Fuel Flexibility Research Articles

Nonpremixed Approaches for Fuel Flexible, Low NOx Combustors in High-Efficiency Gas Turbines

Abstract Lean, premixed combustor designs have almost completely replaced non-premixed combustors for industrial gas turbine applications where NOx emissions are regulated. Nonetheless, these designs have also introduced turndown and fuel flexibility constraints and made combustion instabilities and flashback more problematic. Future gas turbine applications will require combustors to accommodate a range of alternative fuels, provide operational flexibility, and compete for services with a host of new technologies, including energy storage and fuel cells. The purpose of this paper is to propose nonpremixed, multi-stage designs for the next generation of high turndown, high fuel flexibility, low NOx combustion designs – referred to here as a Nonpremixed, Rich, Relaxation, Lean (NRRL) combustor. The key concept we explore is non-premixed combustion, followed by additional fuel mixing to locally fuel-rich conditions, a relaxation stage, and then a lean stage. This non-premixed approach can handle essentially any fuel composition, including pure hydrogen, liquid fuels, pure methane, pure ammonia, and any combination in between while breaking the NOx-CO tradeoff and reducing combustion instability risk. This paper provides chemical reactor network modeling calculations to identify key kinetic processes and time scales required for such a concept. This concept has completely inverted sensitivities from lean, premixed systems which prefer short residence times, low pressures, and low temperatures to minimize NO formation. This concept prefers long residence times, high pressures, and high temperatures, indicating a very different set of design trades for part load and off-design performance.

GradientFunctionalLayerAnodeforCarbonate-SuperstructuredSolidFuelCellswithEthaneFuel.

Carbonate-superstructured solid fuel cells (CSSFCs) are an emerging type of fuel cells with high flexibility of fuels. However, using ethane fuel for solid fuel cells is a great challenge due to serious degradation of their anodes. Herein, this critical issue is solved by creating a novel gradient functional layer anode for CSSFCs. First, a finer-scale anode with a larger surface area is demonstrated to provide more active sites for the internal reforming reaction of ethane, achieving a 60% higher ethane conversion rate and 40% lower polarization resistance than conventional anodes. Second, incorporating a gradient functional layer into the anode results in an additional 50% enhancement in the peak power density of CSSFCs to a record high value (up to 241mW cm-2) with dry ethane fuel at a low temperature of 550°C, which is even comparable to the power density of conventional solid oxide fuel cellsabove 700°C. Furthermore, the CSSFC with the gradient anode exhibits excellent durability for over 200 h. This finding provides a new strategy to develop efficient anodes for hydrocarbon fuels.

Co-firing ammonia and hydrogen with butane under methane-equivalent calorific value and Wobbe index: Insights into transition in flame propagation and swirl flame characteristics

Fuel flexibility stands as a critical requirement for the development of combustors in future carbon-free energy systems. Carbon-free fuels including ammonia (NH3) and hydrogen (H2) are substantial supports for achieving this target, raising strong needs to counterbalance their distinct fuel thermochemical properties from methane (CH4), such as volumetric calorific value (CV) and Wobbe index (WI). In this work, butane (C4H10) which is an emerging renewable synthetic fuel is proposed to co-fire NH3 and H2 under methane-equivalent calorific value (MECV) and Wobbe index (MEWI). Laminar flame propagation of NH3/H2/C4H10 mixtures under MECV and MEWI are investigated in a cylindrical constant-volume combustion vessel. C4H10 co-firing can simultaneously tune the fuel thermochemical properties to CH4 levels and regulate the laminar flame propagation of NH3 and H2. Kinetic simulation and modeling analysis are performed to provide insights into the dominant kinetics and transition in laminar flame propagation. CV-compensated transition variables can generally well constrain the transition profiles of laminar burning velocity (LBV), while WI-compensated transition variables can linearize the transition profile from NH3 to C4H10 but meet challenges in constraining the transition profiles of H2-blending mixtures. Chemical effects are found to play the dominant role in the transition of laminar flame propagation, while thermal effects also have positive contributions. Test experiments in a gas turbine model combustor are also conducted to assess the swirl flame characteristics of NH3/H2/C4H10 mixtures under MECV and MEWI. The measured swirl flame morphologies and lean blowout limits indicate enhanced fuel reactivity and flame stability with the transition in fuel content, which is in accordance with the observed trends in LBV. Furthermore, comparison with CH4 provides a comprehensive evaluation of NH3/H2/C4H10 mixtures from the aspects of combustion characteristics and thermochemistry.

