Gas Temperature Research Articles

Torrefaction Integrated with Steam Gasification of Agricultural Biomass Wastes for Enhancing Tar Reduction and Hydrogen-rich Syngas Production

Steam gasification is considered as a promising technology for conversion of various biomass wastes to valuable hydrogen (H2)-rich gas products that can be applied for the sustainable production of green hydrogen and methanol. However, some inevitable problems such as high tar content and low cold gas efficiency greatly hinder its broad application. Torrefaction has been widely employed for upgrading low-rank biomass sources that favors the follow-up gasification process, resulting in low tar yield and high syngas yield. Torrefied biomass usually shows higher energy density, improved grindability characteristics, and lower O/C and H/C ratios. This research work studies the effect of torrefaction on steam gasification of corncob (CC) and rice husk (RH). The mechanisms of biomass torrefaction integrated with steam gasification are also given. Biomass torrefied at a relatively high temperature (280 oC) is more efficient to extract the oxygenated volatiles, reducing the generation of tar and particulate matters during the gasification process. The increase of torrefaction temperature resulted in an increase of H2 yield and a decrease of CO yield, corresponding to an increase of H2/CO ratio. Particularly, the H2 yield in the CC-derived syngas increased from 6.38 mmol/g (raw) to 12.01mmol/g (280 °C), and the H2 yield in the RH-derived syngas increased from 4.33 mmol/g (raw) to 12.97 mmol/g (280 °C). Steam gasification of RH torrefied at 280 oC achieved a maximum H2/CO ratio of 2.84. After torrefaction of CC and BB at 280 °C, the tar yield of steam gasification was below 1% [gasification temperature: 800 °C, mass ratio of steam to biomass (S/B): 1]. In general, the torrefaction pretreatment of biomass at relatively high temperatures (i.e., 280 oC) favors the steam gasification process under an appropriate S/B (i.e., 1) in terms of improving the syngas quality and reducing the tar production.

Biodiesel production from the transesterification of waste cooking oil via CaO/HAP/MnFe@K magnetic nanocatalyst derived from eggshells and chicken bones: Diesel engine and kinetic studies

This study focuses on the biodiesel generation from waste cooking oil (WCO) utilizing eggshells/chicken bones-derived magnetic nanocatalyst (CaO/HAp/MnFe@K). Various assessments were applied to demonstrate the CaO/HAp/MnFe@K nanocatalyst surface. These assessments showed that CaO/HAp/MnFe@K nanocatalyst has considerable catalytic attributes (e.g., highly crystalline, suitable surface area, and favorable porosity). The highest biodiesel efficiency employing CaO/HAp/MnFe@K magnetic nanocatalysts was 99.10%, which was obtained at a molar proportion of 15.24:1, catalyst content of 2.97 wt.%, reaction time of 175.72 min, and temperature of 67.72 °C (optimal conditions). Further, the reaction kinetics demonstrated that the transesterification of WCO in the attendance of CaO/HAp/MnFe@K nanocatalyst follows the pseudo-first-order model. Besides, the activation energy and exponential factor reflection reveal that the conversion of WCO to biodiesel is 41.51 kJ/mol and 1.66×105 min-1, respectively. By adding WCO-derived biodiesel to diesel, the release of carbon dioxide (CO2) and nitrogen oxides (NOx) increases while the carbon monoxide (CO) and unburned hydrocarbon (UHC) amounts diminish. By boosting biodiesel in the fuel combination, the quantities of brake specific fuel consumption (BSFC) and exhaust gas temperature (EGT) increased while the Brake Thermal Efficiency (BTE) amount decreased. Moreover, reusability of the CaO/HAp/MnFe@K nanocatalyst revealed that the magnetic particles were considerably stability.

