Gas Conditions Research Articles

Predicting non-ideal effects from the diaphragm opening process in shock tubes

Shock tubes are instrumental in studying high-temperature kinetics and simulating high-speed flows. They rapidly increase the thermodynamic conditions of test gases, making them ideal for examining chemical reactions and generating high-enthalpy flows for aerodynamic research. However, non-ideal effects, stemming from factors like diaphragm opening processes and viscous effects, can significantly influence thermodynamic conditions behind the shock wave. This study investigates the impact of various diaphragm opening patterns on the shock parameters near the driven section's end wall. Experiments were conducted using helium and argon as driver and driven gases, respectively, at pressures ranging from 1.32 to 2.09 bar and temperatures from 1073 to 2126 K behind the reflected shock. High-speed imaging captured different diaphragm rupture profiles, classified into four distinct types based on their dynamics. Results indicate that the initial stages of diaphragm opening, including the rate and profile of opening, play crucial roles in the resulting incident shock Mach number and test time. A sigmoid function was employed to fit the diaphragm opening profiles, allowing for accurate categorization and analysis. New correlations were developed to predict the incident shock attenuation rate and post-shock pressure rise, incorporating parameters such as diaphragm opening time, rupture profile constants, and normalized experimental Mach number. The results emphasize the importance of considering diaphragm rupture dynamics in shock tube experiments to achieve accurate predictions of shock parameters.

Synergistic activation of reburned char for ultra-low NOx emissions using flue gas recirculation and natural gas in a 10kW furnace.

The technology of powdered coal injection with recirculating flue gas and natural gas conditioning for reburning represents an advanced and innovative approach to enhancing the efficiency of coal powder reburning. By consuming excess oxygen in the recirculated flue gas, natural gas fosters an environment enriched with reducing agents, which stimulates the reactivity of reburning coal powder and augments its effectiveness in reducing nitrogen oxides (NO). This technology has been comprehensively investigated through experiments conducted in a segmented multi-reactor flow system, simulating conditions akin to those in industrial boilers. To achieve a high level of NO abatement, complete combustion of coal powder, and operational cost-effectiveness, a series of optimal operating parameters has been identified: the temperature in the reburning zone (T1) should be controlled at approximately 1573K; the reburning fuel ratio (Rf) should be maintained around 20%; the excess air coefficient (λfuel) in the reburning zone should be approximately 0.228; the residence time in the reburning zone (t2) should be 0.6s, and the burnout zone residence time (t3) should also be 0.6s; finally, the oxygen concentration in the recirculating flue gas should be regulated to around 10%. This configuration ensures that reactive intermediates such as CO∗, OH∗, H, and CHi generated through natural gas modification enhance the physicochemical structure of coal char, thus amplifying the coal char's capacity for the chemical reduction of NO. Precise control of these parameters is expected to facilitate ultra-low NO emissions, while minimizing the consumption of costly active gases and ensuring the economic efficiency of the system.

Porous biochar with a tubular structure for photothermal CO2 cycloaddition: One-step doping versus two-step doping

Solar-powered carbon dioxide (CO2) conversion over biomass derived carbon (BC) has shown great promise for alleviating global warming and producing useful chemicals. However, their lack of active sites, rapid recombination of photogenerated electron-hole pairs, and low CO2 uptake abilities pose significant challenges for photo-induced catalysis. Here, we report the fine-tuning of active sites of BC via one-step and two-step calcination of corn stalk with a tubular structure. Strikingly, compared with samples prepared by two-step doping strategies, NB-BC synthesized via a one-step doping process harbors much enhanced activity under relatively mild conditions (Xe lamp, 400 mW cm−2, 1 bar CO2) with a considerable cyclic carbonate yield of 99 %. The high catalytic performance is attributed to the alteration of pore structure, electronic structure, and active sites due to N, B doping. Moreover, this biochar displays excellent recyclability and retains its applicability under simulated flue gas conditions. Various characterizations and control experiments reveal the combination of thermal catalysis and photocatalysis over this N, B co-doped BC catalyst. Our work provides some insights into the effective applications of biochar in the field of CO2 catalytic conversion.