Investigation of Fuel and Load Flexibility of an Atmospheric Single Nozzle Jet-Stabilized FLOX® Combustor With Hydrogen/Methane-Air Mixtures

Abstract In this work, an existing single nozzle FLOX® (FLOX®, WS Wärmeprozesstechnik GmbH, Renningen, Germany) burner was modified with a fuel nozzle that was installed concentrically inside the outer air nozzle and was arranged in two different configurations. In the first, nonpremixed case, the fuel and air nozzles were flush at the nozzle exit. In the second, technically premixed case, the fuel nozzle terminated 50 mm below the air nozzle exit. A third, fully premixed case was also achieved by injecting fuel into the air delivery line via an inline-mixer upstream of the nozzle exit. Additionally, measurements were performed using fuel nozzles with two different sizes. For all these cases, hydrogen volume fraction in the fuel was varied from 0 to 100% at a constant equivalence ratio and thermal power. The resulting flames were characterized using two-dimensional OH-chemiluminescence measurements. In addition, load-flexibility was investigated on the 100 vol. % H2 case by varying the equivalence ratio. Some selected conditions were further investigated using particle imaging velocimetry (PIV) to obtain velocity fields. The experimental results demonstrated a strong influence of nozzle configurations (mixedness), equivalence ratio, and H2-content on flame shapes. First of all, increasing H2-content reduced the flame liftoff height (LOH) above the nozzle exit for all three configurations. Second, for the cases with 100 vol. % H2 and independent of the nozzle configuration, the liftoff height increased drastically when Φ was reduced to below 0.3 while the flame became visibly unstable. Overall, increasing level of mixedness generally caused the flame to stabilize closer to the nozzle exit. A remarkable decrease in the liftoff height was observed for the technically premixed case compared to the nonpremixed case. Increasing H2-content from 0 to 100 vol. % also increased the measured NOx emission by nearly a factor of 4, which was also strongly affected by the level of mixedness. Experimental results from this work are being used in a joint effort to validate numerical models for jet-stabilized hydrogen combustion.

Highly Connected Oxygen Ion Conduction Pathways for Solid Oxide Fuel Cells Operating in Intermediate Temperatures with Fuel Flexibility

Solid oxide fuel cells are promising eco-friendly power generating devices directly utilizing various fuels such as hydrogen, methane, and carbon dioxide. However, a technical breakthrough is required for further commercialization by lowering the high operating temperature to the intermediate temperature regime. Introducing the anode functional layer (AFL) between the electrolyte and anode is one of the crucial methods in the development of high performance solid oxide fuel cells by maximizing the triple phase boundary (TPB) sites. To activate the TPB sites, ensuring the continuous oxygen ion conduction from the electrolyte to the TPB sites is essential to maximize their utilization for hydrogen oxidation reactions (HORs). In this study, we modify the connectivity of oxygen ion conduction pathways in the AFL by controlling the microstructure in AFLs. We calculated active reaction site using image processing of cross-sectional scanning electron microscopy (SEM) image and the strong correlation between the electrochemical performance and calculated active reaction site is revealed. The modified AFL with highly connected oxygen ion conduction pathways exhibits substantially higher maximum power density (MPD) compared with conventional AFL: ~1.7-fold higher MPD of 1.51 Wcm-2 at 550 ℃ with hydrogen and ~3.5-fold higher MPD of 1.11 Wcm-2 at 550 ℃ with methane and carbon dioxide, surpassing previously reported values. Moreover, excellent carbon tolerance is observed in the modified AFL, exhibiting nearly no degradation at 550 ℃ for 130 h. This result substantiates the role of connectivity of the oxygen ion conduction pathways in the HOR and carbon tolerance in AFLs. Figure 1

