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The article analyzes the environmental costs of Diesel Multiple Unit and Diesel Railcars operated in Poland. It consisted in determining the annual cost of gases and particulate matter emitted into the ambient air by the analyzed rolling stock. For this purpose, tests were carried out on the emission of harmful exhaust gases from a railbus equipped with the most commonly used drive system. The vehicle had two identical compression ignition engines meeting the Stage IIIB standard with a displacement of 12.8 dm3. Maximum power of the engine was 390 kW at a rotational speed of 1800 rpm and a maximum torque of 2200 Nm at 1300 rpm. In order to measure harmful exhaust compounds, tests were carried out in real operating conditions using Portable Emission Measurement System (PEMS) equipment. The tests carried out in track conditions showed that the rail vehicle did not meet the approval limits for nitrogen oxides (real value -- 2.43 g/kWh, emission standard -- 2.0 g/kWh). However, it should be remembered that the limit values are established in stationary tests and not in actual operating conditions. In the next stage, the annual emissions of rail buses operating in Poland were estimated. For this purpose, data from the Office of Rail Transport on the number of vehicles registered in the country and the average distance traveled by the vehicles were used. The data obtained indicate that the vast majority (over 98%) of environmental costs are costs related to carbon dioxide emitted into the atmosphere. [ABSTRACT FROM AUTHOR]

AbstractThe objective of this study is to investigate the potential of combined pond fly ash (PFA) and flue gas desulfurization gypsum (FGDG) as a partial replacement for cement by mixing them with fine river sand for green mortar development. We studied the physical, mechanical, and microstructural properties of mortars by using techniques such as scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (SEM-EDXS) and X-ray diffraction (XRD) for chemical component identification of the hydrated phase. These experimental results show that mortar containing pond fly ash, FGDG, and cement concentrations of 5 wt%, 5 wt%, and 90 wt% yields the maximum compressive strength (8.9 MPa) and flexural strength (3.4 MPa) after 28 days. This mortar has 12.6% higher compressive strength and 48% lower shrinkage in comparison with control specimens. A reduction in shrinkage is attributed to the denser structure of the mortar, as the calcium silicate hydrate (C–S–H) gel is found to exist in the SEM image and also identified through XRD studies. It is also concluded that excessive ettringite formation causes expansion in the volume of mortar, voids formation, and results in the reduction of strength. The application of this mortar can be in the internal plaster, bricks, and masonry. [ABSTRACT FROM AUTHOR]

CO2 capture and reduction with H2 (CCR) to synthesise CH4 over dual-functional materials (DFMs) possessing CO2 capture and hydrogenation abilities has recently attracted attention as a promising methodology for utilising low-concentration CO2 in air or exhaust gases without pressure and/or temperature swing operations. Much effort has been devoted to the development of Ni-based DFMs for the CCR of CH4 formation owing to their low cost and high catalytic potential for methanation. However, previous studies have been investigated under relatively high reaction temperatures (400–600 °C) and/or pressurised H2 conditions. In addition, experiments were conducted in the absence of O2 in the simulated CO2 gas. The development of efficient Ni-based DFMs under milder and more realistic reaction conditions is still necessary. In this study, we developed La-modified Al2O3-supported Ni nanoparticles (Ni–La(X)/Al2O3, X denotes the La loading) for the selective formation of CH4 from low-concentration CO2 (1%) in a simulated gas containing O2 (20%). The optimised Ni–La(15)/Al2O3 showed 99% selectivity for CH4 formation under isothermal (350 °C) and non-pressurised conditions. The effect of the La loading amount on the CCR performance was studied using X-ray diffraction, temperature-programmed surface reactions, and steady-state CO2 hydrogenation. Furthermore, the developed Ni–La(15)/Al2O3 was applied to direct capture of ultralow concentration CO2 in air (ambient direct air capture (DAC)) and methanation. [ABSTRACT FROM AUTHOR]

In this study, green hydrogen production by utilizing diesel engine exhaust gas waste heat in steam and organic Rankine with internal heat exchanger with two thermoelectric generators and proton exchange membrane electrolyzer combined system under different load conditions is investigated. Thermo-economic, enviro-economic and exergo-environmental analyses of the maximum hydrogen production point determined for different waste heat conditions are carried out. Total and specific investment cost and levelized cost of hydrogen determined under different loads are compared. Simple and dynamic payback period, profit ratio of investment and net present value of the combined system at different selling prices of hydrogen are determined and their feasibility is analyzed. Carbon reduction and carbon credit gain amount due to green hydrogen produced in line with zero emission targets are compared under different waste heat conditions. Exergetic sustainability index of the system were determined within the scope of exergo-environmental analysis. In terms of economic and environmental performance, a hydrogen cost of 2.04 $/kg was obtained under 100% load and a carbon saving of 7211 $ was achieved depending on the hydrogen produced. Dynamic payback period and net present value were found to be 4.467 years and 404,696 $, respectively, if the hydrogen selling price was 5 $/kg under 100% load. It is found that a 50% load reduction leads to an increase in dynamic payback period and levelized cost of hydrogen by 18.6% and 13.72%, respectively, and a decrease in net present value and profit ratio of investment by 54.39% and 12.39%, respectively. On the other hand, since the exergy destruction decreases with the decrease in the load, exergo-environmental index is found to decrease by 2.03%. • 7211 $ carbon recovery was obtained. • Dynamic payback period between 1.942 and 9.578 years was determined. • The maximum net present value reached 1,123,000 $. • Combined hydrogen production system is unfeasible if the hydrogen price is 2 $/kg. • Within the scope of sustainability, exergo-environmental indices were examined. [ABSTRACT FROM AUTHOR]

An improved method was developed to calculate direct emissions from seven municipal solid waste incineration plants by adjusting the physical compositions of waste by invoking the proportion of co-incinerated waste and the bottom ash yield. The fossil carbon fractions of the waste components were determined by carbon-14 (14C) testing. Based on the improved method, direct emissions were in the range of 222–610 kg CO2-eq/t waste, corresponding to reductions of 3.4–221 kg CO2-eq/t waste compared with the method without waste composition adjustment. The 14C contents of the flue gas before and after gas cleaning were tested to validate the improved method, and indicated fossil CO2 emissions of 249–446 and 233–405 kg CO2-eq/t waste, respectively. The direct emissions obtained by the improved method were closer to the results of 14C testing, due to more accurate estimations of the actual waste composition. The method was further combined with a life cycle analysis of the waste incineration process, obtaining total carbon emissions in the range from –33.2 to 483 kg CO2-eq/t waste. The findings provide a new means of accurately calculating carbon emissions from waste incineration. Highlights: • Co-incinerated waste and bottom ash yield were used to adjust waste composition. • Fossil carbon contents of the waste and flue gas were determined by 14C testing. • The improved method reduced fossil CO2 emissions by 3.4–221 kg CO2-eq/t waste. • Life cycle GHG emissions from waste incineration was –33.2–483 kg CO2-eq/t waste. [ABSTRACT FROM AUTHOR]

The paper presents experimental studies on the effect of co-combustion of aviation kerosene with hydrogen in the GTM400 turbojet engine on the change in the carbon footprint generated by the engine in relation to its standard operation without hydrogen in the fuel. This research is in line with current research and development trends carried out in the EU, linking them to the issues of the European Green Deal, the Fit for 55 directive and current environmental trends in aviation and energy. The main objective of the research was to check the effect of hydrogen co-combustion in a turbojet engine on the change of the carbon footprint, while a secondary objective was to verify the impact of higher exhaust gas temperatures generated by the new, high-calorific fuel on the secondary generation of nitrogen oxides (NOx), especially in the thermal mechanism, as an undesirable effect. The research shows that the co-combustion of hydrogen with aviation kerosene in a turbojet engine reduces the carbon footprint (reduction of CO2 maximum of 15% and CO emissions maximum of 24%), but also increases the emission of nitrogen oxides (NOx) maximum of 58%, including those generated in the thermal mechanism (significant increase in the temperature of exhaust gases), moreover, the increase in nitrogen oxide emissions is proportional to the amount of co-combusted hydrogen, which is directly related to the stoichiometry of the combustion process. The main conclusion of the research is that technologies for the combustion or co-combustion of hydrogen in turbojet engines require further research and development, mainly on the side of the use of excess exhaust gas temperature generated during combustion and methods of reducing secondary nitrogen oxides. [ABSTRACT FROM AUTHOR]