Multisystem impact of altering acid load of ingested exogenous ketone supplements at rest in young healthy adults

Disruptions to acid-base are observed in extreme environments as well as respiratory and metabolic diseases. Exogenous ketone supplements (EKS) have been proposed to mitigate these processes and provide therapeutic benefits by altering acid-base balance and metabolism, but direct comparisons of various forms of EKS is lacking. Twenty healthy participants (M/F: 10/10; age: 20.62.0 y, height: 1.720.08 m, body mass: 67.910.2 kg) participated in a single-blind, randomized crossover design comparing ingestion of the (R)-3-hydroxybutyl (R)-3-hydroxybutyrate (R-BD R-βHB) ketone monoester (KME), KME+sodium bicarbonate (KME+BIC), an R-βHB ketone salt (KS), and a flavor-matched placebo. Acid-base balance, blood R-βHB, glucose and lactate concentrations, blood gases, respiratory gas exchange, autonomic function, and cognitive performance were assessed at baseline, and various time points for up to 120 min after ingestion. Compared to PLA, blood R-βHB concentration were elevated in each EKS condition (~2 to 4 mM; P<0.01) and blood glucose concentration were lower. Blood pH was lower in KME (-0.07 units), and higher in KS and KME+BIC (+0.05 units), compared to PLA (all P<0.05). Heart rate was elevated, and autonomic function was altered in KME+BIC. There were no differences between conditions for blood gases, respiratory gas exchange, blood pressure or cognitive performance. Exploratory analyses of between-sex differences demonstrated males and females responded similarly across all outcome measures. Altering the acid load of EKS modulated the response of blood R-βHB and glucose concentrations, but had only modest effects on other outcomes measures at rest in young healthy adults, with no differences observed between sexes.

A Study on the Development of Real-Time Chamber Contamination Diagnosis Sensors.

Plasma processes are critical for achieving precise device fabrication in semiconductor manufacturing. However, polymer accumulation during processes like plasma etching can cause chamber contamination, adversely affecting plasma characteristics and process stability. This study focused on developing a real-time sensor system for diagnosing chamber contamination by quantitatively monitoring polymer accumulation. A quartz crystal sensor integrated with flexible printed circuit boards was designed to measure the frequency shifts corresponding to polymer thickness changes. An impedance probe was also employed to monitor variations in the plasma discharge characteristics. The sensor demonstrated high reliability with a measurement scatter of 2.5% despite repeated plasma exposure. The experimental results revealed that polymer accumulation significantly influenced the plasma impedance, and this correlation was validated through real-time monitoring and scanning electron microscopy (SEM). The study further showed that the sensor could detect the transition point of the plasma state changes under varying process gas conditions, enabling the early detection of potential process anomalies. These findings suggest that the developed sensor system can be crucial for diagnosing plasma and chamber conditions, providing valuable data for optimizing preventive maintenance schedules. This advancement offers a pathway for improving process reliability and extending the operational lifetime of semiconductor manufacturing equipment.

Functional Near-Infrared Spectroscopy Analysis of Cerebral Physiological Changes in Response to Atmospheric Gas Concentrations

Compared with other organs in the body, the human brain is extremely sensitive to changes in O2 and CO2 levels. This study applied functional near-infrared spectroscopy (fNIRS) to analyze the changes in cerebral oxygen saturation (COS) and hemoglobin (Hb) concentrations in response to various atmospheric gas concentrations and investigate their effects on brain function. Twenty-nine adults were exposed to four gas conditions, namely atmospheric concentration (C1), high O2 concentration (C2), high CO2 concentration (C3), and high O2 and CO2 concentrations (C4). Changes in COS and Hb concentrations were measured using fNIRS, whereas heart rate (HR) and percutaneous oxygen saturation (SpO2) were measured using a patient monitor. COS, oxy-Hb (HbO), and total-Hb (HbT) increased progressively from C1 to C4, whereas deoxy-Hb (HbR) exhibited a decreasing trend. Moreover, the COS and Hb concentrations were more strongly influenced by high CO2 levels than by high O2 levels. High O2 concentrations increased the blood O2 saturation, whereas high CO2 concentrations increased blood flow as a physiological response, enhancing O2 delivery to the brain. Additionally, HR and SpO2 increased at high CO2 concentrations. However, at high O2 concentrations providing a sufficient O2 supply, SpO2 increased while HR decreased. Therefore, adjusting the concentrations of CO2 and O2 may improve cerebral blood flow and change brain function, supporting cerebrovascular health and preventing related diseases.

