scholarly journals Analysis of the Physicochemical Characteristics of Biochar Obtained by Slow Pyrolysis of Nut Shells in a Nitrogen Atmosphere

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 8075
Author(s):  
Alexander Gorshkov ◽  
Nikolay Berezikov ◽  
Albert Kaltaev ◽  
Stanislav Yankovsky ◽  
Konstantin Slyusarsky ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Heating Rate ◽  
Particle Surface ◽  
Physicochemical Characteristics ◽  
Nitrogen Atmosphere ◽  
Medium Temperature ◽  
Cellulose Decomposition ◽  
Slow Pyrolysis ◽  
Macadamia Nut ◽  
Heating Medium

The process of slow pyrolysis of seven nut shell samples, in a nitrogen-purged atmosphere, has been studied, as well as characteristics of biochar obtained. The heat carrier with a temperature of 400–600 °C (with a step of 100 °C) was supplied indirectly using a double-walled reactor. The heating rate was 60 °C/min. At increased temperature of the heating medium, a decrease in the amount of the resulting carbon residue averaged 6.2 wt%. The release of non-condensable combustible gas-phase compounds CO, CH4, and H2, with maximum concentrations of 12.7, 14.0, and 0.7 vol%, respectively, was registered. The features of the obtained biochar sample conversions were studied using thermal analysis in inert (nitrogen) and oxidative (air) mediums at 10 °C/min heating rate. Kinetic analysis was performed using Coats–Redfern method. Thermal analysis showed that the main weight loss (Δm = 32.8–43.0 wt%) occurs at temperatures ranging between 290 °C and 400 °C, which is due to cellulose decomposition. The maximum carbon content and, hence, heat value were obtained for biochars made from macadamia nut and walnut shells. An increased degree of coalification of the biochar samples affected their reactivity and, in particular, caused an increase in the initial temperature of intense oxidation (on average, by 73 °C). While technical and elemental composition of nut shell samples studied were quite similar, the morphology of obtained biochar was different. The morphology of particles was also observed to change as the heating medium temperature increased, which was expressed in the increased inhomogeneity of particle surface. The activation energy values, for biochar conversion in an inert medium, were found to vary in the range of 10–35 kJ/mol and, in an oxidative medium—50–80 kJ/mol. According to literature data, these values were characteristic for lignin fibers decomposition and oxidation, respectively.

scholarly journals Modification of a Solar Thermal Collector to Promote Heat Transfer inside an Evacuated Tube Solar Thermal Absorber

2021 ◽  
Vol 11 (9) ◽  
pp. 4100
Author(s):  
Rasa Supankanok ◽  
Sukanpirom Sriwong ◽  
Phisan Ponpo ◽  
Wei Wu ◽  
Walairat Chandra-ambhorn ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Solar Thermal ◽  
Heat Transfer Fluid ◽  
Small Scale ◽  
Medium Temperature ◽  
Change Behavior ◽  
Set Up ◽  
Evacuated Tube ◽  
Heating Medium

Evacuated-tube solar collector (ETSC) is developed to achieve high heating medium temperature. Heat transfer fluid contained inside a copper heat pipe directly affects the heating medium temperature. A 10 mol% of ethylene-glycol in water is the heat transfer fluid in this system. The purpose of this study is to modify inner structure of the evacuated tube for promoting heat transfer through aluminum fin to the copper heat pipe by inserting stainless-steel scrubbers in the evacuated tube to increase heat conduction surface area. The experiment is set up to measure the temperature of heat transfer fluid at a heat pipe tip which is a heat exchange area between heat transfer fluid and heating medium. The vapor/ liquid equilibrium (VLE) theory is applied to investigate phase change behavior of the heat transfer fluid. Mathematical model validated with 6 experimental results is set up to investigate the performance of ETSC system and evaluate the feasibility of applying the modified ETSC in small-scale industries. The results indicate that the average temperature of heat transfer fluid in a modified tube increased to 160.32 °C which is higher than a standard tube by approximately 22 °C leading to the increase in its efficiency by 34.96%.