Ceria-Nickel Fuel Electrode for Reversible and Fuel Flexible Operation: Scaling-up from Electrolyte- to Electrode-Supported Cell

Solid oxide cells are devices that figure great versatility of fuels whilst in fuel cell mode like biogas, bioalcohols, or hydrogen with no need of high purification, and are also reversible, meaning that the same equipment can operate as an electrolyser being thus capable of converting water/steam or carbon dioxide into fuel for strategic reserve purposes. The FleXelL project, aims to develop a fuel electrode material based on nickel, cerium oxide and yttria-stabilised zirconia to accommodate such virtues – flexibility and reversibility. The physical assessment of the materials was done via X-ray diffraction analysis, which confirmed the phases integrity, and dilatometry outputs that allowed the fabrication of the fuel electrode and electrolyte layers by the tape casting technique with minimum thermal mismatches. The gadolinium-doped ceria protective layer and the lanthanum-strontium cobalt ferrite oxygen electrode were both deposited by spin coating. After the successful manufacturing, the cells were tested electrochemical by polarisation both in fuel cell mode whilst hydrogen or anhydrous methane served as fuels reaching peak power densities as high as 0.7 W.cm-2, or under electrolysis mode achieving current densities above 2 A.cm-2 with a voltage of 1.25 V. The high efficiencies of the cells specially under electrolysis is attributed to the ability of ceria to act as an oxygen buffer, which avoided the deactivation/oxidation of the nickel catalyst under high electrical currents. After operation, the microstructure was investigated with scanning electron microscopy and energy dispersive X-ray spectroscopy to confirm the suitability of the microstructure even after the harsh operation.

Lightweight Solid Oxide Cell Design for Ammonia-Fed SOFC Systems

A lightweight solid oxide fuel cell (SOFC) was developed by OxEon Energy that demonstrates the potential for increased specific power (kW/g) suitable for the requirements of electric Vertical Take-off and Landing (eVTOL) applications. Fuel flexibility was demonstrated in button cells and stacks using both legacy electrolyte-supported SOFC structure and the lightweight structure. Button cell and stack performance was nearly identical among hydrogen, ammonia, and reformed natural gas. Durability testing shows similarly stable performance in each fuel. A button cell test in ammonia at 800 °C using the lightweight cell structure measured area specific resistance (ASR) of 0.25 Ω-cm2 in H2/N2 and NH3 fuel feeds and showed a peak power density of 0.98 W/ cm2 in NH3 fuel. Short term hold at 0.7 V showed stable performance.

Ceria-Nickel Fuel Electrode for Reversible and Fuel Flexible Operation: Scaling-up from Electrolyte- to Electrode-Supported Cell

The energy transition calls upon the urgent necessity of clean and scalable energy production. In that context, green hydrogen delivery will be key to a successful change. Efforts to support higher efficiencies and degradation resistance are the main objectives of our research. In this work, we show the scaling-up step taken from electrolyte- to electrode-supported reversible high-temperature fuel cells, figuring a novel structure based on 8YSZ, CeO2, and NiO. The results show that the performance can be leveraged more than twofold from one concept to the other. The cells were operated with hydrogen, methane, and ethanol serving as fuels directly to the fuel electrode chamber, and under steam electrolysis.