Dynamics of cosmological phase crossover during Bose–Einstein condensation of dark matter in Tsallis cosmology

AbstractDuring the cosmic evolution process, as the temperature of a cosmological boson gas falls below a certain threshold, a Bose–Einstein condensation process can occur at various points throughout the cosmic history of the Universe. In this model, dark matter, conceptualized as a non-relativistic, Newtonian gravitational condensate is governed by the Gross–Pitaevskii–Poisson system. In our present study, we investigate the Bose–Einstein condensation process of bosonic DM by treating it as an approximate first-order phase transition within a modified cosmological framework, known as Tsallis cosmology. We examine the evolution of relevant physical quantities characterizing the evolution dynamics of the Universe, including energy density, temperature, redshift, scale factor, Hubble parameter, and dimensionless deceleration parameter before, during, and following the Bose–Einstein condensation phase transition takes place. Additionally, we especially investigate the specific era of the evolution of the Universe characterized by a mixture of normal and condensate phases of dark matter. We analyze the behavior of temporal evolution of an important time-dependent parameter, called the condensate dark matter fraction throughout the condensation process and find the time duration of condensation of dark matter in the Tsallis cosmological model. We see that the presence of Bose–Einstein condensate dark matter in the framework of Tsallis-modified cosmology significantly alters the cosmological evolution of the Universe as compared to the standard model of cosmology. We also find for a typical value of Tsallis non-extensive parameter $$\beta =0.35$$ β = 0.35 , the model could explain an accelerated Universe without invoking any additional energy component and solve the age problem of our Universe.

Numerical Simulation Study on the Stable Combustion of a 660 MW Supercritical Unit Boiler at Ultra-Low Load

To investigate the safe, stable, and economically viable operation of a boiler under ultra-low-load conditions during the deep peaking process of coal-fired units, a numerical simulation study was conducted on a 660 MW front- and rear-wall hedge cyclone burner boiler. The current research on low load conditions is limited to achieving stable combustion by adjusting the operating parameters, and few effective boiler operating parameter predictions are given for very low-load conditions, i.e., below 20%. Various burner operation modes under ultra-low load conditions were analyzed using computational fluid dynamics (CFDs) methods; this operation was successfully tested with six types of pulverized coal combustion in this paper, and fitting models for outlet flue gas temperature and NOx emissions were derived based on the combustion characteristics of different types of pulverized coal. The results indicate that under 20% ultra-low-load conditions, the use of lower burners leads to a uniform temperature distribution within the furnace, achieving a minimum NOx emission of 112 ppm and a flue gas temperature of 743 K. Coal type 3, with the highest carbon content and a calorific value of 22,440 kJ/kg, has the highest average section temperature of 1435.76 K. In contrast, coal type 1 has a higher nitrogen content, with a maximum cross-sectional average NOx concentration of 865.90 ppm and an exit NOx emission concentration of 800 ppm. The overall lower NOx emissions of coal type 3 are primarily attributed to its reduced nitrogen content and increased oxygen content, which enhance pulverized coal combustion and suppress NOx formation. The fitting models accurately capture the influence of pulverized coal composition on outlet flue gas temperature and NOx emissions. This control strategy can be extended to the stable combustion of many kinds of coal. For validation, the fitting error bar for the predicted outlet flue gas temperature based on the elemental composition of coal type 6 was 8.09%, whereas the fitting error bar for the outlet NOx emissions was only 1.45%.

A Survey of Sulfur-bearing Molecular Lines toward the Dense Cores in 11 Massive Protoclusters

Sulfur-bearing molecules are commonly detected in dense cores within star-forming regions, but the total sulfur budget is significantly lower when compared to the interstellar medium value. The properties of sulfur-bearing molecules are not well understood due to the absence of large sample studies with uniform observational configurations. To deepen our understanding of this subject, we conducted a study using Atacama Large Millimeter/submillimeter Array 870 μm observations of 11 massive protoclusters. By checking the spectra of 248 dense cores in 11 massive protoclusters, a total of 10 sulfur-bearing species (CS, SO, H2CS, NS, SO2, 33SO, 34SO2, 33SO2, SO18O, and OC34S) were identified. The parameters including systemic velocities, line widths, gas temperatures, column densities, and abundances were derived. Our results indicate that SO appears to be more easily detected in a wider range of physical environments than H2CS, despite these two species showing similarities in gas distributions and abundances. Molecules 34SO2 and H2CS are good tracers of the temperature of sulfur-bearing species, in which H2CS traces the outer warm envelope and 34SO2 is associated with high-temperature central regions. High-mass star-forming feedback (outflow and other nonthermal motions) significantly elevates the sulfur-bearing molecular abundances and detection rates specifically for SO2 and SO. A positive correlation between the SO2 abundance increasing factor (F) and temperatures suggests that SO2 could serve as a sulfur reservoir on the grain mantles of dense cores and then can be desorbed from dust to gas phase as the temperature rises. This work shows the importance of a large and unbiased survey to understand the sulfur depletion in dense cores.