CO Isotopologue-derived Molecular Gas Conditions and CO-to-H2 Conversion Factors in M51

Over the past decade, several millimeter interferometer programs have mapped the nearby star-forming galaxy M51 at a spatial resolution of ≤170 pc. This study combines observations from three major programs: the PdBI Arcsecond Whirlpool Survey, the SMA M51 large program, and the Surveying the Whirlpool at Arcseconds with NOEMA. The data set includes the (1–0) and (2–1) rotational transitions of 12CO, 13CO, and C18O isotopologues. The observations cover the r < 3 kpc region, including the center and part of the disk, thereby ensuring strong detections of the weaker 13CO and C18O lines. All observations are convolved in this analysis to an angular resolution of 4″, corresponding to a physical scale of 170 pc. We investigate empirical line ratio relations and quantitatively evaluate molecular gas conditions such as temperature, density, and the CO-to-H2 conversion factor (α CO). We employ two approaches to study the molecular gas conditions: (i) assuming local thermodynamic equilibrium (LTE) to analytically determine the CO column density and α CO, and (ii) using non-LTE modeling with RADEX to fit physical conditions to observed CO isotopologue intensities. We find that the α CO values in the center and along the inner spiral arm are ∼0.5 dex (LTE) and 0.1 dex (non-LTE) below the Milky Way inner disk value. The average non-LTE α CO is 2.4 ± 0.5 M ⊙ pc−2 (K km s−1)−1. While both methods show dispersion due to underlying assumptions, the scatter is larger for LTE-derived values. This study underscores the necessity for robust CO line modeling to accurately constrain the molecular interstellar medium’s physical and chemical conditions in nearby galaxies.

Functionalized Dual/Multiligand Metal-Organic Frameworks for Efficient CO2 Capture under Flue Gas Conditions.

Reducing carbon dioxide (CO2) emissions has become increasingly urgent for China, particularly in the industrial sector. Striking a balance between a high CO2 adsorption capacity and long-term stability under practical conditions is crucial for effectively capturing CO2 from flue gas. In this study, a series of functionalized MFM-136 adsorbents were synthesized in which -NO2 and -NH2 groups were grafted onto the kagome lattice of MFM-136. Modifications with -NH2 groups were found to be highly effective for CO2 adsorption, specifically, the CO2 adsorption capacity peaked at 4.35 mmol/g for NH2(0.6)-MFM-136, representing a 55% enhancement more than MFM-136. Concurrently, the CO2/N2 selectivity for NH2(0.6)-MFM-136 was increased 1.57 times. Verification of novel adsorption sites introduced by NH2-H2L4 was conducted by using in situ DRIFT analysis and DFT calculations. It turns out that NH2-H2L4 modification can effectively mitigate the chemical deposition from the impurity gases and significantly improve the adsorbent's hydrophobicity and its tolerance to impurity gases. Remarkably, the reduction in the CO2 absorption capacity for NH2(0.6)-MFM-136 was 34% less than that for MFM-136 after 24 h of exposure to simulated flue gas, making NH2(0.6)-MFM-136 a promising candidate for the potential application of stable and selective CO2 capture under industrial flue gas conditions.

The SUPERCOLD-CGM Survey. II. [C i](1–0) Emission and the Physical Conditions of Cold Gas in Enormous Lyα Nebulae at z ∼ 2