The Fuel Flexibility of Gas Turbines: A Review and Retrospective Outlook

Land-based gas turbines (GTs) are continuous-flow engines that run with permanent flames once started and at stationary pressure, temperature, and flows at stabilized load. Combustors operate without any moving parts and their substantial air excess enables complete combustion. These features provide significant space for designing efficient and versatile combustion systems. In particular, as heavy-duty gas turbines have moderate compression ratios and ample stall margins, they can burn not only high- and medium-BTU fuels but also low-BTU ones. As a result, these machines have gained remarkable fuel flexibility. Dry Low Emissions combustors, which were initially confined to burning standard natural gas, have been gradually adapted to an increasing number of alternative gaseous fuels. The paper first delivers essential technical considerations that underlie this important fuel portfolio. It then reviews the spectrum of alternative GT fuels which currently extends from lean gases (coal bed, coke oven, blast furnace gases…) to rich refinery streams (LPG, olefins) and from volatile liquids (naphtha) to heavy hydrocarbons. This “fuel diet” also includes biogenic products (biogas, biodiesel, and ethanol) and especially blended and pure hydrogen, the fuel of the future. The paper also outlines how, historically, land-based GTs have gradually gained new fuel territories thanks to continuous engineering work, lab testing, experience extrapolation, and validation on the field.

Numerical analysis on the effect of diluted hydrogen fuel by a fixed amount of supplied hydrogen using a quasi-three-dimensional solid oxide fuel cell model

Solid oxide fuel cell (SOFC) has excellent fuel flexibility for various fuels. Despite some drawbacks like storage and transportation, hydrogen stands up as the best fuel for SOFC. Hydrogen fuel is diluted non-reactive gas species before it is supplied to the SOFC. In this study, a quasi-three-dimensional SOFC model with real microstructure is used to analyse the effect of the diluted fuel mixture. The hydrogen fuel is diluted with nitrogen and a small amount of steam. The mole amount of hydrogen within fuel mixtures is kept constant. On the other hand, the air that is supplied to the air channel of the SOFC remains unchanged. It is found that the cell that is supplied with the highest concentration of hydrogen has the highest performance due to its high partial pressure of hydrogen within the fuel mixture. Such a high partial pressure promotes a low anode concentration loss. Also, the cell that is supplied with a low hydrogen concentration is unable to benefit from its high average cell temperature as its performance is drained by the low partial pressure of hydrogen within the fuel mixture.

Ni-doped Ba0.9Zr0.8Y0.2O3-δ as a methane dry reforming catalyst for direct CH4–CO2 solid oxide fuel cells

Fuel flexibility is one of the significant advantages of solid oxide fuel cells (SOFCs). The utilization of methane in SOFCs can not only reduce fuel costs, but also greatly expand its application scenarios, which is of great significance to the commercial development of SOFCs. However, when methane is directly used, Ni-based cermet anode suffers from coking, which seriously affects the durability of the cell. To alleviate the coking issue, a reforming layer outside the Ni-based anode-supporter was proposed in this study, and Ba0.9(Zr0.8Y0.2)1-xNixO3-δ (BZYNix, x = 0.05, 0.1, 0.15 and 0.2) was used as reforming layer material. Among BZYNix catalysts, BZYNi0.2 exhibited excellent catalytic activity toward dry reforming of methane, and methane conversion was as high as 85% at 750 °C. The excellent catalytic durability and coking-resistance of BZYNi0.2 were also confirmed. When BZYNi0.2 reforming layer was applied, the single cell fueled with CH4–CO2 fuel showed significantly improved electrochemical performance, durability and coking-resistance. The utilization of BZYNi0.2 reforming layer provides guidance for solving the coking issue of SOFC cermet anodes when fueled with hydrocarbon.

On the Technology of Solid Oxide Fuel Cell (SOFC) Energy Systems for Stationary Power Generation: A Review

