Search Results (78)

The use of sustainable energy sources is an alternative for fossil fuels, which can represent a positive factor to alleviate many current environmental issues. In that sense, not only sustainable industrial development is important, but also sustainable practices at the local level, including households. Specifically, heating and cooking are one of the most important activities that require energy in households, where the role of biomass could be of interest, as it can provide an energy source with lower environmental impact. However, there is room for improvement in biomass stoves, whose adaptability to specific wastes, as well as their improvement in efficiency, should be accomplished. The aim of this work was to assess the improvement of combustion performance of a domestic stove by the implementation of a programmable logic converter for a better adaptation to different biomass samples (holm oak, pear tree, poplar, and sugarcane bagasse pellets). This work provides further information about the current working protocol, being an alternative for better approaches that could be implemented in future works. Thus, the working regime of the stove was controlled, especially concerning the screw conveyor (to regulate pellet feeding) and flue gas fan (to change oxygen supply). As a result, better combustion performances were obtained, with heat capacities from 5.66 to 8.67 kW for the selected samples. Also, thermal capacities of the stove (1.43, 1.60, 2.22, and 1.83 kW for holm oak, pear tree, poplar, and sugarcane bagasse, respectively) were obtained, with a better combustion performance compared to previous studies (1600 and 120 ppm peak emissions for CO and NO_x, respectively, and 15% as the lowest O₂ concentration). On the other hand, different improvements of the combustion stove to avoid blockages, for instance, are proposed as further steps. Full article

This study evaluated the suitability of two types of beech wood pellets as renewable, low-emission biofuel sources in order to combat the energy mix and poor air quality in Serbia. Key solid biofuel characteristics, including the heating values (18.5–18.7 MJ/kg), moisture content (5.54–7.16%), and volatile matter (82.4–84.4%) were assessed according to established standards. The elemental composition (mass fractions of 48.26–48.53% carbon, 6% hydrogen, 0.12–0.2% nitrogen, 0.02% sulfur, non-detected chlorine) and ash content (0.46–1.2%) demonstrated that the analyzed beech pellets met the criteria for high-quality classification, aligning with the ENplus A1 and ENplus A2 standards. The emissions of O₂, CO₂, CO, NO_x, SO₂, and TOC were quantified in the flue gas of an automatic residential pellet stove and compared with the existing literature. While combustion of the beech pellets yielded low emissions of SO₂ (6 mg/m³) and NO_x (188 mg/m³), the fluctuating CO (1456–2064 mg/m³) and TOC (26.75–61.46 mg/m³) levels were influenced by the appliance performance. These findings underscore the potential of beech wood pellets as a premium solid biofuel option for Serbian households, offering implications for both end-users and policymakers. Full article

A couple of air quality (AQ) parameters were monitored with two types of low-cost sensors (LCSs) before, during and after the garden fence rebuilding of a dwelling house, located at the junction of a main road and a side street in a suburban area of Budapest, Hungary. The AQ variables, recorded concurrently indoors and outdoors, were particulate matter (PM₁, PM_2.5, PM₁₀) and some gaseous trace pollutants, such as CO₂, formaldehyde (HCHO) and volatile organic compounds (VOCs). Medium-size aerosol (PM_2.5-1), coarse particulate (PM_10-2.5) and indoor-to-outdoor (I/O) ratios were calculated. The I/O ratios showed that indoor fine and medium-size PM was mostly of outdoor origin; its increased levels were observed during the renovation. The related pollution events were characterized by peaks as high as 100, 95 and 37 µg/m³ for PM₁, PM_2.5-1 and PM_10-2.5, respectively. Besides the renovation, some indoor sources (e.g., gas-stove cooking) also contributed to the in-house PM₁, PM_2.5-1 and PM_10-2.5 levels, which peaked as high as 160, 255 and 220 µg/m³, respectively. In addition, these sources enhanced the indoor levels of CO₂, HCHO and, rarely, VOCs. Increased and highly fluctuating VOC levels were observed in the outdoor air (average: 0.012 mg/m³), mainly due to the use of paints and thinners during the reconstruction, though the use of a nearby wood stove for heating was an occasional contributing factor. The acquired results show the influence of the fence renovation-related activities on the indoor air quality in terms of aerosols and gaseous components, though to a low extent. The utilization of high-resolution LCS-assisted monitoring of gases and PM_x helped to reveal the changes in several AQ parameters and to assign some dominant emission sources. Full article

