACT FROM AUTHOR]

This paper presents the results of three-dimensional computational modeling of processes in the combustion chamber of a hybrid solid-fuel engine. Polymethylmethacrylate was used as a solid fuel, and air was used as an oxidizer. In the model used, the heated oxidizer in gaseous form was fed into the combustion chamber at supersonic speed. As a result of the interaction of the oxidizer with the surface of the solid fuel, it begins to warm up and decompose with the release of flammable gases. The geometry of the combustion chamber and solid fuel was based on experimental work. The results of a series of calculations for various geometries of the combustion chamber were presented. The distribution of physical parameters corresponding to the diffusion mode of combustion was obtained. [ABSTRACT FROM AUTHOR]

Spent mushroom substrate (SMS), often disregarded as waste despite its abundance in organic matter and mineral micronutrients, has emerged as a valuable resource for diverse applications. While Europe and Asia have witnessed extensive research in this field over the past decade, Ukraine's exploration remains limited. This study conducts a thorough investigation into SMS recycling and reutilization over a 4-year period. Employing experimental and comparative methods, this research unveils compelling insights into the potential of SMS for reintroduction into the primary production cycle and secondary activities. The main conclusions reveal the success of SMS valorization in the production of additives, fertilizers, and alternative fuels. Furthermore, the application of SMS in agroecosystems significantly enhances the soil biological activity. The integration of these methods into production chains not only yields economic benefits for companies but also fosters environmental stewardship, aligning with waste-free practices and the principles of bioeconomy and sustainability. [ABSTRACT FROM AUTHOR]

BackgroundThis study aimed to explore the effect of household solid fuel usage on the multimorbidity trajectories among middle-aged and older adults.MethodsBased on the 2011–2018 China Health and Retirement Longitudinal Study, the group-based trajectory modeling and the multinomial logistic regression model were used to explore the relationship between multimorbidity trajectories of older adults with different fuel types, duration of solid fuel usage, and potential interaction with PM2.5. Three multimorbidity trajectory patterns were identified by group-based trajectory modeling and labeled as “non-chronic morbidity” (no disease increase), “newly developing multimorbidity” (diseases grew from 0 to 2), and “multi-chronic multimorbidity” (diseases grew from 2 to 4).ResultsCompared to “Non-chronic morbidity,” solid fuel was significantly associated with adverse multimorbidity trajectories, with an odds ratio (OR) and 95% confidence interval (CI) of 1.33 (1.11, 1.60) and 1.35 (1.18, 1.55) for newly developing and multi-chronic group, respectively. An adverse multimorbidity trajectory tended to be established with longer durations of solid fuel usage than “Non-chronic morbidity.” For “Newly-developing multimorbidity,” the ORs (95% CI) for 1–7 years and ≥ 8 years of solid fuel usage were 1.16 (0.94, 1.42) and 1.41 (1.12, 1.76), respectively, with P trend=0.001, while in “Multi-chronic multimorbidity,” those were 1.25 (1.07, 1.47) and 1.68 (1.41, 2.00), respectively, with P trend

Abstract The association between cooking fuel and hearing loss still needs more research to clarify, and two longitudinal cohort studies were explored to find if solid fuel use for cooking affected hearing in Chinese adults. The data from Chinese Health and Retirement Longitudinal Survey (CHARLS) and Chinese Longitudinal Healthy Longevity Survey (CLHLS) were analyzed. Participants (older than 18) without hearing loss at baseline and follow-up visits were included, which were divided into clean fuel and solid fuel groups. Hearing loss rate was from follow-up visits (both in year 2011) until the recent one (year 2018 in CHARLS and 2019 in CLHLS). Cox regressions were applied to examine the associations with adjustment for potential confounders. Fixed-effect meta-analysis was used to pool the results. A total of 9049 participants (average age 8.34 ± 9.12 [mean ± SD] years; 4247 [46.93%] males) were included in CHARLS cohort study and 2265 participants (average age, 78.75 ± 9.23 [mean ± SD] years; 1148 [49.32%] males) in CLHLS cohort study. There were 1518 (16.78%) participants in CHARLS cohort and 451 (19.91%) participants in CLHLS cohort who developed hearing loss. The group of using solid fuel for cooking had a higher risk of hearing loss (CHARLS: HR, 1.16; 95% CI 1.03–1.30; CLHLS: HR, 1.43; 95% CI 1.11–1.84) compared with the one of using clean fuel. Pooled hazard ratio showed the incidence of hearing loss in the solid fuel users was 1.17 (1.03, 1.29) times higher than that of clean fuel users. Hearing loss was associated with solid fuel use and older people were at higher risk. It is advised to replace solid fuel by clean fuel that may promote health equity.