Impact of nano cerium oxide addition with pyrolysis waste plastic oil on combustion, performance and emission characteristics of CRDI diesel engine

Abstract This investigation examined the effect of incorporating cerium oxide (CeO2) nanoparticle into diesel and waste plastic oil (WPO) blends on the combustion, performance and emission characteristics of the diesel engine. The WPO was extracted from low density polyethylene using plastic pyrolysis. The blending of diesel and WPO with combination of D70:WPO30 and D50:WPO50 was prepared to evaluate the engine operation. Additionally, the spherical sized CeO2 with 50 mg/L and 100 mg/L was added with this blend. The various blends named as Diesel, D-WPO30, D-WPO30+Ce50, D-WPO30+Ce100, D-WPO50, D-WPO50+Ce50 and D-WPO50+Ce100 were used in this investigation to operate the engine under various load conditions. The experiment was performed using water cooled common rail direct injection (CRDI) diesel engine with prepared D-WPO blend. Different characteristics such as In-cylinder pressure (CP), heat release rate (HRR), ignition delay time (IDT), brake thermal efficiency (BTE), brake specific fuel consumption (BSFC) and exhaust gas temperature (EGT), carbon monoxide (CO), hydrocarbon (HC), nitrogen oxide (NOx) and smoke opacity emission are studied with respect to the effect of different blends and applied load used. It was observed that increasing of CeO2 nanoparticles in blend improved the overall performance and emission of the engine. Form the results, D-WPO30+Ce100 blend showed enhanced brake thermal efficiency (BTE), brake specific fuel consumption (BSFC) and exhaust has temperature (EGT) are 28.2%, 3% and 465oC respectively. Similarly, reduced emission of CO, NOx, HC and smoke opacity was observed in the CeO2 added blends particularly at 100 mg/L. It was concluded that among all blends prepared, the D70:WPO30 with 100 mg/L of CeO2 showed improved combustion, performance and emission characteristics in proposed diesel engine.

Targeting Full-Hydrogen Operation on Industrial-Scale Gas Turbines: Impact of Unconventional Fuels on Turbine Module Performance and Aeromechanics

Abstract With the trend to full decarbonization, a full hydrogen economy development is a key industrial objective. Gas turbines, currently one of the cleanest fossil fuel-based power generation solutions, provide reliable and on-demand power. The introduction of hydrogen into the fuel mix of existing gas turbines represents a solution with great potential to provide low-carbon or even carbon-free energy. High-hydrogen content fuels, however, challenge the efficient operation of the gas turbine expander, as crucial aspects such as increased flow rate, different gas properties and temperature operating range may affect performance and structural integrity. To evaluate the impact of this conversion, a numerical investigation of five cases with increasing percentages of hydrogen in the fuel was carried out for an industrial four stages gas turbine module. The variation of turbine inlet temperature distribution from combustion chamber was considered, to assess the impact of the unconventional fuel on the well-known aeromechanical behavior of the last stage blades. Variations in capacity, efficiency, power and potential limits due to aeroelasticity were evaluated, identifying the most relevant differences with respect to the full methane case. All these analyses confirm the possibility to employ high-hydrogen fuel operation in a current gas turbine without the need of a further redesign, while maintaining acceptable performance levels.

Sulfur-bearing molecules in a sample of early star-forming cores

The sulfur content in dense molecular regions is highly depleted in comparison to diffuse clouds. The reason for this phenomenon is unclear, and it is therefore necessary to carry out observational studies of sulfur-bearing species toward dense regions, mainly in early evolution stages. In this context, the analysis of sulfur-bearing molecules in a large sample of dense starless molecular cores is of great importance to help us uncover the early sulfur chemistry in these regions. From the Atacama Large Millimeter Array (ALMA) data archive, we selected a project in Band 7 (275--373 GHz), which contains the emission of several sulfur-bearing species. The observations were performed toward a sample of 37 dense cores that are embedded in the most massive infrared-quiet molecular clumps from the ATLASGAL survey. The lines of 34SO, SO$_ $, NS, SO, SO$^ $, and H$_ $CS were analyzed, and the column densities of each molecular species were obtained. Based on the continuum emission and two CH$_ $OH lines, the 37 cores were characterized in density and temperature, and the corresponding H$_ $ column densities were derived. The abundances of these sulfur-bearing species were derived and studied. We find that the abundances of the analyzed sulfur-bearing species increase with increasing gas temperature. Based on the correlation between abundances and temperature, we suggest that the chemistry involved in the formation of each of the analyzed molecules may similarly depend on T$_ k $ in the range 20 to 100 K. Additionally, we find that the comparisons among abundances are highly correlated in general. Taking into account that this correlation decreases in more evolved sources, we suggest that the sulfur-bearing species we analyzed have a similar chemical origin. Our observational results show that the X(SO$_ $)/X(SO) ratio can be used as a chemical clock of molecular cores. Based on the line widths of the molecular lines, we point out that molecules with an oxygen content (34SO, SO$_ $, SO, and SO$^ $) may be associated with warmer and more turbulent gas than the other molecules. H$_ $CS and NS are associated with more quiescent gas, probably in the external envelopes of the cores, which trace similar physical and chemical conditions. We complement recent similar works done toward more evolved sources with a large sample of sources, but also provide quantitative information about abundances that might be useful in chemical models for explaining the sulfur chemistry in the interstellar medium.

