Energy lost in endothermic reactions in the production of clay blocks in a continuous kiln

In Ocaña, Norte de Santander, Colombia, the production of ceramic materials is done in a traditional and empirical manner, generating heat losses, low productivity and product quality, and increased emissions of polluting gases into the environment. A virtual instrument for temperature data acquisition was developed and the firing process was monitored in two loading doors of a Hoffman kiln. 29040 blocks were produced, and 1370.76 kg of pulverized charcoal were consumed. The firing process lasted sixty-two hours and the virtual instrument was programmed to record data every 5 minutes. The energy supplied to the brick kiln was 340.16x106 kJ and the heat due to loading of the products and heat lost in the endothermic reactions of the clay was 107.71x106 kJ and 105.71x106 kJ respectively, representing 31.66% and 31.08% of the energy supplied. The results have made it possible to establish trends in the temperatures and energy consumed in the endothermic reactions in the clay. This will allow the implementation of coal quality and grinding procedures, increasing energy efficiency, and reducing gas emissions into the environment, thus avoiding acute respiratory diseases.

Morphogenesis of Silicovanadate Glasses: Investigation of Physical Properties

In this article, we demonstrate the synthesis and various characterizations of silicovanadate glasses of xSiO2 (100-x)V2O5 for x = (10-50) mol%, glasses which are prepared by the melt quenching method. FTIR spectra analysis confirms dominant chemical bonds among silicon, vanadium, and oxygen elements as expected. The assigned chemical bonds are Si-O-Si, O-Si-O, V-O-V, V=O, Si-O-V, O-H from FTIR spectra. The IR spectra of all glass specimens were baseline corrected and deconvoluted to distinct peaks of chemical bonds in overlapped Gaussians with employing computer program. The chemical bond's position shifted and affected due to the addition of vanadium pentaoxide by the heat treatment process. The X-ray diffractions (XRD) patterns of glass samples exhibit partial crystalline nature for 10S90V and 50S50V that is influenced by high-temperature application. The differential thermal analysis (DTA) of base and heat-treated specimen determines the glass transition (Tg), crystallization, and liquidus temperature with prominent exothermic and endothermic reactions. It is seen that the pH of the glass specimens abruptly changes due to the surface effect of V2O5 while bulk effects become robust after about 30 minutes. The measured hardness of three glass samples shows high HV-values and a slight linear increment is observed for higher V2O5 contents. The current-voltage (I-V) characteristic connected to the electrical conductivity of the glass specimen (20S80V) shows a relatively higher and non-linear trend of conductivity which reveals the behavior of a semiconductor. Moreover, temperature-dependent electrical resistivity measurement of the same sample (20S80V) manifests the semiconducting nature up to 427 °C as well.

Adsorption Characteristics of Phosphate Ions by Pristine, CaCl2 and FeCl3-Activated Biochars Originated from Tangerine Peels

This study has evaluated the removal efficiencies of phosphate ions (PO43−) using pristine (TB) and chemical-activated tangerine peel biochars. The adsorption kinetics and isotherm presented that the enhanced physicochemical properties of TB surface through the chemical activation with CaCl2 (CTB) and FeCl3 (FTB) were helpful in the adsorption capacities of PO43− (equilibrium adsorption capacity: FTB (1.655 mg g−1) > CTB (0.354 mg g−1) > TB (0.104 mg g−1)). The adsorption kinetics results revealed that PO43− removal by TB, CTB, and FTB was well fitted with the pseudo-second-order model (R2 = 0.999) than the pseudo-first-order model (R2 ≥ 0.929). The adsorption isotherm models showed that the Freundlich equation was suitable for PO43− removal by TB (R2 = 0.975) and CTB (R2 = 0.955). In contrast, the Langmuir equation was proper for PO43− removal by FTB (R2 = 0.987). The PO43− removal efficiency of CTB and FTB decreased with the ionic strength increased due to the compression of the electrical double layer on the CTB and FTB surfaces. Besides, the PO43− adsorptions by TB, CTB, and FTB were spontaneous endothermic reactions. These findings demonstrated FTB was the most promising method for removing PO43− in waters.

Biomass Gasification Process with Catalyst

Gasification is a thermo-chemical process used to convert biomass fuelsinto a fuel gas. Biomass gasification is considered amongst the best methods to enhance biomass-based energy production’s efficiency as it allows common biomass utilization.It has become more important as a mean of converting low energy-density such as biomass feeds or into a transportable high value gas for heat and power generation, chemicals and fuels. Operating conditions are affecting the gasification reactions. the review identified that in high-temperature gasification, endothermic reactions the secondary cracking and reforming of heavy hydrocarbons are favored and hence enhances the whole process’s efficiency. Finally, catalysts are vital for the biomass gasification process, and it is important to select the appropriate ones taking into consideration possible setbacks discussed above and will be explored further in this study.