Objectives In the context where the greenhouse gas (GHG) emissions from livestock manure (LSM) account for more than half of the GHG emissions in the livestock sector, it is necessary to find alternatives to composting due to the decrease in agricultural land. This study aims to calculate the GHG reduction contribution and economic benefits when converting LSM into solid fuel as an alternative to traditional composting. Methods The study compares the results of converting the entire LSM generated domestically into solid fuel replacing it with hard coal for fuel (HC-F), bituminous coal for raw materials (BC-R), bituminous coal for fuel (BC-F). The GHG reduction contribution is calculated following the domestic GHG inventory methodology, using the IPCC guidelines and the method for calculating carbon emission reduction effects. For the assessment of economic benefits, were evaluated by aggregating the impacts of reducing coal imports and GHG reduction benefits in line with EU-ETS standards. Economic benefits are assessed by combining the effects of avoiding coal imports and the GHG reduction benefits according to the EU-ETS. Results and Discussion The GHG reduction effect was found to be highest when replacing with HC-F, and this is attributed to the lower heating value and higher GHG emission coefficient of HC-F compared to BC-R, and BC-F, indicating that the substitution with HC-F is most effective in terms of import avoidance. If 20% of the annual coal consumption in 2022 is replaced with solid fuel from LSM, the GHG reduction effects for coal substitution are 1.4% for HC-F, 2.1% for BC-R, and 1.9% for BC-F based on the LSM generation CO2 emissions from biomass fuel are considered climate-neutral and are excluded from the national total emissions. Solid fuel from LSM serves as an alternative in addressing the GHG generated during the LSM treatment process, contributing to potential reduction. If all generated LSM is replaced with HC-F, BC-R, or BC-F, there are respective GHG reduction effects of 13,193,591 tGHG, 11,320,572 tGHG, and 11,226,331 tGHG. Conclusion In 2018, the livestock sector accounted for approximately 42% of the GHG emissions in the agricultural sector, totaling 9.4 million tCO2 eq. Assuming the complete conversion of LSM into solid fuel for coal substitution, regardless of the type of coal replaced, it offsets the entire GHG emissions from the agricultural sector. Currently, there is limited demand for the conversion of LSM into solid fuel due to a lack of proof and awareness, but with some coal-fired power plants scheduled for partial shutdown and the government considering energy options for LSM, a promising stage is anticipated in the future for the substitution and expanded use of solid fuel from LSM in place of coal in the coal fuel. Although it may not be possible to entirely replace the coal used in power plants and steel mills with solid fuel from LSM, it can be utilized by increasing the proportion of coal blending. However, even if not reported in the national GHG inventory, the treatment of pollutants generated by solid fuel combustion remains an ongoing challenge. As solid fuel becomes more commonplace in the future, a comprehensive assessment of the entire process, including potential environmental impacts throughout the life cycle, will be necessary to establish a basis for GHG reduction measures.

The association between cooking fuel and hearing loss still needs more research to clarify, and two longitudinal cohort studies were explored to find if solid fuel use for cooking affected hearing in Chinese adults. The data from Chinese Health and Retirement Longitudinal Survey (CHARLS) and Chinese Longitudinal Healthy Longevity Survey (CLHLS) were analyzed. Participants (older than 18) without hearing loss at baseline and follow-up visits were included, which were divided into clean fuel and solid fuel groups. Hearing loss rate was from follow-up visits (both in year 2011) until the recent one (year 2018 in CHARLS and 2019 in CLHLS). Cox regressions were applied to examine the associations with adjustment for potential confounders. Fixed-effect meta-analysis was used to pool the results. A total of 9049 participants (average age 8.34 ± 9.12 [mean ± SD] years; 4247 [46.93%] males) were included in CHARLS cohort study and 2265 participants (average age, 78.75 ± 9.23 [mean ± SD] years; 1148 [49.32%] males) in CLHLS cohort study. There were 1518 (16.78%) participants in CHARLS cohort and 451 (19.91%) participants in CLHLS cohort who developed hearing loss. The group of using solid fuel for cooking had a higher risk of hearing loss (CHARLS: HR, 1.16; 95% CI 1.03–1.30; CLHLS: HR, 1.43; 95% CI 1.11–1.84) compared with the one of using clean fuel. Pooled hazard ratio showed the incidence of hearing loss in the solid fuel users was 1.17 (1.03, 1.29) times higher than that of clean fuel users. Hearing loss was associated with solid fuel use and older people were at higher risk. It is advised to replace solid fuel by clean fuel that may promote health equity. [ABSTRACT FROM AUTHOR]

BACKGROUND: Globally, a substantial burden of disease is attributable to environmental risk factors including indoor air pollution. Nearly half of the world's population relies on solid fuel. Almost all (98.8%) residents in Ethiopia are dependent on biomass fuel as their basic source of energy for cooking. Thus, we set out to quantify the concentration of indoor air pollutants and household exposures in different housing characteristics and cooking conditions METHODS: A survey was conducted in 280 randomly selected households in Jimma town, Ethiopia. A real-time concentration of fine particulate matters (PM2.5, PM10) and pollutants including carbon monoxide (CO), carbon dioxide (CO2), and volatile organic compounds (VOC) were measured using Laser PM2.5 Meter-5800D/5800E and Aeroqual's TM series 500 portable air quality monitors. Data on housing characteristics, kitchen configuration, and ventilation status were collected using observation checklist. RESULTS: The median concentrations of pollutants in all measured households were PM2.5; 294 µg/m³, PM10; 270 µg/m³, CO2; 577 mg/m³, CO; 7.9 mg/m³, and VOC; 1077 mg/m³. Households that used solid fuels had significantly higher concentration of PM2.5 (U = 53.0, p < 0.001), PM10 (U =63.0, p < 0.001), CO2 (U = 3519.50, p < 0.001), and CO (U = 3246.0, p < 0.001) than households that used clean fuel. CONCLUSIONS: All households in this study were exposed to high concentration of indoor air pollutants that exceeded WHO's air quality standard. Effective strategy should be put in place to reduce the emission of air pollutants and to set air quality management and improvements policy. [ABSTRACT FROM AUTHOR]