Biomass, due to its neutrality in terms of greenhouse gas emissions into the atmosphere during its life cycle, is considered an interesting renewable source for energy production as an alternative to the use of more polluting fossil fuels. Among the different wood fuels, pellets are convenient for use in dedicated stoves, and pellet heating systems have a high energy efficiency. The aim of this work was to estimate the economic and global warming potential (GWP100a) generated along the thermal energy supply chain of wood pellets, starting from the production of raw biomass from dedicated poplar cultivations and ending with the use of pellets in stoves by the end-user to produce thermal energy and ash. The Eco-Efficiency Indicator (EEI) was used to link the economic and environmental performance for eight proposed scenarios, obtained by combining different levels of mechanisation for poplar harvesting and wood biomass management before arrival at the pellet plant. For the thermal energy produced by the poplar wood pellet, the GWP100a ranged from 1.5 × 10⁻² to 2.1 × 10⁻² kg CO₂−eq MJ⁻¹ for three-year-old plantations and from 1.9 × 10⁻² to 2.4 × 10⁻² kg CO₂−eq MJ⁻¹, for six-year-old plantations. In terms of eco-efficiency of the baseline scenario (EEIb), the most favourable scenarios remain those linked to the use of biomass from three-year-old poplar plantations, with EEIb values ranging from 0.31 to 0.60 € kgCO₂−eq⁻¹, compared to from 0.29 to 0.36 € kgCO₂−eq⁻¹ for pellets obtained from biomass produced from six-year-old poplar plantations. In terms of the Global Eco-Efficiency Indicator (EEIg), which also takes into account the positive effect on the reduction of greenhouse gases due to the storage of carbon in the soil by the plantations and the reduction of emissions from avoided fossil fuels, the most favourable scenarios remain those linked to the use of biomass from three-year-old poplar plantations, with EEIg values that vary in the range of 0.60 ÷ 1.04 € kgCO₂−eq⁻¹, compared to 0.55 ÷ 0.62 € kg CO₂−eq⁻¹ for thermal energy obtained using biomass from six-year-old poplar plantations. Full article

The stress corrosion cracking during the operation of the internal combustion hot blast stove was analysed. The computational fluid dynamics and finite element analysis models were established to analyse the temperature, stress and other variables related to the condensation of the water and acids. The corrosion characteristics of condensation of acid and the stress corrosion cracking of the metallic shell of the hot blast stove during the operation were predicted by applying the fluid temperature and mapping it to the solid temperature. The stress corrosion cracking surface mobility mechanism was adopted and modified with a weight concept to consider the effect of the acid condensation and its concentration. The regions that have higher crack propagation rates were analysed. The influence of the increase in the blast temperature on the crack propagation rate was studied with the increase in the blast temperature by 45 K and 90 K from the reference blast temperature. The maximum temperature of the refractory linings was 1847 K in the on-gas period, and the maximum change in the shell temperature was 5.2 K when the blast temperature was increased by 90 K. The maximum crack propagation rate for the reference blast temperature was evaluated as $7.61\times {10}^{-7}$ m/s. The maximum value of the crack propagation rate was increased by 16.7% when the blast temperature increased by 90 K. The conical region was found to have higher crack propagation rates, which means that the conical region should be the region of interest for managing the internal combustion hot blast stoves. Full article

Combustion optimization of hot blast stoves is a promising approach for cost savings and energy conservation of ironmaking. Existing artificial intelligence methods for this optimization rely on air and gas flow meters, which can malfunction under harsh working conditions. To meet this challenge, we propose an intelligent combustion control system based on reinforcement learning (RL). Considering the difficulty of learning state feature representation, five RL models using different deep embedding networks were implemented and evaluated. The Attention-MLP-based RL model is distinguished through experimental testing, achieving an accuracy of 85.91% and an average inference time of 4.85 ms. Finally, the intelligent combustion control system with the Attention-MLP-based RL model runs in the hot blast stove of the blast furnace (1750 m³ in volume) at Tranvic Steel Co., Ltd. in China (Chengdu, China). The results show that our system can achieve good control performance by autonomously learning the implicit relationship between the state of the hot blast stove and the valve control action in the absence of flow meters. Full article