We report Atacama Large Millimeter/submillimeter Array and Atacama Compact Array observations of atomic carbon ([C i](1–0)) and dust continuum in 10 enormous Lyα nebulae hosting ultraluminous Type-I QSOs at z = 2.2–2.5, as part of the Survey of Protocluster ELANe Revealing CO/C i in the Lyα Detected CGM. We detect [C i](1–0) and dust in all 10 QSOs and five companion galaxies. We find that the QSOs and companions have higher gas densities and more intense radiation fields than Luminous Infrared galaxies and high-z main sequence galaxies, with the highest values found in the QSOs. By comparing molecular gas masses derived from [C i](1–0), CO(4−3), and dust continuum, we find that the QSOs and companions display a similar low CO conversion factor of α CO ∼ 0.8 M ☉ [Kkms-1pc2]−1 . After tapering our data to low resolution, the [C i](1–0) flux increases for nine QSOs, hinting at the possibility of [C i](1–0) in the circumgalactic medium (CGM) on a scale of 16−40 kpc. However, the [C i](1–0) sensitivity is too low to confirm this for individual targets, except for a tentative (2.7σ) CGM detection in Q0050+0051 with MH2 = (1.0–2.8) × 1010 M ☉. The 3σ mass limits of molecular CGM for the remaining QSO fields are (0.2–1.4) × 1010 M ☉. This translates into a baryon fraction of <0.4%–3% in the molecular CGM relative to the total baryonic halo mass. Our sample also includes a radio-detected active galactic nuclei, Q1416+2649, which shows [C i](1–0) and CO(4−3) luminosities an order of magnitude fainter for its far-infrared luminosity than other QSOs in our sample, possibly due to a lower molecular gas mass.

Corrosion behavior of Inconel 718 superalloy utilized in an entrained-flow pulverized coal gasifier burner

Cooling water front is a crucial component for protecting the gasifier burner from damage under high-temperature gasification conditions. Its service life plays a significant role in ensuring the long-term, safe and stable operation of the gasifier. In this work, failure analysis was conducted on a cooling water front made of Inconel 718 superalloy based on metallographic examination, scanning electron microscopy observation and energy spectrum analysis. Apart from the center hole region, which is proximate to the high-temperature flame, circumferential cracks were also detected at the reducer position along the cooling water front’s outer edge. The findings reveal that the cracking on the outer edge results from the synergistic effect of fly ash erosion, chemical corrosion and thermal stress. Prolonged exposure to excessive heat weakens the stress corrosion resistance of Inconel 718 superalloy at high temperatures. Oxidation and sulfidation occur within the alloy matrix due to the corrosive influence of oxygen and sulfur elements present in the gasification atmosphere, leading to the formation of surface cracks on the alloy. These cracks facilitate the inward diffusion of oxygen and sulfur elements, promoting further crack propagation under thermal stress and eventually leading to the failure of the cooling water front.

Structure-governed potassium retention mechanism in the slagging and non-slagging gasification condition of corn straw

Structure-governed potassium retention mechanism in the slagging and non-slagging gasification condition of corn straw

Synthesis of fluorinated ether free aromatic backbone copolymers containing trifluoromethyl and dimethylamino groups for CO2 separation: Investigation of pure and mixed gas performance under dry and humid conditions

A novel series of linear, high molecular weight aromatic copolymers containing trifluoromethyl and dimethylamino groups was synthesized via facile super-acid catalyzed polyhydroxyalkylation and investigated as CO2 gas separation membrane materials. The molar ratio of the two ketone comonomers used in copolymerization, trifluoroacetophenone (TFAp) and N,N-dimethylamino trifluoroacetophenone (dMATFAp), was systematically varied to produce five copolymers with different dMATFAp contents ranging from 12 to 73 %. The influence of dMATFAp content on physicochemical and mechanical properties as well as pure gas and water vapor separation performance was studied. All synthesized copolymers displayed excellent film forming ability, high thermal stability and high Tg values (Tgs > 380 °C). Pure gas permeability measurements revealed that the increase of dMATFAp molar content from 12 % to 34 % resulted in improved gas permeability, while, on the contrary, further increase of dMATFAp content from 34 to 73 % led to substantial gas permeability decrease ascribed to FFV decrease. In particular, among copolymers, the one with dMATFAp content of 34 % presented the highest CO2 permeability value of 290 Barrer due to its highest CO2 diffusion and CO2 solubility coefficients associated with its higher FFV value. The CO2/CH4 performance of synthesized copolymers fell very close to 2008 upper bound limit and exceeded most of the super-acid catalyzed copolymer membranes reported in the literature and commercial membranes. CO2/CH4 and CO2/N2 selectivity values for the different synthesized copolymers were in the range of 29.9–40 and 22.7–44, respectively. The study of the effect of dMΑTFA on water permeability unveiled that the membrane with the highest dMΑTFAp molar content (73 %) showed the highest water permeability value (23,100 Barrer) as well. This was attributed to the increased concentration of N-methyl substituent of dMΑTFAp which can interact with water molecules thereby increasing solubility. Under process gas stream conditions using a mixture of 3 % H2O-48.5 % CO2-48.5 % CH4, both CH4 and CO2 permeability were significantly reduced (by 35 % and 47 %, respectively) due to the preferential sorption of water vapor over other gases present in the mixture, highlighting the negative effect of water vapor on gas permeability. Accordingly, the CO2/CH4 separation factor was slightly increased from 23.8 to 29. Finally, stability test of the copolymer (BP-TFAp)66-(BP-dMATFAp)34 at 40 °C under humid mixed gas conditions showed that CO2 and CH4 permeability remained unchanged for one month after an initial condition stabilization that is required implying that these copolymer structures are promising materials for CO2 separation.