Solid fuel (SF) combustions, including coal and biomass, are important sources of pollutants in the particle and gas phase and therefore have significant implications for air quality, climate, and human health. In this study, we systematically examined real-time gas-phase emissions using the Vocus proton20 transfer-reaction time-of-flight mass spectrometer, from a variety of solid fuels, including beech logs, spruce and pine logs, spruce and pine branches and needles, straw, cow dung, and coal. The average emission factors (EFs) for organic gases ranged from 6.7 to 74.2 g kg-1, depending on the combustion phases and fuel types. Despite slight differences in modified combustion efficiency (MCE) for some experiments, increasing EFs for primary organic gases were observed with lower MCE. The CxHyOz family is the most abundant group, but a greater contribution of nitrogen-containing species and CxHy families (related to polycyclic aromatic hydrocarbons) could be found in cow dung burning and coal burning, respectively. Intermediate volatility organic compounds (IVOCs) also constituted a considerable fraction in solid-fuel combustions (from 12.6% to 39.3%), especially for spruce and pine branches and needles (39.3%), and coal (31.1%). Despite the large variability of EFs in the organic gas emissions, the relative contribution of different classes showed large similarities between the combustion phases in beech stove burning. The product from pyrolysis of coniferyl-type lignin and the extract of cedar pine needle were identified as characteristic compounds in the spruce and pine branches and needles open burning (e.g., C10H14O2, C11H14O2, C10H10O2). The characteristic product (C9H12O) from the pyrolysis of beech lignin was identified as the characteristic compound for beech log stove burning. Many series of nitrogen-containing homologues (e.g., C10H11-21NO, C12H11-21N, C11H11-23NO and C15H15-31N) and nitrogen-containing species (e.g., acetonitrile, acrylonitrile, propanenitrile, methylpentanenitrile) were specifically identified in cow dung burning emissions. Polycyclic aromatic hydrocarbons (PAHs) with 9-12 carbons were identified with significantly higher abundance from coal burning compared to emissions from other studied fuels. The composition of these characteristic organic vapors reflects the burned fuel types and can help constrain emissions of solid fuel burning in regional models. [ABSTRACT FROM AUTHOR]

The aim of this study was the characterization and evaluation of applicability as a soil amendment of biochar derived from rose pruning waste at different pyrolysis temperatures (200–500 °C) and process durations (20–60 min). The biochar properties were compared to the raw material. The biochars produced at 300 °C for 40 and 60 min demonstrated the best fuel properties. These variants showed high energy gain rates (77.6 ± 1.5% and 74.8 ± 1.5%, respectively), energy densification ratios (1.35 ± 0.00 and 1.37 ± 0.00, respectively), high heating values (24,720 ± 267 J × g−1 and 25,113 ± 731 J × g−1, respectively), and relative low ash contents (5.9 ± 0.5% and 7.1 ± 0.3%, respectively). Regarding fertilizer properties, such as pH value, ash content, heavy metal content, and pollutant elution, the biochars showed better qualities than the raw material. All tested biochar did not exceed the permissible values for heavy metals, including Cr, Cd, Ni, and Pb. The most optimal properties for soil amendments were noted for biochar variants of 400 °C for 40 min, 450 °C for 20 min, and 500 °C for 20 min. Generally, biochars produced at temperatures ≥400 °C did not inhibit root elongation, except for the material produced at 450 °C for 60 min (4.08 ± 23.34%). Biochars obtained at ≥300 °C showed a positive impact on seed germination (86.67 ± 18.48–100 ± 24.14%). [ABSTRACT FROM AUTHOR]

The current research focuses on the efficiency of energy recovery from non-hazardous organic wastes. It entails the generation of low-chloride refuse-derived fuel (RDF) from municipal solid waste (MSW) through moderate pyrolysis of combustible components. The moderate pyrolysis settings and composition ratio of biogenic/non-biogenic content from MSW combination (food waste, plastic waste, and paper waste) had a significant impact on the thermochemical characteristics and fuel behavior of RDF. Furthermore, pyrolysis with optimal MSW composition was studied to reduce toxic elements (chlorides, sulphides, and nitrides) and enhance the energy value in RDF by utilizing potassium-rich (waste orange peels (OP); banana peels (BP); and maize cob (MC)) and calcium-rich species (waste animal bone meal (ABM); egg shells (ES); and mussel shells (MS)) as natural additives. The results showed that increasing the pyrolysis temperature maximized the carbon concentration with reduced oxygen moieties (low O/C ratio), indicating a high energy value as the oxygenates were eliminated during moderate pyrolysis. The RDF treated at 400 °C (SF4-400) with MSW composition of 55% non-biogenic carbon and 45% biogenic carbon resulted in HHV of 29.22 MJ kg−1, the lowest ash concentration (0.96%), and a densified microstructural surface. The addition of natural maize cob additive into MSW (SF4-400-MC) yielded the maximum HHV (33.07 MJ kg−1) with considerable reductions in chlorides (71.43%), sulphides (87.50%), and insignificant nitrides content, all of which meet ASTM RDF quality criteria Grade I. [ABSTRACT FROM AUTHOR]

The utilization of biomass resources could optimize the energy consumption structure and achieve the goal of carbon neutrality. Torrefaction and densification pretreatment could improve the defects of high oxygen content, low energy density, and low bulk density of biomass. In this work, high-density and hardness pellets were prepared by torrefaction coupling densification (in-situ torrefaction-densification without binders). In-situ torrefaction-densification significantly reduced the pressure required for the densification process. In-situ torrefaction-densification lowered the pressure required to prepare RH pellets with a bulk density of 1000 kg/m3 from 88.23 MPa to 30.95 MPa. The effects of the in-situ torrefaction-densification method and pelletizing pressure on the pellet combustion process were investigated by non-isothermal and isothermal combustion. The volatile and carbon of TCDP could be burned intensively during combustion, and the emissions of CO and C x H y were reduced during combustion. The original structural strength of TCDP was still maintained in the combustion process. The alkali metal K in TCDP was difficult to escape, effectively reducing the emission of K in the flue gas. In-situ torrefaction-densification could not only improve the quality of biomass solid fuel but also facilitate the storage and transportation of biomass solid fuel. [Display omitted] • The volatile and carbon of pellets could be burned intensively by in-situ torrefaction-densification pretreatment. • Emissions of CO and C x H y were reduced during TCDP combustion. • The in-situ torrefaction-densification inhibited the release of K during combustion. [ABSTRACT FROM AUTHOR]