Developing a Real Time Non Invasive Approach to Distinguish Natural and Artificial Ripened Fruits

In this project we focuse on detecting artificial and natural ripened fruit using the sensor introduces a novel Internet of Things-based method. An ESP32 microcontroller serves as the system's central hub and is responsible for gathering and interpreting data from a wide range of sensors. These sensors include a DHT sensor that measures the temperature and humidity inside the fruit container, a moisture sensor that determines the moisture content of the fruits and vegetables, a weight/load sensor that tracks the weight of the produce, and a MQ2 gas sensor that carefully measures the concentration of ethylene gas released by fruits [7]. This strategy reduces food waste and preserves agricultural products by providing a more effective and sustainable substitute for conventional techniques. A key component of guaranteeing the freshness, quality, and market value of fruits and vegetables is their timely ripening.The ability of the system to continuously evaluate the complex interactions between temperature, humidity, moisture, etc. This project presents the development of an IoT-based system for preventing the premature ripening of fruits and vegetables. The system utilizes sensors to monitor ethylene gas concentration, temperature, humidity, moisture content, and weight, enabling timely intervention to regulate ripening conditions. By detecting changes in these parameters, the system can activate a DC fan to improve air circulation and disperse ethylene gas, and a DC pump to spray ethylene absorbent onto the fruits. This helps to control the ripening process and prolong the shelf life of fruits and vegetables.

The cooler past of the intracluster medium in TNG-Cluster

Abstract The intracluster medium (ICM) today is comprised largely of hot gas with clouds of cooler gas of unknown origin and lifespan. We analyze the evolution of cool gas (temperatures ≲ 104.5 K) in the ICM of 352 galaxy clusters from the TNG-Cluster simulations, with present-day mass ∼1014.3 − 15.4 M⊙. We follow the main progenitors of these clusters over the past ∼13 billion years (since z ≲ 7) and find that, according to TNG-Cluster, the cool ICM mass increases with redshift at fixed cluster mass, implying that this cooler past of the ICM is due to more than just halo growth. The cool cluster gas at z ≲ 0.5 is mostly located in and around satellite galaxies, while at z ≳ 2 cool gas can also accrete via filaments from the intergalactic medium. Lower-mass and higher-redshift clusters are more susceptible to cooling. The cool ICM mass correlates with the number of gaseous satellites and inversely with the central supermassive black hole (SMBH) mass. The average number of gaseous satellites decreases since z = 2, correlating with the decline in the cool ICM mass over cosmic time, suggesting a link between the two. Concurrently, kinetic SMBH feedback shifts the ICM temperature distribution, decreasing the cool ICM mass inside-out. At z ≈ 0.5, the predicted Mg ii column densities are in the ballpark of recent observations, where satellites and other halos contribute significantly to the total Mg ii column density. Suggestively, a non-negligible amount of the ICM cool gas forms stars in-situ at early times, reaching ∼102 M⊙ yr−1 and an Hα surface brightness of ∼10−17 erg s−1 cm−2 arcsec−2 at z ≈ 2, detectable with Euclid and JWST.