Gas–liquid two-phase flow measurement by using electrical tomography sensors and Venturi

Gas–liquid two-phase flow is characterized by complexity, non-homogeneity and difficulty in modeling. Therefore, traditional measurement methods often struggle to simultaneously meet the requirements of high precision and a wide measurement range. In this context, this study aims to explore an innovative multi-sensor fusion technique to achieve accurate measurement of gas–liquid two-phase flow under full operating conditions. In this study, a combination of three sensors, Venturi, ERT (Electrical Resistance Tomography) and ECT (Electrical Capacitance Tomography), is used to propose a new method based on the fusion of LVF (Liquid-phase Volume Fraction) calculations with flow results. Firstly, the high sensitivity characteristics of ECT and ERT sensors are utilized to obtain spatial distribution information of the flow, which is then used to calculate the LVF. Subsequently, the calculated LVF is combined with the total flow rate measured by the Venturi. Through an established mathematical model, the individual flow rates of the gas and liquid phases are inversely calculated. The results show that the method exhibits high measurement accuracy in different LVF ranges with the relative error controlled within 10%, especially in wet and non-wet gas conditions, which fills the gap of the traditional methods in this field. In addition, the method not only improves the measurement accuracy, but also broadens the measurement range, which meets the diversified needs of complex two-phase flow measurement in the oil and gas industry.

Experimental investigation of the characteristics of direct injection nozzle sprays in an afterburner environment

This study examined the atomization characteristics of direct injection nozzles under high-temperature, large-Mach inflow conditions using a high-speed camera. The effect of inflow conditions on fuel breakup length, fuel concentration field, and particle size spatial distribution was quantitatively analyzed by using image processing techniques. Experimental results indicate the following: 1) When the liquid-to-gas momentum ratio and inflow Mach number (Ma) are equal, the breakup length, fuel field boundary, and droplet distribution in the jet core region remain consistent for the same nozzle under room-temperature air and high-temperature gas conditions. 2) A breakup length model based on the breakup time of the liquid column is proposed. 3) The logarithmic fuel trajectory formula can effectively predict the physical phenomenon of the movement of fuel particles with the gaseous flow downstream of the injection point after their kinetic energy is depleted, with a prediction error of no >10 %. 4) The spatial distribution of particle sizes reveals that within the selected range of liquid-phase jet velocity, the distribution range of the Sauter mean diameter (SMD) of the jet core area in gas-flow environments with large Ma is similar. At the same axial position, a positive correlation exists between SMD and nozzle diameter. The results of this study have guiding importance for the design of integrated afterburner nozzles.

Harnessing acoustic energy with liquid metal triboelectric nanogenerators: A promising approach for moving-parts-free power generation