The use of solid fuel (dirty fuel) that includes firewood, coal, charcoal, crop residue, kerosene, and dung cake is hazardous to human health and the environment. Therefore, it is crucial to understand the factors influencing the household-level transition to clean fuel. Against this backdrop, the present study analyzes the clean fuel choice and consumption intensity using the latest HIES 2018–2019 data. Findings revealed that 76 and 14% of households in Pakistan use dirty cooking fuel in rural and urban areas, respectively. In addition, choices of fuel for cooking, heating, and lighting fuel vary across provinces. Probit and Tobit model shows that income, wealth, urban location, small family size, and fewer women and children influence households’ transition towards clean fuel. The study underscores the importance of tailored policies, including tariff structures, pricing mechanisms, and financial incentives, to accelerate the adoption of energy-efficient and clean technologies. These recommendations aim to drive sustainable energy access, economic growth, and environmental sustainability in Pakistan. [ABSTRACT FROM AUTHOR]

The results of the study of CFD model of TPP-210A type boiler, built according to the working drawings of TPP-210a. st.n. 3 of Trypillya thermal power plant are presented in the paper. The scientific novelty of the work consists in determining the perspective of using non-design types of fuel, such as gas coal of domestic production and solid biomass, as the raw material base of the TPP-210a boiler, which is part of the energy equipment of the Trypillya TPP of Ukraine. Modeling of solid fuel combustion was carried out using finite-element CFD models of the boiler unit in the ANSYS-Fluent Student software complex with the determination of the relevant characteristics of the boiler. The verification was performed for the case of burning anthracite wood. In the presented work, visualization of the fields of velocities and temperatures of reacting flows in the middle of the furnace was used to analyze the results of CFD modeling. The analysis of the visualization of the interaction between fuel and oxidizer, the release of volatile compounds and the degree of carbon burning in the central section of the fuel boiler unit was also performed. It was determined that the presence of a narrowing of the section of the fuel above the burners leads to uneven energy release on the walls of the boiler unit. It is shown that the deviation of the temperature values in the middle of the CFD model of the fuel from the data taken from the available literature does not exceed 8 %, which allows using a developed computer model for simulating the combustion of domestically produced solid fuel, which differs from the design model in terms of general and specific properties. The verified computer model of the TPP-210a boiler, art. no. 3 of the Trypillya TPP will make it possible to draw up a mode map of boiler operation during solid fuel burning and obtain data for further adjustment of indicators of normative characteristics of boiler operation. [ABSTRACT FROM AUTHOR]

The mechanism of erosive combustion of gunpowder and its consideration in solid propellant rocket engines are analyzed. The issues of the influence of erosive combustion of a solid fuel on changes in the thrust of a jet penetrator engine are considered. A mathematical model is presented for calculating changes in parameters of the intra-chamber process over time, taking into account their changes along the length of the charge for an engine with a freely inserted tubular charge. The obtained calculation results confirm the significant influence of the charge temperature on the intra-ballistic parameters of the penetrator. [ABSTRACT FROM AUTHOR]

Increasing production of municipal solid waste (MSW) drives the need for its disposal in a manner that is safe for the environment and human health. However, this may require short- or long-term storage before it can be properly processed. Similarly, a way of processing waste material is necessary for the re-cultivation of dump sites. This article presents the results of an investigation into the effects of long-term open-air storage upon waste material to be turned into refuse-derived fuel (RDF) by standard methods for the assessment of MSW and RDF pellet quality including bomb calorimetry, sieve analysis, furnace drying/burning for water/ash content assessment, and pellet expansion measurements. Results of the investigation indicate that such a form of storage bears no notable negative effect on the quality of the material; the pellet expansion coefficient, heat of combustion, and ash content were all found to be approximate to pre-storage values, with positive implications for the storage of solid waste and the prospects of its subsequent processing into solid fuel. It is shown that such material can be stored in open-air conditions for prolonged periods without the loss of desired parameters. In addition, a discussion of differences between the properties of material drawn from varying depths of the pile is provided and the potential impact of the findings in the context of the production and the storage of refuse-derived fuel is assessed. [ABSTRACT FROM AUTHOR]

Abstract Background In low- and middle-income countries, households mainly use solid fuels like wood, charcoal, dung, agricultural residues, and coal for cooking. This poses significant public health concerns due to the emission of harmful particles and gases. To address these issues and support Sustainable Development Goals (SDGs), adopting cleaner cooking fuels like electricity and gas are acknowledged as a viable solution. However, access to these cleaner fuels is limited, especially in rural areas. Methods This study conducted a face-to-face survey with 1240 individuals in rural Bangladesh to explore the link between health issues and cooking fuel type, as well as barriers to transitioning to clean cooking. Using a convenient sampling technique across four divisions/regions, the survey gathered socio-demographic and health data, along with information on clean cooking barriers through a semi-structured questionnaire. Binary and multivariable logistic regression analyses were then employed to identify significant associations between cooking fuel type and health problems. Results The study revealed that a majority of participants (73.3%) relied on solid fuel for cooking. The use of solid fuel was significantly correlated with factors such as lower education levels, reduced family income, location of residence, and the experience of health issues such as cough, chest pressure while breathing, eye discomfort, diabetes, asthma, and allergies. Economic challenges emerged as the foremost obstacle to the adoption of clean cooking, accompanied by other contributing factors. Conclusion The use of solid fuel in rural Bangladeshi households poses substantial health risks, correlating with respiratory, eye, cardiovascular, and metabolic issues. Lower education and income levels, along with specific residential locations, were associated with higher solid fuel usage. Economic challenges emerged as the primary obstacle to adopting clean cooking practices. These findings emphasize the need for implementing strategies to promote clean cooking, address barriers, and contribute to achieving Sustainable Development Goal targets for health and sustainable energy access in Bangladesh.

