Journal of Thermal Analysis and Calorimetry

Alfellag, Mohanad A.; Ahmed, Hamdi E.; Jehad, Mohammed G.; Farhan, Ammar A.

doi: 10.1007/s10973-022-11247-1pmid: N/A

In the last decades, heat transfer enhancement techniques have been varied and increased rapidly to produce more efficient heat exchange equipment and in turn save energy and cost. One of the effective methods used for augmenting heat transfer is employing corrugations on heat exchanger equipment surfaces. Different applications of using corrugations such as circular and non-circular channels, microchannel heat sink, mini-channel heat sink, and solar air collector have been presented and reviewed in this paper. Researchers investigated various shapes of corrugations along with several corrugation configurations. In addition, using corrugations with other heat transfer enhancement techniques, namely perforations, phase change materials, and nanofluids was discussed. From this overview study, it was found that some research topics are still attractive and need more investigations, while other topics have some limitations either in the application or side effects such as additional pressure drop penalty, further machining costs, more additional material, or more costs for synthesizing the coolants such as nanofluids or sedimentation.

Alfellag, Mohanad A.; Ahmed, Hamdi E.; Jehad, Mohammed G.; Farhan, Ammar A.

doi: 10.1007/s10973-022-11317-4pmid: N/A

Quan, Yufeng; Zhang, Zhuoran; Tanchak, Rachel N.; Wang, Qingsheng

doi: 10.1007/s10973-022-11279-7pmid: N/A

The cone calorimeter is an efficient instrument used to evaluate the reaction-to-fire properties of measured materials via simulating a forced combustion bench-scale fire scenario. With the increasing use of polymers and plastics in society, it is particularly significant to investigate their combustion behaviors using the cone calorimeter due to their inherent flammability. Therefore, with the aim to provide guidance for developing novel fire-safe polymer composites, this review discusses polymer combustion behaviors under different key operating parameters and setup geometries in a cone calorimeter, including external heat flux, ventilation conditions, ignition source, and sample geometry (thickness and size). Measured reaction-to-fire properties during combustion within the cone calorimeter, such as heat release, smoke production, and gas analysis, are also fully discussed. Lastly, nanofillers in polymer composites and their fire behaviors in cone calorimetry are explored through example polymer systems, including polyethylene (PE), polypropylene (PP), polystyrene (PS), poly(methyl methacrylate) (PMMA), polyamide (PA), and acrylonitrile–butadiene–styrene (ABS).

Przyłucka-Bednarska, Aleksandra; Augustyn-Nadzieja, Joanna; Rywotycki, Marcin

doi: 10.1007/s10973-022-11309-4pmid: N/A

The article concerns high-temperature corrosion of steel S235. Samples were oxidized in air for 480 s. The experiment was carried out at the following temperatures: 1100 °C or 1200 °C. The emissivity factor of the scale was measured with a thermal camera. The emissivity of the oxidation layer formed at the lower temperature was 0.65, and for the layer oxidized at the higher temperature, it was 0.59. The formed scale had a tree-layer structure, which included: Fe2O3, Fe3O4, FeO. The thickness and structure of the scale were compared, both in cross section and on their surface. The oxide scale formed at 1200 °C was twice as thick as that formed at 1100 °C. The scale layer with the lowest oxidation state at the higher temperature was 60.5% and at the lower temperature 54.4%. The scale surface formed at 1100 °C consisted of several phases and was delaminated, whereas the surface of oxidized layer at 1200 °C was compact and homogeneous.

Fahd, Ahmed; Dubois, Charles; Chaouki, Jamal; Wen, John Z.

doi: 10.1007/s10973-022-11259-xpmid: N/A

Following recent developments in micro-scale energy systems, such as microthruster and igniters among others, there is now considerable interest in using tertiary nanothermites to meet the increasing demand in high energy density propulsion systems. The first objective of this research is to compare and analyze the thermal behaviour of different nanothermite tertiary compositions based on nano-aluminium (n-Al), graphene oxide (GO), various salt and metallic oxidizers. The second objective is to identify the thermite reaction mechanism through correlations with the activation energy and exothermic peaks. Thermogravimetry analysis coupled with a differential scanning calorimeter (TGA/DSC) was employed to elucidate the reaction process of these nanothermite compositions, while bomb calorimetry was used to measure their heat of combustion. The apparent kinetics parameters were calculated using Kissinger and Ozawa approaches. The results demonstrate that the addition of GO enhances the reactivity of nanothermites with both salt and metallic oxidizers by reducing the reaction onset temperature, activation energy and increasing the heat release. For nanothermites with oxidizing salts, the heterogeneous solid–gas reaction mechanism plays a more important role than the condensed phase reactions. In general, nanothermites based on oxidizing salts are more reactive than those with metallic ones, as indicated in both theoretical and experimental data. Among them, the GO/Al/KClO4 nanothermite exhibits the highest heat release (9614 J g−1), while the GO/Al/K2S2O8 nanothermite shows the lowest onset temperature and activation energy (380 °C and 105 kJ mol−1). This study provides benchmark information for optimizing the tertiary nanothermites design, use, storage and handling.

