Gas Temperature Research Articles

Evaluation of Some Uncertainties in the Modeling of Blast Furnace Hydrogen Injection

While blast furnaces remain the dominant ironmaking technology, there is growing interest in using hydrogen to partially replace coke and pulverized coal to reduce CO2 emissions in this hard‐to‐decarbonize process. However, significant discrepancies in modeling the tuyere injection of hydrogen are noted in the literature, which can challenge the scale‐up from modeling predictions and pilot trials to actual blast furnace operations. To address this, the impact of uncertainties in the assumptions of the temperature in the thermal reserve zone and the ratio of H2 and CO utilization on the results of blast furnace process modeling are evaluated using a 1D steady‐state zonal model. The study indicates that variations in the assumed value of thermal reserve zone temperature significantly impact the estimation of optimal hydrogen injection rate, coke replacement ratio, and direct CO2 emissions reductions. In contrast, the same parameters are much less affected by the variations in the assumed value of the proportion between H2 and CO utilization ratios, which, however, affect the top gas composition. A need for further research to determine the range of the difference in temperatures of gas and solid in the thermal reserve zone tolerable for smooth blast furnace operation is highlighted.

Comparative Study of Temperature and Pressure Variation Patterns in Hydrogen and Natural Gas Storage in Salt Cavern

Clarifying the distribution of temperature and pressure in the wellbore and cavern during hydrogen injection and extraction is crucial for quantitatively assessing cavern stability and wellbore integrity. This paper establishes an integrated flow and heat transfer model for the cavern and wellbore during hydrogen injection and withdrawal, analyzing the variations in temperature and pressure in both the wellbore and the cavern. The temperature and pressure parameters of hydrogen and natural gas within the chamber and wellbore were compared. The specific conclusions are as follows. (1) Under identical injection and withdrawal conditions, the temperature of hydrogen in the chamber was 10 °C higher than that of natural gas, and 16 °C higher in the wellbore. The pressure of hydrogen in the chamber was 2.9 MPa greater than that of natural gas, and 2.6 MPa higher in the wellbore. (2) A comparative analysis was conducted on the impact of surrounding rock’s horizontal and numerical distance on temperature during hydrogen and natural gas injection processes. As the distance from the cavity increases, from 5 to 15 m, the temperature fluctuation in the surrounding rock diminishes progressively, with the temperature effect in the hydrogen storage chamber extending to at least 10 m. (3) The influence of rock thermal conductivity parameters on temperature during the processes of hydrogen injection and natural gas extraction is also compared. The better the thermal conductivity, the deeper the thermal effects penetrate the rock layers, with the specific heat capacity having the most significant impact.

The Influence of Helium Addition on the Combustion Process in a Hydrogen-Fueled Turbulent Jet Ignition Engine