Abstract Background Indoor air pollution causes severe psychological stress and promotes depression. A better understanding of the impact of solid fuel consumption and socioeconomic indicators on mental health is critical to promote successful aging. In this study, we analyzed the relationship of depression with socioeconomic status (SES) and solid fuel use, and illustrated the mediating role of solid fuel use in the relationship between SES and depression. Methods 9250 participants from the 2018 wave of the Chinese Longitudinal Healthy Longevity Survey were included in this study. A logistic regression analysis was used to calculate odds ratio (OR) and 95% confidence interval (CI) of depression for different types of fuel consumption. The stepwise approach and the Sobel test were used to test the mediation effect. Results Older people who reported the consumption of solid fuels showed higher odds of having depressive symptoms (OR = 1.16, 95% CI:1.03, 1.31). In model with depression as the outcome variable, the ORs of low education level and low annual household income level were 1.30 (95% CI: 1.15, 1.47) and 1.43 (95% CI: 1.28, 1.59) respectively. Solid fuel consumption accounted for 38.40% of the effect of a low education level and 54.73% of the effect of low income on depression. Conclusions Solid fuel use and SES are associated with depression, and solid fuel use may act as a potential mediator connecting socioeconomic indicators and depression.

The high frequency of rocket launches requires low-cost solid rocket fuel. Currently, the fuel manufacturing process faces increased launch costs caused by the risk of ignition from rotary mixers and increased equipment and labor costs from batch processes in which mixing and conveying are separated. Therefore, this paper proposes and verifies an automatic switching system between mixing and conveying modes for a peristaltic mixing conveyor that enables safe and continuous mixing and conveying of solid fuel. In a previous study, peristaltic mixing conveyor with low shear force was developed and successfully produced solid fuel. However, there was room for improvement for more efficient fuel production because the device was controlled by pre-determined driving pattern. The actual intestine generates movement autonomously by enteric nerves. Therefore, the development of a sensing function that imitates the enteric nervous system and generates movement patterns based on the acquired data is expected to improve manufacturing efficiency. In this study, the sensor data of a mixed solid fuel simulant packaged in a bag were acquired, and the degree of mixing (unmixed and mixed completely) was discriminated using supervised learning (the k-nearest neighbor method). Furthermore, a system was constructed to continue the mixing mode when unmixing and automatically switch the motion to the conveying mode when the mixing was complete. The experiment showed that the motion mode automatically switched to the conveying mode at almost the same time as the labeled training data, and mixing and conveying of the simulated material was successfully performed.

. Currently, the transition to alternative fuel during the operation of thermal power plants (TPP) occurs due to the reduction and unreliability of coal supplies, deterioration of its quality, proposals for the use of cheaper fuel, tightening environmental requirements. Alternative fuel means such coal, for the use of which the boilers have not been designed during their design or reconstruction, as well as coal that has not previously undergone industrial or experimental combustion at this TPP. When converting boilers to alternative fuels, the main problems are: slag of the furnace shields and heating surfaces located above the furnace; fouling of convective heating surfaces; instability of non-designed fuel combustion; abrasion of the convective part of boilers; reduction of environmental performance; change in operating conditions of dust preparation, slag removal, ash collection and fuel supply systems. Before conducting experimental combustion of alternative fuels, it is advisable to carry out a preliminary assessment of its combustion possibility using numerical simulation, which makes it possible to identify emerging problems in advance. The most important factor in assessing the possibility of using alternative fuels is the influence of thermal performance, fuel and ash characteristics on the slagging of heating surfaces in the furnace. For a long time, the ability of ash to slagging was determined by the results of a fusibility test by changing the shape of a pyramid of ash particles during its gradual heating to various states according to the specific temperatures, viz. the initial deformation temperature, the softening temperature, the hemispherical temperature. The fusibility test cannot predict the real situation that occurs during the boiler operation. In addition, it does not allow ranking coals according to their tendency to slagging, which is necessary for the preliminary selection of alternative coal. Therefore, it is proposed to use the Watt - Fereday method with Bomkamp’s refinement for calculating the slagging index for ranking coals according to suitability as non-design fuels.

. Currently, there is a tendency to diversify the generation of heat and electricity and to improve solid fuel technologies. These trends actualize the search for mathematical tools for describing and predicting the operation of apparatuses with a fluidized bed of dispersed fuel materials. However, since the mechanics of heterogeneous media (and dispersed media in particular) is to a certain extent in its infancy in relation to the mathematical foundations of modeling, it is often difficult to predict the operation of equipment. In particular, the poor quality of mathematical basis does not allow predicting the fields of concentrations and velocities of the phases of the fluidized bed, although this knowledge serves as the fundamental basis for calculating heat and mass transfer and chemical processes. In the present work, a computational and experimental study of the local hydromechanical characteristics of a monodisperse fluidized bed has been carried out. The mathematical apparatus of the theory of Markov chains was used as a basis for modeling. The tasks were solved in a one-dimensional formulation, which implied the division of the bed in height into cells of small but finite sizes. Fluidized bed phase distributions were described by state vectors whose evolution was controlled by transition probability matrices. The elements of these matrices were matched to the physical parameters of the processes. The model was verified by comparing the calculated predictions with the data of a full-scale experiment conducted as part of the study, aimed at measuring the local velocities of the gas phase inside the fluidized bed. The experimental data with a good accuracy for engineering calculations were described by the proposed model, which makes it possible to consider it as a reliable scientific basis for the computer method for calculating installations using the fluidization technique.