Based on the three-dimensional (3D) steady-state CFD numerical simulations conducted previously on an industrial Kalugin top combustion hot blast stove, a two-dimensional (2D) transient CFD numerical model for a single channel (hole) of a column of checker bricks in the regenerator of the same hot stove was established in the present work. The average mass flowrate and temperature of the flue gas flowing into the checker brick holes during the combustion period predicted by the 3D model were used as the inlet boundary conditions of the 2D model. Inside the hole of the checker bricks, processes of fluid flow and heat transfer of the flue gas during the combustion period and those of cold air during the hot-air-supply period were simulated using the 2D model for multiple operation cycles (combustion and hot-air-supply periods) of the hot stove, enabling rapid predictions of hot-air temperature under different operating conditions. The simulation results show that when the fuel gas flowrate and air consumption coefficient during the combustion period are controlled within the range of 80,000–100,000 Nm³/h and 1.02–1.28, respectively, a hot-air temperature in the range from 1273 °C to 1295 °C can be obtained during the hot-air-supply period. Applying this optimized operating condition to the industrial hot stove investigated in this study can achieve significant effects of reducing fuel gas flowrate by 8.6% and increasing hot-air temperature by 32 °C. In addition, a regression analysis on the numerical simulation results and the data measured from the industrial hot stove yields a roughly linear relationship between the dome temperature during the combustion period and the hot-air temperature during the hot-air-supply period, that is, the hot-air temperature would be increased by about 16 °C for every increment of 10 °C in the dome temperature, for instance. Therefore, the influences of the operating parameters on heat transfer characteristics in the regenerator and on hot-air temperature obtained in the present work provide a useful reference for guiding the hot stove operation optimization to achieve significant energy saving and emission reduction through facilitating more efficient combustion to minimize fuel gas consumption in steel plants. Full article

In order to explore the indoor air quality during different cooking procedures, a very common kitchen in China is selected for experimental research. An indoor air quality meter is used to measure the temperature, relative humidity, and CO and CO₂ concentrations of the indoor air above the stove when people cook four different dishes under different ventilation patterns in the kitchen. The results indicate that the heat and gas consumed during cooking are closely related to the temperature and concentrations of CO and CO₂. Some cooking procedures such as boiling water are related to the indoor air temperature and relative humidity in the kitchen. In addition, in kitchens without mechanical ventilation, natural ventilation shows a more significant positive effect on controlling temperature, relative humidity, and concentrations of CO and CO₂ during cooking procedures. Full article

Gas-fired boilers, gas stoves, and wall-mounted gas boilers are the main consumers of gas fuel, but they generally encounter problems when operating at high altitudes, such as reduced thermal efficiency and increased pollutant emissions. Previous studies on gas combustion characteristics under sub-atmospheric pressure were mostly carried out in a large space, which is quite different from chamber combustion equipment. Therefore, it is insufficient to guide the design and operation optimization of plateau gas equipment. In this paper, experimentations were carried out to explore the characteristics of a methane diffusion flame under sub-atmospheric pressures. The mass flow rates of methane and air remain consistent under different pressure conditions. The centerline temperature ($T_c$) distribution, flame appearance, smoke point, CO emission, and NO_x emission under different pressures (ranging from 61.66 to 97.75 kPa) were examined under both fuel rich and lean conditions. The results show that $T_c$ at the rear and front of furnace variation with pressure is opposite under fuel-lean and -rich combustion. The $T_c$ at the front of furnace decreases with decreasing pressure, whereas $T_c$ at the rear of furnace increases with decreasing pressure. With decreasing pressure, flame length decreases under lean combustion, but increases under rich combustion. The smoke point fuel flow rate, flame length, and residence time increases with decreasing pressure, following the law of negative exponent. The CO emission decreases with decreasing pressure, which indicates that the reduced pressure makes methane combustion more complete. For NO emission, the reduced pressure results in an opposite tendency under fuel-lean and -rich combustion. With decreasing pressure, the NO emission decreases under fuel-lean combustion but increases under fuel-rich combustion. Full article