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

DEVELOPMENT OF THE THEORY OF GAS FUEL COMBUSTION TAKING INTO ACCOUNT MODERN KINETIC MECHANISMS OF COMBUSTION

An actuality of modernizing advancement the modern adopted combustion theory is due to a significant change in the composition of fuels at the market of developed countries by rejection of basic mineral (organic) fuels (fossil fuels), which have been used in the world for 250 years. The transformation of traditional fuels’ orientation towards an application of carbon-free fuels, primarily to hydrogen and its mixtures with natural gas. Each way of mentioned activity is connected with to ensure an environmental decarbonisation. Criteria for evaluating the CO2 emissions by fuels’ choice and selection have been proposed while numerical calculations of the specific CO2 content in the combustion products of the hydrocarbon-hydrogen mixture jʹ and j have been evaluated. It is possible to reduce these values when adding the shared H2 in the fuels (m3 CO2/ MJ; kg CO2/ MJ). Considering the combustion process in combustion systems (combustion chambers, boilers, furnaces) at constant pressure (p =const, dp =0 — isobaric process), the enthalpy of the reactants’ flow of the mixture (total (chemical) enthalpy I) can serve as a measure of the specific energy of the reacting mixture. An approach is proposed, according to which the main equations of heat and mass transfer in the torch (premixed flame) are composed basing upon the principle of conservation the total (chemical) enthalpy representing energy as basic function. The basic approach to the development of a modern combustion theory is focused on the concept of T. von Karman, according to which the combustion process is considered as “aerothermochemistry”, i.e. the description of physical and chemical processes is based on the combination of heat and mass transfer equations with chemical kinetics’ equations. At the current period, the problem of chemical kinetics (burning process) is considered through the combustion mechanisms of basic fuels, which consist of a large number of equations for molecules and particles involved in process at various stages of the combustion — from the preheating of the reaction mixture and through the stage of ignition (or self-ignition) — to the final temperature of flue gases. The laminar combustion velocity SL is a determinative characteristic of the combustible properties of gas fuels and, accordingly, of the safety restrictions by the fuel choice. Quantitative values of SL for the separate basic fuels, including the hydrogen, both the organic (fossil fuels) and alternative ones could be differed by an order of magnitude and more. The problem of estimable forecasting the SL value provides an option of the composition of the fuel-oxidant mixture in the industry, power and municipal energetics. The SL value’s prediction makes an especially important action at the current stage of modelling completion with an account of the global warming and by preventing an excess of CO2 emissions, including involvement of hydrogen-containing gases by substitution the carbon-friendly fuels, firstly the fossil fuels. The contemporary theory of combustion has been developed by extensive use the adequate kinetic mechanism GRI-Mech 3.0, the universality of which has been confirmed by our calculations of SL values for a wide range of the gas fuels — from methane CH4 to hydrogen H2 and their mixtures. An advanced modern theory of combustion using the adequate and approved GRI-Mech 3.0 combustion kinetic mechanism has been developed. The universality of this mechanism is confirmed by our calculations of SL values for a wide range of gaseous fuels — from methane CH4 to hydrogen H2 and their mixtures (mixed gases MG). For further analysis and development, the model of combustion in the reacting flow by Y.B. Zeldovich and D.A. Frank-Kamenetsky was used, considering the transfer processes of total enthalpy I as the energy characteristic of the combustible mixture. The kinetic component (on the example of natural gas) is taken into account using the combustion mechanism for GRI-Mech 3.0. The latter summarizes the combustion process of through 325 constituent reactions for 53 components. The adequacy of the combustion model proposed in the paper is confirmed by numerical examples of the coincidence of numerical SL values: ours — calculated; literary — experimental. The validity of experimental values of SL is provided by the use of different methods of measuring the SL. Calculations of the specific total enthalpy I of the reacting mixture along the length x º l (thickness of the front for a homogeneous flame in a one-dimensional formulation) have been performed as a result of researches confirmed the initial position: I(x) = const with deviations for CH4 +7 % / –2 %; for H2 +9,2 % / –2,8 % in relation to the heat of combustion. Bibl. 52, Fig. 9, Tab. 3.

Design of experimental facility for helium gas component testing

The current state-of-the-art helium gas test loops for component testing are constrained by the maximum operating temperatures, pressures, and flow rates of such facilities. Idaho National Laboratory is designing a new experimental facility known as HECTOR (HElium Component Testing Out-of-pile Research), which is a helium gas test loop for evaluating the performance of components to helium gas pressures, temperatures, and flow rates up to 8 MPa, 800 °C, and 0.15 kg/s, respectively. The construction of this facility will enable researchers to perform experiments across a wide range of Reynolds and Nusselt numbers, which could result in the maturation of technology for high-temperature gas-cooled reactor (HTGR) components.

ВЛИЯНИЕ ТЕПЛОФИЗИЧЕСКИХ СВОЙСТВ ПРОДУКТОВ СГОРАНИЯ БИОГАЗА НА ТЕПЛОВЫЕ ПАРАМЕТРЫ ВОДОГРЕЙНЫХ КОТЛОВ

The combustion products of biogas and natural gas differ in the content of components, which affects their heat content and heat exchange in boilers. To determine the possibility of using biogas in boilers designed for burning natural gas, the work compares the thermophysical properties of the combustion products of natural gas and biogas and their influence on the results of boiler calculations. Methods were obtained for calculating the thermal conductivity and viscosity of a mixture of gases depending on their composition and temperature. The comparison showed that the calorimetric and thermophysical properties of biogas combustion products differ from the properties of natural gas combustion products by up to 4 %, and the difference from the reference properties of combustion products given in the standard method for calculating boiler units is on average 6 %. A comparison has been made of the results of verification thermal calculations of low-power hot water boilers KVMG-1.0 and KSV-1.0 using the properties of combustion products given in the standard method for calculating boiler units, and when calculating them using the proposed equations. Calculations have shown that the results of calculations based on reference data of the standard method lead to higher values of exhaust gas temperatures and fuel consumption. It can be concluded that natural gas in boilers can be replaced by biogas without the need to reconstruct the boiler, but for thermal calculations it is necessary to take into account changes in the composition and properties of fuel combustion products.