The intensive development of road transport has resulted in a significant increase in air pollution. This phenomenon is particularly noticeable in urban areas. This creates the need for analyses and forecasts of the scale and extent of future emissions of harmful substances into the environment. The aim of this study was to estimate the costs of the emission of toxic components of exhaust gases generated by all users of conventionally propelled vehicles travelling on a section of urban road in the next 25 years. The traffic study was carried out on an urban traffic route, playing a key role for road transport in the dimension of a given urban agglomeration. The traffic forecast for the analysed road section was based on the results of our own measurements carried out in April 2023 and external data from the General Directorate for Roads and Motorways. The results of the observations concerned six categories of vehicles for the morning and afternoon rush hours. Based on the data obtained, the generic structure of the vehicle population on the analysed section and the average daily traffic were determined. Using the methodology contained in the Blue Book of Road Infrastructure, parameters were calculated in the form of annual indicators of traffic growth on the analysed section, travel speed, and annual air pollution costs for selected vehicle categories, remembering at the same time that the Blue Book-based methodology does not distinguish between unit costs in relation to the type of emissions. The results of the study confirmed that there was an increase in the cost of toxic emissions for each vehicle category over the projected 25-year period. The largest increases were seen for trucks with trailers and passenger cars. In total, for all vehicle categories, emission costs nearly doubled from 2024 to 2046, from EUR 3,745,229 to EUR 7,443,384, due to the doubling of the number of vehicles resulting from the traffic forecast. The analyses presented here provide an answer to the question of what pollution costs may be faced by cities in which road transport will continue to be based on conventional types of propulsion. In addition, the research presented can be used to develop urban mobility transformation plans for the coming years, within the scope of the widely promoted smart city concept and the idea of electromobility, by pointing out to local authorities the direct economic benefits of these changes. [ABSTRACT FROM AUTHOR]

The increasing number of vehicles operating in Poland, especially passenger vehicles, justifies the need to conduct air pollution emission tests in the context of the impact of vehicles on the natural environment. Firstly, this article reviews the publications related to air pollutant emissions and passenger vehicles traveling on Polish roads. However, it presents a special method using advanced research equipment to determine air pollutant emissions. The above research methods are justified in implementing clean transport zones. Real Driving Emissions represent an essential procedure in the implementation of clean transport zones in Poland, verifying the actual emissions of air pollutants and modeling this phenomenon using the results of real air pollutant emissions. The results of this research state that establishing a link between a vehicle's air pollutant emissions and its age can support making transport or delivery planning more sustainable and choosing less carbon-intensive means of transport to reduce the negative impact of transport on the environment. The scientific novelty of the proposed solutions is the verification of the actual emissions of Euro 6 vehicles and the modeling of air pollutant emissions as a function of speed and acceleration. The research results are included in this article and will become input data for further analysis in examining the impact of vehicle operating age on air pollution emissions. Consequently, the novelty of the present research also lies in its focus on the verification of the impact of operating age, particularly in the context of vehicles exceeding 15 years of age, on air pollutant emissions. By establishing a correlation between a vehicle's air pollutant emissions and its operating age, it becomes possible to make transport or delivery planning more sustainable. Furthermore, the selection of less carbon-intensive means of transport can contribute to reducing the negative impact of transport on the environment. [ABSTRACT FROM AUTHOR]

To eliminate the flow dead zone and homogenize the asymmetric flow field of a grate furnace, spirally twisted tape inserts (STTIs) with a pitch ratio of 1.5 were installed in the vertical flues of an SCL1000-13.5/450 grate boiler. The arrangement schemes found to be present inside the chosen 1000 t/d grate furnace, determined using the orthogonal experimental method, included separate installation in chamber II, separate placement in chamber III, and simultaneous arrangement in both chamber II and chamber III. The effects of row spacing H, column spacing W, and mounting angle φ were investigated by means of the practicable and feasible numerical simulation method. With a focus on the uniformity degree of the flue gas, the results showed that temperature distribution is directly correlated with the velocity field. When it comes to the uniformity of the flow field, the exclusive use of STTIs in chamber II was better than that in chamber III. Under the optimal combination scheme of STTIs in both chamber II and chamber III (scheme N323), the exhaust gas temperature reached the minimum value and the uniformity index of temperature increased to the range of 0.994~0.997. The findings in this work could provide a reference for the optimization of the flow field in a grate furnace. [ABSTRACT FROM AUTHOR]

The utilization of lignocellulosic biomass for the generation of diverse value‐added biochemicals and biofuels is crucial in modern biorefineries and bioenergy initiatives, contributing significantly to the pursuit of a climate‐neutral future. Agricultural, forest and industrial sources of lignocellulosic biomass serve as exceptionally renewable precursors in biorefinery processes. In spite of its abundance, the effective breakdown of biomass poses a significant challenge. Thus, it is essential to integrate various unit processes, including biochemical, thermochemical, physical, enzymatic and catalytic conversion, to generate a wide array of bio‐based products. Intensive integration of these processes not only enhances yield and reduces reaction time but also proves to be economically efficient. Furthermore, these process integration approaches may contribute to the establishment of a circular bioeconomy through biorefineries, effectively reducing both bioresource waste and greenhouse gas emissions. This review offers fundamental insights into biomass and its chemistry, with a detailed discussion on lignocellulosic conversion systems. It explores how integrating conversion processes can facilitate the transition toward a circular economy. Additionally, it summarizes the challenges and prospects associated with advancing integrated biorefineries and circular economy principles to achieve complete biomass valorization. [ABSTRACT FROM AUTHOR]

Mersin, K. and Mısırlıoğlu, T., 2024. A new approach for calculating ship emissions and energy efficiency of a fleet using the Cobb-Douglas function. Journal of Coastal Research, 40(6), 1182–1188. Charlotte (North Carolina), ISSN 0749-0208. This paper delves into the intricate relationship between fuel consumption and CO2 emissions within the context of maritime transportation, shedding light on a formula developed by Mersin, Misirlioglu, and Alkan for calculating fuel consumption. This formula, which considers factors such as ship displacement and machinery type, offers a nuanced understanding of fuel usage in maritime operations. Furthermore, the Energy Efficiency Design Index (EEDI) is meticulously examined, delineating its mandate of setting minimum energy efficiency standards for various ship types and models based on cargo transported per ton/mile. The EEDI formula is analyzed to facilitate a comprehensive comparison with reference EEDI scores to effectively interpret data. Through this analysis, this paper offers invaluable insights into the environmental ramifications of ship emissions and underscores the critical significance of enhancing energy efficiency within maritime transportation practices. [ABSTRACT FROM AUTHOR]