Heat-driven acoustic engines (HDAEs) offer a promising approach to energy generation without solid moving parts. However, integrating linear alternators for acoustic-to-electric conversion introduces moving components, diminishing this advantage. To tackle this issue, we investigate using an acoustically-driven liquid–metal triboelectric generator (LM-TEG) within HDAEs for acoustic-to-electric conversion. Experiments were conducted in three settings: mechanically-driven LM-TEGs under atmospheric and pressurized gas conditions, and acoustically-driven LM-TEGs. Results from mechanically-driven LM-TEG tests show that using FEP material, increasing LM-TEG contact area, stacking TEGs in parallel, and using pressurized gas enhance performance. Acoustically-driven LM-TEG experiments demonstrate significant improvements with pressurized nitrogen, achieving a short-circuit current approximately 4.5 times higher than with helium at equivalent pressures. Notably, charge and power densities reached 388 μC/m2 and 1.7 W/m2, respectively, surpassing typical values from conventional TEGs. Importantly, these results were obtained with a complete, fully integrated acoustically driven LM-TEG system. This study represents the first investigation in the literature of acoustically driven LM-TEGs, offering a distinct power generation system with no solid moving parts. The findings validate the feasibility of integrating LM-TEGs with HDAEs and suggest their potential for large-scale power generation, moving beyond the small-scale applications that have dominated prior TEG research.

Decomposition mechanism of furfural under supercritical water gasification conditions using ReaxFF simulations

The supercritical water gasification (SCWG) is a convenient and efficient method to utilize hydrogen stored in biomass. Furfural is an important platform during the conversion of biomass thus it is of great significance to understand the microscopic mechanism of the SCWG of furfural. In this work, the SCWG of furfural is investigated using reactive molecular dynamic (RMD) simulations under the temperature range from 1800 K to 2800 K. Based on the detailed reaction scheme of furfural pyrolysis and SCWG, it is found pyrolysis dominates the conversion of furfural under low temperature such as 2400 K and produces only a small amount of H2; while under higher temperature, H2O participates in SCWG as reactant and actively reacts with furfural and C3 fragments in forms of H and OH radicals, which promotes the production of H2. In addition, the combination of water and C3 fragments also effectively inhibits the coke formation. This work could provide a further insight for the conversion of biomass to hydrogen energy at the atomic level.

Effect of Post-Heat Treatment of Catalysts Under Various Gas Conditions on the Microstructure of Catalysts Ink and Electrode for PEMFC

Polymer electrolyte membrane fuel cells (PEMFCs) directly convert the chemical energy of fuel into electrical energy, producing electricity through a high-efficiency, ecofriendly energy conversion device. While PEMFCs are commercialized now, enhancing their competitiveness compared to other energy sources is critical and requires an understanding of the microstructure of the membrane-electrode assembly. Typically, fuel cell electrodes are manufactured by coating an electrolyte membrane with catalyst inks composed of electrode catalyst, ionomer, and solvent or additives. To maximize the performance of fuel cells, the proper distribution of catalysts and ionomers within the electrode is essential, and the microstructure within the electrode is determined by the interactions between the carbon support and platinum surface, as well as the dispersion of catalysts and ionomers in the solvent. Thus, the internal microstructure of the catalyst ink, determined by the interactions among its constituents, ultimately defines the final electrode microstructure, affecting the performance and durability of the fuel cell. This study aims to analyze the effects of post-heat treatment of catalyst in various gas atmospheres, including NH3 gas, on the surface characteristics and to examine the changes in interactions between the catalysts and ionomers within the catalyst ink following surface modification. Additionally, this research seeks to elucidate the correlation between the properties of the catalyst ink and the characteristics of the electrode produced by drying the ink. To this end, the physical properties of the thermally modified catalysts were analyzed, and the resulting catalyst ink was also manufactured and examined. The physical and rheological properties of the catalyst ink were assessed using a dispersing analyzer and rheometer to understand the interactions between the catalysts and ionomers. Furthermore, the coatability of the catalyst ink and the structural characteristics of the electrode were investigated. Figure 1

EIS Analysis and Optimization Using AI for Different Cathode Channel Cross-Sections for Open Cathode Fuel Cell Stack