This paper presents a comprehensive overview on the current status of solid oxide fuel cell (SOFC) energy systems technology with a deep insight into the techno-energy performance. In recent years, SOFCs have received growing attention in the scientific landscape of high efficiency energy technologies. They are fuel flexible, highly efficient, and environmentally sustainable. The high working temperature makes it possible to work in cogeneration, and drive downstream bottomed cycles such as Brayton and Hirn/Rankine ones, thus configuring the hybrid system of a SOFC/turbine with very high electric efficiency. Fuel flexibility makes SOFCs independent from pure hydrogen feeding, since hydrocarbons can be fed directly to the SOFC and then converted to a hydrogen rich stream by the internal thermochemical processes. SOFC is also able to convert carbon monoxide electrochemically, thus contributing to energy production together with hydrogen. SOFCs are much considered for being supplied with biofuels, especially biogas and syngas, so that biomass gasifiers/SOFC integrated systems contribute to the “waste to energy” chain with a significant reduction in pollution. The paper also deals with the analysis of techno-energy performance by means of ad hoc developed numerical modeling, in relation to the main operating parameters. Ample prominence is given to the aspect of fueling, emphasizing fuel processing with a deep discussion on the impurities and undesired phenomena that SOFCs suffer. Constituent materials, geometry, and design methods for the balance of plant were studied. A wide analysis was dedicated to the hybrid system of the SOFC/turbine and to the integrated system of the biomass gasifier/SOFC. Finally, an overview of SOFC system manufacturing companies on SOFC research and development worldwide and on the European roadmap was made to reflect the interest in this technology, which is an important signal of how communities are sensitive toward clean, low carbon, and efficient technologies, and therefore to provide a decisive and firm impulse to the now outlined energy transition.

Slightly ruthenium doping enables better alloy nanoparticle exsolution of perovskite anode for high-performance direct-ammonia solid oxide fuel cells

• Slightly Ru doping promotes the exsolution of alloy nanoparticles in perovskite anode. • Ru doping greatly reduces the particle size and increase the amount of exsolved alloy nanoparticles. • Ru doped perovskite anode shows superior catalytic activity for NH 3 decomposition and anti-sintering capability. • DA-SOFCs with Ru doped perovskite anode exhibits a superior operational stability to Ru-free counterpart. Fuel flexibility is one of the most distinguished advantages of solid oxide fuel cells (SOFCs) over other low-temperature fuel cells. Furthermore, the combination of ammonia fuel and SOFCs technology should be a promising clean energy system after considering the high energy density, easy transportation/storage, matured synthesis technology and carbon-free nature of NH 3 as well as high efficiency of SOFCs. However, the large-scale applications of direct-ammonia SOFCs (DA-SOFCs) are strongly limited by the inferior anti-sintering capability and catalytic activity for ammonia decomposition reaction of conventional nickel-based cermet anode. Herein, a slightly ruthenium (Ru) doping in perovskite oxides is proposed to promote the alloy nanoparticle exsolution, enabling better DA-SOFCs with enhanced power outputs and operational stability. After treating Ru-doped Pr 0.6 Sr 0.4 Co 0.2 Fe 0.75 Ru 0.05 O 3-δ single-phase perovskite in a reducing atmosphere, in addition to the formation of two layered Ruddlesden-Popper perovskites and Pr 2 O 3 nanoparticles (the same as the Ru-free counterpart, Pr 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ ), the exsolution of CoFeRu-based alloy nanoparticles is remarkably promoted. Such reduced Pr 0.6 Sr 0.4 Co 0.2 Fe 0.75 Ru 0.05 O 3-δ composite anode shows superior catalytic activity and stability for NH 3 decomposition reaction as well as anti-sintering capability in DA-SOFCs to those of reduced Pr 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ due to the facilitated nanoparticle exsolution and stronger nanoparticle/substrate interaction. This work provides a facile and effective strategy to design highly active and durable anodes for DA-SOFCs, promoting large-scale applications of this technology.

ReaxFF reactive molecular dynamics study on electrochemistry of H2/CO hybrid fuel in Ni/YSZ anode

Fuel flexibility, e.g. using reformate or syngas fuel directly, is one of the most advantages of solid oxide fuel cells (SOFC). However, the electrochemical mechanism of the H2/CO mixture, which is common and key in hydrocarbon fuel-fed SOFC, is unclear and relatively rarely studied at present. This article makes Reactive Force-Field (ReaxFF) reactive molecular dynamics (RMD) simulations on the electrochemical co-oxidation of H2/CO hybrid fuel in Ni (nickel)/YSZ (yttria-stabilized zirconia) anode. The RMD simulations at different fuel gas components show that in the H2/CO/Ni/YSZ system the H2 conversion rate maintains the maximum (100%), and the conversion rate of CO improves compared with that of pure CO fuel in the case of 30%H2−70%CO. Two ways of CO2 generation are found: one is that the CO(Ni) species formed by the adsorption and activation of CO on the Ni surface is oxidized by the lattice oxygen; the other is the oxidation of CO(Ni) by spillover atomic oxygen, which is adsorbed on the Ni surface. It is worth noting that the effect of oxygen vacancies on the oxidation of CO is more significant than that of H2. A viewpoint is proposed to explain how H2 enhances the oxidation of CO. The results help understand the electrochemistry of H2/CO involved fuel in the context of SOFC operations.