Biodiesel has been chosen as a decent alternative to diesel in the context of establishing environmentally pleasant conditions and saving petroleum‐based resources for future generations. It is well‐established that biodiesel‐powered diesel engines may achieve outcomes equivalent to those of diesel engines. The current investigation was conducted to study the effect of injection pressure (190, 210, and 230 bar) and exhaust gas recirculation (EGR) (5%, 10%, and 15%) on a single‐cylinder variable compression ratio (VCR) diesel engine running using a B20 (20% MB + 80% PD) blend of microalgae biodiesel (MABD). This experiment was conducted in two stages. During the first stage of experimentation, the efficiency and emission characteristics of a diesel engine with a B20 blend of MABD at various fuel injection pressures and fresh air were investigated. During the second phase, fresh air was mixed with 5%, 10%, and 15% exhaust gases, and the experiment was conducted. It was discovered that increasing injection pressure to 230 bar provided considerable improvements. Brake thermal efficiency increased by 2.35%, brake‐specific fuel consumption decreased by 3.57% and pollutants such as carbon monoxide (CO), hydrocarbon, and smoke were reduced by more than 50% compared to conventional diesel. These reductions were similarly significant (over 22%) as compared to the B20 blend at lower injection pressure (210 bar). However, there was a slight trade‐off: nitrogen oxide (NOx) emissions increased partially (3.14%), while exhaust gas temperature (EGT) increased by 1.72% at a higher pressure. The study then investigated the influence of EGR (5%, 10%, and 15%) at various injection pressures. The optimal value seems to be 10% EGR at 230 bar injection pressure. This combination substantially reduced NOx emissions (by over 41% compared to the normal B20 blend) and EGT (by more than 8%), while having no notable effect on other performance or emission variables. Overall, the results show that employing a B20 MABD blend with high injection pressure (230 bar) and moderate EGR (10%) improves engine performance while reducing hazardous emissions. [ABSTRACT FROM AUTHOR]

Detecting dangerous gases is crucial for protecting human and environmental health. Industrial waste gases like CO, NO2, H2S, and NH3 have long been a concern for investigators. Gas sensors, particularly chemi-resistive sensors, are widely used in industries to detect leaks and manage gas concentrations. Traditional gas sensors have utilized semiconducting oxides such as SnO2, ZnO, Fe2O3, and In2O3. However, conducting polymers, like polyaniline, have emerged as ideal materials for gas sensors due to their ability to operate at room temperature. This paper investigates the simulation performance of gas sensors based on a polyaniline-graphene oxide (PANI/GO) nanocomposite, fabricated using inkjet printing. The study analyzes various factors that affect sensor performance, including responsivity, sensitivity, gas concentration, response time, and recovery time, using Atomistix ToolKit. The results show that the PANI/GO nanocomposite-based gas sensor outperforms existing nanomaterial-based sensors, demonstrating its potential as an effective candidate for detecting dangerous gases. To improve the behavior of the gas sensor, the chemicals are first synthesized, and then the composite is printed using inkjet technology. The simulation using Atomistix ToolKit allows for a comprehensive analysis of the sensor's performance, considering factors like responsivity, sensitivity, gas concentration, response time, and recovery time. Compared to existing nanomaterial-based sensors, the proposed gas sensor proves to be effective. [ABSTRACT FROM AUTHOR]

To meet the escalating electricity demand and rising fuel costs, along with notable losses in power transmission, exploring alternative solutions is imperative. Gas turbines demonstrate high efficiency under ideal International Organization for Standardization (ISO) conditions but face challenges during summer when ambient temperatures reach 40°C. To enhance performance, the proposal suggests cooling inlet air by 15°C using a vapor absorption chiller (VAC), utilizing residual exhaust gases from a combined cycle power plant (CCPP) to maximize power output. Additionally, diverting a portion of exhaust gases to drive an organic Rankine cycle (ORC) for supplementary power generation offers added efficiency. This integrated approach not only boosts power output but also minimizes environmental impact by repurposing exhaust gases for additional operations. This study presents a detailed energy and economic analysis of a modified combine cycle power plant, in Kotri, Pakistan. R600A is used as organic fuel for the ORC while LiBr-H2O solution is used for the VAC. Two performance parameters, efficiency and energy utilization factor, Four energetic parameters, Work output of ORC, modified CCPP, original CCPP and cooling rate, and one economics parameter, payback period were examined under varying ambient conditions and mass fraction of exhaust gases from outlet of a gas turbine (ψ). A parametric investigation was conducted within the temperature range of 18°C to 50°C, relative humidity between 70% and 90%, and the ψ ranging from 0 to 0.3. The findings reveal that under elevated ambient conditions (40°C, 90% humidity) with ψ at 0, the Energy Utilization Factor (EUF) exceeds 60%. However, the ORC exhibits a low work output of 100 KW alongside a high cooling load of 29,000 kW. Conversely, the modified system demonstrates an augmented work output of approximately 81,850 KW compared to the original system's 78,500 KW. Furthermore, the integration of this system proves advantageous across all metrics. Additionally, the payback period of the system is contingent on ambient conditions, with lower conditions correlating to shorter payback periods and vice versa. [ABSTRACT FROM AUTHOR]

To reduce fossil energy consumption and achieve global carbon neutrality, it is essential to develop alternative fuels such as hydrogen (H2) and dimethyl ether (DME). In order to analyze the energy-mass conversion behavior of alternative fuels for power units (including gas turbines) and to explore the principles of efficiency enhancement, the exergy loss characteristics of methane (CH4)/air laminar premixed flames blended with H2/DME were investigated. The effects of blending ratio, unburned gas temperature, operating pressure, and equivalence ratio on the exergy loss fraction were considered. The results indicated that DME and H2 had opposite effects on the total exergy loss fraction of the premixed flame. Elevating the operating pressure was beneficial to reducing the exergy loss caused by chemical reactions and exhaust gas, which more significantly enhanced the exergy efficiency of each fuel mixture compared to increasing the unburned gas temperature. The exergy loss fraction due to the exhaust gas was also lower in the lean flame, suggesting that DME could be a promising alternative to CH4 in this scenario. As the exergy loss fraction due to chemical reaction was minimized at an equivalence ratio of 1.2, a variable equivalence ratio operating strategy was expected to further optimize the exergy efficiency of each fuel mixture. Furthermore, response functions of the total exergy loss fraction, which considered the combined effects of multiple operating parameters, were constructed. These response functions allow the total exergy loss fractions of CH4 premixed flames with high DME blending ratios and moderate H2 blending ratios to be quantified. The results from this study enable a deeper understanding of the energy-mass conversion behavior of systems with added H2/DME during combustion and provide theoretical support for the application of alternative fuels to more complex configurations of industrial burners. [ABSTRACT FROM AUTHOR]

To investigate the evolution of CO and NOx pollution in the exhaust gas from diesel-powered shuttles under the double lane ventilation system of short-walled continuous mining face, this article uses a combination of numerical simulation and field tests to numerically simulate and analyze the pollution transport law of CO and NOx emitted from the shuttles at three locations: heading tunnel, contact alley and supporting tunnel. The results show that when the shuttle car in heading tunnel, the CO and NOx discharged from the shuttle discharge port move toward the exit of the tunnel at an average speed of 1.25 m/s. The high CO and NOx concentration area appears at the discharge port, with the highest CO volume fraction of 82.5 ppm and the highest NOx volume fraction of 28.25 ppm. When the shuttle car at the contact alley, by the two walls of the alleyway on the gas diffusion space extrusion effect, CO and NOx in X = 37.5 m ~ 42.5 m range gathered, appear high CO and NOx concentration band. When the shuttle car in supporting tunnel, it is hindered by the belt conveyor within the range of X = 63 m ~ 64.5 m, so CO and NOx fail to spread to the outlet of the roadway in time and pile up at the bottom of the roadway. The highest CO volume fraction is 76.25 ppm and the highest NOx volume fraction is 28.28 ppm.According to the different positions of the car, the pollution areas of CO and NOx exceeding the specified threshold (24 ppm, 2.5 ppm) were divided, and the distribution characteristics of CO and NOx pollution were obtained by quantitative analysis through curve fitting, which provided a theoretical basis for the prevention and control of harmful substances emitted by fuel power equipment in underground environment. [ABSTRACT FROM AUTHOR]

