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A char cone, whose shape is similar to Bunsen flame and varies with oxidation conditions, was found in steady smoldering of biomass rods. In this short communication, characteristics of this char cone in natural downward smoldering of char rods with different diameters (2 – 7 mm) and ash contents (30–46%) were investigated via measuring propagation velocity and analyzing shape of char cone. Results showed that smoldering propagates steadily in all prepared char rods and the propagation velocity decreases with increasing diameter and ash content of char rods. Height of char cone is proportional to the mass flowrate of carbon, similar to the relationship between flame length and volume flowrate of gas fuel in laminar jet diffusion flame. It implies that oxygen diffusion through ash plays a dominant role in natural smoldering of char rod. This work provides some experimental basis for further investigation on mechanism of steady smoldering. [ABSTRACT FROM AUTHOR]

In this paper, a novel two-stage hydrocarbon fuel heating and delivery system was used to more accurately simulate the state of fuel in the cooling channel of the regenerative cooling engine. Mildly cracked (<10%) experiments of n-dodecane were conducted by using the new heating system and pyrolysis products were sampled and analyzed. The ignition delay time and laminar flame speed of the cracked products were different from those of the surrogate gas fuel. When the temperature is 1100 K, the ignition delay time of the cracked products are ~50% higher than that of surrogate gas fuel. The laminar flame speed of the cracked products is about 30% lower than that of surrogate gas fuel at the equivalence ratio of 1.0. The supersonic combustion experiments of mildly cracked and different equivalence ratios n-dodecane were also employed at Mach number 3.0 of the isolator entrance, with total temperature ~1550 K and total pressure ~1.5 MPa. The static pressure along the axis of combustor was measured, while the velocity and temperature of the airflow at the exit of combustor were also measured by the tunable diode laser absorption spectroscopy (TDLAS). The distributions of airflow velocity, static temperature, and total temperature along the combustor at different conditions were analyzed through a one-dimensional analysis method. The deviations of velocity and temperature of the airflow are less than 4% and −6%, respectively, which indicates the calculation is in great accordance with the TDLAS detections. The experimental data will be helpful for validating the simulation of supersonic combustion, and studying the influence of mildly cracked fuel on supersonic combustion characteristics. [ABSTRACT FROM AUTHOR]

Enhanced methods of energy conversion present a viable solution for addressing energy load challenges. This study introduces a vibrating combustion engine designed to enhance energy conversion efficiency by harnessing flexible dynamics and variable asymmetric motion. However, the consideration of its unique dynamic effects has emerged as a pivotal challenge in fuel-air mixing and combustion research. This study introduces a fuel spray and mixing simulation method that facilitates the reciprocal exchange of coupling parameters between the combustion and dynamics models. It iterates the simulation outcomes of motion and combustion to predict mixture formation. Subsequently, the method is employed to explore the impact of injection position on fuel spray and mixture formation. Results show that there is an optimum injection position for the operation frequency, and retarding or advancing leads to slow compression and weak gas motion for fuel spray and mixing, although retarded injection provides high in-cylinder gas pressure and temperature. The early injection generally causes long penetration, small droplet diameter, slight impingement, and fast evaporation, unless it is too early. The results further indicate that when IAP = 6 mm, a more uniform mixture can be attained at the beginning of combustion, leading to a thermal efficiency of up to 42.9% for the engine. [ABSTRACT FROM AUTHOR]

Subterranean structures such as aquifers and depleted gas reservoirs (DGRs) offer a scalable, high-pressure, secure, cost-efficient, and ecologically friendly means of hydrogen (H 2) storage. Underground H 2 storage (UHS) has emerged as a potential solution to alleviate the imbalance between the fluctuating renewable energy generation and the demand for a constant energy supply. Quantifying the recovery efficiency is of paramount importance in the effort toward large-scale UHS. In this numerical simulation study, we employed a high-resolution grid for the discretization of a synthetic (but realistic) heterogeneous anticline intended as a H 2 storage facility, and we assessed the H 2 recovery efficiency, and the purity of produced gas associated with UHS in natural reservoirs involving different pre-existing gases and their quantities. All of these studies included an initial phase of cushion gas injection, followed by 4 cycles of H 2 storage operations composed of injection-idle-withdrawal periods. The simulation results indicated that the H 2 round-trip recovery efficiency R H increased (a) with an increasing number of storage cycles, routinely exceeding 90% and providing evidence of a self-enhancement or self-optimization H 2 recovery mechanism and (b) with an increasing amount of pre-existing gas in the storage zone prior to the H 2 injections — at the end of the 4-cycle test, the highest R H is associated with a DGR with a pre-existing gas consisting of residual CH 4 and additional injected N 2 , and the lowest R H corresponds to an aquifer with no cushion gas. Conversely, the H 2 mass fraction of the produced gas F HQ (a) increased with an increasing number of storage cycles, but (b) decreased rapidly with an increasing amount of pre-existing gas. The presence of a pre-existing gas inevitably leads to severe contamination of the produced H 2 , which never exceeds 40% in the produced gas, can be as low as 4% in early cycles, and cannot be used as a H 2 fuel without gas separation. Aquifer storage without a cushion gas may exhibit the lowest H 2 recovery (about 75% in the long run), but yields practically pure H 2 that does not require further processing before use. A positive conclusion is that, under the conditions of this study, total H 2 losses (including H 2 escaping into the caprock, and inaccessible H 2 dissolved in the aqueous phase of the formation or remaining in the gas storage zone) are limited and manageable, indicating the technical feasibility of geologic H 2 storage. • Discussed the advantages and disadvantages of H 2 storage (UHS) in aquifers and depleted gas reservoirs (DGRs). • Explained reasons for the benefits of cushion gas (CG) or DGRs in UHS performance using material balance theory. • Injecting CG or adding cycles enhances the UHS performance by improving the overall compressibility of reservoirs. • Pre-existing gas improves the H 2 recovery efficiency but leads to the contamination of produced H 2. • Quantified the H 2 loss evolution during a UHS consisting of four injection-idle-withdrawal cycles. [ABSTRACT FROM AUTHOR]

Carbon-free ammonia is a promising hydrogen energy carrier. Using ammonia as gas turbine fuel can effectively reduce carbon emissions. This study examines thermoacoustic instabilities of partially premixed CH 4 /NH 3 flame in a laboratory-scale swirl burner. Results show that as α NH 3 increases from 0 to 20%, the co-firing flame switches from stable mode to medium-frequency oscillation mode (105.4–151.2Hz) and then to low-frequency oscillation mode (36.7–44.1Hz). The oscillation intensity first increases and then decreases. Increasing α NH 3 and combustion chamber length will expand the unstable Φ range and enhance the pressure and heat release pulsation. When α NH 3 = 20%, CO 2 emissions are reduced by 12.5%, while NO increases sharply to over 1000 ppm. The flame is more likely to induce the low-frequency oscillation at high Φ. The shorter combustor can mitigate thermoacoustic instability. • Thermoacoustic instability of partially premixed CH 4 /NH 3 flame are studied. • Thermoacoustic frequency decreases as NH 3 ratio and equivalence ratio increase. • Thermoacoustic effect is weaker in short combustion chambers. [ABSTRACT FROM AUTHOR]

