scholarly journals Thermochemical Conversion of Biomass in the Presence of Molten Alkali-Metal Carbonates under Reducing Environments of N2 and CO2

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5395
Author(s):  
Tahereh Jalalabadi ◽  
Behdad Moghtaderi ◽  
Jessica Allen
Keyword(s):  
Elevated Temperatures ◽  
Eutectic Mixture ◽  
Thermochemical Conversion ◽  
Boudouard Reaction ◽  
Molten Carbonate ◽  
Carbon Particles ◽  
Carbonate Decomposition ◽  
Carrier Gases ◽  
Lower Temperature ◽  
The Impact

The impact of N2 and CO2 atmospheres on the interaction between Eucalyptus pilularis biomass and a ternary molten carbonate eutectic (Li2CO3: Na2CO3: K2CO3) has been investigated at 600 °C and 900 °C. For lower temperature conversion under CO2, prevention of volatile release in the eutectic treated biomass is slightly higher than under N2 injection; however, similar bubble-shaped morphology of the remnant char is observed under both carrier gases. By increasing the temperature to 900 °C under CO2, the reverse Boudouard reaction begins to consume carbon fuel, while molten carbonate gasification also accelerates the reaction to a lower temperature set point (shifted from ~735 °C to ~640 °C). The mass loss of carbonate under CO2 and N2 at 900 °C is 0 (negligible) and 18 wt.%, respectively. In the absence of carbon particles, the decomposition of carbonate to M2O (l) and CO2 (g), as well as molten salt vaporization, are the sole potential routes of weight loss in an inert gas. Previous observations of biomass and eutectic mixture thermochemical conversion under N2 have suggested carbon/carbonate gasification is dominant at elevated temperatures, with production of CO expected. However, analysis of gas chromatography (GC) suggests that carbon/carbonate gasification is the weaker pathway by producing only 7 vol.% of CO, compared with molten carbonate decomposition with 27 vol.% CO2 emission for this system.

scholarly journals Effect of Biochar Prepared from Food Waste through Different Thermal Treatment Processes on Crop Growth

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 276
Author(s):  
Hang Jia ◽  
Haoxi Ben ◽  
Fengze Wu
Keyword(s):  
Crop Growth ◽  
Raw Material ◽  
Synthetic Methods ◽  
Thermochemical Conversion ◽  
Growth Trend ◽  
Wheat Growth ◽  
Preparation Methods ◽  
Treatment Processes ◽  
Ft Ir ◽  
The Impact

Biochar is generally accepted and increasingly valued in scientific circles as solid products in the thermochemical conversion of biomass, mainly because of its rich carbon content. The purpose of this research is to investigate the impact of biochar from different sources on wheat growth. In particular, this work focused on the effect of different preparation methods and raw material of biochar on the growth of wheat and aim to find a potential soil substitute that can be used for crop cultivation. Two synthetic methods were evaluated: hydrothermal conversion and pyrolysis. The characterization of biochar was determined to explore the impact of its microstructure on wheat growth. The results show that the yield of biochar produced from high-pressure reactor is significantly higher than that obtained by using microwave reactor. For example, the biochar yield obtained through the former is about six times that of the latter when using steamed bread cooked as biomass raw material. In addition, the growth trend of wheat indicates that biochar has different promoting effects on the growth of wheat in its weight and height. The pyrolyzed carbon is more suitable for wheat growth and is even more effective than soil, indicating that pyrolyzed biochar has more potential to be an alternative soil in the future. Moreover, this research tries to explore the reasons that affect crop growth by characterizing biochar (including scanning electron microscopy (SEM), biofilm electrostatic test (BET) and Fourier transform infrared (FT-IR)). The results indicate that the biochar containing more pits and less hydroxyl functional are more suitable for storing moisture, which is one of the significant factors in the growth of crops. This study provides evidence of the effects of biochar on crop growth, both in terms of microstructure and macroscopic growth trends, which provides significant benefits for biochar to grow crops or plants.

scholarly journals Fire Resistance Behaviour of Geopolymer Concrete:An Overview

Buildings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 82
Author(s):  
Salmabanu Luhar ◽  
Demetris Nicolaides ◽  
Ismail Luhar
Keyword(s):  
Compressive Strength ◽  
Thermal Resistance ◽  
Building Materials ◽  
Elevated Temperatures ◽  
Construction Materials ◽  
Flexural Behavior ◽  
Thermal Shrinkage ◽  
Physico Chemical ◽  
The Impact ◽  
Loss Of Strength

