Impact Of Heating Rate Research Articles

The impact of heating rate on the synthesis of Ca3Co4O9 using rice starch as a soft template

This study examines how the heating rate at calcination temperature (5 °C/min, 10 °C/min, 15 °C/min, and 20 °C/min) on the synthesis of Ca3Co4O9 (CCO) material using soft template (rice starch) affects the thermal conductivity (κ), electrical resistivity (ρ), particle size, and crystallite size in addition to the Ca3Co4O9 phase. The sol-gel combustion method uses the precursor compounds CaCO3, Ca(NO3)2∙4H2O, and Co(NO3)2·6H2O. The Rietveld refinement technique verified the crystal structure, and the Williamson-Hall (WH) plot was used to calculate crystallite size. The heating rate variations were related to the phase transition, reaction rate, and combustion energy that affected the crystal size and p-type thermoelectric (TE) capabilities. Using calcium nitrate as the precursor yields a higher purity of CCO than calcium carbonate. With an increase in heating rate temperature, the values of κ and ρ tend to rise; they vary from 1.7414 to 1.9827 W/m·K and 90.8222–194.1667 mΩ cm, respectively. The occurrence of CaCO3 in the final product and the anomaly of crystallite size at 20 °C/min are discussed.

Experimental investigation on gas-liquid–solid tri-phase product distributions during the simulated in-situ pyrolysis of tar-rich coal

The in-situ pyrolysis of tar-rich coal is a new technology for converting coal into tar and gas underground, which involves unique environmental conditions of high temperature, high pressure, large-sized coal and extremely low heating rate. Due to the different research purposes and application scenarios, the unique experimental environment of the in-situ pyrolysis is significantly different from that of conventional pyrolysis. Existing pyrolysis studies cannot be directly applied to the field of the in-situ pyrolysis of tar-rich coal, and the specialized research is indispensable. The product distribution exerts important impacts on the subsequent processing, hence an essential evaluation criterion for in-situ pyrolysis characteristics is the yield of gas-tar-char three-phase products. However, there have been few reports on the distribution of tri-phase products during in-situ pyrolysis of tar-rich coal. High temperature, high pressure, and extremely slow heating under multi-factor control were the environment of the in-situ pyrolysis which were experimentally simulated by gas pressurization in the autoclave, and the impacts of temperature, heating rate, and atmosphere at various reservoir pressures were studied. The optimal tar production temperature is 500 °C, with a yield of 12.13 %. With the increase of temperature, the aromatic hydrocarbons content in the tar product increases, the aliphatic hydrocarbons content gradually decreases and reaches 0 at 500 °C, and the phenols content first climbs and subsequently falls. There is a negative relationship between the tar yield and reservoir pressure. The impact of heating rate and atmosphere upon pyrolysis products distributions is insignificant. The present work is favorable to effective tar extraction by controlling pyrolysis parameters, and also provides better understanding for the development of large-scale tar-rich coal in-situ pyrolysis technology.

Variations of silicon species, dissolution and crystallinity within sichars prepared under different heating rate

Silicon within Si-rich biochars (sichar) plays a crucial role in immobilizing heavy metals and providing slow-releasing bioavailable silicon for silicophilic plants. However, the impact of heating rate on the silicon properties and carbon‑silicon interactions in sichars remains unclear. In this study, rice husk was used as a silicon-rich biomass to prepare sichars at different heating rates (10, 30 and 60 °C per minute, and ultra-fast-pyrolysis), then experiments such as silicon concentration measurement, Raman and XRD characterization were conducted. The results showed that a faster heating rate reduced the carbon content during pyrolysis while promoted the formation of amorphous silica, resulting in a threefold increase in dissolved silicon in sichars prepared at 400 °C. Additionally, we observed the formation of a meta-stable SiO2 polymorph (tridymite) in rice husk-derived biochars under fast heating, differing from the previously observed quartz generated at slow heating rates. Regarding the CSi relationship, a faster heating rate facilitated the removal of the surface carbon layer, exposing the underlying silicon layer. This led to more soluble silicon species and less encapsulated silicon, resulting in a continuous release and cumulative silicon dissolution amount 1.2 times and 1.6–1.9 times higher, respectively, than those in slow heating rate-derived sichars. Consequently, this enhanced silicon uptake in rice seedlings. Our findings indicate that beyond pyrolysis temperature, the heating rate significantly affects the silicon species, silicon dissolution behavior, and carbon‑silicon relationships of biochar, ultimately determines the properties and applications of sichars.

Distribution and characterization of products obtained from pyrolysis of cooked food waste- Impact of heating rate