Hydrogen blending has proved to be a promising alternative to reduce CO 2 emissions in current applications such as the industrial sector in which natural gas is the fuel source since it can mitigate GHG emissions and help to reach nation's goal of decarbonization. This study explored the feasibility of different hydrogen blend compositions going from 1% to 30% hydrogen content (by volume) by computational simulations to determine the best performance of the system considering real operating conditions from Central Plant at UC Irvine. This work also performed an economic analysis as part of the implementation plan. It was determined that a blend of 19% H 2 content could be implemented without any major renovation of utility infrastructure based on the operating conditions and change in the properties of the mixture. An addition of 30% H 2 can reduce around 11% of the emissions produced by pure natural gas. This is equivalent to 1422 kg of CO 2 in 1 h. It is evident that the higher the H 2 content, the better the CO 2 benefits that would be produced, but for the actual application of higher hydrogen content, there is a need for a better understanding of the effects of hydrogen in the current natural gas pipeline. Based on the CO 2 savings, it was determined that a 30% blending of hydrogen may save about 22.2% of the economic cost compared to natural gas. • A hydrogen blending model is developed considering a hydrogen content between 1% and 30% by volume. • Real operating conditions such as temperature, pressure, pipeline dimensions, and power output requirements were considered based on UCI power plant for validation. • An economic analysis is considered as part of the implementation plan. • A blend of 19% H 2 content could be implemented without major renovation of infrastructure based on the operating conditions and change in the properties of the mixture. • 30% H 2 can reduce ∼11% of the emissions produced by pure natural gas. [ABSTRACT FROM AUTHOR]

Microtubular (MT) geometry of solid oxide cells have a number of distinctive properties, such as high volumetric power density, thermocycling stability and fast start-up capability. In this study, we evaluate the performance of the MT cell with LNO-SDC as air electrode under both fuel cell and electrolysis cell mode operation. While working in the fuel cell mode, the maximum power densities of MT cell reached 533, 740 and 792 mW cm−2 at 750, 800 and 850 °C, respectively. Moreover, the MT cell exhibit excellent long-term stability with no critical performance degradation operating at 750 °C. In the electrolysis mode, current density at 800 °C reached value of 780 mA cm−2 under applied voltage of 1.3 V with fuel gas containing 30 % H 2 O. The results on CO 2 electrolysis indicate remarkable efficiency of studied MT cell with current density of 854 mA cm−2 at an applied voltage of 1.5 V. • Microtubular solid oxide cells with LNO-SDC air electrode were fabricated. • Maximum power density reached 792 mW cm−2 in H 2 (3% H 2 O). • Under steam electrolysis condition, current density of 780 mA cm−2 was obtained at 1.3 V with 30 % H 2 O in fuel gas at 800 °C. • MT cell demonstrated great performance under CO 2 electrolysis condition. • Long-term stability is investigated. [ABSTRACT FROM AUTHOR]

Rational design of robust photocatalytic systems to direct capture and in-situ convert diluted CO2 from flue gas is a promising but challenging way to achieve carbon neutrality. Here, we report a new type of host-guest photocatalysts by integrating CO2-enriching ionic liquids and photoactive metal-organic frameworks PCN-250-Fe2M (M = Fe, Co, Ni, Zn, Mn) for artificial photosynthetic diluted CO2 reduction in gas-solid phase. As a result, [Emim]BF4(39.3 wt%)@PCN-250-Fe2Co exhibits a record high CO2-to-CO reduction rate of 313.34 μmol g−1 h−1 under pure CO2 atmosphere and 153.42 μmol g−1 h−1 under diluted CO2 (15%) with about 100% selectivity. In scaled-up experiments with 1.0 g catalyst and natural sunlight irradiation, the concentration of pure and diluted CO2 (15%) could be significantly decreased to below 85% and 10%, respectively, indicating its industrial application potential. Further experiments and theoretical calculations reveal that ionic liquids not only benefit CO2 enrichment, but also form synergistic effect with Co2+ sites in PCN-250-Fe2Co, resulting in a significant reduction in Gibbs energy barrier during the rate-determining step of CO2-to-CO conversion. Artificial photosynthetic diluted CO2 reduction from fuel gas is promising but challenging for carbon neutrality. Here, the authors report a host-guest system by integrating CO2-enriching ionic liquids and photoactive metal-organic frameworks, greatly enhancing CO2-to-CO conversion efficiency. [ABSTRACT FROM AUTHOR]

To reduce carbon emissions, hydrogen is a clean energy as fuel to co-combustion with natural gas. This experimental work focuses on studying the effects of hydrogen addition to methane on combustion performance and emissions in non-premixed coaxial burners, establishing performance prediction models and optimizing operation conditions involving fuel velocity, hydrogen blending ratio and equivalence ratio. The global sensitivity and analysis of variance were adopted to quantify the contributions of independent variables on the output responses of temperature, O 2 , NO, CO and CO 2 emissions. The hydrogen blending ratio is the most influential parameter, whose total effects of NO and CO 2 emissions are 64.6% and 83.5%, respectively. The equivalence ratio is not significant to NO and CO 2 emissions, and the adjusted determination coefficient of the reduced prediction model is 0.9707 and 0.9360, demonstrating a better goodness of fit. Based on the response surface model and particle swarm optimization algorithm, a Pareto was solved showing NO and CO 2 emissions decrease by 42.0%–73.6% and 60.8%–89.5%, and peak temperature in the chamber centerline increases by 1.02%–3.61%. The research results provide a profound guide to predict and optimize combustion performance and emissions for methane-hydrogen non-premixed flame. [Display omitted] • Prediction models of CH 4 –H 2 non-premixed burner were built by response surface method. • Total effects of hydrogen blending ratio on NO and CO 2 emissions are 64.6% and 83.5%. • Equivalence ratio is not significant to flue gas temperature, NO and CO 2 emissions. • A Pareto set was obtained by optimizing flame temperature and pollutants via PSO. • Peak temperature increases by 2.30%, NO and CO 2 decrease by 59.4% and 78.3%. [ABSTRACT FROM AUTHOR]

The SPARC tokamak is a high-field, Bt0 ∼12 T, medium-sized, R0 = 1.85 m, tokamak that is presently under construction in Devens, MA, led by Commonwealth Fusion Systems. It will be used to de-risk the high-field tokamak path to a fusion power plant and demonstrate the commercial viability of fusion energy. SPARC's first campaign plan is to achieve Qfus > 1 using an ICRF-heated, <10 MW, high current, Ip ∼ 8.5 MA, L-mode fueled by D–T gas injection, and its second campaign will investigate H-mode operations in D–D. To facilitate plasma control and scientific learning, a targeted set of ∼50 plasma diagnostics are being designed and built for operation during these campaigns. While nearly all diagnostics are based on established techniques, the pace of deployment, relative to the first plasma, and the harshness of the thermal, electromagnetic, and radiation environment are unprecedented for medium-sized tokamaks. An overview of the SPARC diagnostic set is given, providing context to further details communicated by the SPARC team in companion publications that are system-specific. The system engineering philosophy for SPARC diagnostics is outlined, and the design and engineering verification process for components inside and outside the primary vacuum boundary are described. Diagnostics are mounted directly to the vacuum vessel as well as housed within a series of eight midplane and 24 off-midplane replaceable port plugs. With limited exceptions, signal conditioning, digitization electronics and cameras as well as lasers and microwave sources are localized to a series of five Diagnostic Lab spaces, totaling ∼350 m2, located >15 m from the center of the tokamak, on the other side of a 2.4 m concrete shielding wall. A series of 31 large-scale penetrations have been included in the SPARC Tokamak Hall to facilitate integration of early campaign diagnostics and to provide upgradability. [ABSTRACT FROM AUTHOR]

Polyurethane (PU) foam has a high flammability and is widely used in aircraft interiors, presenting a significant danger to occupants. This study analysed three composite intumescent flame-retardant (IFR) coatings for flexible PU foam; expandable graphite (EG), ammonium polyphosphate (APP) and alginate (AG). The coatings were prepared in concentrations of 5 wt%, 10 wt%, and 50 wt% with an acrylic binder. The coated samples were characterised using cone calorimetry, SEM, and mechanical testing. The findings showed peak heat release rate, total heat release, and carbon dioxide production from the 10 wt% triple-layer coating (EG:APP:AG) was 52%, 32%, and 58% less than the PU control. The char of the 10 wt% triple-layer sample effectively suppressed smoke release and inhibited the transfer of fuel and gas volatiles. Mechanical testing demonstrated a 3.4 times increase in tensile strength and a 15.4 times increase in compressive strength (50% compression) compared to the control PU with the 10 wt% triple-layer coating. A fire dynamics simulator model was developed that demonstrated large-scale flammability modelling for commercial aircraft. Future work can explore the integration of IFR coatings into computational analysis. These new bio-based coatings produced promising results for aircraft fire safety and flammability performance for PU polymers. [ABSTRACT FROM AUTHOR]