The high‐temperature oxidation behavior of 444 ferritic stainless steel has been studied in cyclic oxidation experiments using synthetic automotive exhaust gas atmospheres at 950 and 1050 °C. The weight gain per unit area of the 444 ferritic stainless steel following oxidation at 950 °C for 100 h iss 85.7% lower than recorded at 1050 °C. The oxide scale at both temperatures consisted of Fe–Cr and Mn–Cr spinels in the outer layer and Cr2O3 in the inner layer. Nodule formation and spallation of the oxide scale are identified as the main causes of breakaway oxidation. The depth of the internal oxides gradually increases with the oxidation time. The nucleation and growth of internal SiO2 result in the formation of metal protrusions, which are eventually consumed in the formation of a SiO2 layer. The SiO2 layer is formed at the interface between the oxide scale and the substrate at 1050 °C. The nucleation and growth of internal SiO2, in combination with lateral growth of SiO2 at the Cr2O3 layer/substrate interface contributed to the formation of the SiO2 layer. [ABSTRACT FROM AUTHOR]

Existing research on finance mainly focuses on credit, and there are few studies on the pollution reduction effects of digital finance. Based on a sample of 278 cities from 2011 to 2019, this article empirically examines the impact of digital finance on greener emissions. We find that digital finance, particularly in its usage depth, reduces industrial waste gas emissions, and exhibits a significant green emission effect. After using robustness tests such as Bartik instrument as an instrumental variable for digital finance, our conclusions still hold. Mechanism analysis finds that supporting green credit projects and promoting public energy conservation are the critical path for digital finance to enhance greener emissions. Furthermore, we compare the roles of traditional finance and digital finance in greener emissions, and find that digital finance reduces industrial waste gas emissions, while traditional finance is not conducive to emission reduction. [ABSTRACT FROM AUTHOR]

The USA has committed to cutting its emissions of methane, an extremely potent greenhouse gas, by at least 30% by 2030 (‘30 × 30’). This is part of the Global Methane Pledge, signed by 155 countries, to keep global warming within 1.5 °C and thereby to forestall the disastrous effects of ‘runaway climate change’. It will be a major challenge for the USA to reach 30 × 30 and there is no consensus on how to do so. This paper provides a concrete, data‐driven roadmap to indicate how to reach 30 × 30 feasibly, focusing on two enormous sources of methane emissions: organic waste and oil and gas production. It calculates that building approximately 4700 anaerobic digesters (ADs) to process food waste and animal manure would cost about $74.2 billion in capital expenditure (capex) and cut 13.6% of total US methane emissions per year. On average, each project would take roughly 2–6 years to build. Of the various methane mitigation measures analyzed in the oil and gas sectors, the most impactful would be full compliance with the US Environmental Protection Agency's (EPA's) revised New Source Performance Standards (NSPS) for oil and gas production by 2029. This would cut 17.5% of total US methane emissions annually, at a cumulative capex of $20.7 billion from 2024 to 2029. Together, the 13.6% cut from food waste and manure ADs and the 17.5% cut from full NSPS compliance would amount to a 31.5% reduction, exceeding the 30 × 30 goal. Greater clarity from the federal government on funding eligibility and additional incentives would accelerate the buildout of ADs. [ABSTRACT FROM AUTHOR]

A tubular proton‐conducting fuel cell, anode‐supported, was fabricated using dip‐coating and followed by the co‐sintering of anode and electrolyte at 1500°C. The electrolyte and anode thicknesses are respectively 6 and 500 µm. The outer diameter of the tubular cell is 5.8 mm, featuring an anode porosity of 23%. Ammonia‐fueled single cell with Ru‐catalyzed internal cracking reactor is operated at various temperatures from 400°C to 600°C. Calculation results indicate that double‐ring current collection is an efficient current‐collecting mode. At 600°C, the device exhibited a high open‐circuit voltage of 1.02 V and a peak power density of 216 mW cm−2, with a total active area of 2.28 cm2. Exhaust gas analysis reveals a 99.13% ammonia decomposition rate at 600°C. [ABSTRACT FROM AUTHOR]

The exhaust gas burner, a critical component of a solid oxide fuel cell (SOFC) thermal management system, is essential for the stable and reliable operation of the entire system. This study establishes a test bench that simulates the gas composition and temperature of the fuel cell stack anode and cathode gases and conducts comprehensive experimental research on an exhaust gas burner used in a 15-kW SOFC power generation system. The experimental results show that the burner has the operational characteristic of reliable combustion over a wide range of excess air ratios. The burner can achieve stable and reliable combustion under low-flow ignition, steam injection, reforming, and power-generation conditions with excess air ratios of 29–45, 21–28, 23–37, and 11–27, respectively. Rapid changes in the excess air ratio did not lead to combustion instability; for example, during power generation, an increase of 47.6% in the excess air ratio resulted in a 3.5% decrease in the burner outlet temperature. However, under the steam injection condition, with an excess air ratio of 28 and a steam-to-carbon ratio of 3, the temperature decreased significantly. The burner also exhibited low-pressure loss, with a maximum anode exhaust pressure drop of only 233 Pa. Furthermore, the burner exhibited excellent performance during condition transitions, although a certain time delay occurred in the temperature response to the flow rate changes. • Established a test platform to explore burner characteristics comprehensively. • Proven reliable combustion across various conditions. • Maintained stable combustion despite rapid air ratio changes. • Significant temperature drop during steam injection. • Low pressure loss and excellent performance in condition transitions. [ABSTRACT FROM AUTHOR]

Direct decomposition of H 2 S into H 2 and S is an attractive alternative to the Claus process, because CO x -free H 2 and S can be simultaneously recovered from an abundant and toxic waste gas, which has huge social economic and ecological environmental benefits. However, it is still a great challenge to achieve the direct H 2 S decomposition reaction with high efficiency due to the thermal equilibrium limitation. Herein, a core-shell structured Mo x C@ZrO 2 was developed as novel microwave catalyst for microwave catalytic H 2 S decomposition. More specifically, the H 2 S conversion over Mo x C@ZrO 2 catalyst is as high as 99.9% at 650 °C, which immensely surpasses the H 2 S equilibrium conversion (6.1% at 650 °C). This study provides an effective strategy for the design of highly active microwave catalysts, and supplies a strategy for efficiently catalytic decomposition of H 2 S waste and recovering high-value hydrogen and sulfur at lower reaction temperatures. [Display omitted] • H 2 S conversion is highly up to 99.9% at 650 °C under microwave irradiation. • Mo x C@ZrO 2 display excellent catalytic performance at low temperature in the MCRM. • Catalytic performance in the MCRM is much higher than that in the CRM. • Microwave irradiation can break chemical equilibrium of H 2 S decomposition reaction. [ABSTRACT FROM AUTHOR]

Microalgae are considered to be a promising and prospective source of lipids for the production of biocomponents for conventional liquid fuels. The available sources contain a lot of information about the cultivation of biomass and the amounts and composition of the resulting bio-oils. However, there is a lack of reliable and verified data on the impact of fuel blends based on microalgae biodiesel on the quality of the emitted exhaust gas. Therefore, the main objective of the study was to present the emission characteristics of a compression-ignition engine fuelled with a blend of diesel fuel and biodiesel produced from the lipids accumulated in the biomass of a heterotrophic culture of Schizochytrium sp. The final concentrations of microalgal biomass and lipids in the culture were 140.7 ± 13.9 g/L and 58.2 ± 1.1 g/L, respectively. The composition of fatty acids in the lipid fraction was dominated by decosahexaenoic acid (43.8 ± 2.8%) and palmitic acid (40.4 ± 2.8%). All parameters of the bio-oil met the requirements of the EN 14214 standard. It was found that the use of bio-components allowed lower concentrations of hydrocarbons in the exhaust gas, ranging between 33 ± 2 ppm and 38 ± 7 ppm, depending on the load level of the engine. For smoke opacity, lower emissions were found in the range of 50–100% engine load levels, where the observed content was between 23 ± 4% and 53 ± 8%. [ABSTRACT FROM AUTHOR]