scholarly journals An Experimental Study of the Decomposition and Carbonation of Magnesium Carbonate for Medium Temperature Thermochemical Energy Storage

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1316
Author(s):  
Daniel Mahon ◽  
Gianfranco Claudio ◽  
Philip Eames
Keyword(s):  
Thermal Analysis ◽  
Thermal Decomposition ◽  
Energy Storage ◽  
Magnesium Carbonate ◽  
Experimental Results ◽  
Future Research ◽  
Medium Temperature ◽  
Different Temperatures ◽  
Decomposition Enthalpy ◽  
Co2 Atmosphere

To improve the energy efficiency of an industrial process thermochemical energy storage (TCES) can be used to store excess or typically wasted thermal energy for utilisation later. Magnesium carbonate (MgCO3) has a turning temperature of 396 °C, a theoretical potential to store 1387 J/g and is low cost (~GBP 400/1000 kg). Research studies that assess MgCO3 for use as a medium temperature TCES material are lacking, and, given its theoretical potential, research to address this is required. Decomposition (charging) tests and carbonation (discharging) tests at a range of different temperatures and pressures, with selected different gases used during the decomposition tests, were conducted to gain a better understanding of the real potential of MgCO3 for medium temperature TCES. The thermal decomposition (charging) of MgCO3 has been investigated using thermal analysis techniques including simultaneous thermogravimetric analysis and differential scanning calorimetry (TGA/DSC), TGA with attached residual gas analyser (RGA) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) (up to 650 °C). TGA, DSC and RGA data have been used to quantify the thermal decomposition enthalpy from each MgCO3.xH2O thermal decomposition step and separate the enthalpy from CO2 decomposition and H2O decomposition. Thermal analysis experiments were conducted at different temperatures and pressures (up to 40 bar) in a CO2 atmosphere to investigate the carbonation (discharging) and reversibility of the decarbonation–carbonation reactions for MgCO3. Experimental results have shown that MgCO3.xH2O has a three-step thermal decomposition, with a total decomposition enthalpy of ~1050 J/g under a nitrogen atmosphere. After normalisation the decomposition enthalpy due to CO2 loss equates to 1030–1054 J/g. A CO2 atmosphere is shown to change the thermal decomposition (charging) of MgCO3.xH2O, requiring a higher final temperature of ~630 °C to complete the decarbonation. The charging input power of MgCO3.xH2O was shown to vary from 4 to 8136 W/kg with different isothermal temperatures. The carbonation (discharging) of MgO was found to be problematic at pressures up to 40 bar in a pure CO2 atmosphere. The experimental results presented show MgCO3 has some characteristics that make it a candidate for thermochemical energy storage (high energy storage potential) and other characteristics that are problematic for its use (slow discharge) under the experimental test conditions. This study provides a comprehensive foundation for future research assessing the feasibility of using MgCO3 as a medium temperature TCES material. Future research to determine conditions that improve the carbonation (discharging) process of MgO is required.

scholarly journals INFLUENCE OF SOME PARAMETERS IN THE RESULTS OF THERMAL ANALYSIS OF POLYVINYL ALCOHOL

2019 ◽  
Vol 16 (31) ◽  
pp. 235-241
Author(s):  
Mariana Fornazier BORGES
Keyword(s):  
Thermal Analysis ◽  
Polyvinyl Alcohol ◽  
Heating Rate ◽  
Synthetic Polymer ◽  
Qualitative And Quantitative ◽  
Physical Form ◽  
Series Of Experiments ◽  
Rate Type ◽  
Tga And Dsc ◽  
Dsc Curves

The present work seeks to demonstrate through a series of experiments such as the parameters heating rate, type of stand and physical form of the sample, can influence the qualitative and quantitative aspects of the results of the thermal analyzes of TGA and DSC. To do this, polyvinyl alcohol, a synthetic polymer was used as a model and its thermal behavior was discussed by the results obtained by the thermogravimetric (TGA) and DSC curves, showing the effect of the alteration of each parameter, such as the displacement at the temperature at which the thermal events occur in the TGA curves, related to the alteration of the physical form of the sample; the intensification of the DSC peaks due to the increase of the heating rate, the change in the heat flow by changing the stand and masking some events such as the glass transition temperature.