Cogeneration is widely recognized as one of the most efficient methods of electricity generation, with gas turbine-based systems playing a critical role in ensuring reliability, sustainability, and consistent power output. This paper presents an energy efficiency analysis of a 14 MW high-efficiency cogeneration unit, featuring a modernized gas turbine as its core component. Since gas turbines often operate under varying loads due to fluctuating demand, this study examines their performance at 100%, 75%, and 50% load levels. It is observed that the efficiency of the gas turbine declines as the load decreases, primarily due to losses resulting from deviations from the design flow conditions. A detailed energy balance, Sankey diagram, and a comparative analysis of performance metrics against the manufacturer's guarantees are provided for each load scenario. The results indicate that net thermal efficiency decreases by 10.7% at 75% load and by 30.6% at 50% load compared to nominal performance at full load. The performance at full load closely aligns with the values guaranteed by the gas turbine supplier. The gross electrical power output is 1.33% higher than the guaranteed value, and the thermodynamic circuit's efficiency is 0.49% higher under real conditions. This study represents the initial phase of transitioning the turbine to operate on a fuel blend of natural gas and up to 20% hydrogen, with the goal of reducing CO2 emissions. As a novel contribution, this paper provides a systematized method for calculating and monitoring the in-service performance of gas turbines. The mathematical model is implemented using the Mathcad Prime 8.0 software, which proves to be beneficial for both operators and researchers. [ABSTRACT FROM AUTHOR]

Significant effort has been made to understand the recommended operational practices required for safe and energy‐efficient steel ladle logistics. However, the discussion of how thermal management affects sustainability and costs is still limited. Hence, this article proposes a methodology to explicitly minimize direct and indirect emissions involved in the ladle dispatching problem. For that, linear regression models correlating the refractory wear with the thermal state of the ladle and process conditions are integrated into the optimization model. Next, mixed‐integer linear programming solvers can be employed to estimate the Pareto front efficiently. Finally, the costs can be estimated by applying the refractory value‐in‐use model. As an example, the proposed method is applied to the Tata Steel, IJmuiden, use case. The results show limited opportunity to reduce refractory consumption and indirect emissions by increasing the heating applied. Hence, evaluating additional sustainability indicators beyond CO2 emissions and replacing natural gas with cleaner fuels becomes essential in this context. The Value‐in‐use model reveals that up to 8% in refractory costs can be saved, but most benefits come from reducing steel temperature losses. Steelmakers can leverage this method to adapt their processes more effectively to achieve more sustainable and cost‐effective operations. [ABSTRACT FROM AUTHOR]

Underground storage tanks (USTs) primarily store and dispense fuel products (petroleum hydrocarbons) such as gasoline and diesel as well as some hazardous substances. When a release occurs from an UST, it must be cleaned up and remediated as necessary. As part of the site characterization process, monitoring wells are installed to measure petroleum hydrocarbon concentrations, such as benzene, to help site managers make decisions on remediation strategies and effectiveness, determine site status, and whether sites pose a risk to local receptors—with implications to human health and the environment. Previous studies have used various approaches to estimate benzene plume lengths using these monitoring well data. Examining one state's large database of monitoring well data from leaking underground storage tank (LUST) cleanup sites, and through statistical and spatial analysis, we find that studies that used existing monitoring well data may have underestimated plume lengths. Our study identified elevated benzene concentrations at the boundaries of monitoring well extents, including at the leading edge of plumes. For example, in 3,495 LUST sites, 83% exceeded a selected threshold concentration of 5 ug/L in a monitoring well at the site boundary, and 76% of sites exceeded 5 ug/L at the monitoring well furthest from a defined source, the point used to delineate length. Of the total 17,816 monitoring wells that delineated UST site boundaries, 47% had concentrations exceeding 5 ug/L. These data analyses and results are done over the lifetime of a monitored UST site, not targeted over time periods when decisions are being rendered. However, results suggest that studies to date using existing monitoring well data may have underestimated plume lengths and extents. Furthermore, results suggest monitoring wells in combination with other site information, such as modeling, should be used to guide site managers in their decisions regarding leaked UST products, the area and extent of contamination, risks to receptors, and remedial approaches. Practical Applications: USTs, which store fuel at locations such as gas stations, are known to leak fuel products into soil and groundwater. Fuel products contain petroleum hydrocarbons like benzene, a cancer-causing chemical. Previous studies that have attempted to identify the maximum distance benzene plumes travel have been hampered by a bias in available data—specifically, that monitoring wells are often not placed at far enough distances to be able to map a plume to concentrations below concerning levels. This paper identifies this bias and provides insight into how it may be considered in the future to more effectively map plumes and identify potential biases that can lead to inconclusive results related to plume behavior. While traditional physics-based models remain useful, they can be augmented with data-driven models to more accurately estimate plume extents, especially when real-world data are lacking. [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]

Copyright of Low-Carbon Chemistry & Chemical Engineering is the property of Low-Carbon Chemistry & Chemical Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study empirically evaluated the performance of a downdraft biomass gasifier integrated with a diesel engine using a combination of biomass and diesel fuel. The employed downdraft gasifier consisted of two interconnected oil drums measuring 60x151 cm. A combustion chamber was installed in the conical steel drum with a central axis having a throat diameter of 31 cm. Rubberwood, tamarind wood, and sawdust were used as fuel sources. These woods were combusted to produce gas, which was subsequently channeled through a filtering and temperature-reduction apparatus before being blended with diesel fuel. A Nissan RD28 94 hp diesel engine was used for the experiments, with an airflow rate set at 0.226 m³/s. The experimental results showed that burning a mixture of rubberwood and sawdust (7.5 kg each) produced gas for 61 minutes. Tamarind wood combustion (15 kg) resulted in 58 minutes of gas production. Burning pure rubberwood (15 kg) produced gas for 37 minutes. Combusting a blend of tamarind wood and sawdust (7.5 kg each) produced gas for 45 minutes. The gooseberry wood (15 kg) was burned for 57 minutes with gas formation lasting 48 minutes. Adjusting the air input to the gasifier combustion chamber to 100%, the rubberwood and sawdust mixture exhibited the highest gas production. Furthermore, engaging the RD28 engine at 978 RPM in gear L resulted in the gear halting at 99 RPM after gradually adding steel blocks. The torque required to cease the gear was measured at 10.68 N.m, highlighting the potential for stopping gear L within the low-speed range due to misalignment between the engine's end flywheel and the gear pulley spline. [ABSTRACT FROM AUTHOR]

There is growing global concern regarding the detrimental health impacts of PM2.5 emissions from traditional stoves that utilize polluting fuels. Conventional methods for estimating daily personal PM2.5 exposure involve personal air samplers and measuring devices placed in a waist pouch, but these instruments are cumbersome and inconvenient. To address this issue, we developed a novel neck-mounted PM2.5 monitoring device (Pocket PM2.5 Logger) that is compact, lightweight, and can operate continuously for 1 week without recharging. Twelve participants who utilized charcoal, firewood, or propane gas for cooking in rural regions of Rwanda wore the Pocket PM2.5 Logger continuously for 1 week, and time-series variations in personal PM2.5 exposure were recorded at 5-min intervals. Individual daily exposure concentrations during cooking differed significantly among users of the different fuel types, and PM2.5 exposure was at least 2.6 and 3.4 times higher for charcoal and firewood users, respectively, than for propane gas users. Therefore, switching from biomass fuels to propane gas would reduce daily individual exposure by at least one-third. An analysis of cooking times showed that the median cooking time per meal was 30 min; however, half the participants cooked for 1.5 h per meal, and one-third cooked for over 4.5 h per meal. Reducing these extremely long cooking times would reduce exposure with all fuel types. The Pocket PM2.5 Logger facilitates the comprehensive assessment of personal PM2.5 exposure dynamics and is beneficial for the development of intervention strategies targeting household air pollution. [ABSTRACT FROM AUTHOR]