Characterisation of Varying Iron Ores and Their Thermal Decomposition Kinetics Under HIsarna Ironmaking Conditions

In the pre-reduction cyclone of the HIsarna process, both thermal decomposition and gas reduction of the injected iron ores occur simultaneously at gas temperatures of 1723–1773 K. In this study, the kinetics of the thermal decomposition of three iron ores (namely OreA, OreB and OreC) for HIsarna ironmaking were analysed as an isolated process with a symmetrical thermogravimetric analyser (TGA) under an inert atmosphere. Using various methods, the chemical and mineralogical composition, particle size distribution, morphology and phase distribution of the ores were analysed. The ores differ in their mineralogy and morphology, where OreA only contains hematite as iron-bearing phase and OreB and OreC include goethite and hematite. To obtain the kinetic parameters in non-isothermal conditions, the Coats–Redfern Integral Method was applied for heating rates of 1, 2 and 5 K/min and a maximum temperature of 1773 K. The TGA results indicate that goethite and hematite decomposition occur as a two-stage process in an inert atmosphere of Ar. The proposed reaction mechanism for the first stage of goethite decomposition is chemical reaction with an activation energy ranging from 46.55 to 60.38 kJ/mol for OreB and from 69.90 to 134.47 kJ/mol for OreC. The proposed reaction mechanism for the second stage of goethite decomposition is diffusion, showing an activation energy ranging between 24.43 and 44.76 kJ/mol for OreB and between 3.32 and 23.29 kJ/mol for OreC. In terms of hematite decomposition, only the first stage was analysed. The proposed reaction mechanism is chemical reaction control. OreA shows an activation energy of 545.47 to 670.50 kJ/mol, OreB one of 587.68 to 831.54 kJ/mol and OreC one of 424.31 to 592.32 kJ/mol.

Multi‐aspect assessment and multi‐objective optimization of preheated tallow biodiesel‐diesel blend as alternate fuel in CI engine

AbstractThis study meticulously examined the impact of preheated tallow biodiesel on the performance and emission characteristics of a diesel engine. Employing a single‐cylinder, water‐cooled diesel engine configured with exhaust gas recirculation in this investigation, exhaust gas temperature (EGT) could be used to preheat the biodiesel, reducing its viscosity and density. This improvement in viscosity and density could enhance the injection process, which is often hindered by the higher density and viscosity of biodiesel compared with diesel fuel. The investigation achieved a peak preheat temperature of 70°C for the biodiesel, leading to notable improvements in brake thermal efficiency and brake power, particularly under high‐load conditions. A significant reduction in emissions was observed, with hydrocarbon and carbon monoxide levels decreasing by 46.87% and 50%, respectively, when using preheated biodiesel. To refine the engine's performance further, this study utilized response surface methodology (RSM) for the optimization of operational parameters, including injection timing, engine load, and biodiesel preheat temperatures. Optimal conditions were identified at an injection timing of 21° before top dead centre, a preheat temperature of 64°C, and an engine load of 45.45% for which output response was 18.68% brake thermal efficiency, 307°C EGT, 0.0247% vol. CO, 15.32 ppm hydrocarbons, and 131.37 ppm nitrogen oxides (NOx). The successful implementation of preheated tallow biodiesel signifies a crucial step forward in the pursuit of a more sustainable and efficient transportation industry. This advancement holds the promise of reducing reliance on traditional fossil fuels, thereby contributing to the global efforts towards achieving a more environmentally friendly energy landscape.

Transport properties of high Mach number hypersonic air plasmas

Abstract The collisional and transport properties of hypersonic plasmas have been simulated by an air plasma chemistry model, which includes collisions with electrons, ions and neutral species, elastic scattering, vibrational relaxation and a transport model. Species and thermal fluxes at the surface of the vehicle have been investigated as a function of post-shock gas temperature and species sticking coefficient for a fixed altitude of 50 km. At temperatures below about 5,000 K, the leading species are vibrationally excited nitrogen molecules, while at higher temperatures the molecular nitrogen and atomic oxygen dominate. Large fluxes of oxygen atoms have been observed in the simulations, on the order of 10^20 cm^-2s^ -1, which may lead to high rates of surface oxidation. Another subject of this study is temperature equilibration. For electrons, equilibration takes tens of microseconds, while the vibrational temperature equilibration time vary widely; from a few microseconds to hundreds of microseconds, depending on the gas temperature. Finally, the adiabatic parameter  was calculated for post-shock gas temperatures 5,000 K and 10,000 K and total gas density 1.2×10^17 cm^(-3). For post-shock gas temperature 5,000 K, only a slight reduction of gamma from the ideal gas value of ~1.4 is observed, while for 10,000 K it drops to ~1.26, which has a considerable impact on plasma properties. It was further established that the vibrational kinetics plays a leading role. While a single excited vibrational level of the N2 molecule captures the salient properties of the plasma, a detailed vibration kinetics is required for high-fidelity simulations.