Design and development of an advanced gas storage device and control method for a novel compressed CO2 energy storage system

Compressed CO2 energy storage (CCES) has advantages over compressed air in energy density and efficiency. Compared to air, CO2 needs to be in a closed-loop cycle in the CCES. The development of CCES is constrained by low-pressure CO2 storage. Storage density can be increased by adsorption without changing pressure. However, the control of the flow rate during adsorption/desorption has rarely been studied experimentally. In this paper, an adsorption tower for CCES is proposed and the regulation of the desorption flow rate is experimentally investigated. Using temperature-swing adsorption, the storage and release can be regulated without reducing the energy storage capacity. During the desorption process, the temperature of the exhaust gas can also be maintained stably. The adsorbent with a volume of 51.81 L was able to release 6121.9 g of CO2 when heated to 200 °C. Under the same pressure conditions, the effective storage density of the tower can reach 118.2 g/L, which is 67.5 times higher than the gaseous density (1.75 g/L, 1 bar, 303 K). The desorption flow rate is linearly related to the forward speed of the front in the adsorption tower. The flow rate can be regulated by controlling the superficial gas velocity and the desorption temperature. This method can match the flow rate of the adsorption tower with the gas consumption of the compressor, providing a novel solution for CCES.

Application of acetylene in multi-cylinder low heat rejection diesel engine fueled with ternary blend

The depletion of fossil fuels and environmental degradation have driven researchers worldwide to seek suitable alternative fuels for diesel engines. Internal combustion engines typically emit carbon monoxide (CO), hydrocarbon (HC), and smoke, contributing to environmental pollution. To address this issue, petroleum fuels can be substituted with alternative options like acetylene gas, hydrogen, CNG, or LPG. One effective strategy is to incorporate renewable fuels into diesel engines by partially or fully replacing diesel in a dual fuel mode (DFM). This research focuses on alternative renewable fuels for diesel engines like biodiesel and alcohol and its blends. The current research investigates the engine characteristics of diesel engines fueled with ternary blend (TB) fuel and different flow rates of acetylene in DFM. TB fuel was prepared using 70 % diesel, 20 % waste cooking oil biodiesel (WCOB), and 10 % methanol by volume. The induction of acetylene at different flow rates, such as 2, 4, and 6 lpm. Waste cooking oil is used to prepare biodiesel by transesterification. Partially stabilized zirconia (PSZ) is used to coat the cylinder head, piston crown, inlet, and exhaust valves with a thickness of 0.5 mm. The HC, CO, and smoke emissions are decreased by about 35.7 %, 29.8 %, and 21.6 %, respectively, for TB fuel with acetylene at 6 lpm at full load condition. The high calorific value of acetylene gas raised the in-cylinder temperature, significantly accelerating the combustion process. The heat release rate (HRR) and cylinder pressure are increased by 9.8 % and 6.8 %, respectively, at TB fuel with 6 lpm of acetylene induction. Acetylene induces rapid fuel combustion, resulting in increased energy transfer. The brake thermal efficiency (BTE) is improved by about 10.3 % for TB fuel with acetylene at 6 lpm and exhaust gas temperature (EGT) increased to 461oC at full load condition.

Sustainable Energy Application of Pyrolytic Oils from Plastic Waste in Gas Turbine Engines: Performance, Environmental, and Economic Analysis

The rapid accumulation of polymer waste presents a significant environmental challenge, necessitating innovative waste management and resource recovery strategies. This study investigates the potential of chemical recycling via pyrolysis of plastic waste, specifically polystyrene (PS) and polypropylene (PP), to produce high-quality pyrolytic oils (WPPOs) for use as alternative fuels. The physicochemical properties of these oils were analyzed, and their performance in a gas turbine engine was evaluated. The results show that WPPOs increase NOx emissions by 61% for PSO and 26% for PPO, while CO emissions rise by 25% for PSO. Exhaust gas temperatures increase by 12.2% for PSO and 8.7% for PPO. Thrust-specific fuel consumption (TSFC) decreases by 13.8% for PPO, with negligible changes for PSO. The environmental-economic analysis indicates that using WPPO results in a 68.2% increase in environmental impact for PS100 and 64% for PP100, with energy emission indexes rising by 101% for PS100 and 57.8% for PP100, compared to JET A. Although WPPO reduces fuel costs by 15%, it significantly elevates emissions of CO2, CO, and NOx. This research advances the understanding of integrating waste plastic pyrolysis into energy systems, promoting a circular economy while balancing environmental challenges.