While hydrogen is a promising clean fuel for gas turbines, reconciling its physical and chemical characteristics with the requirements of low NOx emissions is challenging. Consequently, hydrogen combustion often results in high NOx emissions and susceptibility to flashbacks, limiting its widespread application in the gas turbine industry. While moderate or intense low-oxygen dilution (MILD) combustion technology offers the potential to address these problems, its performance degrades significantly under partial-load conditions, making it unsuitable for the wide range of load requirements of gas turbines. This study explores a novel method for expanding the stable operating range of MILD combustion using catalytic combustion to promote the development of a carbon-free energy society and address the severe performance degradation of MILD combustion. Increasing the heat energy of the gas to compensate for the lack of kinetic energy in the air reduced the dependence of MILD combustion on the recirculation ratio, resulting in high combustion efficiency and low NOx emissions. The performance of a simplified combustor model was studied through numerical simulations using a decoupling catalytic and MILD combustion strategy. Under two typical operating conditions, the numerical results showed combustion efficiencies of 99.99% with NOx emissions of 23 ppm and 3 ppm, thus demonstrating that the proposed scheme can achieve MILD combustion with high efficiency and low NOx emissions under different load conditions, thereby realising stable operation. Moreover, this approach can provide a feasible combustion path for future decarbonisation of gas turbines. • A stage and catalytic combustion scheme is designed. • MILD combustion, thermal and emission characteristics are investigated. • Excellent combustion performance and low emissions under wide load conditions is achieved. [ABSTRACT FROM AUTHOR]

The present research describes one of the processes outlined in the literature, known as Chemical Looping Dry Reforming of Methane, which is currently to gain attraction to produce clean fuels from natural gas using a metal oxide support as a catalyst. This two‐step method offers distinct advantages by physically separating the reaction steps. This spatial separation effectively eliminates undesirable side reactions, leading to highly efficient syngas production with minimal carbon deposition. Crucial to optimizing this process is a deep understanding of the oxygen storage capacity (OSC) of the support (oxygen carrier) that will work in synergy with the supported active phase. Among the candidates, praseodymium stands out due to its favourable redox properties and exceptional OSC characteristics, making it a promising option for cleaner fuel technologies. In particular, this study emphasizes the significant influence of the nature of the active phases (Ni, Co or their bimetallic combinations), with bimetallic phases being the most promising (even without reduction, they can exhibit activity that equals or improves that of the Ru as benchmark), underscoring the fundamental role of catalyst design in achieving optimal performance. The results indicate that these compositions have high activities to generate the products, remaining close to the activity of ruthenium and generating minimal coke deposits in one reaction cycle. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Refinery Engineering is the property of Petroleum Refinery Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As a highly efficient and environmentally friendly gas fuel, hydrogen has emerged as one of the most promising sources of energy. However, the hydrogen explosion limit is low, the explosion risk is high, and the production, storage and transportation processes are prone to explode. Therefore, it is necessary to explore hydrogen explosion inhibitor to prevent and mitigation hydrogen explosions. In this study, the synergistic effect of the combination of inert gas and ultrafine water mist on the suppression of hydrogen explosion was studied by using a standard 20 L spherical explosive container bomb. The results of the study indicate that the combined use of inert gas and ultrafine water mist yields better suppression effects in terms of explosion pressure, flame propagation speed, and flame cellular structure formation, compared to the use of a single inert gas. Inert gas and ultrafine water mist have synergistic effects, but the synergistic effect of N 2 was significantly stronger than that of CO 2. Through chemical kinetic simulation, it was found that the formation rate of O, H, and OH, which were three active free radicals, decreased significantly compared with that of the single inhibition condition in the process of inhibiting the hydrogen explosion reaction by inert gas and ultrafine water mist. The pairing of nitrogen with ultrafine water mist demonstrates a superior collaborative effect in comparison to the combination of carbon dioxide and ultrafine water mist. • Synergistic explosion suppression effect of inert gas and ultra-fine water mist. • Twin-fluid can effectively slow down the formation of flame honeycomb structures. • Analyzed the synergistic explosion suppression mechanism of twin-fluid. • N 2 is more synergistic than CO 2 with ultra-fine water mist. [ABSTRACT FROM AUTHOR]

To achieve zero carbon emissions, replacing conventional fuels in combustion engines and gas turbines with carbon-free fuel is of utmost important. While hydrogen is effective in mitigating climate change, the cost challenges in liquefaction and transportation persist. Ammonia (NH 3), a carbon-free fuel with its higher volumetric energy density and cost advantages, emerges as a potential substitute. This review reports the most recent studies on NH 3 as a fuel for micro gas turbine (MGT), highlighting both advantages and limitations. The performance and emissions in gas turbines are discussed. The main obstacles to a widespread usage of NH 3 blends as fuel for MGT power generation are addressed, along with the current stage of commercialization. The review explores all the numerical and experimental works on NH 3 blend in combustion system of MGT, and further presents ways to overcome the limitations associated with the combustion, such as high NO x emissions and low burning velocity. [Display omitted] • A comprehensive analysis of ammonia blend reactive fuels for micro gas turbine power generation is presented. • Advantages and limitations of ammonia combustion in micro gas turbine over hydrocarbon fuels are summarized. • The issues that hinder a widespread usage of ammonia and ammonia/blend as fuel for micro gas turbine are addressed. • The current stages of commercialization are discussed. • Possible approaches to overcome ammonia combustion barriers in micro gas turbine are highlighted for future research. [ABSTRACT FROM AUTHOR]

One of the primary concerns with fuel combustion in internal combustion engines is the significant quantity of energy that is dissipated as waste heat, which leads to thermal pollution and reduced engine efficiency. To address this issue, a new integrated system incorporating a natural gas fueled homogeneous charge compression ignition (HCCI) engine for different hydrogen fractions (0%–20%) in fuel blends and its exhaust heat is recovered to drive the NH 3 –H 2 O based absorption refrigeration cycle (ARC) and process heat exchanger has been developed, which encompasses the generation of electricity, heating, and cooling. A comprehensive energy-exergy model was built and the impact of some key operating variables on the performance of combined system are investigated. Simulation of the proposed system was performed using Engineering Equation Solver (EES) software and REFPROP toolbox library data. The energy and exergy efficiencies of HCCI engine resulted in an increase from 45.26% to 55.45% and from 41.15% to 46.14%, whereas the combined system efficiencies were increased by 15.90% and 10.13% when hydrogen addition is promoted from 0% to 20%. Utilization of 10% hydrogen resulted in energy efficiency of 49.57% for electrical, 11.89% for cooling, and 4.51% for heating. Illustration of exergy flow diagram identified HCCI engine (118.29 kW, 32.11%) as the most fuel exergy destructive component, followed by ARC cycle (30.86 kW, 8.37%), catalytic converter (27.24 kW, 7.39%) and process heat exchanger (11.103 kW, 3.01%). Impressive exergetic results from the system include a power exergy of 158.91 kW (43.14%), heating exergy 10.697 kW (2.90%), and cooling exergy 3.92 kW (1.06%). • H 2 enriched natural gas fueled HCCI engine based trigeneration system was developed. • HCCI engine's exhaust waste heat was harnessed through the ARC cycle and PHE. • A single effect NH 3 –H 2 O absorption chiller was employed for cold production. • Energy and exergy-based assessment was carried out to analyze the proposed system. • HCCI engine (32.11%) were identified as the primary exergy destructive components. [ABSTRACT FROM AUTHOR]