Background. The study is relevant due to a significant number (more than 74 thousand) of autonomous heat sources (AHS) in the Russian Federation, especially in its eastern regions. Such sources use solid fuels (coal). AHS, along with other heat and power objects, make a considerable contribution to ambient air pollution in the ground layers and consequently produce harmful effects on public health. The aim of this study was to perform hygienic assessment of negative effects produced by autonomous heat sources (AHS) on ambient air quality, health risks and additional associated incidence on the example of a territory included into the Clean Air Federal project. Materials and methods. We calculated dispersion of pollutants in ambient air in residential areas due to AHS; performed hygienic assessment of calculated and instrumental data on ambient air quality; assessed public health risks; identified the number of additional associated diseases in accordance with the conventional established methods and algorithms valid at the present moment. Results. More than 170 AHS are located on the analyzed territory; they all use soli fuel (coal). Hygienic standards are violated in areas influenced by AHS for four out of sever chemicals emitted by chimneys of private houses. Pollutant levels reach 5.1 single maximum MPC for four pollutants according to dispersion calculation; 4.8 single maximum MPC, 38 average daily MPC and 4.7 average annual MPC for four pollutants according to instrumental data; 29.9 single maximum MPC, 3.5 average daily MPC and 7.0 average annual MPC for three pollutants according to verified data. Identified carcinogenic, acute, and chronic health risks are ranked as ‘alerting’ and ‘high’ in areas under direct influence of AHS; these risks reach 13.4 HQ (acute), 7.0 HQ (chronic), CRT 1.19∙10-7 (carcinogenic). AHS create more than 11 thousand additional respiratory diseases (6,379.9 cases per 100 thousand people); of them, 98% cases are registered in children. Conclusion. AHS create high levels of exposure to harmful pollutants and elevated health risks as well as additional incidence associated with ambient air quality. This situation requires immediate attention of the local authorities, control and surveillance organs; it is necessary to develop and implement complex air protection activities as soon as possible.

Background: In low- and middle-income countries, households mainly use solid fuels like wood, charcoal, dung, agricultural residues, and coal for cooking. This poses significant public health concerns due to the emission of harmful particles and gases. To address these issues and support Sustainable Development Goals (SDGs), adopting cleaner cooking fuels like electricity and gas are acknowledged as a viable solution. However, access to these cleaner fuels is limited, especially in rural areas. Methods: This study conducted a face-to-face survey with 1240 individuals in rural Bangladesh to explore the link between health issues and cooking fuel type, as well as barriers to transitioning to clean cooking. Using a convenient sampling technique across four divisions/regions, the survey gathered socio-demographic and health data, along with information on clean cooking barriers through a semi-structured questionnaire. Binary and multivariable logistic regression analyses were then employed to identify significant associations between cooking fuel type and health problems. Results: The study revealed that a majority of participants (73.3%) relied on solid fuel for cooking. The use of solid fuel was significantly correlated with factors such as lower education levels, reduced family income, location of residence, and the experience of health issues such as cough, chest pressure while breathing, eye discomfort, diabetes, asthma, and allergies. Economic challenges emerged as the foremost obstacle to the adoption of clean cooking, accompanied by other contributing factors. Conclusion: The use of solid fuel in rural Bangladeshi households poses substantial health risks, correlating with respiratory, eye, cardiovascular, and metabolic issues. Lower education and income levels, along with specific residential locations, were associated with higher solid fuel usage. Economic challenges emerged as the primary obstacle to adopting clean cooking practices. These findings emphasize the need for implementing strategies to promote clean cooking, address barriers, and contribute to achieving Sustainable Development Goal targets for health and sustainable energy access in Bangladesh. [ABSTRACT FROM AUTHOR]

Background: Indoor air pollution causes severe psychological stress and promotes depression. A better understanding of the impact of solid fuel consumption and socioeconomic indicators on mental health is critical to promote successful aging. In this study, we analyzed the relationship of depression with socioeconomic status (SES) and solid fuel use, and illustrated the mediating role of solid fuel use in the relationship between SES and depression. Methods: 9250 participants from the 2018 wave of the Chinese Longitudinal Healthy Longevity Survey were included in this study. A logistic regression analysis was used to calculate odds ratio (OR) and 95% confidence interval (CI) of depression for different types of fuel consumption. The stepwise approach and the Sobel test were used to test the mediation effect. Results: Older people who reported the consumption of solid fuels showed higher odds of having depressive symptoms (OR = 1.16, 95% CI:1.03, 1.31). In model with depression as the outcome variable, the ORs of low education level and low annual household income level were 1.30 (95% CI: 1.15, 1.47) and 1.43 (95% CI: 1.28, 1.59) respectively. Solid fuel consumption accounted for 38.40% of the effect of a low education level and 54.73% of the effect of low income on depression. Conclusions: Solid fuel use and SES are associated with depression, and solid fuel use may act as a potential mediator connecting socioeconomic indicators and depression. [ABSTRACT FROM AUTHOR]