Even though, an innovative inorganic family of geopolymer concretes are eye-catching potential building materials, it is quite essential to comprehend the fire and thermal resistance of these structural materials at a very high temperature and also when experiencing fire with a view to make certain not only the safety and security of lives and properties but also to establish them as more sustainable edifice materials for future. The experimental and field observations of degree of cracking, spalling and loss of strength within the geopolymer concretes subsequent to exposure at elevated temperature and incidences of occurrences of disastrous fires extend an indication of their resistance against such severely catastrophic conditions. The impact of heat and fire on mechanical attributes viz., mechanical-compressive strength, flexural behavior, elastic modulus; durability—thermal shrinkage; chemical stability; the impact of thermal creep on compressive strength; and microstructure properties—XRD, FTIR, NMR, SEM as well as physico-chemical modifications of geopolymer composites subsequent to their exposures at elevated temperatures is reviewed in depth. The present scientific state-of-the-art review manuscript aimed to assess the fire and thermal resistance of geopolymer concrete along with its thermo-chemistry at a towering temperature in order to introduce this novel, most modern, user and eco-benign construction materials as potentially promising, sustainable, durable, thermal and fire-resistant building materials promoting their optimal and apposite applications for construction and infrastructure industries.

scholarly journals Thermodynamic Behavior of Fe-Mn and Fe-Mn-Ag Powder Mixtures during Selective Laser Melting

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 234
Author(s):  
Jakob Kraner ◽  
Jožef Medved ◽  
Matjaž Godec ◽  
Irena Paulin
Keyword(s):  
Selective Laser Melting ◽  
Manganese Oxides ◽  
Elevated Temperatures ◽  
Manganese Content ◽  
Chemical Compositions ◽  
Metal Powders ◽  
Laser Melting ◽  
Powder Mixtures ◽  
Ε Martensite ◽  
The Impact

Additive manufacturing is a form of powder metallurgy, which means the properties of the initial metal powders (chemical composition, powder morphology and size) impact the final properties of the resulting parts. A complete characterization, including thermodynamic effects and the behavior of the metal powders at elevated temperatures, is crucial when planning the manufacturing process. The analysis of the Fe-Mn and Fe-Mn-Ag powder mixtures, made from pure elemental powders, shows a high susceptibility to sintering in the temperature interval from 700 to 1000 °C. Here, numerous changes to the manganese oxides and the αMn to βMn transformation occurred. The problems of mechanically mixed powders, when using selective laser melting, were highlighted by the low flowability, which led to a less controllable process, an uncontrolled arrangement of the powder and a large percentage of burnt manganese. All this was determined from the altered chemical compositions of the produced parts. The impact of the increased manganese content on the decreased probability of the transformation from γ-austenite to ε-martensite was confirmed. The ε-martensite in the microstructure increased the hardness of the material, but at the same time, its magnetic properties reduce the usefulness for medical applications. However, the produced parts had comparable elongations to human bone.

scholarly journals R-BPMV-Mediated Resistance to Bean pod mottle virus in Phaseolus vulgaris L. Is Heat-Stable but Elevated Temperatures Boost Viral Infection in Susceptible Genotypes

Viruses ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1239
Author(s):  
Chouaïb Meziadi ◽  
Julie Lintz ◽  
Masoud Naderpour ◽  
Charlotte Gautier ◽  
Sophie Blanchet ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Phaseolus Vulgaris ◽  
Elevated Temperatures ◽  
Heat Waves ◽  
Dominant Gene ◽  
Atmospheric Temperature ◽  
Mottle Virus ◽  
Bean Pod Mottle Virus ◽  
Heat Stable ◽  
The Impact

In the context of climate change, elevated temperature is a major concern due to the impact on plant–pathogen interactions. Although atmospheric temperature is predicted to increase in the next century, heat waves during summer seasons have already become a current problem. Elevated temperatures strongly influence plant–virus interactions, the most drastic effect being a breakdown of plant viral resistance conferred by some major resistance genes. In this work, we focused on the R-BPMV gene, a major resistance gene against Bean pod mottle virus in Phaseolus vulgaris. We inoculated different BPMV constructs in order to study the behavior of the R-BPMV-mediated resistance at normal (20 °C) and elevated temperatures (constant 25, 30, and 35 °C). Our results show that R-BPMV mediates a temperature-dependent phenotype of resistance from hypersensitive reaction at 20 °C to chlorotic lesions at 35 °C in the resistant genotype BAT93. BPMV is detected in inoculated leaves but not in systemic ones, suggesting that the resistance remains heat-stable up to 35 °C. R-BPMV segregates as an incompletely dominant gene in an F2 population. We also investigated the impact of elevated temperature on BPMV infection in susceptible genotypes, and our results reveal that elevated temperatures boost BPMV infection both locally and systemically in susceptible genotypes.

Assessing the impact of exceptional inter-annual climatic variability on rates of net ecosystem carbon dioxide exchange at Clara bog.