This study focuses on the effect of pressure level and H 2 content in the CH 4 –H 2 fuel mixture on the global consumption-based turbulent flame speed (S T). The data considered in the analysis are collected for a variety of CH 4 –H 2 fuel compositions (from 50% to 100% H 2 vol.), pressure levels ranging from 0.5 to 1.5 MPa, and preheating temperatures up to 623.15 K. Different trends of S T /S L0 (S L0 is the adiabatic unstretched laminar flame speed) are observed as a function of the normalized turbulence intensity (u'/S L0), depending on the H 2 content in CH 4 –H 2 fuel blends. Yet, for all the CH 4 –H 2 fuel mixtures considered, S T /S L0 consistently increases with H 2 content. Rising pressure levels are responsible for larger S T /S L0 , in direct proportion with the H 2 content. These trends are mostly caused by the decrease in S L0 , which causes changes to the characteristics of the flamelet that becomes more sensitive to hydrodynamic wrinkling through the high molecular diffusivity of H 2. • Global consumption based turbulent flame speed of H 2 –CH 4 fuel mixtures at gas turbine relevant conditions. • Effect of high H 2 content and high-pressure level. • Data reduction with Ze/ Pe scaling method. [ABSTRACT FROM AUTHOR]

Dual Fuel (DF) combustion concept has demonstrated to be a valid solution to ensure the utilization of diesel engines in heavy duty and naval applications. The substitution of part of diesel fuel with a cleaner gaseous one can reduce among others: carbon dioxides (CO 2), nitrogen oxides (NO x) and surely particulate matter (PM). Nevertheless, the difficulties encountered by the reduced pilot liquid jet to reach out the furthest areas of the combustion chamber, especially at partial load, lead to unburned emissions of the premixed charge. They can be a serious issue to overcome when the premixed fuel is represented by a carbonaceous fuel like natural gas (NG). For this reason, hydrogen, that is carbon-free, represents the new progression to clean mobility. This work aims at deepening the in-cylinder phenomena through a synergetic methodology that involves experimental optical diagnostics and 3D numerical investigations. The experimental activity is carried out on a single cylinder research engine (SCRE) equipped with an optical apparatus allowing the visualization of the combustion process, later processed via high speed visible (VIS) and infrared (IR) imaging. Several filters applied on the IR camera permit to detect specific species such as CO 2. Subsequently, these outcomes are used to validate numerical models, and in turn, the numerical results help to validate the species detected qualitatively via optical diagnostics and to identify which ones majorly affect the physical and chemical processes. Numerical simulations are performed with ANSYS Forte ® code on a geometry which accurately reproduces the shape of the combustion chamber. Combustion models include a turbulent-kinetic interaction model with a mechanism of 124 species and 660 reactions to deal with the autoignition phase and diesel surrogate oxidation, while to account for the flame propagation through the premixed charge the G-equation is considered. The reference test cases are characterized by two different engine speeds, 1500 and 2000 rpm, and a low load level, corresponding to 2 bar of brake mean effective pressure (BMEP) on light-duty vehicle. The hydrogen energy shares are between 83.2 and 81.8%. Results demonstrate that IR images and OH radical are key for the detection of ignition process of both diesel and hydrogen. The flame propagation in the air/H 2 charge can be observed with the help of CFD elaborations. Finally, emission levels are adequately predicted by the chosen oxidation models. • IR and VIS imaging are used to visualize the in-cylinder process in a diesel SCRE operating in DF mode supplied with H 2. • CFD is used to identify the species that better represent the oxidation process of both fuels. • IR imaging together with OH allows to identify the ignition phases of both diesel and H 2. • CFD flame front visualizations are necessary to overcome the limits of IR imaging for the representation of premixed flame. • The chosen kinetics well predict pollutant emissions. [ABSTRACT FROM AUTHOR]

During Fuel Cell Vehicle (FCV) operation, the liquid water in gas diffusion media (GDM) prevents the reaction gas from reaching the reaction zone and lead to output power fluctuation and reduce the lifespan of FCV. In the present research, hydrophobicity gradient settings of micro-porous layer (MPL) and gas diffusion layer (GDL) are optimized to improve the water removal ability of GDM. Computational fluid dynamics (CFD) model is constructed for numerical simulations to analyze the fuel cell power output and the water content in the GDM with different hydrophobicity gradients. Experiments with different hydrophobicity gradients, which are specifically prepared with corresponding concentrations of polytetrafluoroethylene (PTFE) solutions, are conducted for validation of simulation results. It is shown that the positive hydrophobicity gradient of MPL and GDL provides a better capacity for water removal and oxygen transport. The contact angles of MPL and GDL are further optimized as 147.9°-138.6° by genetic algorithm integrated with the CFD simulations. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to provide an overview of the computational progress in the development of hydrogen-fired gas turbines. This review aims to identify suitable combustion models, appropriate NOx chemistry mechanisms and NOx emission levels for effective utilization of hydrogen as an alternative fuel in gas turbines. Design/methodology/approach: Hydrogen is recognized as a potential alternative fuel for achieving exceptionally low emissions in gas turbines. The developments in conventional, trapped vortex combustor and micromix combustors are discussed, along with various computational models aimed at accurately predicting combustion and emission characteristics. The results of numerical simulations were then discussed with emphasis on their role in optimizing the combustor geometry. Findings: Computational studies that were used to optimize the combustor geometry to reduce NOx emissions and the flashback phenomenon are discussed. To retrofit existing gas turbines for hydrogen fuel, minor modifications that are required were discussed by analyzing extensive literature. The influence of key design and geometrical parameters on NOx emissions and the appropriate selection of combustion models for numerical simulations in optimizing various combustion systems are elaborated. Originality/value: The review emphasizes the computational studies in the progress of hydrogen-fired gas turbine developments. The previous reviews were primarily focused on the combustion technologies for hydrogen-fired gas turbines. This comprehensive review focuses on the key design parameters, flame structure, selection of combustion models, combustion efficiency improvement and impact of parametric studies on NOx formation of various combustion systems, in particular hydrogen combustion for gas turbine applications. [ABSTRACT FROM AUTHOR]

The increasing energy demand, the reduction of non-renewable resources, and the increase in environmental damage factors have drawn attention to energy supply through multi-generation systems. This study proposes a multi-generation system based on the Allam cycle, integrated with geothermal energy, with the aim of minimizing natural gas fuel consumption. This system includes the main sub-systems: an electrolyzer unit, a reverse osmosis unit, an organic Rankine cycle, a hydrogen engine, an absorption chiller, and a compression chiller. The proposed multi-generation system provides the hourly demands of freshwater, cooling, heating and electricity of a residential building located in the city of St. Petersburg (in Russia). For the purpose of feasibility, the system is studied from the thermodynamic, environmental, and economic points of view. The results of the thermodynamic analysis showed that the system has maximum energy and exergy efficiency of 29.759 and 25.879% respectively. The use of geothermal energy reduced CO2 emissions to a maximum of 1895043 gr. Calculation of the NPV index for interest rates of 15 to 30% showed that this system will be profitable in the twelfth year at most. [ABSTRACT FROM AUTHOR]