Due to its good corrosion resistance and high rigidity, fluoroplastic steel heat exchangers have become one of the main feasible solutions to the problem of flue gas waste heat recovery. Therefore, a heat transfer performance test of a fluoroplastic steel heat exchanger was carried out, and a new heat transfer correlation (Nu = 0.11Re0.72Pr0.36, 1900 < Re < 4100, Pr ≈ 0.8) of a fluid transverse tube bank suitable for smooth fluoroplastic surfaces was proposed. Comparing the results of the proposed correlation and the Zhukauskas correlation, the calculation discrepancy was decreased when using the proposed correlation, and the average discrepancy dropped from 16.8% to 3.3%. As the thickness of the fluoroplastic film was reduced, the gap between the two correlations widened. Thus, the Zhukauskas correlation was not applicable to fluoroplastic steel heat exchangers with a thin fluoroplastic film. However, the deviation between the two correlations decreased as the condensing heat transfer area increased. For the fluoroplastic steel heat exchanger with a large condensation heat transfer area, the Zhukauskas correlation could still be utilized. It was interesting to observe that the deviation between the two correlations was reduced when only flue gas condensation was present, but it showed an increasing trend with the increase in condensation intensity. [ABSTRACT FROM AUTHOR]

China's manufacturing industry needs to change from a high-emission model to one that is more environmentally friendly to reduce air pollution and achieve sustainable growth. Therefore, it is important to decrease manufacturing waste gas emissions by improving green productivity. This paper expands on the theories of green economic growth and sustainable development to present a framework for analysis of manufacturing green productivity at various levels of air pollution. It applies the Metafrontier Malmquist Luenberger index and SBM model to data from 30 Chinese manufacturing sectors from 2012 to 2022 to identify the obstacles to developing green productivity in the manufacturing sectors. The results show that: (1) From 2012 to 2022, the overall waste gas emission efficiency and GTFP of China's manufacturing industry showed an increasing trend. (2) The manufacturing industry with light air pollution had the fastest growth in GTFP, followed by manufacturing with heavy air pollution, and manufacturing with moderate air pollution had the lowest. (3) The primary driver of GTFP growth is technological progress, while technical inefficiency has severely hindered GTFP growth. (4) There is a "Matthew effect" in the green productivity of China's manufacturing industry. High waste gas emission efficiency often accompanies high levels of GTFP, and vice versa. Finally, this paper proposes policy suggestions to improve the green productivity of the manufacturing industry and reduce air pollution. [ABSTRACT FROM AUTHOR]

The selection of adsorbents is critical for developing an adsorption unit. In this study, a activated carbon fibers (ACF) and a granular‐activated carbon (GAC) were evaluated in dynamic toluene adsorption to determine their benefits and limitations. A variety of physicochemical approaches were used to characterize the samples. Adsorption under varied circumstances demonstrated that ACF has a larger adsorption capacity and a longer saturation time than GAC. The Langmuir isotherm suited equilibrium data well. Thermodynamic characteristics showed that adsorption was spontaneous and exothermic. The adsorption kinetics were found to be dominated by the pseudo‐first‐order model, with GAC having a greater sorption rate. Thermal regeneration appeared to be more favorable for ACF. [ABSTRACT FROM AUTHOR]

Sulfur dioxide (SO2) emissions from ship exhausts pose serious health and environmental concerns. Herein, the SO2 absorption and desorption characteristics of tertiary amines with different functional groups were explored under simulated ship exhaust gas conditions. Tertiary amines with electron‐donating groups had superior absorption performance to those with electron‐withdrawing groups, and highly polar absorbents exhibited enhanced SO2 absorption loading. Dimethylaniline (DMA) showed excellent desorption performance, outperforming other absorbents (amino acids, ionic liquids, and deep eutectic solvents) in terms of cyclic capacity. Thus, tertiary amines, especially DMA, can be potentially used for the prevention of SO2 emissions from ship exhausts and other desulfurization applications. [ABSTRACT FROM AUTHOR]

A sudden transition to a state of high-amplitude periodic oscillations is catastrophic in a thermo-fluid system. Conventionally, upon varying the control parameter, a sudden transition is observed as an abrupt jump in the amplitude of the fluctuations in these systems. In contrast, we present an experimental discovery of a canard explosion in a turbulent reactive flow system where we observe a continuous bifurcation with a rapid rise in the amplitude of the fluctuations within a narrow range of control parameters. The observed transition is facilitated via a state of bursting, consisting of the epochs of large amplitude periodic oscillations amidst the epochs of low-amplitude periodic oscillations. The amplitude of the bursts is higher than the amplitude of the bursts of an intermittency state in a conventional gradual transition, as reported in turbulent reactive flow systems. During the bursting state, we observe that temperature fluctuations of the exhaust gas vary at a slower time scale in correlation with the amplitude envelope of the bursts. We also present a phenomenological model for thermoacoustic systems to describe the observed canard explosion. Using the model, we explain that the large amplitude bursts occur due to the slow–fast dynamics at the bifurcation regime of the canard explosion. [ABSTRACT FROM AUTHOR]

Evaluating aviation emissions and examining the dispersion properties of contaminants are crucial for understanding atmospheric pollution. To assess the pollutant emissions and dispersion of aircraft during the landing and takeoff (LTO) cycle, and address air pollution surrounding the airport resulting from flight operations, this study evaluated emissions throughout the LTO phase based on Quick Access Recorder (QAR) data in conjunction with the first-order approximation method. An improved Gaussian diffusion model for mobile point sources was employed to examine the diffusion characteristics of contaminants. Additionally, CFD calculation outcomes for various exhaust velocities and wind speeds were utilized to validate the trustworthiness of the improved Gaussian model. The discussion also encompasses the influence of diffusion time, wind direction, wind speed, temperature gradient, and particle deposition on the concentration distribution of contaminants. The findings indicated that the Gaussian diffusion model aligned with the results of the CFD calculations. The diffusion distribution of contaminants around airports varies over time and is significantly influenced by atmospheric environmental factors, including wind direction, wind speed, and atmospheric stability. Specifically, a change in wind direction from 0° to 45° caused a shift of approximately 1000 m in the contaminant's center. An increase in wind speed from 3 m/s to 5 m/s led to a decrease in concentration by about 15%. Furthermore, a transition in atmospheric stability from category 'a' (very unstable) to 'f' (very stable) resulted in a two-order-of-magnitude increase in contaminant concentrations. [ABSTRACT FROM AUTHOR]

The use of biodiesel as an alternative to conventional diesel fuels has gained significant attention due to its potential for reducing greenhouse gas emissions and improving energy sustainability. This study explores the impact of TiO2 nanoparticles on the emission characteristics and combustion efficiency of biodiesel blends in compression ignition (CI) engines. The fuels analyzed include diesel, SB20 (soybean biodiesel), SB20 + 50 TiO2 ppm, SB20 + 75 TiO2 ppm, PB20 (palm biodiesel), PB20 + 50 TiO2 ppm, and PB20 + 75 TiO2 ppm. Experiments were conducted under a consistent load of 50% across engine speeds ranging from 1000 to 1800 RPM. While TiO2 nanoparticles have been widely recognized for their ability to enhance biodiesel properties, limited research exists on their specific effects on soybean and palm biofuels. This study addresses these gaps by providing a comprehensive analysis of emissions, including NOX, CO, CO2, and HC, as well as exhaust gas temperature (EGT), across various engine speeds and nanoparticle concentrations. The results demonstrate that TiO2 nanoparticles lead to a reduction in CO emissions by up to 30% and a reduction in HC emissions by 21.5% at higher concentrations and engine speeds. However, this improvement in combustion efficiency is accompanied by a 15% increase in CO2 emissions, indicating more complete fuel oxidation. Additionally, NOX emissions, which typically increase with engine speed, were mitigated by 20% with the addition of TiO2 nanoparticles. Exhaust gas temperatures (EGTs) were also lowered, indicating enhanced combustion stability. These findings highlight the potential of TiO2 nanoparticles to optimize biodiesel blends for improved environmental performance in CI engines. [ABSTRACT FROM AUTHOR]

