The paper is aimed at investigating the influence of porous fuel layering on the operating regimes and performance of a low-temperature gas generator for high-speed flying vehicles equipped with a ramjet engine. The gas generator consists of a propellant and a porous fuel arranged sequentially to generate hydrocarbon gases that cool the engine before burning in the combustion chamber. In this paper, using a novel numerical model, gasification of multi-layer solid porous fuels consisting of polymethylmethacrylate (PMMA) and polyethylene (PE) is studied for various volume contents and relative arrangements of fuel parts. It is shown that during the gasification of the multi-layer fuels, several gasification waves can simultaneously occur in the gas generator. The operating time of the gas generator depends on the relative sizes and relative location of the PMMA and PE layers, and an increase in the number of layers leads to a decrease in the influence of their relative arrangement on the process. Thus, during the gasification of two-component multi-layer solid porous fuel, the composition of this fuel, i.e., the relative sizes of the layers and their relative arrangement, can be the control parameter that allows one to choose the desired characteristics of the gasification process.

The work is devoted to the study of gasification of porous material under the conditions of a gas generator of a propulsion system. A low-temperature gas generator for producing combustible gases can be included in a solid fuel engine. The effect of urotropine particle size on the characteristics of its gasification under the conditions of a low-temperature gas generator was experimentally studied. For this purpose, urotropine particles of various fractions were used: 2-3, 3-5, 5-7 and 7-10 mm. It is shown that there is a particle size value above which the gasification characteristics are practically independent of this parameter. The effect of particle size on gasification characteristics only appears for particle size values below a certain size. This is explained by a decrease in the permeability of the porous bed as the particle size decreases.

A reverse flow porous medium reactor with premixed and non-premixed flames was experimentally investigated to evaluate the influence of steam and carbon dioxide on methane (CH4) filtration combustion for syngas production. Premixed, non-premixed, and non-premixed with steam were the tested cases for different injection configurations. Thermal profiles, combustion products, hydrogen (H2) and carbon monoxide (CO) yields for several equivalence ratios are analyzed. Non-premixed case exposed higher maximum temperatures due to the reactant accumulation at the crosswise injection position, with a temperature of 1615 K. The lack of homogenization of the reactants in this configuration leads to low H2 and high CO concentrations compared to the premixed case. The maximum CO yield was 92.81% for the non-premixed configuration with alternated air injection, while the maximum H2 yield was 37.8% for the premixed air-methane-steam case. It was found that the air-methane-carbon dioxide mixtures had lower temperatures, combustion wave velocities, and H2 and CO concentrations, compared to the air-methane, and air-methane-steam mixtures, but higher CH4 and CO2 concentrations. The premixed configuration with air-methane-carbon dioxide mixture showed higher temperatures, and H2 and CO concentrations, compared to the non-premixed configuration. Further studies are necessary to optimize the operation of these types of reactors.

The experimental study of the kinetics and modes of the thermal degradation of polymethyl methacrylate (PMMA) in an argon flow was carried out. During thermogravimetric analysis the sample heating rates were 2, 5, 8, 20 and 35 K/min. Based on the integral isoconversional method the values of the kinetic rate constants of the PMMA thermal degradation were determined. When modeling the decomposition process of PMMA for low conversion degrees, it is advisable to use the reaction rate constant obtained for the conversion degree equal to 20%, and for modeling the whole process – 50%. Therefore, for evaluation calculations, it is possible to describe the process of PMMA decomposition with one gross reaction. Also, the investigation of the thermal degradation of PMMA particles under conductive heating conditions (680, 700, 720 K) in an argon and air was carried out. Based on the analysis of the data obtained, a scheme for the decomposition of PMMA, consisting of four stages, was established.

A new process is proposed for the pyrolysis of ammonia in a filtration combustion moving bed reactor to produce hydrogen. The process can be implemented in reactors with energy recovery with a separate supply of reagents (including swiss-roll reactors, etc.). The mass-energy balance of the process is calculated. The pyrolysis products are analyzed under a condition of thermodynamic equilibrium with varying temperature and pressure. The system pressure is varied from 1 to 10 bar. The temperature range from 300 to 1100 K iss considered. It is shown that the pyrolysis of ammonia ends at a temperature of 620 K at atmospheric pressure. An increase in pressure in the system leads to a slight increase in the temperature of the pyrolysis of ammonia. The portion of hydrogen that needs to be burned to cover the energy for heating and pyrolysis of the initial ammonia in the case of an adiabatic reactor is 0.13. From one mole of ammonia it is possible to obtain 1.31 moles of hydrogen.

