Authors:L. Brown, A. Ray, P. Thomas, and J. Guerbois
Naturally occurring opals from three different regions in Australia were studied for their thermal characteristics. All the
opals showed initial expansion followed by contraction in thermomechanical analysis (TMA) although the temperature at which
the change from expansion to contraction occurred depended on their provenance. Thermogravimetric analysis (TG) revealed different
rates and temperatures of dehydration for these opals. A general correlation between the temperature at which there was a
zero thermal expansion and that of the maximum rate of dehydration was observed. A dehydration–sintering mechanism is proposed
with the effect of sintering being more pronounced following total dehydration.
As examples of studies on thermal characteristics of materials with a nanometer scale two topics are discussed. One is heat
capacity and thermal conductivity of small materials at low temperatures. It based upon the recent findings that heat capacity
depends on the limited number of the phonon modes in low angular frequency region and the distinct characteristic is the appearance
of quantized thermal conductance in heat transfer through a narrow wire with hundreds nm. The other is the thermophysical
properties at the ordinary interface. The disordered structure appearing in the interfacial region with a width of a few nm
is discussed, which is comparable to the phonon mean free path, should be taken into account to reveal the characteristic
thermal behavior at room temperature.
Authors:M. Kök, J. Letoffe, P. Claudy, D. Martin, M. Garcin, and J. Volle
Thermal characteristics of eight crude oils and their treatment with additives were studied by differential scanning calorimetry
(DSC), thermomicroscopy, viscometer and pour point tester. Different additives were found as more effective for different
type of crude oils depending on the wax content. Crude oils showed a reduced pour point after treatment with additives. Effects
of different additives were also discussed by analysing the DSC curves and thermomicroscopy result.
Authors:Sonia Degeratu, P. Rotaru, Gh. Manolea, H. Manolea, and A. Rotaru
For two typical actuators of intelligent systems (Ni–Ti SMA cantilever and SMA helical spring), the evaluation of their thermal
characteristics is presented. In order to determine the transformation temperatures and other thermal parameters of the two
studied elements, the attention was concentrated on thermal analysis experiments. For each actuator configuration, comprehensive
graphical interfaces have been developed, to run in Visual Basic, with respect to the results of performed thermal analyses.
The thermal characteristics of mixtures of cyclonite (RDX) and nitroglycerine (NG) and of RDX and diazidonitrazapentane (DIANP)
were studied. The thermal decomposition processes of NG and RDX are not synchronous with those of RDX/NG mixtures. The DSC
curves show two obviously exothermic peaks, one at 203°C for NG and other at 240°C for RDX. However, there is only a single
exothermic peak in the DSC curves of RDX/DIANP mixtures within certain ratio limits, due to the coincidence of the exothermic
decomposition peaks for both RDX and DIANP and their mutual dissolution.
The effects of the different thermal characteristics of different explosives on the combustion performance are also discussed.
Authors:Ghalib Al-Saidi, Mohammad Shafiur Rahman, Ahmed Al-Alawi, and Nejib Guizani
parameters were gelatin yield, gel strength, and viscosity.
Structural attributes of gelatin are related to its thermalcharacteristics, such as glass transition, freezing point, thermal unfolding, solids-melting, and decomposition. Thermal analysis
Authors:Chung-Hwei Su, Sheng-Hung Wu, Sun-Ju Shen, Gong-Yih Shiue, Yih-Weng Wang, and Chi-Min Shu
Volatile organic compounds (VOCs) are the main factors involved in pollution control and global warming in industrialized
nations. Various treatment methods involving incineration, adsorption, etc., were employed to reduce VOCs concentration. Various
absorbents, such as activated carbon, zeolite, silica gel or alumina, and so on were broadly used to adsorb VOCs in various
industrial applications. Differential scanning calorimetry (DSC) was handled to analyze the thermal characteristics of absorbents.
Typically, a scanning electron microscope (SEM) has been used to evaluate the structure variation of absorbents under high
temperature situations. In view of pollution control and loss prevention, versatility and analysis of recycled adsorbents
are necessary and useful for various industrial applications.