Objective To explore the relationship between body mass index (BMI), household fuel type, and peak expiratory flow (PEF) in middle-aged and elderly Chinese people aged 45 and above. Methods Based on the data of China Health and Retirement Longitudinal Study in 2013 and 2015, the BMI and PEF of the participants were measured and evaluated. Ac- cording to the self-reported household fuel types, cooking and heating fuels were divided into solid fuel and clean fuel. Lin- ear mixed model was used to analyze the relationships of BMI and household solid fuels using with PEF changes, and residential location was included as a random term. Subgroup analysis and interaction analysis were conducted by gender, urban-rural setting, smoking status, and fuels types. Results There was a significant correlation between the reduction of BMI and PEF (B=-1.33, 95%CI: -2.31 to -0.33). Compared with the group using clean fuel, the PEF of the group using solid fuel decreased faster than that of the group using clean fuel (cooking: B=-10.16, 95%CI: -16.78 to 3.55; heating: B=-10.13, 95% CI: -18.70 to -1.46). Solid fuels use for heating increased the magnitude of BMI-related PEF decline (interaction P= 0.030). Conclusion High BMI and solid fuel use are the risk factors for the reduction of PEF in the middle-aged and elderly in China, and there is an interaction between BMI and solid fuel for heating on the reduction of PEF. [ABSTRACT FROM AUTHOR]

BACKGROUND AND OBJECTIVES: The decreasing availability of fossil fuels requires the adoption of renewable energy sources that facilitate the mitigation of greenhouse gas emissions. Meeting Indonesia's goal of achieving a 23 percent mixed energy composition by 2025 through co-firing demands a substantial increase in the availability of renewable energy sources. Bamboo is a valuable biomass resource because of its fast growth rate and potential for energy production. Innovative processes like torrefaction are necessary to improve the quality of biomass due to its challenging low density and hydrophilic properties. The objective of this study is to evaluate the characteristics of torrefied bamboo pellets made from Gigantochloa pseudoarundinacea by using a fixed counter-flow multi-baffle reactor. This study aims to investigate the properties and viability of torrefied G. pseudoarundinacea pellets for solid fuel applications to fill existing knowledge gaps about this technology's potential. METHODS: A fixed counter-flow multi-baffle reactor was used to torrefy G. pseudoarundinacea bamboo pellets. The baffles in the reactor column held the pellets, while hot gas flowed through them. Torrefaction was conducted at 280 degrees Celsius with a 3-5 minutes resident time, and the gas flow rate was 4.25 cubic meters per minute. Torrefied pellets at the column bottom were counted as the first cycle. Three cycles of torrefaction were used, and each cycle was evaluated. The second and third cycles used torrefied pellets from the first and second cycles. The physical, chemical, and bioenergetic properties of the pellets before and after torrefaction were evaluated. FINDINGS: The bamboo pellets' physical, chemical, and thermal properties changed significantly after torrefaction. Torrefaction at 285 degrees Celsius produced 78.5 percent of the production yield, according to thermogravimetric and derivative thermogravimetric analyses. Lightness, red/green, and yellow/blue chromaticity decreased, indicating darker, better solid fuel pellets. Torrefaction in the third cycle reduced moisture content by 99.8 percent. The lower moisture content reduced fungal growth, and improvinged biomass transport and storage. Torrefaction also raised the bamboo pellets' calorific value and physical and mechanical properties. The highest calorific value of 21.62 megajoules per kilogram was obtained after the third cycle of torrefaction, and it was 16.6 percent higher than that of raw pellets. Torrefaction improved pellet grindability and combustion by decreasing density and compressive strength. Torrefaction increased ash, volatile matter, and fixed carbon. The ultimate analysis showed increased carbon and reduced nitrogen, hydrogen, and oxygen, improving solid fuel quality, energy density, and combustion emissions. According to a Fourier-transform infrared analysis, torrefaction caused extractive and hemicellulose degradation and lignin increase. The chemical analysis showed that temperature and residence time degraded hemicellulose and increased lignin in the torrefied pellets. CONCLUSION: The torrefaction process using a fixed counter-flow multi-baffle reactor demonstrated the enhanced properties of G. pseudoarundinacea bamboo pellets for their application as solid fuel. The study's findings contribute to the comprehension of torrefaction and the enhancement of conditions for producing superior biomass products. These findings have implications for exploring the potential applications of torrefaction in diverse industries and energy sectors. [ABSTRACT FROM AUTHOR]

Boron carbide (B4C) is known for its exceptional hardness and high energy release during combustion, despite its ignition processes presents considerable challenges. This study focuses on exploring the potential of B4C as an enhancer for the energy output of solid fuels designed for hybrid rocket engines (HRE) or solid fuel ramjets (SFRJ). This study presents the successful incorporation of B4C and fluorinated PTFE (polytetrafluoroethylene) polymer into the HTPB (hydroxyl‐terminated polybutadiene) fuel matrix, aiming to enhance the ignition, combustion, and regression rate performance of solid fuel. Five different fuel compositions were formulated with varying mass ratios of B4C, and their post‐combustion products were characterized using XRD (X‐ray diffraction), HRSEM (high‐resolution scanning electron microscopy), and EDS (energy‐dispersive X‐ray spectroscopy) techniques. The HRSEM‐EDS analysis confirmed a uniform dispersion of B4C/PTFE additives throughout the HTPB matrix. To evaluate the combustion behavior of the B4C/PTFE additives, an opposite flow burner was employed with a gaseous oxygen oxidizer. The F4 fuel sample, loaded with B4C/PTFE (10/20), exhibited an average regression rate increase ranging from 0.61 to 1.15 mm/s when evaluated within the oxidizer flux range of 36–77 kg/m2s, in comparison to that of pure HTPB (0.4 mm/s to 0.76 mm/s). The ignition delay time was investigated as a key parameter affected by the B4C concentration in the solid fuel formulations. Furthermore, a comprehensive combustion mechanism is proposed and discussed for B4C/PTFE loaded in the HTPB matrix under an oxygen environment. [ABSTRACT FROM AUTHOR]