The experimental study was carried out to investigate the gasification of urotropine (hexamethylenetetramine) in a low-temperature solid fuel gas generator under varying inlet gas flows. Nitrogen was applied as the filter gas. The filter gas flow was varied from 0.6 to 1.4 L/s with a step of 0.2 L/s. The inlet gas's initial temperature was equal to 910 K. It was shown that with an increase in the nitrogen flow, the fuel gasification time decreased. Increasing the flux of inlet nitrogen from 0.6 to 1.4 L/s results in an increase in the average urotropine gasification mass rate from 0.63 to 1.61 g/s. When the initial nitrogen flow is raised, the rate of fuel gasification increases almost linearly. Studies have demonstrated that the proportion of mass flows between urotropine gasification products and nitrogen remains constant regardless of the incoming gas flow. The mass flow ratio remains steady at approximately 0.9 g/g when the incoming gas flow is altered. It has been shown that the gaseous products of urotropine gasification consist of nitrogen with a small amount of hydrogen and hydrocarbons. The content of simple gaseous products does not exceed 4% vol.

Using thermogravimetric analysis (TGA), the kinetic constants of the thermal decomposition of polymethylmethacrylate (PMMA) in an oxidizing environment are determined over a wide range of sample heating rates. The values of the kinetic constants of polymer decomposition are determined by the Kissinger method. It is shown that as the degree of polymer decomposition increases, the rate constant decreases at a constant temperature.

The air gasification of wood at increased pressure in the filtration combustion mode is experimentally studied. It is experimentally shown that increasing the pressure in the reactor (up to 3 atm) during the gasification of wood leads to an increase in the productivity of the experimental setup (by a factor of 1.6), a decrease in the quantity of tars formed (by a factor of 1.5), and a change in the concentrations of outgoing gases. Thermodynamic calculations of the effect of pressure at the stage of wood pyrolysis are carried out. With an increase in pressure from 1 to 9 atm, the volume concentrations of hydrogen and carbon monoxide decrease, while the volume concentrations of the water vapor and carbon dioxide increase. However, at a pyrolysis temperature of 1300 K, an increase in pressure has practically no effect on the composition of gaseous products.

The work is devoted to the simulation of the propulsion system. A low-temperature gas generator might be included in the solid-fuel ramjet to produce high-calorific gases. The gasification of a solid porous hexamethylenetetramine (urotropine) during the filtration of high-temperature gas through it was experimentally studied. It is shown that with an increase in the initial temperature of the filtered gas, the time of urotropine gasification decreases, the intensity of the fuel gasification process increases, which leads to an increase in the flux of urotropine gasification products. In the temperature range of 450-500 K, an intensive gasification of urotropine occurred, while the temperature of the outgoing gaseous products changed slightly. An increase in the inlet gas temperature from 650 to 850 K led to an increase in the mass rate of urotropine gasification from 0.23 to 0.69 g/ s, as well as an increase in the flux of urotropine gasification products from 0.31 to 0.93 g per 1 g of nitrogen. At temperatures below 800 K urotropin only sublimates. At higher gasification temperatures not only sublimation occurs, but also decomposition of urotropin to simpler gaseous products (mainly hydrogen).

Hydrogen (H2) and syngas (a mixture of H2 and carbon monoxide) can be thermochemically produced from various sources, such as fossil fuels, biomass, water, and solid wastes, via steam reforming, dry reforming, and partial oxidation. Hybrid filtration combustion (HFC) has been introduced to produce H2/syngas by gasifying solid fuels or by simultaneously reforming gaseous and solid fuels. This article presents a comprehensive review of HFC modeling, development of HFC reactors, industrial applications, and future directions. Until now, several mathematical models have been proposed and analytically and numerically solved with novel approaches to the relatively complex chemical kinetics found in these reactors. The HFC reactors for solid fuel gasification and simultaneous homogeneous and heterogeneous reactions have shown high temperatures in the reaction wave (900-2300 K) due to high heat recirculation inside. The geometry and orientation, hybrid porous bed compo-sition, gasifying agent, and mode of operation are crucial parameters for optimizing the hydrogen and syngas yield. The various solid feedstocks studied include coal, biomass, and polyethylene, and the gasifying agents used are air, steam, carbon dioxide, and premixed air/fuel flows. At the industrial scale, HFC has been successfully implemented for producing hydrogen/syngas from municipal solid waste. The present review has revealed the promising potential of this technology as an energy-efficient and sustainable alternative to produce H2 and syngas from various solid and gaseous feedstocks.

The gasification of a solid porous fuel during the filtration of high-temperature gaseous products through it is experimentally studied. A sublimating material, urotropine, is used as a solid fuel. It is shown that with an increase in the initial temperature of the filtered gas, the time of urotropine gasification decreases and the intensity of the fuel gasification process increases, which leads to an increase in the flow of urotropine gasification products. In the temperature range of 470 to 500 K, intensive gasification of urotropine occurred, while the temperature of the outgoing gaseous products changed slightly. The hydrogen content in gaseous products reached 7 vol %.

The gasification of a two-layer porous solid fuel in a combined charge of a low-temperature gas generator has been studied using a mathematical model and a computational algorithm implemented in the OpenFOAM software. In the computational experiments, the influence of the two-layer nature of a porous solid fuel on its gasification has been investigated for gasifiers containing polymethylmethacrylate and polyethylene as fuels with different relative position of their layers. It has been shown that in two-layer fuels, two gasification waves can propagate simultaneously, due to which the relative mass flow rate of gasification products can have two local maxima. The operating time of a gas generator with a two-layer porous fuel depends ambiguously on the relative position of the layers and can go beyond the range between the operating times of the gasifier with each of the fuels.

Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation E. A. Salgansky, N. A. Lutsenko, L. S. Yanovskiy; Simulation of gasification of solid porous fuel in a low-temperature gas generator of ramjet. AIP Conference Proceedings 16 February 2023; 2504 (1): 020008. https://doi.org/10.1063/5.0132339 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioAIP Conference Proceedings Search Advanced Search |Citation Search

Experiments on filtration combustion of car tires mixed with a solid coolant are carried out. The mass content of tire particles in a mixture varies from 10 to 70

The gasification of solid urotropine was experimentally studied at filtering a high-temperature flow of carbon dioxide through it. It was shown that with an increase in the temperature of the filtered gas from 650 to 920 K, the time of urotropine gasification decreased and the average gasification rate increased from 0.38 to 1.25 g/s, leading to an increase in the flow of urotropine gasification products. The maximum achieved value of the mass of urotropine gasification products was 0.8 g per 1 g of incoming gas. In the temperature range of 480–530 K, intensive gasification of urotropine occurred, while the temperature of the gaseous products leaving the reactor remained practically unchanged. The amount of noncondensable gaseous gasification products did not exceed 1

The review contains a comparative analysis of studies on the production of hydrogen and syngas based on the processes of partial oxidation of natural gas and other types of gas feedstock. The results presented in the literature show the high potential of non-catalytic autothermal processes of partial oxidation of hydrocarbons for the development of gas chemistry and energetics. The partial oxidation of hydrocarbons makes it possible to overcome such serious shortcomings of traditional syngas production technologies as technological complexity and high energy and capital intensity. The features of non-catalytic partial oxidation of hydrocarbon gases, the obtained experimental results and the results of kinetic modeling of various options for the implementation of the process, which confirm the adequacy of the kinetic mechanisms used for the analysis, are considered in detail. Examples of industrial implementation of processes based on partial oxidation and proposed alternative options for its organization are considered. Designs of reactors used to ensure stable conversion of rich mixtures of hydrocarbons with an oxidizer are presented. The possibility of obtaining other chemical products by partial oxidation of hydrocarbons is discussed.

Based on the data of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), the kinetic characteristics of the thermal decomposition of urotropine in flows of N 2 and CO 2 are determined. The sample heating rates are 20, 60, and 90 K/min. The values of the kinetic rate constants of the decomposition of urotropine are determined by the Kissinger method. During gasification in nitrogen, the activation energy of the thermal decomposition of urotropine increases from 106 to 139 kJ/mol under conditions of an increase in the degree of conversion of the substance. The preexponential value also increases from 0.35 × 10 9 up to 145 × 10 9 s –1 . The decomposition of urotropine proceeds by an exothermic reaction with a heat of 368, 339, and 275 kJ/kg for heating rates of 20, 60, and 90 K/min, respectively. During gasification in carbon dioxide, the activation energy of the thermal decomposition of urotropine first increases from 110 to 132 kJ/mol as the degree of conversion increases, and then decreases to 120 kJ/mol. The heat of decomposition of urotropine in a flow of CO 2 is 382, 327, and 303 kJ/kg for heating rates of 20, 60, and 90 K/min, respectively.

A thermodynamic assessment of biogas conversion regimes with the production of hydrogen and synthesis gas is out. The air conversion of the original and dried biogas, as well as conversion with an increased oxygen content in the air, is studied. Model mixtures of high-calorie (50 vol % methane) and low-calorie (25 vol % methane) biogas are considered. Calculations are performed for mixtures with an adiabatic combustion temperature of at least 1000 K. It is shown that during air conversion of low-calorie dry biogas, the maximum content of hydrogen and carbon monoxide in gaseous products can be 22.3 and 20.8 vol %, respectively. With air conversion of high-calorie dry biogas, the maximum content of hydrogen and carbon monoxide in gaseous products can reach 26.0 and 16.3 vol %, respectively. At an oxygen content of 41 vol %, the conversion of low-calorie dry biogas makes it possible to obtain a gas with a content of 31.0 vol % hydrogen and 28.3 vol % carbon monoxide. With an oxygen content of 41 vol %, the conversion of high-calorific dry biogas makes it possible to obtain a gas with a hydrogen content of 39.0 vol % hydrogen and carbon monoxide content of 25.0 vol %.

This paper presents an improved mathematical model for gasification of a solid porous fuel when hot gases are filtered through it. Gasification modes were studied at a constant pressure drop between the gasifier inlet and outlet and at a constant gas velocity at the gasifier inlet using polymethyl methacrylate as an example. In the case of a constant pressure drop, fuel gasification takes longer and the gas temperature at the outlet increases more slowly than in the case of a constant gas velocity at the inlet under comparable conditions.