Unlike convention polymer electrolyte fuel cell (PEMFC), open-cathode polymer electrolyte membrane fuel cells (OC-PEMFC) use oxidant supply fed directly from the atmosphere, owing to its simple balance of plant (BOP) and integration. Whereas concerns such as lower performance compared to PEMFC, needs to be studied carefully to understand mechanisms and parametric optimization for efficient operation of OC-PEMFC stack.The performance of OC-PEMFC is restricted due to proton conductivity, reaction mechanism, and mass transport limitation1. The effective flow-field (FF) designs can mitigate the detrimental performance degradation arising from dehydration in OC-PEMFC by effective cooling rate2. The simplified designs with optimum pressure drop enhances the performance with balanced effect of parameters such as gas distribution, water removal/retention, heat removal/accumulation.To enhance the performance of OC-PEMFC, we need to understand the physical and chemical mechanisms of the system. These mechanisms help to understand the losses involved caused due to low protonic conductivity, Oxygen reduction reaction, mass transfer, operating conditions, and nature/composition of materials3 etc. Among all electrochemical techniques, Electrochemical impedance spectroscopy (EIS) stands out as a powerful technique that provides a vast extent of information in a short period of time.The presented work investigates the performance of three distinct novel cathode channels with various cross-section designs (CSDs) such as square, boot, and triangular for four cells OC-PEMFC stack of active area 100 cm2. The analysis incorporates EIS examination for critical parameters, including airflow rate, current, temperature, H2 gas condition (humidified and dry). Furthermore, a parametric optimization technique is developed based on EIS and Artificial intelligence (AI) random forest regression (RFR) algorithm, the flow chart illustrating the RFR algorithm is presented in Fig. 1(a).The findings show that, for square design the minimum low frequency resistance 7 Ω cm2 is achieved at airflow rate 3 m3/sec, current 10-15 A, and stack temperature ~ 39 ̊C, as shown in Fig 1(b). Moreover, the AI algorithm successfully predicted the suitable operating condition with root mean square error value of 98%, as illustrated in Fig. 1(c). References J. C. Kurnia, B. A. Chaedir, A. P. Sasmito, and T. Shamim, Appl Energy, 283, 116359 (2021).S. Thapa, V. Ganesh, H. Agarwal, and A. K. Sahu, J Power Sources, 603, 234398 (2024).Z. Tang, Q. Huang, Y. Wang, F. Zhang, W. Li, A. Li, L. Zhang, and J. Zhang, J Power Sources, 468, 228361 (2020). Figure 1

Ohmic Resistance Response of a Practical Protonic Ceramic Fuel Cell upon Hydration/Dehydration

Protonic Ceramic Fuel Cells (PCFCs) can show high performance, power density and efficiency at an intermediate temperature range from 400°C to 600°C. Proton-conducting ceramics is reported to have multiple mobile defects such as proton, hole, and oxygen vacancy. Conductivity of those defect species depends on the concentration of the atmosphere gas such as hydrogen, oxygen and water vapor. To date, the effect of hydration/dehydration on the proton conductivity as a single electrolyte material has been studied1,2. However, as a whole cell assembled with electrolyte and electrode, there are few reports on that effect. When using such a whole cell to measure the hydration/dehydration effect, practical gas for a real operation can be supplied. This study focuses on the transition characteristics with hydration/dehydration in practical gas condition by using a BaZrO3-based perovskite cell.Firstly, to assess the time delay of hydration/dehydration reactions at the electrolyte-electrode interface, experiments were conducted using the cells with different electrolyte thicknesses, 6μm, 13μm and 24μm at open-circuit voltage. Figure1(a) shows the results. Time constant increased with thicker electrolyte. Despite the difference in electrolyte thicknesses, almost the same Fourier numbers were calculated by using each of the response time point crossing 63% from one steady state to another. This result suggests that the reaction rate at the interface was fast enough compared to the transport rate within the bulk of electrolyte.Secondly, transport within the electrolyte was considered. Incorporation of water vapor into the electrolyte is considered to follow next equilibrium:H2O+Vo ··+OO ×⇔OHO · (1)When the water vapor concentration in supplied gas is switched, a pair of proton and oxygen, described as OHO · in equation (1), is generated into the electrolyte. Protons detached from OHO · can be transported by hopping to the neighboring oxygen atom1. Protons could be also transported via vehicle mechanism, as a pair of proton and oxygen. Diffusion coefficient for the measured curve was determined from the solid curve in Figure1(a), which was fitted by using Fick's law. Fitted diffusion coefficient was 4.5×10-13 m2/s at 600 °C. This diffusion coefficient is significantly smaller than reported diffusion coefficients of proton and hole3. In this cited paper, those diffusion coefficients are determined through conductivity measurement. Protons could mainly be transported via hopping mechanism in a fixed atmosphere gas, suggesting that the reported value for proton was related to hopping mechanism. Holes are considered to be similar with electrons, suggesting high diffusivity. Therefore, the fitted value in our research could be for the transport via vehicle mechanism, potentially influencing the determination of the relaxation time by limiting the proton transport. For further investigation of the relaxation characteristics, experiments will be conducted at different external current densities providing varying potential gradients within the electrolyte. Acknowledgements This presentation is the result of the research and development of ultra-efficient proton-conducting ceramic fuel cell devices, JPNP20003, funded by the New Energy and Industrial Technology Development Organization (NEDO), Japan. We would like to express our gratitude to all parties involved. Reference Rongzheng R., et al., ACS Appl. Energy Mater., 3(5), 4914 (2020)Han-Ill Y., et al., Solid State Ion, 180(28), 1443(2009)Kwati L., et al., J Mater Chem A, 6 (39) (2018) Figure 1