Numerical Study of Hydrogen-Rich Fuel Coherent Jet in Blast Furnace Tuyere

Injecting hydrogen-rich fuel into blast furnaces is an effective strategy to reduce carbon dioxide (CO2) emissions. The present study established a three-dimensional (3D) model based on a coherent jet of hydrogen-rich fuel. The combustion characteristics and the flow, heat, and mass transfer behaviors in the reaction region were simulated by the Computational Fluid Dynamics (CFD) method. The effects of fuel jet velocity on the distributions of gas velocity, temperature, and species in the reaction region were systematically analyzed. The results show that hydrogen-rich fuel burned around the main jet, generating a high-temperature, low-density flame. As flame length increased, the main jet experienced less decay. The outward expansion of the jet caused continuous diffusion of gas temperature and its components. As the fuel jet velocity increased, the temperature along the main jet centerline rose sharply, while the length of the high-concentration gas region extended. Doubling the jet velocity increased its centerline velocity by 11% and raised the average reaction region temperature by 4.12%. The obtained highlighted results are of paramount importance for optimizing hydrogen-rich smelting in blast furnaces.

Modeling the Impact of Global Warming on Ecosystem Dynamics: A Compartmental Approach to Sustainability

Environmental degradation driven by human activities has heightened the need for sustainable development strategies that balance economic growth with ecological preservation. This study uses a compartmental model approach to examine the effects of global warming on ecosystem dynamics, focusing on how rising temperatures alter interactions across trophic levels. Three case studies of varying complexity, including a human ecosystem incorporating social and economic factors, were analyzed by integrating feedback loops between greenhouse gas emissions, temperature anomalies, and ecosystem responses. The results quantitatively demonstrate that even minor disruptions in one part of an ecosystem can cause significant instability across trophic levels, potentially driving the system to collapse in a short period. These findings from all case studies highlight the cascading impacts of global warming, underscoring the intricate relationship between climate change and ecosystem stability. Furthermore, this study offers qualitative insights into the potential consequences of climate change on biodiversity and resource availability in real ecosystems, highlighting the vulnerability of such systems and the importance of incorporating feedback mechanisms into environmental policy and decision-making processes. The approach employed in this study offers a more robust framework for understanding ecosystem responses and for developing strategies to enhance resilience against climate change, thereby protecting the long-term sustainability of ecosystems.

Effects of Tube Diameter and Gas Flow Rate on the Discharge Dynamics Characteristics and Reactive Species of Nanosecond Pulsed Discharge Plasma in Contact With Water

ABSTRACTThe use of millimeter quartz tubes to generate non‐thermal plasma in contact with liquid is widely applied in medicine, such as the effective disinfection of catheter tubes and tooth cavities. Here, the effects of tube diameter and gas flow rate on discharge dynamics and reactive species characteristics of nanosecond pulse needle‐water discharge are studied using an ICCD camera and optical emission spectra. The discharge diffusion is increased significantly by an appropriate combination of tube diameter and gas flow rate. Besides, the discharge intensity, emission spectra intensities of reactive species, gas temperature, and electron density increase with the increase of quartz tube diameter and gas flow rate, which contributes to enhance the production of OH and H2O2 species in aqueous samples.

CO2-assisted gasification of Patagonian rosehip bio-wastes: Kinetic modeling, analysis of ash catalytic effects, and product gas speciation