Nitrogen oxides (NOxs) are some of the most important hazardous air pollutants from industry. In China, the annual NOx emission in the waste gas of industrial sources is about 8.957 million tons, while power plants remain the largest anthropogenic source of NOx emissions, and the precise control of NOx in power plants is crucial. However, due to inherent issues with measurement and pipelines in coal-fired power plants, there is typically a delay of about three minutes in NOx measurements, bringing mismatch between its control and measurement. Measuring delays in NOx from power plants can lead to excessive ammonia injection or failure to meet environmental standards for NOx emissions. To address the issue of NOx measurement delays, this study introduced a hybrid boosting model suitable for on-site implementation. The model could serve as a feedforward signal in SCR control, compensating for NOx measurement delays and enabling precise ammonia injection for accurate denitrification in power plants. The model combines generation mechanism and data-driven approaches, enhancing its prediction accuracy through the categorization of time-series data into linear, nonlinear, and exogenous regression components. In this study, a time-based method was proposed for analyzing the correlations between variables in denitration systems and NOx concentrations. This study also introduced a new evaluation indicator, part of R2 (PR2), which focused on the prediction effect at turning points. Finally, the proposed model was applied to actual data from a 330 MW power plant, showing excellent predictive accuracy, particularly for one-minute forecasts. For 3 min prediction, compared to predictions made by ARIMA, the R-squared (R2) and PR2 were increased by 3.6% and 30.6%, respectively, and the mean absolute error (MAE) and mean absolute percentage error (MAPE) were decreased by 9.4% and 9.1%, respectively. These results confirmed the accuracy and applicability of the integrated model for on-site implementation as a 3 min advanced prediction soft sensor in power plants. [ABSTRACT FROM AUTHOR]

A flue gas condenser (FGC) system recovers heat from exhaust flue gases in energy production and chemical plants, reducing air pollution due to dust, SOx, and HCl. An FGC system is divided into indirect contact condenser (ICC) and direct contact condenser (DCC) types. In an ICC, the exhaust gases do not mix with the working fluid, and a water film is formed during flue gas condensation for partial SOx removal. In a DCC, direct mixing of the exhaust flue gas with the cooling fluid (mainly water) occurs, with simultaneous absorption of SOx. In this study, we investigated the SO2 removal efficiency and heat recovery of an ICC, a DCC, and a DCC–ICC hybrid system, and compared the results of the hybrid system with those obtained for a single DCC type at the same liquid-to-gas (L/G) ratio. The SO2 removal characteristics of the hybrid system were examined based on the L/G ratio and absorbent-to-SO2 molar ratio. In the reference ICC-type FGC system, the exit temperature of the mixed gas was 28 °C, with the condensed water ratio and heat recovery efficiency being 80.9% and 93.4%, respectively. At an L/G ratio of 1.5–3.5, the SO2 removal efficiency of a single DCC was 31.5–65.9%, whereas that of the hybrid FGC system (with packing material) increased from 47.1% to 72.3%, which further increased to ~90% upon the addition of NaOH at a molar ratio of 0.7 and an L/G ratio of 1.5. [ABSTRACT FROM AUTHOR]

The article presents the results of testing the validity of the hypothesis about the possibility of isolating the exhaust gases of the internal combustion engine (exhaust gas source). The objective was to conduct an experimental study of the "exhaust gas source - storage tank" system. In the experimental study, the following was performed: establishment of influencing factors and output parameters; selecting the number of experiments; methods and means of measurement; conducting an experiment at the stand. [ABSTRACT FROM AUTHOR]

Malaysia has been struggling to effectively manage waste which accounts for a substantial amount of greenhouse gases. Thus, the objective of this study was to identify whether renewable energy from combustible renewable and waste could significantly reduce the total greenhouse gas emissions in both the short and long run in Malaysia. This study applies time series estimation techniques which cover 47 years of Malaysia's data from the year 1971–2018. The model fits VECM estimation which examines the renewable energy effect on greenhouse gas emissions in the short and long run. The empirical analysis significantly establishes that the renewable energy reduced the total greenhouse gas emissions in the long run. Statistically, a 1% increase in combustible renewable and waste (CRW) reduced the total greenhouse gas emissions by nearly 0.14% in the long run. Furthermore, arable land, methane emissions potentially reduced greenhouse gas emissions between 1971–2018. However, economic growth and carbon dioxide emissions from manufacturing industries and construction significantly increased total greenhouse gas emissions in the long run. The study concludes empirically that waste generation could be utilized to produce renewable energy through combustible renewable and waste which could slowly reduce greenhouse gas emissions. [ABSTRACT FROM AUTHOR]

In this study, the effect of using vortex generators in the form of semicircular plates with different angles and at different longitudinal distances in the chimney of a laboratory furnace with natural gas fuel on the hydrodynamics of the flow and the rate of heat transfer from combustion products has been investigated exfaimentally and numerically. The investigated parameters were angles for blades and the number of blades. The results show that vortex generators with reducing the speed in the central area of the chimney and increasing the residence time of the combustion products and also by directing the flow towards the boundary layer adjacent to the wall, increases the heat transfer to the chimney. The angle of 55º and the number of blades 7 was the optimum condition that prevents the flow of exhaust gases from returning, and in this case, by changing the gas flow rate in the range of 0.5 to 0.75 m3/hr, the heat transfer to the chimney wall increases by 21% on average. [ABSTRACT FROM AUTHOR]

Detecting anomalies in engine and machinery data during ship operations is crucial for maintaining the safety and efficiency of the vessel. We conducted experiments using device data from the maritime industry, consisting of time series records from IoT (Internet of Things) datasets such as cylinder and exhaust gas temperatures, coolant temperatures, and cylinder pressures collected from various sensors on the ship's equipment. We propose data enrichment and validation techniques by generating synthetic outliers through data degradation and data augmentation with a Transformer backbone, utilizing the maritime operational data. We extract a portion of the input data and replace it with synthetic outliers. The created anomaly data are then used to train the model via a self-supervised learning approach. Synthetic outliers are generated using methods such as the arithmetic mean, geometric mean, median, local scale, global scale, and magnitude warping. With our methodology, we achieved a 17.23% improvement in F1 performance compared to existing state-of-the-art methods across five publicly available datasets and actual maritime operational data collected from the industry. [ABSTRACT FROM AUTHOR]

A promising approach for carbon dioxide (CO2) valorization and storing excess electricity is the biological methanation of hydrogen and carbon dioxide to methane. The primary challenge here is to supply sufficient quantities of dissolved hydrogen. The newly developed Inverse Membrane Reactor (IMR) allows for the spatial separation of the required reactant gases, hydrogen (H2) and carbon dioxide (CO2), and the degassing area for methane (CH4) output through commercially available ultrafiltration membranes, enabling a reactor design as a closed circuit for continuous methane production. In addition, the Inverse Membrane Reactor (IMR) facilitates the utilization of hydraulic pressure to enhance hydrogen (H2) input. One of the process's advantages is the potential to utilize both carbon dioxide (CO2) from conventional biogas and CO2-rich industrial waste gas streams. An outstanding result from investigating the IMR revealed that, employing the membrane gassing concept, methane concentrations of over 90 vol.% could be consistently achieved through flexible gas input over a one-year test series. Following startup, only three supplemental nutrient additions were required in addition to hydrogen (H2) and carbon dioxide (CO2), which served as energy and carbon sources, respectively. The maximum achieved methane formation rate specific to membrane area was 87.7 LN of methane per m2 of membrane area per day at a product gas composition of 94 vol.% methane, 2 vol.% H2, and 4 vol.% CO2. [ABSTRACT FROM AUTHOR]