Thermal characteristics of refined wheat flour blend made with 90% Ohio soft red winter wheat and 10% Canadian Hard Red Winter Wheat are explored using a series of modulated differential scanning calorimeter conditions. Influences of pan type, period, amplitude of the thermal modulation, and underlying thermal heating rate on flour starch thermal transitions are presented. Wheat flour was blend 1:1 with water, and then heated at various heating rates while the amplitude and period of the instantaneous heating rate was modulated between ±0.5 and ±1.0 °C amplitude and 60 s to 80 s period. Study shows faster heating rates favor increased total heat flow and results in proportional increases in both reversing and non-reversing thermokinetic events of recrystallization. Slower overall heating rates (e.g., 2.5 °C min−1) produced better resolution of thermal events related to preexisting structural phases, but allowed more time for creation of new events such as recrystallization, annealing.
Authors:Hou-yin Zhao, Yan Cao, Song P. Sit, Quentin Lineberry, and Wei-ping Pan
The pyrolysis behavior of bitumen was investigated using a thermogravimetric analyzer–mass spectrometer system (TG–MS) and a differential scanning calorimeter (DSC) as well as a pyrolysis-gas chromatograph/mass spectrometer system (Py-GC/MS). TG results showed that there were three stages of weight loss during pyrolysis—less than 110, 110–380, and 380–600 °C. Using distributed activation energy model, the average activation energy of the thermal decomposition of bitumen was calculated at 79 kJ mol−1. The evolved gas from the pyrolysis showed that organic species, such as alkane and alkene fragments had a peak maximum temperature of 130 and 480 °C, respectively. Benzene, toluene, and styrene released at 100 and 420 °C. Most of the inorganic compounds, such as H2, H2S, COS, and SO2, released at about 380 °C while the CO2 had the maximum temperature peaks at 400 and 540 °C, respectively. FTIR spectra were taken of the residues of the different stages, and the results showed that the C–H bond intensity decreased dramatically at 380 °C. Py-GC/MS confirmed the composition of the evolved gas. The DSC revealed the endothermic nature of the bitumen pyrolysis.
Authors:Hou-yin Zhao, Yan Cao, Zhi-zhong Kang, Yau-bang Wang, and Wei-ping Pan
Chemical looping combustion (CLC) is a novel combustion technology with the capability for segregation of exhaust products (i.e., carbon dioxide/H2O or N2/O2). The combustion is performed in two interconnected reactors with a solid oxygen carrier circulating between them, transferring oxygen from the air to the fuel. The feasibility of a successful CLC system depends on the selection of an appropriate oxygen carrier. Cu-based oxygen carriers are good oxygen carriers due to high reactivity. However, it faces low melting point, agglomeration problems in fluidized bed. In this study, a circular reduction–oxidation reaction simulated to the cyclic operation of the Cu-based oxygen carrier was conducted on the thermogravimetric analyzer (TG). The thermal behaviors of the potential Cu-based oxygen carrier were investigated by using an X-ray diffraction (XRD), scanning electron microscope (SEM), and surface analyzer. Multiple TG results show that the weight loss was 3.4%, indicating that the loading CuO amount was 17%. Moreover, the weight loss and weight gain was equal during 73 redox cycles, suggesting the good thermal stability of the oxygen carrier. The conversion rate of reduction and oxidation for each redox cycle remained constant even after 73 redox cycles. XRD results show the new phase formation of CuAl2O4 during redox cycles, which promotes the thermal stabilization of the oxygen carrier. The surface area of the oxygen carrier decreased from 105 to 13 m2 g−1 after 73 redox cycles and the particle size distribution shifted from 5–15 nm to 15–30 nm, suggesting that the micorpores were blocked or collapsed. However, the reactivity of the oxygen carrier didn't decrease. SEM results show that CuO was evenly distributed on the surface of Al2O3 after 73 redox cycles. Overall, these results suggested that the Cu-based oxygen carrier was ready for fluidized bed tests.