Pressure-Assisted Sintering of Multilayer Transformer Using LTCC-Compatible NiCuZn-Ferrite and Silver Conductor

2012 ◽  
Vol 2012 (CICMT) ◽  
pp. 000476-000483
Author(s):  
Hamid Naghib-zadeh ◽  
Torsten Rabe
Keyword(s):  
Thermal Expansion ◽  
Copper Oxide ◽  
Heating Rate ◽  
Glassy Phase ◽  
Dielectric Material ◽  
Nitrogen Atmosphere ◽  
Divalent Copper ◽  
Nicuzn Ferrite ◽  
Silver Diffusion ◽  
Sintering Behaviour

A low-fired NiCuZn-ferrite and a new LTCC dielectric material with matched sintering shrinkages and coefficients of thermal expansion were used for integration of magnetic function into LTCC. Silver was used as inner conductor material. Silver diffusion during sintering into the surrounding glassy phase modifies the sintering behaviour of LTCC near the silver conductor and generates warping and delamination of the multilayer. Silver diffusion can be prevented by sintering in nitrogen atmosphere. However, sintering in nitrogen atmosphere causes partial decomposition of NiCuZn-ferrite by reduction of divalent copper oxide (CuO) to cuprite (Cu2O). It was found that diffusion of silver and associated deformation can be highly reduced if a higher heating rate during sintering in air is used. A Defect-free multilayer transformer with several silver conductive layers could be manufactured by pressure-assisted sintering only.

scholarly journals Thermal Degradation of Four Bamboo Species

BioResources ◽  
2015 ◽  
Vol 11 (1) ◽  
pp. 414-425 ◽  
Author(s):  
Parnia Zakikhani ◽  
Rizal Zahari ◽  
Mohamed Thariq Hameed Sultan ◽  
Dayang Laila Abang Abdul Majid
Keyword(s):  
Thermal Analysis ◽  
Thermal Degradation ◽  
Nitrogen Atmosphere ◽  
Bamboo Species ◽  
Scanning Calorimetry ◽  
Degradation Behaviour ◽  
Thermal Stabilities ◽  
Higher Temperature ◽  
Dendrocalamus Asper ◽  
Bottom To Top

Bamboo, among other natural plants, has a special structure, with different characterization along the culms and between species. In this study, the thermal stabilities of four bamboo species, named Dendrocalamus pendulus (DP), Dendrocalamus asper (DA), Gigantochloa levis (GL), and Gigantochloa scortechinii (GS), were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) under a nitrogen atmosphere. Each species was divided into three different portions: bottom, middle, and top, and fibres were manually extracted from the specified sections of each species. The thermal analysis of extracted bamboo fibres indicated that the thermal degradation behaviour of each bamboo species varied from bottom to top and between species. However, these variations were lower in DA species compared to GS, GL, and DP, because of minor differences between lignocellulosic components of its three portions. The top and middle portions of the four species degraded at a higher temperature range (314 to 379 °C) than the bottom portions. The results of this study suggest that DA and GS species, according to their thermal stabilities, are most suitable for use as reinforcement in composite materials.