There are considerably fewer requirements for the quality of hydrogen combusted in an engine than its quality for fuel cells. Therefore, the analysis was carried out on the combustion of hydrogen–helium mixtures in an engine with a two-stage combustion system (TJI—Turbulent Jet Ignition). A single-cylinder research engine with a passive and active prechamber was used. A hydrogen–helium mixture was supplied to the main chamber in proportions of 100:0, 90:10, 80:20, 30:70, and 60:40 volume fractions. The prechamber was fueled only with pure hydrogen. Combustion was carried out in the lean charge range (λ = 1.5–3) and at a constant value of the Center of Combustion (CoC = 8–10 deg aTDC). It was found that the helium concentration in the mixture affected the changes in combustion pressure, heat release rate and the amount of heat release. It was observed that increasing the proportion of helium in the mixture by 10% also reduces the IMEP by approximately 10% and reduces the rate of heat release by approximately 20%. In addition, helium influences knock combustion. Limits of MAPO = 1 bar mean assumed that knock combustion occurs in the main chamber at values of λ < 1.9. Increasing the excess air ratio results in a gradual reduction in the temperature of the exhaust gas, which has a very rapid effect on changes in the concentration of nitrogen oxides. Studies carried out on the helium addition in hydrogen fuel indicate that it is possible to use such blends with a partial deterioration of the thermodynamic properties of the two-stage combustion process. [ABSTRACT FROM AUTHOR]

The aim of this study is to solve the problem of the difficulty of accurate detection of CN- and SCN- due to the interference of multiple ions in the wastewater produced by coke oven gas desulfurization. To this end, based on the basic principles of analytical chemistry and elimination of inter? ionic interferences, this paper proposed a conventional inorganic chemical analytical method for the detection of CN-, SCN- in the alkaline wastewater generated from coking gas desulfurization by vacuum potassium carbonate method, including pretreatment method and instrumental detection step. Among them, the elimination of SCN-, S2-, SO32- and S2O32- from the interference of silver nitrate volumetric method on CN- was realized by the pretreatment method of the first acidification and distillation, and the second precipitation with distillation, and then the concentration of CN- was determined by silver nitrate volumetric method. The elimination of the interference of CN-, S2- and phenol on SCN- detection by precipitation, extraction and coordinated pretreatment methods was realized, on the basis of which SCN- was then determined spectrophotometrically by ferric thiocyanate. More explicit detection steps and discussion of influencing factors were also given. The method can be used for the detection of CN- and SCN- in complex environmental samples, which will provide better technical support for the control of coke oven barren gas desulfurization process and wastewater treatment. [ABSTRACT FROM AUTHOR]

The study introduces an innovative three-stage nested power generation system that enables the cascading utilization of LNG cold energy. It makes the most of wasted energy by using ship jacket cooling water (JCW) and exhaust gas (EG) as heat sources, a trans-critical carbon dioxide cycle as internal circulation, and utilizing the pressure exergy of LNG. We choose two azeotrope mixing fluids that match the requirements and create four cases for the outer and middle cycle working fluids in the three-stage nested system. To discover the ideal system performance from the perspectives of exergy (E), economy (E), and environment (E), four cases were subjected to multi-objective optimization using the multi-objective particle swarm optimization technique (MOPSO). Finally, the optimal solution was found by applying the TOPSIS decision-making method. Through comparative analysis, the optimal system is selected among the four optimization results. R170 (22.66%) and R1150 (77.34%) are used as the outer circulating working medium, while R170 (90.86%) and R1270 (9.14%) are utilized as the inter-cycle working fluid. The net output work is 575.75 kW, the optimal exergy efficiency is 46.09%, the optimal electricity production cost is $0.04009 per kWh, the carbon dioxide emissions can be reduced by 36,910 tons, and the payback period is 2.548 years. After optimization, a more energy-efficient and environmentally friendly power generation system is obtained. [ABSTRACT FROM AUTHOR]

A carbon monoxide sensor with composite detection capabilities for carbon monoxide, hydrogen sulfide, and nitric oxide gases was developed using gas concentration detection technology based on composite electrochemical components to address the issue of crossinterference between exhaust gas and sulfur-containing gases from diesel vehicles and gas detection by mining carbon monoxide sensors. The sensor gas detection module includes two parts: a carbon monoxide hydrogen sulfide dual gas detection module and a nitric oxide gas detection module. The module is composed of gas detection components and signal detection circuits. An experiment was conducted to study the effects of hydrogen sulfide and nitric oxide gases on the detection results of carbon monoxide gas concentration. Through data analysis and linear fitting, a gas cross-interference compensation algorithm formula was obtained. The compensated carbon monoxide sensor experiment results show that the carbon monoxide sensor based on composite electrochemical elements has a measurement error of less than 5% in the mixed gas environment, meets the requirements of the AQ6205-2006 coal mine electrochemical carbon monoxide transducer, and can meet the technical requirements for the accurate detection of carbon monoxide gas of an underground rubber-tire truck transportation roadway. [ABSTRACT FROM AUTHOR]

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Activated carbon has potential in energy storage and conversion, however, conventional methods often struggle to enhance specific surface area and control pore structure precisely, hindering its application in hydrogen storage and electrochemical fields. Therefore, this study aims to utilize pine sawdust as carbon precursor and employ "restricted activation" technology to regulate the specific surface area and pore structure of carbon materials, thereby enhancing their performance in hydrogen and electrochemical energy storage. Results demonstrate activated carbon's exceptional microporous structure and specific surface area, leading to outstanding hydrogen storage (achieving a capacity of 7.73 wt% at 77 K and 40 bar) and electrochemical properties (with the highest energy density of 12.92 Wh∙kg−1 and power density of 125 W kg−1). A comprehensive array of contrasting results has revealed that while micropores experience single-layer adsorption, the engagement of certain micropores and small mesopores in the physical adsorption process markedly boosts hydrogen storage capacity. This investigation sheds light on the relationship between material structure and storage performance, offering insights into multifunction carbon materials for high-capacity hydrogen storage and superior electrochemical performance. • Enhanced sample surface area by physical-chemical dual activation methods. • Waste gas recycling to achieve double reuse and protect the environment. • Porous carbon materials offer excellent hydrogen storage and supercapacitor. • The conversion treatment can also be applicable to other areas of biomass activation. [ABSTRACT FROM AUTHOR]

Electrosynthesis, a viable path to decarbonize the chemical industry, has been harnessed to generate valuable chemicals under ambient conditions. Here, we present a membrane-free flow electrolyzer for paired electrocatalytic upcycling of nitrate (NO3−) and chloride (Cl−) to ammonia (NH3) and chlorine (Cl2) gases by utilizing waste streams as substitutes for traditional electrolytes. The electrolyzer concurrently couples electrosynthesis and gaseous-product separation, which minimizes the undesired redox reaction between NH3 and Cl2 and thus prevents products loss. Using a three-stacked-modules electrolyzer system, we efficiently processed a reverse osmosis retentate waste stream. This yielded high concentrations of (NH4)2SO4 (83.8 mM) and NaClO (243.4 mM) at an electrical cost of 7.1 kWh per kilogram of solid products, while residual NH3/NH4+ (0.3 mM), NO2− (0.2 mM), and Cl2/HClO/ClO− (0.1 mM) pollutants in the waste stream could meet the wastewater discharge regulations for nitrogen- and chlorine-species. This study underscores the value of pairing appropriate half-reactions, utilizing waste streams to replace traditional electrolytes, and merging product synthesis with separation to refine electrosynthesis platforms. Electrosynthesis offers a greener alternative to traditional chemical production by utilizing renewable energy and waste streams. Herein, the authors report a membrane-free electrolyzer that efficiently produces and separates ammonia and chlorine from wastewater. [ABSTRACT FROM AUTHOR]