Karajz, Dániel; Cseh, Domonkos; Parditka, Bence; Erdélyi, Zoltán; Szilágyi, Imre

doi: 10.1007/s10973-022-11255-1pmid: N/A

In this paper, we combine the atomic layer deposition synthesis method of inverse opal with the hydrothermal growth of nanorods. From 460 nm polystyrene nanospheres opal crystals were produced using vertical deposition on Si wafers. The opal templates were covered with ZnO by atomic layer deposition. High temperature annealing was used to remove the polystyrene nanospheres to obtain the inverse opal structure. For the hydrothermal growth of ZnO nanorods, two production routes were analysed: hydrothermal reaction before and after the removal of the template. The two paths produced two distinct structures, one with plate like formations and one with nanorods, respectively. Also, the sample modified by the hydrothermal growth after the annealing showed slight differences in optical properties compared to the regular inverse opal. Morphology, composition and structure of the samples were explored using SEM, EDX and XRD. Optical properties were investigated with reflectance UV–Vis spectroscopy. Thermal stability of the polystyrene opal was determined using TG.

Xi, Xiang; Chung, D. D. L.

doi: 10.1007/s10973-022-11240-8pmid: N/A

Pyropermittivity refers to the effect of temperature on the electric permittivity of a material. It is an emerging thermoanalytical method that is relevant to materials characterization, capacitance-based temperature sensing and thermal energy harvesting. Pyropermittivity is well-known for electrically nonconductive materials, but not conductive materials, which include structural materials (e.g., carbon fibers). This work provides the first determination of the activation energy of permittivity and pyropermittivity-based energy density for any material, and that of the temperature coefficient of permittivity (associated carrier-atom interaction) for conductive materials. Pyropermittivity is discovered in carbon fibers. The permittivity temperature coefficient is positive for uncoated/nickel-coated carbon fibers and polycrystalline graphite of prior work, despite the difference in sign of the temperature coefficient of resistivity between the fibers and graphite. The pyropermittivity is stronger when the fiber is nickel-coated, but is yet stronger for graphite. The coefficient values are all higher than or comparable to those previously reported for nonconductive materials, indicating that nonconductivity does not necessarily enhance pyropermittivity. The activation energy of permittivity is ≤ 40 meV. The pyropermittivity-based volumetric energy density is higher when the carbon fiber is nickel-coated, and is lowest for the graphite. The greater energy density when the carbon fiber is nickel-coated is in line with the greater temperature coefficient of permittivity and the higher permittivity. The low energy density of graphite relates to the low permittivity. The highest energy density obtained is 1.73 × 10–4 J m−3 (nickel-coated carbon fiber for the temperature change of 50 °C); the temperature coefficient of permittivity is 1.37 × 10–3/K for this fiber.

Pizzimenti, Silvia; Saitta, Francesca; Signorelli, Marco; Tinè, Maria Rosaria; Bonaduce, Ilaria; Duce, Celia; Fessas, Dimitrios

doi: 10.1007/s10973-022-11227-5pmid: N/A

In this work, we propose to follow the crystallization capability of oils in oil-based paints, during curing, as an indirect index of the matrix status in the early stages of paint film formation that usually are indicative and crucial to understand the process evolution. To proof the concept, the oil crystallization properties were investigated through DSC measurements on samples of both unpigmented linseed oil and two model paints, composed by lead white + linseed oil (LWLO) and ultramarine blue + linseed oil (UBLO), at different ageing time at room and oxygen-limiting conditions. The results indicate that the curing process strongly affects the oil’s ability of forming crystals in the paint layers, and the proposed experimental approach is rather suitable and sensitive enough to discriminate differences between the action of pigments and environmental conditions. On the other hand, despite the simplicity and the potentiality, this approach is limited at the early stages of paint curing offering an index of the overall matrix status and therefore must be intended as a complementary method that has to be integrated with other approaches if the aim is to explore in detail the chemical and physical aspects of the curing process.

Yu, Long; Wang, Qi; Wu, Kai; Tan, Zhijun; Pan, Feng; Yang, Zhenghong; De Schutter, Geert

doi: 10.1007/s10973-022-11301-ypmid: N/A

Bridging the gap among various phases is an effective approach to modify the overall performance of concrete. This paper presents a systematical investigation via multi scale methods, including macro performance, meso ITZ features and quantitative microstructure determination, to evaluate the effect of limestone powder (LP) and slag on the homogeneity of concrete. Although substituting 10% of LP, or 70% of slag for Portland cement could reduce the compressive strength, the differences among pastes, mortars and concretes are reduced remarkably. The addition of LP and slag is able to promote the hydration of cement and homogenize the mineralogical compositions. Using LP and slag for preparing binary or ternary binder would refine the pore structure especially in the region close to aggregate via micro filling, nucleation sites and latent hydration. It is expected to enhance the understanding of behavior modification of blended cement concrete from the perspective of multi-scale homogeneity.

Bondareva, Nadezhda S.; Sheremet, Mikhail A.

doi: 10.1007/s10973-022-11296-6pmid: N/A

Passive temperature control and thermal storage systems using phase change materials are widespread and have a high potential in modern technologies. This research deals with the computational analysis of natural convection melting in a multi-PCM thermal sink heated from an element of volumetric energy production. The influence of the geometric parameters of the system and the arrangement of materials in it is analyzed. Numerical modeling has been carried out using the finite difference technique. Governing equations for the mass, momentum and energy transfer have been written employing stream function, vorticity and temperature. Based on the obtained distributions of local fields for energy and mass transference and changes in the average temperature of the heater, it is shown that, despite the smaller surface area, separation by vertical flat fins provides lower temperatures and longer melting when the source is located below.