A total of 37.5 million tons of palm empty fruit bunches (EFBs) produced in Indonesia in 2018 have the potential to be used as an alternative eco-friendly solid fuel. However, a pretreatment process is necessary to increase the heating value and reduce the potassium content of EFBs. Several methods can be employed to improve the characteristics of EFBs as a solid fuel, such as drying and torrefaction to increase the heating value and the leaching process for reducing the potassium content of EFBs. The main concept of increasing the heating value is to increase the fuel content, which is carbon. Through drying, the carbon ratio can be increased by reducing the moisture content and, through torrefaction, the carbon ratio could be increased due to the decomposition of lignocellulose. A simple way to reduce the potassium content of EFBs is the leaching process. Two types of leaching treatment have been studied before: soaking and stirring treatment. This study reviews those methods to make EFBs more suitable as a solid fuel with a high heating value and less potassium content. Increasing the carbon content in EFBs is crucial for enhancing their heating value as a fuel. Drying and torrefaction decrease the moisture content and modify the chemical structure, resulting in higher carbon ratios. The leaching process effectively reduces the potassium content of EFBs and stirring treatment is more effective than immersion treatment. Torrefaction positively affects leaching by decreasing the potassium content, while hydrophobicity may hinder leaching by repelling water. The high moisture content of leached EFBs requires additional energy for evaporation during torrefaction, resulting in a lower energy density yield compared with raw EFBs. Adjustments may also be required to account for the decreased mineral content, which functions as a torrefaction catalyst in EFBs that have not been leached. [ABSTRACT FROM AUTHOR]

Background The prevalence of hypertension in population is still increasing by year, and the significant increase in the prevalence of chronic diseases caused by aging of the population results in a serious medical burden. There are still about 450 million people in China who use solid fuels for cooking or heating, causing indoor air pollution as an important public health problem in China. At present, the relationship between solid fuels use and the risk of hypertension in Chinese older adults still remains unclear. Objective To analyze the association between solid fuels use and the risk of hypertension in older adults in urban and rural areas of China through a prospective cohort study, so as to provide a theoretical basis for the prevention and treatment of hypertension in the elderly. Methods This study is a prospective cohort study. Data were obtained from 2011 to 2018 China Longitudinal Healthy Longevity Survey (CLHLS) by using baseline questionnaire and physical examination. A total of 1 453 non-hypertensive older adults aged 65 years and above from 2011 to 2012 cohort were included in the study, and the occurrence of hypertension during follow-up was considered as the outcome indicator, follow-up as of 2018-12-31. The included subjects were divided into the clean fuel (electrical appliances such as induction cooker, pipeline natural gas, solar energy) group (n=654) and solid fuel (charcoal, kerosene, coal, firewood) group (n=799). Multivariate Cox proportional hazard regression model was used to analyze the association between cooking with solid fuels and the risk of hypertension. Results A total of 1 453 non-hypertensive older adults at baseline with an average age of (77.6±8.8) years and a median follow-up of 7 years, and a total of 838 people developed hypertension at the outcome. The results of this study showed that the proportion of cooking with solid fuels in rural areas was significantly higher than that in urban areas (70.3% vs. 1.1%, P

The purpose of the work is to select replacing design coal possible options for low slagging potential reasons in the furnace and on adjacent heating surfaces. Solved problems: the main slagging indices (SI) are summarized, based on considering the two main parameters of the formation of ash deposits, namely viscosity and fusibility. An analysis of existing methods for assessing slagging processes of heating surfaces in steam power boilers was carried out. The scientific goal is achieved by the proposed method of ranking coals according to their slagging tendency on power boiler heating surfaces based on their physicochemical properties. The methodology is based on the slagging potential dependence of the fusibility and viscosity ash characteristics, considering the ratio of the ash percentage content to the heating value of coal. The most important result is ranking of 28 coals of various grades (subbituminous, bituminous, anthracite) burned at Russian power plants according to their tendency to form ash deposits on the furnaces of power boilers. The significance of the results obtained lies in the identification of two coal deposits, subbituminous Irsha-Borodinsky and Berezovsky in Easten Siberia and Kuznetsky bituminous in Western Siberia, which are universal during the transition to burning non-design fuel from the slagging potential point of view. The dependences of the change in ash viscosity and SI on the and ratios in ash for Irsha-Borodinsky and Moscow region coals were under consideration. It was concluded that the value of the SI is directly proportional to the load ash content and could differ more by an order of magnitude for different coals.

Abstract Background Exposure to air pollution brings the advent effect for various diseases, but study about the relationship between air pollution and ageing is scant. We aimed to determine the associations between household air pollution for cooking and heating with muscle and sarcopenia in Chinese older population by a nationally representative study. Methods This cross‐sectional study included individuals aged 60 and above from the China Health and Retirement Longitudinal Study between 2011 and 2015. The diagnosis of sarcopenia was defined by low muscle mass with low muscle strength and/or reduced physical performance. Generalized additive analyses and dose‐dependent analyses with three models were used to assess the effects of different pattern of cooking and heating on muscle and sarcopenia. Results A total of 8126 Chinese older individuals with predominant male (53.7%) and mean age of 67.3 ± 6.0 years were included in our study. Solid fuel use in cooking showed significant declines in muscle strength (β = −0.424, 95% CI: −0.767, −0.082, P = 0.01 in model 3) and mass (β = −0.034, 95% CI: −0.051, −0.017, P