The British government used to herald shale gas as a bridge fuel to a zero-carbon economy, trying (and ultimately, failing) to incorporate this hydrocarbon into a punctuated energy transition that is still under way in the country. On the one hand, planning translated central political decisions into local priorities, but on the other hand, it politicized public opposition to fracking. Although, there have been considerable criticisms of the planning process for fracking in Great Britain, we still lack a grounded understanding of how planning influenced the wider dynamics of public engagement with shale gas development. Drawing on ethnographic and participatory research across three locations in northern England, I explore how the planning process was experienced by the public and how its local participants were impacted by it. The ways in which planning dealt with evidence, public perception and democratic legitimacy suggested that planning was reinforcing the governmental pro-fracking policies while simultaneously undermining its own legitimacy, as questions about validity, impartiality and democracy were being raised. Rather than merely a technocratic arena for adjudicating between private and public interests, planning had a transformative effect on local participants and served as an important moment for mobilizing more politicized forms of public opposition against fracking, which undermined the energy-transition narratives touted by the government. I use anthropological theorizations of ritual to explain the concrete local dynamics that led to this unintended effect. This case study suggests that centrally orchestrated energy transitions may fail when they are enacted through local processes that foster experiences of injustice and lack of local control among the opposing publics. [ABSTRACT FROM AUTHOR]

With the increasingly serious problems of energy shortage and environmental degradation, countries around the world are actively developing safe, environmentally friendly, and renewable energy. Biomass energy has become an ideal substitute for fossil fuels due to its abundant reserves, good renewable performance, and zero carbon emissions. This paper discusses the importance and potential of biomass energy as a renewable energy source for China's energy development, mainly including the three biomass conversion methods of physics, chemistry, and biology, seven utilization technologies, such as direct combustion, gasification, and pyrolysis, and five application approaches, such as biomass power generation, biomass gas fuel, biomass liquid fuel, and bio-based materials. This review systematically analyzes the challenges faced by China's development of biomass energy and discusses the future development direction of biomass. The utilization of biomass resources should take a comprehensive and high-value path. China is actively looking for new energy utilization paths, and biomass energy has become a key measure to cope with carbon emission reduction, climate change, and ecological environment protection. [ABSTRACT FROM AUTHOR]

Petroleum-based fuels are generally used in internal combustion engines. Petroleum-based fuels now have difficulty meeting Euro standards in terms of emissions. That's why different methods are used. One of these is that adding natural gas to fuels can be beneficial in reducing emissions and increasing engine performance. In the experimental study, the engine performance and emissions of adding natural gas at different rates (50, 100, 150 and 200 g/h) into the intake air of an engine using gasoline fuel at different torque values (5, 10, 15 and 20 Nm) at a constant 3000 rpm were examined. The engine used in the study is a Lombardini LGW 523 MPI gasoline two-cylinder engine. When the experimental results are examined, the addition of natural gas to gasoline fuel reduces fuel consumption. The lowest values in specific fuel consumption were obtained when natural gas was added. Emissions decreased with increasing torque. As the natural gas addition rate increased, the thermal efficiency increased. [ABSTRACT FROM AUTHOR]

The paper presents research results of the synthesis, phase composition, and structure of products obtained by highly exothermic reactions between Ti and C10H8O4 mixture components, depending on the plastic waste concentration and Ti powder dispersiveness, density of initial samples, and synthesis medium. The dependence of the phase composition and structure of the synthesis products on the concentration of the polymer (plastic) component in the initial Ti -PET (C10H8O4) system was found. When the plastic waste content is 20 wt% to 25 wt %, synthesis products contain TiC0.5O0.5-TiC0.6-0.75 particle agglomerates. Further growth in the polyethylene terephthalate content from 30 wt% to 45 wt% leads to the formation of synthesis products consisting of titanium carbide (TiC0.6-1.0). The gaseous byproduct composition of the exothermic reaction is investigated for the Ti--C10H8O4 mixture composition. It is found that the gaseous by-product mostly contains hydrogen and carbon monoxide as well as impurities of different hydrocarbons (methane, acetylene, ethane, ethene) and carbon dioxide. The maximum adiabatic temperature of the gas combustion temperature is 2080 °C, which demonstrates the possibility of using gas as a fuel for energy generation devices. Based on the data obtained, it is possible to create a basis for a new plastic waste technology to fabricate carbide-containing materials. [ABSTRACT FROM AUTHOR]

Fuel consumption, fuel cost savings, environmental pollution, and navigation safety are significant factors for shipping companies. Maritime transport represents 3% of total greenhouse gas emissions globally. Trim optimization is one of the ways to save energy and reduce ship emissions. Thus, this study aimed to evaluate how the optimization of the trim of container ships at different speeds can decrease exhaust gas emissions and fuel consumption while considering the safety of navigation. This research was conducted by calculating the fuel consumption in real conditions and calculating the optimal trim for different speeds and gases of a container ship of 11,400 TEU. All obtained results were statistically processed to analyze fuel consumption at various speeds, considering the ship's trim. It turns out that savings should never be at the expense of navigation safety, especially in limited maneuvering areas, such as canals. When maneuvering in such places it is necessary to adjust the trim to ensure navigation safety, i.e., to improve the rudder and propulsion device response, instead of reducing fuel consumption [ABSTRACT FROM AUTHOR]

Indonesia is a country that has abundant natural resources such as palm oil, coal and so on. These two types of coal mining and palm oil plantation sectors have provided many benefits for community welfare. The aims of research is to utilize palm oil industry waste in the form of empty fruit bunch (EFB) and fine coal waste (FCW) into synthetic gas (syngas) through a catalytic gasification process which is then used as a source of energy and/or synthesis chemicals. Gasification temperatures are 450 ℃, 550 ℃ and 650 ℃. Gasification time 20, 30 and 40 minutes. The ratio between pillared bentonite catalyst and EFB is 0.125 and 0.25. The resulting syngas is analyzed for the content of H2, CO, CH4 and CO gases. At gasification temperatures of 450 ℃, 550 ℃ and 650 ℃, the H2/CO gas ratio is 1.90; 2.05 and 2.27. The increase in this ratio is not very significant, because the increase in the H2/CO ratio increases only 19.47% from a temperature of 450 ℃ to a temperature of 650 ℃. The comparison value between combustible gas (H2, CO and CH4) and non-combustible gas (CO2), namely the CG/NCG ratio shows the quality of a syngas. The higher the CG/NCG value, the better syngas is as a gas fuel because it has a higher heating value. The CG/NCG value at a temperature of 450 oC is 14.18, while at a temperature of 550 ℃ it is 17.16 and at 650 ℃ it is 21.41. With an increase in temperature from 450 oC to 650 oC the increase in CG/NCG value is 51%. Therefore, by increasing the CG/NCG value, the quality of the syngas will increase and the calorific value of burning the syngas will improve. The HHV value at a temperature of 450 ℃ is 8.34 MJ/Nm3, at a temperature of 550 ℃ is 12.32 MJ/Nm³ and at a temperature of 650 ℃ is 15.53 MJ/Nm³. Thus, increasing the temperature from 450 ℃ to 650 ℃, there is an increase in HHV of 86.21%. This result is economically beneficial because the increase in calorific value will increase the benefits of syngas. The higher the HHV value, the better the syngas is used as gas fuel. The HHV value at a temperature of 450 ℃ is 7.49 MJ/Nm³, at a temperature of 550 ℃ is 11.06 MJ/Nm3 and at a temperature of 650 ℃ is 13.91 MJ/Nm³. Thus, by increasing the gasification temperature from 450 ℃ to 650 ℃, there is also an increase in LHV of 85.71%, meaning it has increased quite significantly. When compared with the use of 0.125% catalyst, the increase in catalyst concentration of 0.25% is smaller than 91.90%. From the experimental results it can be concluded that increasing temperature will improve the quality of syngas. Improving the quality of syngas can be done through the syngas enrichment process through the conversion of CO2 gas reacting with carbon to produce CO gas. The concentration of CO2 gas can be reduced by absorbing CO2 gas by the Ca(OH)2 solution. [ABSTRACT FROM AUTHOR]