A Combined Mixed Potential Sensor, Machine Learning, and Iot Platform for Methane Emissions Detection and Flare Monitoring

Methane’s global warming potential is 28x higher than that of CO2 on a 100 year basis.[1] The US has over 300,000 miles of pipeline transporting natural gas, and recent estimates put the cost of emissions in terms of lost product and societal impacts on the order of billions of dollars.[2] In the natural gas industry, excess gas which cannot be economically used for production is destroyed by burning in flares. A recent aerial study found that the methane destruction efficiency was only 91%, a result of inefficient flaring instruments or unlit flares.[3] Continuous monitoring solutions using networked Internet of Things (IoT) sensor platforms are a promising solution to give natural gas infrastructure operators real time insight into leaks, methane destruction efficiency, and warn of events like flameouts.Solid-state mixed potential electrochemical sensors (MPES) are an attractive option as a sensor technology due to their low cost, robustness in harsh exhaust gas conditions, and ability to modify selectivity by the electrode composition and temperature.[4] They use the difference in catalytic activity between two dissimilar electrodes in the presence of an oxidation and reduction reaction to generate a voltage signal. We have developed a sensor platform which pairs this sensor with artificial neural networks for mixture identification and quantification and an IoT platform for data acquisition, edge processing, and transmission. We have achieved 5-5000 ppm sensitivity to CH4 in natural gas mixtures, carried out field testing of this platform for surface and underground leaks,[5] and demonstrated the ability to detect precursors to flameout in simulated methane combustion flares.This work was sponsored by DOE SBIR Office of Science Award DESC0023770 and Office of Fossil Energy and Carbon Management Award FE0031864.[1] M. Saunois, et al., The Global Methane Budget 2000–2017, Earth Syst. Sci. Data 12 (2020) 1561–1623. https://doi.org/10.5194/essd-12-1561-2020.[2] E.D. Sherwin, J.S. Rutherford, Z. Zhang, Y. Chen, E.B. Wetherley, P.V. Yakovlev, E.S.F. Berman, B.B. Jones, D.H. Cusworth, A.K. Thorpe, A.K. Ayasse, R.M. Duren, A.R. Brandt, US oil and gas system emissions from nearly one million aerial site measurements, Nature 627 (2024) 328–334. https://doi.org/10.1038/s41586-024-07117-5.[3] G. Plant, E.A. Kort, A.R. Brandt, Y. Chen, G. Fordice, A.M. Gorchov Negron, S. Schwietzke, M. Smith, D. Zavala-Araiza, Inefficient and unlit natural gas flares both emit large quantities of methane, Science 377 (2022) 1566–1571. https://doi.org/10.1126/science.abq0385.[4] S. Halley, K.P. Ramaiyan, L. Tsui, F. Garzon, A review of zirconia oxygen, NOx, and mixed potential gas sensors – History and current trends, Sens. Actuators B Chem. 370 (2022) 132363. https://doi.org/10.1016/j.snb.2022.132363.[5] S. Halley, K. Ramaiyan, J. Smith, R. Ian, K. Agi, F. Garzon, L. Tsui, Field Testing of a Mixed Potential IoT Sensor Platform for Methane Quantification, ECS Sens. Plus 3 (2024) 011402. https://doi.org/10.1149/2754-2726/ad23df.