Calibrated the direct current potential drop method for fatigue crack propagation testing of nickel-based superalloy with film cooling hole

Turbine blades in aviation engines commonly feature a nickel-based superalloy structure integrated with film cooling holes to enhance inlet gas temperature. However, the presence of these film cooling holes often results in frequent occurrences of fracture failures nearby. The direct current potential drop (DCPD) method, renowned for its exceptional crack sensitivity, is frequently utilized for crack length monitoring. This study establishes a FEM model of the film cooling hole plate specimen to determine the optimal probe point location. Subsequently, a mapping relationship is derived to calibrate Johnson’s formula, accounting for the unequal crack lengths at the edges of film cooling holes. It is confirmed that the crack length measured by the DCPD method represents the cumulative crack lengths on both sides of the hole. Fatigue crack propagation experiments are then conducted, with crack length monitored using a microscope. The results affirm the successful application of the calibrated formula to the film cooling hole plate specimen, exhibiting an average error within 0.1 mm.

Nitrogen migration and gasification characteristics of pulverized coal using the novel gasification-combustion technology

This study proposes a feasible gasification-combustion technology for coal-fired boilers operating at low loads for the purpose of providing strong support for stable output of the power grid system that accommodates more renewable energy power. In this technology, a multi-nozzle impinging entrained-flow gasifier is used for the first time to preheat pulverized coal (PC), and the gasified fuel enters a down-fired combustor (DFC) for complete combustion with air-staged method. A 75 kW novel self-sustained gasification-combustion test rig was constructed. The stability and feasibility of the test rig were verified, and the gasification characteristics and nitrogen migration mechanism of PC under loads of 45 kW, 55 kW, 65 kW and 75 kW were investigated. The results demonstrated that the gasifier could continuously and steadily provide high-temperature gasified gas-char mixture to the combustor. The gas-char mixture, consisting of coal gas which was rich in high-concentration flammable gases (CO, H2, and CH4) and char with enlarged specific surface area, was easy to ignite, which could enhance the flame stability of boilers operating at low loads. Additionally, more than 61.6 % of coal-N was released in the gasifier. The liberated coal-N primarily transformed to N2 and NH3 instead of NOx, while the amount of NH3 produced was influenced by the gasification temperature. The gasified gas-char mixture entering the combustor achieved stable combustion with uniform temperature distribution. Before the injection of tertiary air, the released char-N and the NH3 in coal gas transformed primarily to N2, and there was no production of NO due to the strong reducing environment. The lowest NOx emission was 122.31 mg/Nm3 (@6% O2) at 65 kW, and the combustion efficiencies under all loads exceeded 99.62%, indicating that the gasification-combustion technology could enable efficient combustion and reduce NOx emission. Hopefully, the proposed technology could provide an innovative solution for the stable combustion of PC boilers at low loads and provide a feasible way to achieve clean combustion.

Enrichment of Chlorophyta growth via cerium oxide and utilized for hydrogen production via hydrothermal gasification process

Abstract The growing interest in alternative fuels stems from the need to address energy security and economic challenges. Hydrogen fuel is considered a promising solution due to its versatility, efficiency, and potential for zero emissions, as well as continuous technological advancements and increasing policy support. This study intends to enhance Chlorophyta growth by incorporating different volume percentages of cerium oxide (CeO2) as feedstock for hydrogen production through hydrothermal gasification. The research findings indicate that the highest concentration (0.2 vol %) of CeO2 resulted in the maximum growth of 0.63 μ/day, which was utilized for hydrogen extraction. Additionally, the investigation explored the impact of Chlorophyta algae loading (0.05-0.15 g/mL) and processing temperature (500-650°C) on molar fraction, hydrogen yield, gasification efficiency, carbon efficiency, and total hydrogen production. Higher feedstock (0.15 g/mL) and gasification temperature (650°C) were found to improve hydrogen fraction (61.8%), yield (10.2 mol/kg), gasification efficiency (43.8 %), and total hydrogen production (62.5%).