The article presents the results of theoretical studies of the ignition process of a water-coal fuel particle under conditions of high-temperature heating at high pressures of the external environment. The authors have developed a new mathematical model of the water-coal fuel particles ignition under stress (pressure – Pg = 1–200 bar, and temperature Tg = 873–1273 K) heating conditions. The mathematical model differs from the known ones by a detailed description of the physicochemical processes occurring during the induction period of time, as well as the processes of phase transitions under high pressure conditions. Based on the results of numerical simulation of the ignition process, it was found that the pressure of the external environment (Pg) has a significant effect on the characteristics and conditions of ignition of water-coal fuel particles. It was shown that the tign(Pg) dependence is essentially nonmonotonic. The authors have established that when Pg changes in the range from 1 to 30 bar (for oxidizer temperatures (Tg = 873–1273 K), an increase in the ambient pressure leads to a nonmonotonic increase in tign. In this way such a dependence tign(Pg) is due to the joint influence of two significant parameters of the factor space, which significantly affects the dynamics of the thermal treatment of fuel. With an increase in the pressure of the mixture of oxidizer and combustible gases, the saturation temperature (the temperature of intense evaporation of water) increases, at the same time, the heat of the phase transition (QL) decreases and the rate of release of pyrolysis gases into the oxidizing environment decreases. Based on the results of the theoretical studies, it has been shown that for efficient combustion of water-coal fuel under the conditions of the combustion chambers of a GT at oxidizer temperatures Tg≥1073K, the pressure in the combustion chamber of the GT must be at least 50 bar. [ABSTRACT FROM AUTHOR]

Blending the capabilities of the strontium hexaferrite SrFe 12 O 19 (SRF) with tri zinc substituted Keggin-type polyoxometalate PMo 9 Zn 3 O 37 (PMZ), to yield PMo 9 Zn 3 O 37 @SrFe 12 O 19 (PMZ@SRF) will have notable ability of hydrogen storage. The use of hydrogen gas as an alternative gas fuel for solving the air pollution has increased its demand by far and need for investigating its storage ways can be clearly observed. Herein, the hypothesis of the ability of novel PMZ@SRF on hydrogen storage was confirmed by chronopotentiometry analysis under a constant current of ±1.5 mA in an electrochemical cell containing of the 6 M of KOH as an electrolyte and the modified cupper foam plate coated with PMZ@SRF nanocomposite as a working electrode. The novel nanocomposite was synthesized by the sol-gel method and characterized by FT-IR, XRD, UV–vis, SEM, EDX, and BET analysis. The characteristic spectra showed the proper synthesis and SEM analysis evaluated the mean size of the nanoparticles 39.44 nm. However, the size of the nanoparticles was calculated by the Debye-Scherrer formula as 29.75 nm with an XRD pattern of the as-prepared PMZ@SRF nanocomposite. Also, BET analysis proved that when PMZ is immobilized on the SRF host the whole new composite will have 0.08 (cm3/g) more pore volume than the raw compound of PMZ. The hydrogen storage capacity will be in priority for thinking new ways of how to have less air pollution, and introducing the significant capabilities of the novel PMZ@SRF on hydrogen storage technology will make a full impact on research areas. [Display omitted] • The heterogeneous nanocomposite (PMZ@SRF) was synthesized successfully. • The catalytic activity of PMZ@SRF was tested on the electrochemical hydrogen storage process. • PMZ@SRF proves to be a preferred active material for hydrogen adsorption-desorption process. • PMZ@SRF discharge capacity has shown a significant increase from ∼ 1550 to 2929 mAh/g after 10 runs. [ABSTRACT FROM AUTHOR]

The utilization of hydrogen as an energy carrier faces a challenge due to its limited presence in its pure form in the Earth's atmosphere, necessitating its extraction from various sources. Among hydrogen production methods, microwave-induced plasma molecular cracking shows promise as an alternative. This review explores how different operational parameters of a microwave-induced plasma system with gas-phase discharge impact hydrogen production performance. Performance indicators include hydrogen production rate, energy yield, and final hydrogen concentration. Parameters influencing hydrogen production encompass microwave power, gas flow rate, initial hydrogen concentration, steam addition, gas injection method, and plasma-forming gas type. Other vital system parameters are also discussed. Higher absorbed power leads to increased hydrogen production, albeit less efficiently. Elevated carrier gas flow rate reduces residence time, consequently lowering performance, while higher fuel gas flow rates enhance hydrogen production. Introducing steam can enhance indicators and reduce soot, and injecting fuel gas directly into the plasma torch tip yields optimal hydrogen production. Avoiding excessive power, fuel gas flow, or water vapor is important, as hydrogen saturation can limit further performance enhancement. • Microwave-induced plasma appears as a promising alternative for H 2 production. • Operational parameters' impacts on the system performance were analyzed. • Steam addition and gas injection methods' impacts on H 2 production were discussed. • Optimal practices for enhanced H 2 production were determined. [ABSTRACT FROM AUTHOR]

Composite pipe is preferred over metal and other materials for water supply, liquid chemical transport, and fuel and gas transport. This is because composite pipes are more corrosion resistant, have a high strength/density ratio, high stiffness/density ratio, and more durable than metal pipes. The properties of the composite pipes employed may differ based on the operating environment. Therefore, determining the properties of the composite pipe according to the working environment is extremely important for its lifespan. The thickness of the samples is increased in line with different needs (such as increased strength). Increasing the thickness of samples, especially those exposed to different environmental conditions, and investigating the changes that will occur in the physical and mechanical properties of the samples are another important situation. In this investigation, glass fiber (GFRP) reinforced epoxy composite pipes have been examined, which were manufactured using the filament winding method with different layers [±55°]. To determine their properties in different working environments, the GFRP composite pipes were subjected to hydrothermal aging in pure water at 80°C for several days (7, 14, 21, and 28). The changes in their mechanical properties under working conditions were determined through hoop tensile strength tests and low velocity impact tests applied at different energy levels. The experimental results show that the tangential stress values increased by 10.59% as the number of layers increased. As the aging time increased, the durability of the 6-layer composite pipe decreased by 17.69%. Furthermore, the ability of the aged pipes to withstand damage was evaluated, revealing that the aging process exacerbated the damage within the pipes. [ABSTRACT FROM AUTHOR]

Low temperature combustion (LTC) mitigates the nitrogen oxide (NOx) and particulate matter (PM) trade-off in conventional compression ignition engines. Significant research on LTC using partially premixed charge compression ignition (PPCI) has typically reduced the compression ratio of the engine to control combustion phasing and lower peak temperatures. This study investigates LTC using PPCI with a high-compression-ratio (=21.2) engine by varying fuel injection timing (FIT) from 12.5° to 30.0° before top dead center (BTDC) while modulating EGR (0%, 7%, 14%, and 25%). Advancing FIT led to a gradual rise in the equivalence ratio of the mixture, in-cylinder pressure, temperature, and rate of heat release due to energy losses associated with ignition occurring before the end of the compression stroke. PPCI was successfully achieved with minimal performance impact using a combination of FIT advancements in the presence of high rates of EGR. Specifically, fuel injected at 25.0° BTDC and 25% EGR reduced PM emissions by 59% and total hydrocarbons by 25% compared with conventional FIT (12.5°) without EGR. Moreover, carbon monoxide and NOx emissions were comparable across set points. As a result, PPCI using high compression ratios is possible and can lead to greater thermal efficiencies while reducing emissions. [ABSTRACT FROM AUTHOR]