2021 ◽  
Author(s):  
Matthew Saunders ◽  
Ruchita Ingle ◽  
Shane Regan
Keyword(s):  
Water Table ◽  
Elevated Temperatures ◽  
Ecosystem Respiration ◽  
Anthropogenic Activities ◽  
Climatic Variability ◽  
Growing Season ◽  
Carbon Dioxide Exchange ◽  
Mean Annual Temperature ◽  
Monitoring Networks ◽  
The Impact

<p>Peatland ecosystems are integral to the mitigation of climate change as they represent significant terrestrial carbon sinks. In Ireland, peatlands cover ~20% of the land area but hold up to 75% of the soil organic carbon stock however many of these ecosystems (~85% of the total area) have been degraded due to anthropogenic activities such as agriculture, forestry and extraction for horticulture or energy. Furthermore, the carbon stocks that remain in these systems are vulnerable to inter-annual variation in climate, such as changes in precipitation and temperature, which can alter the hydrological status of these systems leading to changes in key biogeochemical processes and carbon and greenhouse gas exchange.  During 2018 exceptional drought and heatwave conditions were reported across Northwestern Europe, where reductions in precipitation coupled with elevated temperatures were observed. Exceptional inter-annual climatic variability was also observed at Clara bog, a near natural raised bog in the Irish midlands when data from 2018 and 2019 were compared. Precipitation in 2018 was ~300 mm lower than 2019 while the average mean annual temperature was 0.5°C higher. The reduction in precipitation, particularly during the growing season in 2018, consistently lowered the water table where ~150 consecutive days where the water table was >5cm below the surface of the bog were observed at the central ecotope location. The differing hydrological conditions between years resulted in the study area, as determined by the flux footprint of the eddy covariance tower, acting as a net source of carbon of 53.5 g C m<sup>-2</sup> in 2018 and a net sink of 125.2 g C m<sup>-2</sup> in 2019. The differences in the carbon dynamics between years were primarily driven by enhanced ecosystem respiration (R<sub>eco</sub>) and lower rates of Gross Primary Productivity (GPP) in the drier year, where the maximum monthly ratio of GPP:R<sub>eco</sub> during the growing season was 0.96 g C m<sup>-2</sup> month in 2018 and 1.14 g C m<sup>-2</sup> month in 2019. This study highlights both the vulnerability and resilience of these ecosystems to exceptional inter-annual climatic variability and emphasises the need for long-term monitoring networks to enhance our understanding of the impacts of these events when they occur.</p>

scholarly journals Experiment on Foreign Object Damage of Gas Turbine-Grade Silicon Nitride Ceramic

1998 ◽  
Author(s):  
Hiro Yoshida ◽  
Takashi Nakashima ◽  
Makoto Yoshida ◽  
Yasushi Hara ◽  
Toru Shimamori
Keyword(s):  
Elevated Temperature ◽  
Silicon Nitride ◽  
Elevated Temperatures ◽  
Tensile Load ◽  
Strength Degradation ◽  
Spall Fracture ◽  
Silicon Nitride Ceramic ◽  
Impact Tests ◽  
The Impact ◽  
Bending Fracture

A new high quality turbine system using monolithic silicon-nitride ceramic is under development. In this study particle impact tests of the silicon-nitride have been tried at room and elevated temperatures with and without tensile load, which simulates centrifugal force of blade rotation. In the experiment 1 mm diameter particle is impacted at velocities up to 900 m s−1. In this paper, critical velocities for bending fracture and Hertzian cracks are examined. Moreover, strength degradation at elevated temperature and spall fracture of the blade are discussed. The main results are: 1) The bending fracture mode critical impact velocity for soft particles is higher than that for hard particles. 2)The impact parameter ϕ for initiation of Hertzian cracks ranges 1.08×10−5 – 1.56×10−5 for the materials tested. 3)Strength degradation at elevated temperature was clearly observed. 4) In the impact tests on blades spall fracture, which was caused by interaction of stress waves, appeared.

scholarly journals Mechanical Performance Under Various Conditions of 3D Printed Polylactide Composites With Natural Fibers

2021 ◽  
Author(s):  
Karolina E. Mazur ◽  
Aleksandra Borucka ◽  
Paulina Kaczor ◽  
Szymon Gądek ◽  
Stanislaw Kuciel
Keyword(s):  
Elevated Temperatures ◽  
Mechanical Performance ◽  
Natural Fibers ◽  
Crystallization Rate ◽  
Mechanical Tests ◽  
Hydrothermal Degradation ◽  
3D Printed ◽  
The Impact ◽  
Different Levels ◽  
Additive Methods