Synthesis of Ultra-Fine ZrB2 Powder by Borothermal Reaction under High Heating Rate

2009 ◽  
Vol 66 ◽  
pp. 77-80 ◽  
Author(s):  
Ge Sun ◽  
Hao Wang ◽  
Wei Min Wang ◽  
Yu Cheng Wang ◽  
Zheng Yi Fu
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Heating Rate ◽  
Zirconium Oxychloride ◽  
Reduction Reaction ◽  
Average Crystalline Size ◽  
High Heating Rate ◽  
Heat Treated ◽  
High Heating ◽  
Borothermal Reduction

Ultra-fine zirconium diboride (ZrB2) powders have been synthesized by borothermal reduction reaction, using zirconium oxychloride (ZrOCl2•8H2O) as the precursors of zirconia. The thermodynamic variation in the amorphous ZrO2-B system was studied by thermogravimetric and differential thermal analysis (TG-DTA). The precursors containing amorphous ZrO2 and B were heat-treated under a high heating rate. It is shown that the borothermal reaction can be completed at a relatively low temperature (~950 °C) and short duration (~5 min) under a heating rate of 200 °C/min. The synthesized powders have an average crystalline size of 300 nm with oxygen content less than 2.62 wt%.

scholarly journals Some Peculiarities of Silica Modification Under High Reagent Pressure. I. Methodological Aspects

1995 ◽  
Vol 12 (3) ◽  
pp. 231-238 ◽  
Author(s):  
V.V. Sidorchuk ◽  
V.A. Tertykh ◽  
R. Leboda ◽  
Z. Hubicki
Keyword(s):  
Thermal Analysis ◽  
Surface Reaction ◽  
Silica Surface ◽  
Porous Silica ◽  
Physicochemical Characteristics ◽  
Geometrical Parameters ◽  
Duration Of Treatment ◽  
Preparation Conditions ◽  
Modification Process ◽  
Methodological Aspects

The effect of the following factors on the chemical and geometrical modification of aerosilogel (prepared from aerosil) was studied: the physicochemical characteristics of the modifying reagent pressures, the preparation conditions for the silica surface, the reaction temperature, the reagent pressures, the duration of treatment and the method employed for the modification process. The course of the surface reaction was followed by IR spectroscopy, differential thermal analysis and adsorption. During high-pressure modification, the geometrical parameters of the porous silica structure may be changed.

High heating rate thermal analysis

1976 ◽  
Vol 14 (1-2) ◽  
pp. 169-181 ◽  
Author(s):  
A.J. Beardell ◽  
J. Staley ◽  
C. Campbell
Keyword(s):  
Thermal Analysis ◽  
Heating Rate ◽  
High Heating Rate ◽  
High Heating

Process Optimization of Preparation and Performance Characterization of Oily Sludge-Based Adsorbent Material by Pyrolysis

2009 ◽  
Vol 79-82 ◽  
pp. 1971-1974
Author(s):  
Guang Ying Zhang ◽  
Ying Fei Hou ◽  
Chun Hu Li ◽  
Wei Zhu ◽  
Jian Zhang
Keyword(s):  
Heating Rate ◽  
Flue Gas ◽  
Pyrolysis Temperature ◽  
Influencing Factor ◽  
Nitrogen Atmosphere ◽  
Flue Gas Desulfurization ◽  
Oily Sludge ◽  
Breakthrough Time ◽  
And Performance

The oily sludge-based adsorbents for flue gas desulfurization were prepared by pyrolysis. Based on benzene adsorptivity, the conditions of pyrolysis process were optimized. The optimum prepared conditions of adsorbent material were in nitrogen atmosphere and 550°C, 4h, 10°C/min for the pyrolysis temperature, pyrolysis time and heating rate, respectively. In this case, the maximum benzene adsorbability was 60.12mg/g. Moreover, the main influencing factor was pyrolysis temperature, secondly was pyrolysis time and finally was heating rate. The sludge-based adsorbents were appropriate for flue gas desulfurization. The sulfur capacity of adsorbents via a flue gas desulfurization test after subsequent processing was about 3% and breakthrough time could keep to 109 min.

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