메탄연료 공급 저온 고체산화물 연료전지를 위한 코스퍼터링법으로 제작한 백금-루테늄 촉매 기능층에 관한 연구

Solid oxide fuel cell is a next generation energy conversion device that can efficiently convert the chemical energy of fuel into electrical energy. Fuel flexibility is one of the advantages of SOFCs over other types of fuel cells. SOFCs can operate with hydrocarbon type fuel. While nickel based composite is commonly used in direct methane fueled SOFC anode because of its great catalytic activity for methane reforming, the direct use of hydrocarbon fuels with pure Ni anode is usually insufficient for facile anode kinetics, and also deactivates the anode activity because of carbon deposition upon prolonged operation. In this report, the Ni based anodes with 20 nm thick catalytic functional layers, i.e., Pt, Ru, and Pt-Ru alloy, are fabricated by using the co-sputtering method to enhance the anode activity and power density of direct-methane SOFC operating at 500℃.

Intelligent charge compression ignition combustion for range extender medium duty applications

Electrified powertrains have been growth in the last few years due to the increase in powertrain efficiency. However, for heavy-duty vehicles the right choice it is not clear. The long-routes and large number of daily kilometres makes that current battery technology it is not prepared to cover the minimum requirements. A mid-term solution is hybrid powertrains. The mix between pure electric range and range extender mode in liquid fuels make perfect to complete a large distance. However, tailpipe pollutant and CO2 emissions are still a disadvantage against pure electric powertrain. This study analyses the potential of hybrid powertrains running in an advanced combustion mode as Intelligent Charge Compression Ignition. Due to the flexibility of the combustion mode different renewable energy fuels are tested: Butanol, Methanol and Biodiesel. The work is focused in urban buses due to the potential of electrified powertrains in this context and the large number of vehicles concentrated in cities. The results show that pure electric bus reduce 54% the CO2 emissions at LCA level. Meanwhile the Intelligent Charge Compression Ignition allows to 32% with one renewable fuel (Diesel-Butanol) and 66% with two renewable fuels (Biodiesel-Methanol) with respect to the non-hybrid diesel reference.

Fuel flexibility potential for isobaric combustion in a compression ignition engine: A computational study

This work numerically explored the potential of using various kinds of fuels for the isobaric combustion concept in a compression ignition engine. Primary reference fuels (PRFs) including PRF0, PRF20, PRF40, PRF60, PRF80, and PRF100 were employed at the same middle engine load. Different injection strategies ranging from single to four injections were studied. The results demonstrated that the tested PRFs showed significant differences when using a single injection method, due to the different fuel auto-ignition characteristics: the lower fuel reactivity led to the longer ignition delay and thus more premixed combustion heat release. Fuel flexibility was achieved by utilizing at least two injection events, under which condition various fuels shared similar engine combustion performance and emissions. Predicted in-cylinder distribution of temperature revealed that the first injection event generated initial high-temperature pockets downstream of the nozzle, which helped to ignite the upstream air–fuel mixture from the following injection events and resulted in a relatively stable spray-controlled heat release process. To reduce soot emissions, various amounts of three shorter-chain alcohols (methanol, ethanol, and n-butanol) were blended with the baseline fuel (n-heptane). The methanol-blended fuels yielded the lowest soot emissions, but the fuel economy suffered due to the highest heat transfer losses. By increasing the nozzle number and introducing an adequate amount of isochoric combustion, the fuel economy for pure methanol combustion was effectively improved.

Metabolic Consequences of IgE- and Non-IgE-Mediated Mast Cell Degranulation.