Impact of ice growth on the physical and chemical properties of dense cloud cores

We investigated the effect of time-dependent ice growth on dust grains on the opacity and hence on the dust temperature in a collapsing molecular cloud core, with the aim of quantifying the effect of the dust temperature variations on ice abundances as well as the evolution of the collapse. To perform the simulations, we employed a one-dimensional collapse model that self-consistently and time-dependently combines hydrodynamics with chemical and radiative transfer simulations. The dust opacity was updated on the fly based on the ice growth as a function of the location in the core. The results of the fully dynamical model were compared against simulations run with different values of fixed ice thickness. We found that the ice thickness increases quickly and reaches a saturation value (as a result of a balance between adsorption and desorption) of approximately 90 monolayers in the central core (volume density ~104 cm−3), and several tens of monolayers at a volume density of ~103 cm−3, after only a few 105 yr of evolution. The results thus exclude the adoption of thin (approximately ten monolayer) ices in molecular cloud simulations except at very short timescales. However, the differences in abundances and the dust temperature between the fully dynamic simulation and those with a fixed dust opacity are small; abundances change between the solutions generally within a factor of two only. The assumptions on the dust opacity do have an effect on the collapse dynamics through the influence of the photoelectric effect on the gas temperature, and the simulations take a different time to reach a common central density. This effect is, however, small as well. In conclusion, carrying out chemical simulations using a dust temperature corresponding to a fixed opacity seems to be a good approximation. Still, although at least in the present case its effect on the overall results is limited – as long as the grains are monodisperse – ice growth should be considered to obtain the most accurate representation of the collapse dynamics. We have found in a previous work that considering a grain size distribution leads to a complicated ice composition that depends on the grain size nonlinearly. With this in mind, we will carry out a follow-up study where the influence of the grain size on the present simulation setup is investigated.

Coupled CFD modeling and thermal analysis of multi-layered insulation structures in liquid hydrogen storage tanks for various vapor-cooled shields

The present study aims to propose a coupled numerical model for analyzing the influence of the configuration of the vapor-cooled shield tubes on insulation performance. The numerical model is developed to calculate the effective thermal conductivity of multi-layer insulation (MLI) and rigorously evaluated. Specifically, the tank evaporation simulation software BoilFAST is manually coupled with the CFD commercial software of ANSYS FLUENT (2020 R2) to accurately determine the mass flow rate and temperature of boil-off gas in a tank, which is then used as inputs for the CFD simulations. This coupling methodology can be used for reliable calculations of boil-off losses for liquid hydrogen and heat transfer inside the MLI structures. Results demonstrate that the estimated effective thermal conductivity agrees with the earlier published data and that increasing the diameter and number of tubes enhances heat exchange between the VCS tubes and MLI structures. Also, the heat flux into the tank is relatively reduced by 32.04 % by increasing the diameter of the tube and 49.14 % by adding the number of tubes. Moreover, the maximum temperature difference of the VCS is estimated to be less than 1 K, indicating nearly uniform distributions of the VCS.

Unsteady conjugate heat transfer simulation around the throat insert in a high enthalpy shock tunnel

High enthalpy shock tunnel is a critical ground testing facility for evaluating the aerodynamic performance of hypersonic vehicles by simulating high-enthalpy, hypersonic flows. However, as the total temperature or pressure of the stagnant gas rises, the throat insert may be subjected to melting or oxidation, leading to a degradation in flow quality or a reduction in effective test time. This study investigates the unsteady heat transfer between the gas flow and the throat insert using a conjugate heat transfer model. The effects of test time, total temperature, and total pressure on the throat temperature are presented. An increase in any of these factors will raise the throat temperature. Moreover, oxidation will cause the copper throat insert to melt more quickly under the same conditions, which should be considered when addressing throat melting issues.

H2S gas sensing behavior of 2-D V2O5 nanowire network structure

In this study, a nanowire network-based V2O5 nanostructure, designed as the active surface in H2S gas sensors, was produced using an environmentally friendly method known as hydrothermal synthesis. The morphological, structural, and electrical properties of the produced nanostructure were characterized using various measurement techniques. XRD, SEM, and EDX analyses confirmed that the nanostructure was in a pure monoclinic phase, had a two-dimensional (2-D) nanowire network morphology, and was deposited stoichiometrically. From UV–Vis analysis, the energy band gap value of the nanostructure was calculated to be 2.65 eV. In gas sensing measurements conducted between 27 °C and 102 °C, the optimal operating temperature of the fabricated sensor was determined to be 42 °C. At this temperature, which is close to room temperature, the sensor exhibited a high sensitivity of 21.16 % for 50 ppm H2S gas, along with good selectivity, stable repeatability, and baseline stability. Moreover, for 2 ppm H2S gas, the response and recovery times were 39 s and 58 s, respectively. A comprehensive electrical analysis of the sensor was carried out through impedance spectroscopy measurements over a wide temperature range. Our findings indicate that the 2-D V2O5 nanowire network structure (NNS) results in several notable effects, including low operating temperature, high selectivity, and stability for H2S gas, demonstrating considerable potential for industrial applications.

