scholarly journals Major Challenges and Recent Advances in Characterizing Biomass Thermochemical Reactions

Author(s):  
Zhennan Han ◽  
Junrong Yue ◽  
Xi Zeng ◽  
Jian Yu ◽  
Fang Wang ◽  
...  

Thermochemical conversions are pathways for the utilization of biomass to produce a variety of value-added energy and chemical products. For the development of novel thermochemical conversion technologies, an accurate understanding of the reaction performance and kinetics is essential. Given the diversity of the thermal analysis techniques, it is necessary to understand the features and limitations of the reactors, ensuring that the selected thermal analysis reactor meets the specific need for reaction characterization. This paper provides a critical overview of the thermal analysis reactors based on the following perspectives: 1) gas flow conditions in the reactor, 2) particle’s external and internal heat and mass transfer limitations, 3) heating rate, 4) temperature distribution, 5) nascent char production and reaction, 6) liquid feeding and atomization, 7) simultaneous sampling and analyzing of bed materials, and 8) reacting atmosphere change. Finally, prospects and future research directions in the development of thermal analysis techniques are proposed.

2004 ◽  
Vol 16 (10) ◽  
pp. 1932-1937 ◽  
Author(s):  
K. Chrissafis ◽  
Theodora Kyratsi ◽  
K. M. Paraskevopoulos ◽  
Mercouri G. Kanatzidis

2004 ◽  
Vol 424 (1-2) ◽  
pp. 201-207 ◽  
Author(s):  
V. Sencadas ◽  
S. Lanceros-Méndez ◽  
J.F. Mano

2012 ◽  
Vol 1449 ◽  
Author(s):  
Jordi Farjas ◽  
Daniel Sanchez-Rodriguez ◽  
Hichem Eloussifi ◽  
Raul Cruz Hidalgo ◽  
Pere Roura ◽  
...  

ABSTRACTThermal analysis techniques are routinely applied to characterize the thermal behavior of metal organic precursors used for oxide film preparation. Since the mass of films is very low, researchers do their thermal analyses on powders and consider that the results are representative of films. We will show here that, in general, this assumption is not true. Several examples involving precursors of YBa2Cu3O7-x (Ba and Y trifluoroacetates and Ba propionate) will serve to appreciate that films can behave very differently than powders due to their enhanced heat and mass transport paths. Ultimately, we will demonstrate that, in some cases, relying on powders thermal analysis may lead to erroneous conclusions.


2018 ◽  
Vol 53 (15) ◽  
pp. 2053-2064 ◽  
Author(s):  
Tassos Mesogitis ◽  
James Kratz ◽  
Alex A Skordos

Thermochemical properties are needed to develop process models and define suitable cure cycles to convert thermosetting polymers into rigid glassy materials. Uncertainty surrounding the suitability of thermal analysis techniques and semi-empirical models developed for conventional composite materials has been raised for the new class of particle interleaf materials. This paper describes kinetics, conductivity, heat capacity and glass transition temperature measurements of HexPly® M21 particle interleaf material. Thermal models describing conventional, non-particle epoxy systems were fit to the data and validated through a thick-section cure. Results from curing experiments agree with heat transfer simulation predictions, indicating that established thermal analysis techniques and models can describe polymerisation and evolving material properties during processing of a material representing the class of interleaf toughened systems. A sensitivity study showed time savings up to about 20%, and associated energy-efficiency-productivity benefits can be achieved by using cure simulation for particle interleaf materials.


2002 ◽  
Vol 718 ◽  
Author(s):  
A.A. Savvinov ◽  
S.B. Majumder ◽  
R.S. Katiyar

AbstractThe renewed interest in KTa1-xNbxO (KTN) mixed perovskite materials is connected with their remarkable dielectric properties in the dilute compositions. KTN thin films with x = 0.35 have been prepared on different substrates by sol-gel technique as well as a set of powders with x = 0, 0.05, 0.1, 0.25, 0.48, 0.65, 0.75, and 1. Properties of the material change drastically with the change of x, because of relaxation of both translational and inversion symmetry due to a static disorder in the Nb distribution and the dynamic effect of a precursor ferroelectric order above Tc. Special attention was paid to the characteristic feature of coupling of the single-phonon state to a two-acoustic-phonon feature through anharmonic terms in the potential function as well as behavior of the TO3 mode which becomes a narrow peak of the first-order scattering in the tetragonal ferroelectric phase and shows a tendency to split below Tc2 in the orthorhombic phase. The wide range of x allows better understanding of dynamic processes in the KTN bulk materials which in turn helps in the studies of thin films. The above mentioned materials were studied using Raman scattering, XRD, and thermal analysis techniques.


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