Mast cells are important effector cells in the immune system and undergo activation (i.e., degranulation) by two major mechanisms: IgE-mediated and non-IgE-mediated mechanisms. Although IgE-mediated degranulation is well researched, the cellular mechanisms of non-IgE-mediated mast cell activation are poorly understood despite the potential to induce similar pathophysiological effects. To better understand non-IgE mast cell degranulation, we characterized and compared cellular metabolic shifts across several mechanisms of degranulation (allergen-induced [IgE-mediated], 20 nm of silver nanoparticle-mediated [non-IgE], and compound 48/80-mediated [non-IgE]) in murine bone marrow-derived mast cells. All treatments differentially impacted mitochondrial activity and glucose uptake, suggesting diverging metabolic pathways between IgE- and non-IgE-mediated degranulation. Non-IgE treatments depleted mast cells' glycolytic reserve, and compound 48/80 further inhibited the ability to maximize mitochondrial respiration. This cellular reprogramming may be indicative of a stress response with non-IgE treatments. Neither of these outcomes occurred with IgE-mediated degranulation, hinting at a separate programmed response. Fuel flexibility between the three primary mitochondrial nutrient sources was also eliminated in activated cells and this was most significant in non-IgE-mediated degranulation. Lastly, metabolomics analysis of bone marrow-derived mast cells following degranulation was used to compare general metabolite profiles related to energetic pathways. IgE-mediated degranulation upregulated metabolite concentrations for the TCA cycle and glycolysis compared with other treatments. In conclusion, mast cell metabolism varies significantly between IgE- and non-IgE-mediated degranulation suggesting novel cell regulatory mechanisms are potentially driving unexplored pathways of mast cell degranulation.

Fuel flexibility study of various fuels with charge dilution and high compression ratio for medium-load operating RCCI engine

This study examines the dual-fuel (RCCI) combustion mode using gasoline, ethanol, methanol, and compressed natural gas (CNG) as low reactive fuels (LRF) and diesel, neem biodiesel as high reactive fuel (HRF). The fresh and diluted charge (with hot EGR) combustion is compared at a high compression ratio for medium load operation. For obtaining the near-zero NOx-soot emissions and improved performance, the feasibility of different reactivity and renewable fuels are studied. The use of methanol and gasoline as LRF and diesel as HRF with charge dilution shows improved fuel-air-mixing, reactivity stratification, and thermal efficiency. The use of ethanol and gasoline as LRF and biodiesel as HRF with charge dilution shows near-zero NOx emissions while soot emissions are above the minimum acceptable range. The use of CNG as LRF and diesel as HRF with charge dilution shows minimum thermal efficiency and high fuel consumption. The reduced combustion rate and increased premixed combustion with charge dilution result in lower combustion temperatures and pressure rise rates for G + D and M + D.

Novel Composite Fuel Electrode for CO2/CO-RSOCs

Reversible solid oxide cell (RSOC) technology allows use of a single device to efficiently derive chemicals from power (power-to-fuel) and power from chemicals (fuel-to-power). Fuel flexibility is a key aspect, as developing SOCs able to operate on fuels other than hydrogen can ease their integration into existing infrastructure. In addition, H2O and/or CO2 reduction is favorable in SOECs as polarization losses are reduced at high temperature. Here, a composite fuel electrode, 60 wt.% La0.6Sr0.4Fe0.8Mn0.2O3−δ (LSFMn) and 40 wt.% (5 wt.% Ni)-containing Ce0.85Sm0.15O2−δ (Ni-SDC) was investigated in H2-fueled, CO-fueled SOFCs and for CO2 reduction in SOEC mode. In reducing conditions, Fe exsolved from the LSFMn perovskite formed a Ni–Fe alloy with Ni present on SDC. The composite fuel electrode showed remarkable activity for CO2 reduction with a current density output of 1.40 A cm−2 (1.5 V) at 850 °C. SOFC/SOEC cell reversibility was obtained in different CO2:CO mixtures. Electrochemical impedance spectroscopy analysis was used to better understand cell mechanisms in SOFC and SOEC mode.