The hydrogen-diesel dual-fuel mode is an efficient way of lowering exhaust emissions from compression-ignition engines. Along with exhaust emissions, mechanical vibration and noise emissions are also problems for these engines. In dual fuel mode, it is possible to reduce all emissions by using the appropriate injection strategy. In this study, different injection strategies were used in an engine with an ECU-controlled liquid and gas fuel system. In experiments, constant load (5 Nm), constant speed (1850 rpm), constant hydrogen energy ratio (12%), 4 different hydrogen injection pressures (1, 1.5, 2.0, and 2.5 Bar), and 5 different hydrogen injection starts (25, 35, 45, 55, and 65 °CA aTDC) were performed. In the study, exhaust, mechanical vibration, and noise emissions were recorded and analysed. When a few of the study's data were looked at, it was determined that CO 2 emissions decreased by 33.4% and PM emissions by 40.7% at 25 °CA aTDC injection start and 2.5 bar injection pressure. Under the same experimental conditions, NO emissions increased by 8.7%, mechanical vibration emissions increased by 19.9%, and noise emissions increased by 2 dBA. [Display omitted] • H 2 -diesel dual fuel use is effective in reducing CO, CO 2 and soot emissions. • In dual fuel mode, H 2 increased NO, mechanical vibration, and noise emissions. • Increasing the injection timing in dual fuel mode reduces emissions. • H 2 injection being lower than 25 °CA aTDC risks combustion safety. [ABSTRACT FROM AUTHOR]

To solve the environmental concerns and cleaner combustion, ammonia has been considered as a new fuel to blend into the traditional hydrocarbon fuels, which acts as a carbon-free hydrogen carrier. The evolution of flame emissivity, view factor and radiative heat flux have been investigated under different flow rates of ammonia and methane or propane, respectively. The experimental results indicate that the flame emissivity, view factor, and radiative heat flux decrease with increasing ammonia concentration. Some correlations have been developed for the flame emissivity, view factor, and radiative heat flux, which play as a function of flame height and flame width. It demonstrates a well predictive capability for the thermal radiation with different ammonia concentrations. These experimental results not only contribute to the fundamental understanding of thermal radiation model of ammonia-hydrocarbon mixed gas, but also useful for fire safety and the burner design for reducing the pollutant emissions. • Both the flame emissivity and view factor decrease with the NH 3 concentration. • The thermal radiation is inverse proportional to the NH 3 concentration. • The correlations of flame emissivity and view factor depend on flame size has been developed. • The prediction model of thermal radiation of jet flame diluted by NH 3 has been simplified. [ABSTRACT FROM AUTHOR]

A possible way to introduce hydrogen into the energy matrix would be to enrich traditional fuels like natural gas and propane with hydrogen. Therefore, the study of the flame propagation behavior of these hydrogen enriched fuels becomes important to future industrial applications. In the present work the aim was to experimentally study the effect of hydrogen enrichment of propane and natural gas. However, in order to achieve more generality, the studied mixtures were characterized through the Lewis (Le), Zeldovich (Ze) and the reaction Damköler (Da°) numbers. A total of six mixtures were considered, in which the Ze varied from 4.94 to 8.45, the Le varied from 0.71 to 1.36 and the Da° varied from 14.56 to 36.11. In addition, the obtained results were compared to previous work to assess the effect of the experimental boundary conditions on the flame propagation velocity. The experimental results show that, for mixtures with similar Le numbers, the lower the Ze number the higher the flame propagation velocity. The maximum propagation velocities obtained in the first propagation section of the module are between 18.60 m/s and 57.11 m/s. Therefore, these flames can be considered as weakly accelerating flames. Moreover, the maximum flame propagation velocities showed a good correlation with the product Le × Ze. Regarding the presence of the flame arrester housing without an arrester element, it was observed that it causes an increase in flame propagation velocity. However, when compared to a previous work in which a flame arrester element was inside the housing, the velocity was higher for the present work. • Hydrogen enrichment of mixtures containing propane and gas natural were considered in this study. • The influence of the Lewis and Zeldovich numbers was investigated. • The flame propagation velocity was investigated in terms of these dimensionless numbers. • The results show that lower Zeldovich numbers promote higher propagation velocities for similar Lewis numbers. • Through comparison with published results the effect of experimental boundary conditions was assessed. [ABSTRACT FROM AUTHOR]

In this work, in situ-generated cobalt oxide was infused into g-BCN to fabricate a heterocomposite (CoBCN) with multiple active sites. The electronic structure of CoBCN was further modified via the introduction of n- (Ni) and p-(Fe) type metals to investigate the activities of CoBCN-type materials with loosely bound electrons for electrocatalytic hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) which symbolize the reduction/oxidation of water and reduction of fuel gas oxygen that goes on in concurrent electrocatalytic and fuel cell. Experimental results indicated that not only the electronic nature of the surface but also the binding energy between the involved metals and intermediates varied accordingly for the association/dissociation steps, resulting in the superiority of p-doped materials in HER and the n-doped material in the OER and ORR. The HER activity was governed by Fe–CoBCN with an overpotential of 97 mV (@ 10 mA cm−2), whereas Ni–CoBCN showed superior performance for the OER and ORR with an overpotential and E 1/2 of 130 mV (@ 10 mA cm−2) and 0.79 V, respectively. p-/n-effect on CoBCN material for its multifunctional electrocatalytic activity for HER, OER and ORR. [Display omitted] • Fe and Ni oxide were doped individually to observe the p-/n-effect. • Fe–CoBCN dominated HER with a low overpotential due to facile Cat-H interaction. • Ni–CoBCN outperformed for OER and ORR with a low overpotential and E 1/2. [ABSTRACT FROM AUTHOR]

Fuel leakage detection is crucial for solid oxide fuel cells (SOFCs) as fuel leakage significantly reduces the reliability and lifetime of SOFC devices. In this study, fuel leakage detection using voltage signals is thoroughly investigated. Rectangular SOFCs with four segmented cathodes are prepared and tested with fuel leakage along the seals. Voltammetric tests show that the ring-shaped area on the current-voltage curve is primarily caused by a delay of gas diffusion. Such a ring-shaped area is exacerbated by fuel leakage but is not sufficient as an indicator for detecting fuel leakage. Additionally, the open-circuit voltages measured at all segmented cathodes are well below the theoretical potential of the fuel gas. This is because a localized steam electrolysis circuit is formed when fuel leakage occurs. The measured open-circuit voltage is the potential difference between the two interconnectors in the closed electrolysis circuit. This work contributes to the accurate detection of fuel leakage and the commercialization of SOFCs. [Display omitted] • OCVs tested with fuel leakage are well below equilibrium potential. • Fuel leakage causes localized steam electrolysis. • The ring-shaped area on I–V curves results from a delay in gas diffusion. • Ring-shaped areas are not sufficient as indicators of fuel leakage. [ABSTRACT FROM AUTHOR]

During a space mission, switching to an electric propulsion system from chemical propulsion, once the spacecraft is out of the Earth's gravity, significantly reduces the mission's overall cost. In electric propulsion, the Hall thruster and gridded ion thruster are established technologies. These thrusters compromise mission longevity due to continuous erosion of the device electrode material. To overcome this issue, an electrode less expanding magnetic field plasma thruster or helicon plasma thruster (HPT), was proposed and research is on going worldwide. The HPT shows scaling of thrust with input power while Hall thrusters and ion thrusters do not. Typically, an inert xenon gas is used as a fuel in HPT devices due to a low ionization potential and non-hazardous nature. Xenon is not easily available in nature and during a space mission it needs to be stored in high pressure tanks. Recently, iodine has been proposed as an alternate to xenon as it is easily available and does not have any storage issues. In most of the numerical simulations, argon is used as a fuel gas to reduce the simulation cost. Using a 1D3V particle-in-cell Monte Carlo collision code, we present here a net thrust generation for different fuel gases such as argon, xenon and iodine. We compare plasma flow rates and directed ion beam velocity for different fuel gases having identical inputs. Thrust and plasma flow are investigated for different magnetic field gradients in the plasma expansion region for unidirectional and bidirectional HPT and is reported here. Using iodine fuel, a significant increase in net thrust is obtained for higher magnetic field divergence for identical simulation input parameters while comparing with xenon fueled cases. [ABSTRACT FROM AUTHOR]