Biomass as a renewable energy resource is a major topic on a global scale. Several types of biomass heat treatment methods have been introduced to obtain useful byproducts via pyrolysis. Microwaves are a practical replacement for conventional stoves and ovens to perform pyrolysis of biomass. Their rapid heating rate and user-friendliness make them a good choice for the pyrolysis process over conventional methods. The current study reviewed research articles that used microwaves for the pyrolysis process on different types of biomass. This study primarily provides comprehensive details about the pyrolysis process, especially microwave-assisted pyrolysis (MAP) and its feasibility for treating biomass. A systematic literature review, according to the PRISMA guidelines, was performed to find research articles on biomass treatment using MAP technology. We analyzed various research studies (n = 32), retrieved from different databases, that used MAP for pyrolysis on various types of biomass, and we achieved good results. The main goal of this study was to examine the usefulness of the MAP technique, comparing its effects on distinguished types of biomass. We found MAP’s effective parameters, namely, temperature, concentration of microwave absorber, moisture percentage of starting material and flow rate, microwave power and residence time of the initial sweep gas that control the pyrolysis process, and effect quality of byproducts. The catalytic agent in MAP pyrolysis was found to be useful for treating biomass, and that it has great potential to increase (nearly double) the production yield. Although MAP could not be used for all types of materials due to some challenges, it produced good results compared to conventional heating (pyrolysis) methods. We concluded that MAP is an effective method for reducing pyrolysis reaction time and improving the quality of value-added products. Also, MAP eliminates the shredding requirement for biomass and improves heating quality. Therefore, it is a viable method for reducing pyrolysis processing costs and should be applied on a larger scale than lab scale for commercialization. Full article

In this study, the temperature and thermal stress fields of an internal combustion hot blast stove were calculated and analysed. Turbulent, species transport, chemical reaction, radiation, and porous media models were implemented in a computational fluid dynamics model. Thermal boundary conditions on the structure of the hot blast stove were calculated based on the analytic adiabatic Y-plus method. A method to interpolate the thermal boundary conditions to a finite element mesh was developed, and the boundary conditions were mapped through the proposed method. In the on-gas period, the vortex was generated in the dome, and it made the variation of the temperature field in the checker chamber. The maximum temperature of the flue gas reached 1841 K in the on-gas period. In the on-blast period, the flow was considerably even compared to the on-gas period, and the average blast temperature reached 1345 K. The outer region of the checker chamber is shown to be continuously exposed to a higher temperature, which makes the region the main domain in managing the deterioration of the refractory linings. The shell temperature did not change during the operation due to the lower thermal diffusivity of the refractory linings, where the inner surface of the refractory had a maximum temperature change from 1441 K to 1659 K. The maximum temperature of the shell was 418.4 K at the conical region of the checker chamber side. The conical region had the higher maximum and middle principal thermal stresses due to the presence of a large temperature gradient around the conical region, where the largest maximum and middle principal stresses were 300.6 MPa and 192.0 MPa, respectively. The conical region was found to be a significant area of interest where it had a higher temperature and thermal stress. Full article

As part of the United Nations’ (UN) Sustainable Development Goal 7 (SDG7), SDG target 7.1 recognizes universal electrification and the provision of clean cooking fuel as two fundamental challenges for global society. Faltering progress toward SDG target 7.1 calls for innovative technologies to stimulate advancements. Hydrogen has been proposed as a versatile energy carrier to be applied in both pillars of SDG target 7.1: electrification and clean cooking. This paper conducts a semi-systematic literature review to provide the status quo of research on the application of hydrogen in the rationale of SDG 7.1, covering the technical integration pathways, as well as the key economic, environmental, and social aspects of its use. We identify decisive factors for the future development of hydrogen use in the rationale of SDG target 7.1 and, by complementing our analysis with insights from the related literature, propose future avenues of research. The literature on electrification proposes that hydrogen can serve as a backup power supply in rural off-grid communities. While common electrification efforts aim to supply appliances that use lower amounts of electricity, a hydrogen-based power supply can satisfy appliances with higher power demands including electric cook stoves, while simultaneously supporting clean cooking efforts. Alternatively, with the exclusive aim of stimulating clean cooking, hydrogen is proposed to be used as a clean cooking fuel via direct combustion in distribution and utilization infrastructures analogous to Liquid Petroleum Gas (LPG). While expected economic and technical developments are seen as likely to render hydrogen technologies economically competitive with conventional fossil fuels in the future, the potential of renewably produced hydrogen usage to reduce climate-change impacts and point-of-use emissions is already evident today. Social benefits are likely when meeting essential safety standards, as a hydrogen-based power supply offers service on a high tier that might overachieve SDG 7.1 ambitions, while hydrogen cooking via combustion fits into the existing social habits of LPG users. However, the literature lacks clear evidence on the social impact of hydrogen usage. Impact assessments of demonstration projects are required to fill this research gap. Full article