In the present study, the valorization of two rosehip wastes –husk and seed– was performed, through the CO2 gasification of biochar obtained by pyrolysis. The kinetics of gasification in a CO2 atmosphere at different partial pressures was investigated, obtaining the activation energy (E), pre-exponential factor (A), conversion function (f(α)), and reaction order with respect to the partial pressure of CO2 (x). The rosehip seed waste biochar (RSWB) yielded the following parameters: E = 302.11 kJ/mol, A = 2.18×1012 1/(s atm0.64), f(α) = 321−α−1/3−1−1; while the rosehip husk waste biochar (RHWB) results were: E = 198.60 kJ/mol, A = 2.13 × 1008 1/(s atm0.64), f(α) = 21−α1/2. The reaction order was the same in both wastes and equal to 0.64. The greater reactivity of RHWB can be attributed to the catalytic effects of the ashes contained in the biomass. To evaluate this effect, tests were conducted on rosehip husk waste ash mixtures with orthoasphaltite mineral char in proportions of 1, 5, 7, and 10 % (m/m). Thermogravimetry determined that the gasification temperature decreased up to 200 °C compared to pure char. Additionally, dry gasification of raw biomass experiments were carried out, and the evolution of gaseous products was analyzed with FTIR spectroscopy, evaluating the absorbance profiles of CO, CH4, and CH3OH, and comparing them with those obtained in a pure N2 atmosphere. The results obtained demonstrated the potential of rosehip wastes as a source in thermochemical processes for its complete valorization in a production chain with a focus on biorefinery.

Transient Thermal Analysis of a Kiln Using Different Numerical Approaches by Means of CFD

A transient study for the prediction of the temperature of hot gases inside a kiln loaded with bricks, using Computational Fluid Dynamics (CFD), is presented in this work. The prediction of transient thermal performance is obtained through four different approaches: the Properties Fitted to Temperature Polynomials (PFTP) model, the density changes according to the Boussinesq Approximation (BA) model with a Constant Thermal Expansion Coefficient (CTEC), the BA model with a Variable Thermal Expansion Coefficient (VTEC) and the density changes according to the Ideal Gas Law (IGL) model. Furthermore, the effects of a layer of ceramic fiber as insulation are investigated. The numerical results of the transient temperature of the hot gases inside the kiln were validated with experimental data. The mean relative error of the transient temperature was 5.0%, 32.6%, 26.4% and 4.4% for the PFTP model, BA model with a CTEC, BA model with a VTEC and IGL model, respectively. It was concluded that IGL model is the best approach to predict the transient temperature of the kiln. Finally, an increase in the temperature of the hot gases of 12.7% was obtained by applying the IGL model and using a layer of 0.07 m of ceramic fiber as insulation. The results of this work could be helpful to improve the design and performance of kilns in further works.

Correlation between temperature distribution and changes in self-organized luminous pattern in an atmospheric pressure DC glow discharge with sheath gas flow

Abstract The self-organized luminous patterns observed above the anode surface in atmospheric-pressure DC glow discharges were changed by the composition of the gas flow. The patterns were observed not only with liquid anodes but also with metal anodes. Various pattern structures were observed by changing the helium gas flow rate in the core and the ambient oxygen gas flow rate supplied during the discharge. When the pattern formation was observed, the emission spectra and the radial spread of the positive column changed, and the voltage–current characteristic also changed. These results suggest that not only the anode surface but the entire discharge affects the pattern formation. Comparing the results for the liquid and metal anodes, the trends in the pattern formation and voltage–current characteristics were almost identical. The gas temperature in the discharge was also investigated in two different ways, by the laser-induced fluorescence spectroscopy of OH radicals and by Rayleigh scattering, showing in good agreement between both methods. Under the condition where the pattern formed, the gas temperature in the discharge was approximately 2500–3000 K and higher than that of the discharge without the pattern formation. Focusing on the gradient of the temperature distribution, the discharge with the pattern formation had a steeper gradient than that of the discharge without the pattern formation. It is suggested that not only the high temperature of the discharge but also the large gradient of the temperature change plays an important role in the pattern formation. The role of oxygen gas in the pattern formation may be the effect of increasing the temperature and altering the temperature gradient in the discharge rather than generating negative ions in the discharge.

Effect of the ash melting on heat and mass characteristics and reaction rate during corn stalk pellet gasification

In order to investigate the effect of ash melting on the gasification process of biomass pellet, a high-temperature visual gasification system was set up, meanwhile, a biomass melting gasification model for a single pellet was built. Considering that the fusion temperature range of ash is from 1418 K to 1558 K, 1396 K (below 1418 K), 1491 K (between 1418 K and 1558 K), 1591 K and 1677 K (above 1558 K) were chosen as the experimental temperatures. Results show that ash melting could absorb heat, thereby resisting the heat transfer inside pellet. When the gasification temperature is higher than 1558 K, as the larger spherical particles caused by ash melting and coalescing peels off from the pellet surface, the pellet covered by melting ash could be directly exposed to the environment, which is conducive to the heat and mass transfer.