Abstract In the study, polylactide-based (PLA) composites modified with natural particles (wood, bamboo, and cork) and with different levels of infilling (100%, 80%, and 60%) obtained by additive methods were tested. The effect of type fiber, infill level and crystallization rate on the mechanical properties were investigated by using tensile, flexural, and impact tests. The materials were subjected to mechanical tests carried out at 23 and 80 °C. Furthermore, hydrothermal degradation was performed, and its effect on the properties was analyzed. The addition of natural fillers and different level of infilling result in a similar level of reduction in the properties. Composites made of PLA are more sensitive to high temperature than to water. The decrease in Young's modulus of PLA at 80 °C was 90%, while after 28 days of hydrodegradation ~ 9%. The addition of fibers reduced this decrease at elevated temperatures. Moreover, the impact strength has been improved by 50% for composites with cork particles and for other lignocellulosic composites remained at the same level as for resin.

scholarly journals The Effect of Nanostructure Modification on the Silicate Binder on Its Binding Characteristics and Functional Properties

2014 ◽  
Vol 59 (3) ◽  
pp. 1033-1036 ◽  
Author(s):  
I. Izdebska-Szanda ◽  
A. Baliński ◽  
M. Angrecki ◽  
A. Palma
Keyword(s):  
Chemical Modification ◽  
Sodium Silicate ◽  
Functional Properties ◽  
Elevated Temperatures ◽  
Technological Properties ◽  
Ferrous Alloys ◽  
Silicate Binder ◽  
Binding Characteristics ◽  
The Impact

Abstract A method for the chemical modification of silicate binder (hydrated sodium silicate) affecting the distribution of its nanostructure elements was disclosed. The effect of silicate binder modification on the resulting technological properties of moulding sands, determined under standard conditions and at elevated temperatures in the range from 1000C to 9000C, was discussed. Modification of this type is done on inorganic binders in order to reduce their unfavourable functional properties. It is particularly important when moulding sands with the silicate binder are used for casting of low-melting alloys. Therefore special attention was paid to the impact that modification of inorganic binders may have on the knocking out properties of sands prepared with these binders, when they are used in the process of casting non-ferrous alloys.

scholarly journals Performance of Parallel Connected SiC MOSFETs under Short Circuits Conditions

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6834
Author(s):  
Ruizhu Wu ◽  
Simon Mendy ◽  
Nereus Agbo ◽  
Jose Ortiz Gonzalez ◽  
Saeed Jahdi ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Short Circuit ◽  
Critical Factor ◽  
Charge Trapping ◽  
Parallel Connection ◽  
Bias Temperature Instability ◽  
Test Methodology ◽  
Threshold Voltages ◽  
Short Circuits ◽  
The Impact

This paper investigates the impact of parameter variation between parallel connected SiC MOSFETs on short circuit (SC) performance. SC tests are performed on parallel connected devices with different switching rates, junction temperatures and threshold voltages (VTH). The results show that VTH variation is the most critical factor affecting reduced robustness of parallel devices under SC. The SC current conducted per device is shown to increase under parallel connection compared to single device measurements. VTH shift from bias–temperature–instability (BTI) is known to occur in SiC MOSFETs, hence this paper combines BTI and SC tests. The results show that a positive VGS stress on the gate before the SC measurement reduces the peak SC current by a magnitude that is proportional to VGS stress time. Repeating the measurements at elevated temperatures reduces the time dependency of the VTH shift, thereby indicating thermal acceleration of negative charge trapping. VTH recovery is also observed using SC measurements. Similar measurements are performed on Si IGBTs with no observable impact of VGS stress on SC measurements. In conclusion, a test methodology for investigating the impact of BTI on SC characteristics is presented along with key results showing the electrothermal dynamics of parallel devices under SC conditions.

Controlling and Minimizing Blistering during T6 Heat Treating of Semi-Solid Castings

2016 ◽  
Vol 256 ◽  
pp. 192-198 ◽  
Author(s):  
Hong Xing Lu ◽  
You Feng He ◽  
Stephen Midson ◽  
Da Quan Li ◽  
Qiang Zhu
Keyword(s):  
Solution Heat Treatment ◽  
Elevated Temperatures ◽  
Die Casting ◽  
Heat Treating ◽  
Pressure Casting ◽  
Shot Sleeve ◽  
Semi Solid ◽  
Entrapped Air ◽  
The Impact ◽  
Subsurface Defects

Surface blistering during T6 heat treating is an artifact that is essentially unique to high pressure casting processes such as semi-solid casting and die casting. It is believed that the blistering originates from subsurface defects present in the castings. When the castings are exposed to elevated temperatures during solution heat treatment, the strength of the aluminum is reduced, and the defects expand to deform the surfaces of the castings. There are three potential sources for the subsurface defects - entrapped air, die lubricant or shot sleeve lubricant.This paper will report on a study to determine the origin of the defects present in the castings that produce the blisters. Along with attempting to separate the influence of air and the two types of lubricants on blister formation, the study will also examine the impact of a number of process parameters on blistering.

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