In recent years we have seen a growing number of applications that use various sensory measurements of physicochemical features. Within the research project “Research on the identification of combustion of unsuitable fuels and systems of self-diagnostics of boilers combustion solid fuels for domestic heating”, the authors tested and evaluated the possible use of an air quality monitoring sensor unit for the measurement of operating parameters of solid fuel burning boilers and stoves. In the Czech Republic, programs to support citizens in the replacement of domestic boilers of poor combustion quality have been subsidized for several years. Unfortunately, no assessment of the impact of subsidies on air quality has been carried out. However, the increased pollutant emissions due to improper use of domestic boilers are supposed to be one of the greatest problems with domestic boilers. Hence, providing users with real-time feedback may lead to changes in combustion conditions and consequently to a reduction in air pollution. We focus on sensory measurements of CO, CO₂, NO, and VOCs as compounds that correspond to the operating conditions of the combustion process. The research included sampling, construction of the flue gas dilution duct, and the influence of direct measurement on the service life of the sensors. Full article

Air pollutants from the incomplete combustion of rural solid fuels are seriously harmful to both air quality and human health. To quantify the health effects of different fuel–stove combinations, gas and particle partitioning of twenty-nine species of polycyclic aromatic hydrocarbons (PAHs) emitted from seven fuel–stove combinations were examined in this study, and the benzo (a) pyrene toxicity equivalent (BaPeq) and cancer risks were estimated accordingly. The results showed that the gas phase PAHs (accounting for 68–78% of the total PAHs) had higher emission factors (EFs) than particulate ones. For all combustion combinations, pPAHs accounted for the highest proportion (84.5% to 99.3%) in both the gas and particulate phases, followed by aPAHs (0.63–14.7%), while the proportions of nPAHs and oPAHs were much lower (2–4 orders of magnitude) than pPAHs. For BaPeq, particulate phase PAHs dominated the BaPeq rather than gas ones, which may be due to the greater abundance of 5-ring particle PAHs. Gas and particle pPAHs were both predominant in the BaPeq, with proportions of 95.2–98.6% for all combustion combinations. Cancer risk results showed a descending order of bituminous coal combustion (0.003–0.05), biomass burning (0.002–0.01), and clean briquette coal combustion (10⁻⁵–0.001), indicating that local residents caused a severe health threat by solid fuel combustion (the threshold: 10⁻⁴). The results also highlighted that clean briquette coal could reduce cancer risks by 1–2 orders of magnitude compared to bulk coal and biomass. For oPAH, BcdPQ (6H-benzo(c,d)pyrene-6-one) had the highest cancer risk, ranging from 4.83 × 10⁻⁵ to 2.45 × 10⁻⁴, which were even higher than the total of aPAHs and nPAHs. The dramatically high toxicity and cancer risk of PAHs from solid fuel combustion strengthened the necessity and urgency of clean heating innovation in Guanzhong Plain and in similar places. Full article

Pellet stoves are popular appliances because they are an affordable technology and because the fuel is easy to store and to use. The increasing concern for environmental issues, however, requires a continuous effort to reduce pollutant levels in the atmosphere. This experimental work focuses on flue gas recirculation (FGR) as a possible way to improve combustion and decrease the emissions of carbon monoxide CO, particulate matter PM, and nitrogen oxides NO_x in order to fulfill European and Italian emission requirements, for NO_x in particular. A pellet stove has been tested in several experimental sessions with and without FGR. Pollutant emissions have been measured and analyzed in terms of statistical summaries and instantaneous trends. With FGR, the average CO and PM emissions were found to be 80% and 45% lower than the corresponding emissions without FGR. Results for PM are significant since FGR reduces emissions well below the most restrictive limits enforced in Italy. The analysis of instantaneous emissions in relation to excess air indicated that FGR can considerably reduce emissions, especially at the extremities of the oxygen O₂ content range. Optimal ranges of excess air, in terms of O₂ in flue gas, were identified for both the tested configurations, in which CO and PM emissions are minimized. The optimal range is 8–9% without FGR, and it decreases to 5–7% with FGR. Finally, a reduction in NO_x emissions by about 11% has been observed in the configuration with FGR. Although this reduction seems modest as compared to CO and PM, it is important in that it lowers the emission level to the most severe limit in Italian regulations and indicates an improved FGR system as the solution for further reduction. Full article