Capturing non-equilibrium in hypersonic flows: Insights from a two-temperature model in polyatomic rarefied gases

The study utilizes a two-temperature model to analyze non-equilibrium in normal shocks within hypersonic flows in polyatomic rarefied gases. Derived from the extended second law of thermodynamics, this model separates translational and internal temperatures in polyatomic gases, providing a more accurate depiction of non-equilibrium gas flow compared to classical theories like the Navier–Stokes and Fourier (NSF) system. Notably, the analysis reveals that the two-temperature model incorporates an additional contribution to the heat flux due to the gradient of the dynamic temperature, resulting in improved accuracy, especially for high Mach numbers. Results show that the model gives satisfactory shock density and temperature profiles up to Mach 10, with very good agreement observed up to Mach 6.1 compared to the classical NSF model. We conduct an order of magnitude analysis on the dynamic temperature and heat flux gradients appearing in the new constitutive equation using the Mott-Smith method. This analysis highlights the impact of these terms on accurately modeling polyatomic gas behavior in high-speed flows. The effects of bulk viscosity and incoming temperature on shock profiles are also investigated, contributing to a better understanding of shock wave structures in polyatomic gases and their implications for hypersonic flow dynamics.

A new ex vivo model system to analyze factors affecting the integrity of fetal membranes in fetoscopic surgery

We developed an ex vivo model system to analyze the influence of relevant environmental and mechanical factors potentially affecting the integrity of fetal membranes during fetoscopic surgery. The set-up exposes amniochorion membranes to insufflation at predefined levels of gas pressure, flow, humidity, and temperature. Change in fetal membranes stiffness is quantified during the phase mimicking surgery through measurement of membranes’ strain in response to cyclic overpressure. The trocar induced perforation creates a mechanical weakness whose stability is assessed by increasing the insufflation pressure until membrane rupture. Damage of the epithelial cells lining the amnion is assessed through live-dead staining. Initial experiments demonstrated the functionality of the new apparatus and the feasibility of the proposed protocols. Fetal membranes exposed to air with low humidity for approximately 1 h demonstrated significant embrittlement, while their mechanical integrity was maintained in case of gas insufflation at high humidity (air as well as CO2). Under dry circumstances, there was a significant rate of epithelial cell death. Separation of amnion and chorion in the region of the trocar site was visible in all experiments. This new model is a versatile platform for analyzing the mechanical, histological, and biological implications of fetoscopic surgery on fetal membranes.

Evaluating the effectiveness of the modified multi-scale multi-physics coupled model for solid oxide fuel cells: A comparative analysis

A multi-scale multi-physics coupling numerical model serves as an effective tool to study the performance and improve the efficiency of solid oxide fuel cells (SOFCs) and provides the theory and data support for optimizing SOFC structure and operational strategy. To improve the accuracy and reliability of the model, this work established a modified simulation model that considers the effect of operational, structural, and physical parameters of SOFCs. First, the electrochemical kinetics equation, multi-component diffusion lattice Boltzmann (LB) model, and heat transfer LB model are modified by incorporating the reaction gas molar fraction, gas mixture concentration, temperature, and other parameters. Second, a regional hierarchical modeling strategy is proposed, and the multi-scale coupling model is modified by coupling mass and heat transfer. Third, considering the effect of carbon monoxide molar fraction, temperature difference, concentration change and porosity on electrochemical, mass, and heat transfer processes, the effectiveness of modification model is analyzed and validated. Results demonstrate that the modified model considerably improves the numerical simulation to handle the complex operational conditions of SOFCs. The modified model's predictions show better accuracy compared with experimental data, while maintaining consistency with the trends predicted by the original numerical models.

Analysis of Combustion Characteristics of Can-Type and Annular-Type Combustion Chamber

Abstract High performance is always desired for the propulsion system and the assortment of a better combustion type is also a vital part of the propulsion system. The analysis of different designs of combustion chambers and comparison of their combustion characteristics. In this paper, the assessment of Can-type and Annular-type combustion chambers and the design developed with SOLIDWORKS software and analysis done with ANSYS FLUENT. The systematic and translucent method approaches reduce the design complexity and time. The combustion with turbulence interface was examined to analyze with precision results, and the analysis specified that the nowadays experiment depends on the behavior of gas exit pressure, temperature, and velocity. Parametric analysis is used to acquire the sizing of the combustion chamber.