The present study conducts a comparative analysis between selective catalytic reduction (SCR) using a Cu-zeolite catalyst and selective non-catalytic reduction (SNCR) for the removal of NO x from industrial waste gas. The primary objective of this investigation is to computationally explore the removal of NO x using NH3 at various reactor conditions, along with the study of different hydrodynamic aspects. The study revealed the impact of different porosity of the catalyst (in SCR) and the number of baffles (in SNCR) on the reaction and fluid flow profile. Distinct geometries were employed to model each process, incorporating a turbulent model and kinetic parameters with an eddy-dissipation model (EDM) for simulations. Analyzing the effect of the NH3/NO ratio on NO conversion efficiency is a crucial component of the study. With diminishing efficiency at higher ratios, the SCR process demonstrated nearly complete NO conversion at a certain NH3/NO ratio, and this value changes with the inlet gas temperature. In contrast, SNCR produced less favorable conversion rates than SCR, indicating that the amount of NH3 supply affects conversion efficiency. At the SCR system’s optimum NH3/NO ratio, SNCR achieved an 83 % conversion, and the conversion rate remained relatively constant as the ratio was increased. The results highlight the various possibilities for optimization of the reactor systems in terms of efficiency and economic feasibility. [ABSTRACT FROM AUTHOR]

Torrefaction is an effective method to improve the quality of biomass feedstocks for a subsequent thermal conversion process. Torrefaction has been widely developed for biomass upgrading in terms of increasing bulk and energy densities, reducing water and oxygen contents, and improving hydrophobic properties, which are favorable for transportation and storage. Moreover, the torrefied biomass can be easily ground to even particle sizes, which favor the downstream thermochemical conversion process such as gasification. This paper reports on the progress in the dry and wet torrefaction of biomass sources. Key findings and challenges of torrefied biomass gasification are highlighted as well. In general, the properties of biomass feedstocks can be improved by the torrefaction process. Torrefaction for biomass gasification can improve the quality of syngas. In particular, gasification of torrefied biomass involves a merit of volatile matter (tar precursor) removal prior to the gasification process. The properties of torrefied biomass are significantly affected by the torrefaction conditions mainly including atmosphere, temperature, and pressure. The presence of an appropriate amount of oxygen gas leads to a superior performance for biomass torrefaction. The oxygen-containing gas and the waste heat from industrial flue gas can be utilized to reduce the operating cost, thus making the biomass torrefaction pretreatment more commercially feasible. [ABSTRACT FROM AUTHOR]

The objective of this study is to develop a 1D CFD simulation model to identify the optimal design parameters, using GT-POWER prior to the optimization of a new rotary engine derived from a three-lobe gerotor pump (GP3 RTE) based on 3D CFD simulation. The models were compared based on their respective development stages (steps 1–4) to ascertain the impact of each parameter on performance. The step 4 model, which exhibited a similar trend to that observed in the 3D CFD results, was selected for further analysis and validation. The developed model accurately predicted GP3 RTE performance in terms of fuel consumption, indicated power, efficiency, and exhaust gas reticulation (EGR) behavior, approaching the accuracy of the CONVERGE model. Furthermore, the optimal intake/exhaust port locations and operating conditions of the GP3 RTE were derived using the developed step 4 model. The model provided a convenient and powerful tool for obtaining basic information regarding the unique behavior of the GP3 RTE, thereby enabling the optimization of the design parameters without the necessity for time-consuming three-dimensional design modifications. [ABSTRACT FROM AUTHOR]

This article analyses the possibility of using hydrogen as fuel in furnaces used in the metallurgical industry. The research was conducted for a selected continuous furnace. For this purpose, based on actual measurements, a heat balance of the furnace was prepared to determine its energy indicators. These values were used to verify the developed numerical model in IPSEpro 7.0 software. Numerical calculations were performed for three variants: pure natural gas; 30% hydrogen, 70% natural gas; and 100% hydrogen. The determined values of gas and combustion air streams allowed for achieving the assumed charge temperature in the heating technology. Calculations of the impact of the excess combustion air ratio on process parameters were also carried out. It was found that no changes are required in the exhaust gas removal system, but verification of the fan supplying air to cool the exhaust gases before the recuperator is necessary. The amount of hydrogen required to fuel the continuous furnace also increases significantly (nearly threefold), which may also affect operating costs. At the same time, the emission of carbon dioxide into the atmosphere is completely reduced, which may be an important criterion when considering modernization options for heating furnaces in the metallurgical industry. [ABSTRACT FROM AUTHOR]

The ever-growing concerns about global warming and the rapid depletion of fossil fuels have triggered a rising interest in the research for cleaner, more efficient, and cost-effective energy generation. Organic Rankine cycle systems have immense potential to become a strong alternative to conventional methods of energy generation. However, such systems' efficiency is limited by the performance of the incorporated gas expanders or prime movers. Conventional gas expanders often utilize ports or cam-operated valves. Ported expanders offer limited efficiency and controllability and produce high emissions, causing a large amount of heated and compressed gas to be wasted. Cam-operated valves, in contrast, increase expansion performance compared to ported expanders; however, they have no variability and adaptability to changes in system parameters such as gas pressure, temperature, dryness fraction, and load variation, to name a few. On a positive note, this issue can be addressed by adopting a variable timing and fast-operating, control valve with an accurate and adaptive control mechanism at the expander inlet. A properly designed and controlled valve can greatly improve the system performance of gas expanders and pave the way for an efficient low-cost alternative energy generation. This manuscript provides a comparative review of recent progress on the design, modeling, optimization, and control aspects of valves for gas expanders. A clear pathway on the scope of further development is also drawn based on the present state of the art. [ABSTRACT FROM AUTHOR]

Selective catalytic reduction (SCR) technology is the main means of reducing NO X emissions. Urea injection structure parameters (i.e., the hole number in a nozzle, spray angle, the distance between the nozzle and the front section of the catalyst) and operating parameters (i.e., exhaust gas temperature, gas hourly space velocity, ammonia-to-nitrogen ratio (ANR)) of the SCR systems have a significant impact on denitrification efficiency (deNO X). A three-dimensional simulation model is developed to investigate the impact of diverse parameters on deNO X. The influence of temperature, ANR and space velocity on the deNO X of SCR system is studied by using the control variable method. The simulation model is modified according to the SCR catalyst gas distribution test results. A diesel bench experiment is conducted to test the deNO X of the SCR system of D2 cycle and two additional operating points to verify the accuracy of the numerical simulation model. Based on this model, the influence of key factors on the deNO X of SCR system is studied. In SCR system, the optimal urea injection angle is about 75°, the optimal number of nozzle holes is 4, the distance between the optimal urea injection point and the front section of the catalyst is 8 times of the pipe diameter, and the optimal operating temperature is 300 ∼ 420℃. The influence trend of ANR on deNO X at different temperatures is obtained. This provides a theoretical support for the realization of SCR system in the future. • The factors influencing the denitrification efficiency (deNO X) of SCR were studied. • Both experimental research and numerical simulation were combined for this study. • When the injection angle of urea was 75 degrees, the atomization effect was the best. • The optimal temperature range for the SCR reaction was between 270°C and 420°C. • DeNO X in the high-temperature range was essentially unaffected by the gas hourly space velocity. [ABSTRACT FROM AUTHOR]