Investigation on Thermal Runaway of Li-Ion Cells Based on LiNi1/3Mn1/3Co1/3O2

The thermal runaway behavior of lithium-ion cells plays a crucial role in the safety management of the powertrain in electric vehicles. In this study, the effect of states of charge (SOC) on the thermal runaway behavior of commercial LiNi1/3Mn1/3Co1/3O2 (NMC)-based pouch cells is investigated using accelerating rate calorimetry (ARC) and ex-situ X-ray diffraction. By studying the differences in the onset temperature of self-heating (T1) and the onset temperature of thermal runaway (T2) along with the mass loss between the different SOCs, we observed that higher SOC led to a decrease in the T2. However, T1 initially increased and then decreased with increasing SOC. These trends were attributed to the phase change of cathode material and separator. The ARC results also indicated the occurrence of endothermic reactions during the self-heating accumulation period. The findings in this study are helpful for thermal safety management of battery powertrain for electric vehicles.

A Predictive Model for Coal Coking Based on Product Yield and Energy Balance

A series of experimental coal pyrolysis studies were conducted to define the parameters of a kinetic model to enable complete mass and energy balances by identifying basic process products. The developed model determines the chemical enthalpy of pyrolytic reactions, making it possible to determine the share of exothermic conversions in the coking process. To validate the model, a series of experimental pyrolysis tests of coking coals used in the coke plant and their blends were conducted, including TGA, retort, and industrial coke oven scale. Despite significant differences in the chemical composition of various coal types, element balancing allowed detection of the difference in product composition and the heat effects of the chemical conversion of such a complex substance as coal. Analysis of the heat effects of pyrolytic coal decomposition indicates substantial variability. In the first coking period, there are endothermic reactions; in the second, exothermic reactions occur. Average heat effect of the pyrolytic reaction for whole coking period is exothermic and, depending on the coal type, ranges from −5 to −50 kJ/kg. The model herein can be used to analyze many other pyrolytic processes because it also takes into account the heating rate.

Short Range Ordering (SRO) Reaction in Ni-base Alloy X-750

The short range ordering (SRO) reaction of the X-750 Ni-base alloy used as a garter spring material for CANDU reactors was systematically investigated through differential scanning calorimeter (DSC) analysis. Water quenching (WQ) after solution annealing (SA) and 20% cold rolled (CR) X-750 were prepared and these samples were subjected to ordering treatment at 475 ^oC for up to 2,160 hours. The WQ and CR specimens showed an exothermic reaction due to the release of entropy formed by the WQ and CR processes, respectively, whereas the ordered WQ and CR specimens exhibited endothermic reactions. The exothermic reaction from the WQ and CR specimens means the SRO reaction occurred. In the WQ specimen, two exothermic reactions at 577 ^oC and 671 ^oC were observed, which corresponds to SRO formation of Ni₂Cr and CrFe, respectively. The critical temperature and thermal activation energy for these specimens were measured by varying the heating rate. The lattice variation with ordering time at 475 ^oC up to 2,160 hours was measured by XRD using CuKa X-ray. A 0.03-0.09% lattice contraction of the (200) plane occurred, depending on prior treatment condition. We discuss whether a lattice contraction due to SRO reaction may cause voids, providing formation sites for He bubbles in the X-750 garter spring exposed to the operating environment of the CANDU reactor.

Chemometric analysis reveals influences of hot air drying on the degradation of polyphenols in red radish

Hot air drying is a commonly used technology in the preservation of red radish. This study was designed to investigate the correlations among total polyphenol content, total flavonoid content, antioxidant activities and polyphenol compounds in hot air dried red radish via chemometric analysis. UHPLC-QqQ-MS/MS analysis detected nine non-anthocyanin polyphenols and one anthocyanin in fresh and dried red radish samples, and found that hot air drying at 80 °C caused an increase in the p-coumaric acid and ferulic acid content of the red radish. The integral effect of hot air drying on the polyphenol profile of red radish was analyzed by principle component analysis, while sparse partial least squares-discriminant analysis showed that hot air drying induced changes mainly in the contents of poncirin, naringenin, phloetin and cyanidin-3-glucoside. These polyphenol degradations occurred as non-spontaneous and endothermic reactions during the hot air drying process, following first-order reaction kinetics.