This work offers a comprehensive investigation of the pyrolysis products—liquid, gas, and solid derived from cooked food waste (CFW) at different heating rates (15–100 °C/min). The heating rate significantly influenced the yield of pyrolysis products. The maximum yield of bio-oil (oil + aqueous) was achieved at a heating rate of 50 °C/min, py-gas at 100 °C/min, and biochar at 15 °C/min. The yields were 34 wt% for bio-oil, 30 wt% for py-gas, and 32 wt% for biochar. Analysis of the bio-oil revealed significant proportions of fatty acids (Methyl-methyltetradecanoate) and esters (Oleic acid ethyl ester), constituting 25 %, and 26 % at 15 °C/min but declining with increasing heating rates. Another ester (9-Octadecenoic acid methyl ester) was found across all heating rate with highest concentration of 33 % at 100 °C/min. Aliphatic hydrocarbons (Octane, Dodecene, Heptadecane, Tetradecyne, Undecane, Dimethylhepta-1,3-triene, Tetradecane, Nonadecane), constituted highest concentration of 12 % at 25 °C/min and aromatic hydrocarbons (Toluene) showed maximum presence of 4 % at 50 °C/min. The aqueous phase showcased cyclic nitrogenated compounds (Piperidine), anhydrosugars (DGP), and furanics (Furanmethanol), with the highest concentrations of 46 %, 12 %, and 38 %, respectively observed at 100 °C/min. Instantaneous py-gas analysis indicated an elevated presence of CO2 and CO in the initial pyrolysis stages (up to 70 min) followed by higher H2 in the latter stages (>70 min). While increasing heating rates (15–100 °C/min) boosted cumulative fractions of CO2 and CO, the highest H2 fraction was observed at 50 °C/min. The proximate and ultimate analysis of biochars indicated increased ash, fixed carbon, HHV and H/C compared to raw CFW. The surface area and morphology were positively influenced by an increase in heating rate, resulting in a microporous biochar having maximum surface area of 340.6 m2/g at 50 °C/min.

Effects of heating rate and deposition cycle on the structural, optical, and photoelectrocatalytic properties of electrodeposited hematite films

In this research, electrodeposited hematite films were prepared at voltammetry deposition cycles of 60 and calcined at 550 °C in a furnace after ramping the temperature at the rates of 2 °C/min, 10 °C/min, 35 °C/min, and rapid heating of about 100 °C/min. Additional samples were fabricated at deposition cycles of 15, 30, and 80, and also calcined at 550⁰C at a heating rate of 10⁰C/min. The impact of heating rate and deposition cycle number variations on the structural, optical, and photoelectrocatalytic (PEC) properties of the hematite films were assessed. All the films' X-ray diffraction (XRD) measurements showed strong peaks at the lattice planes (104) and (110), verifying hematite's rhombohedral crystal structure. The films prepared at the heating rate of 10⁰C/min boosted the crystallization of the films by 47.2 % relative to the ones prepared at 2⁰C/min. An increase in the deposition cycle number resulted in increasing film thickness and the sample’s crystallization. An indirect bandgap of 1.94–2.1 eV was estimated for the samples, with the least value obtained for the films treated at the heating rate of 10⁰/min and deposition cycles of 60. The same samples also yielded the largest photocurrent density of 26.2 μA/cm2 at 1.23 V vs. reversible hydrogen electrode (RHE), while the photoanodes fabricated at 2 °C/min exhibited the lowest photo-activity. The enhanced photocurrent observed for the films has been associated with high crystallinity, improved photon absorption, reduced flatband potential, and increased charge separation at the film’s surface. This research underscores the importance of optimizing both the heating rate and deposition cycle numbers in the fabrication of electrodeposited photoelectrodes for PEC applications.

Understanding the effect of heating rate on hydrothermal liquefaction: A comprehensive investigation from model compounds to a real food waste

Hydrothermal liquefaction (HTL) emerges as an efficient technology for converting food waste into biocrude. Among HTL parameters, the impact of heating rate is understudied. This study systematically explores its variation (5–115 K/min) on HTL performance using actual food waste and model compounds representing its constituents. Results revealed that an increase in heating rates significantly impacts HTL performances (+63 % biocrude and −34 % solid with food waste) with short residence times, as slower heating rates imply a longer overall time and a higher kinetic advancement of the reaction. Conversely, with longer residence times, the influence of heating rates becomes negligible, as kinetics during heating times are overshadowed by those at operating temperatures. A subtle effect of heating variation at extended residence time was observed only with carbohydrates. This research emphasizes the utility of a kinetic severity factor (KSF) as a valuable tool for simultaneously considering heating rates, operating times, and temperatures.

The impact of heating rate on the decomposition kinetics and product distribution of algal waste pyrolysis with in-situ weight measurement

Converting algal biomass to clean energy via a thermochemical pathway is an emerging technique for tackling environment and energy issues. Traditional kinetic studies on biomass pyrolysis employ a thermogravimetric analyzer (TGA) which heats the biomass sample at a rate of 0 ∼ 2 K s−1, so TGA could only replicate the thermal behavior of the biomass sample in a fixed bed reactor. However, biomass samples can be heated at a rate over ∼102 K s−1 in industrial reactors, including fluidized beds, spouted beds, or rotary kilns due to the direct contact between biomass samples and the solid heat carriers, thus TGA is incapable to reproduce these thermal behaviors. In view of the limitation of TGA in fast heating cases, this study has developed a fast-heating thermo-balance consisting of wire-mesh and wireless power supply technique to investigate the kinetics of fast pyrolysis. Seaweed is fast-growing and can be considered a promising feedstock for biofuel production. Therefore, this study selected seaweed as representative biomass waste and compared the pyrolysis behaviors under both slow and fast pyrolysis conditions. A key finding was the TGA-derived kinetic parameters were unable to describe the pyrolysis rate under fast pyrolysis conditions with significant overestimation. When compared to slow pyrolysis, fast pyrolysis can increase bio-oil yield by about 3–17%, but the N- and S-containing compounds in the bio-oil increase by about 1.1% and 0.15% respectively at a final temperature of 700 °C. Fast pyrolysis produced about 16–53% more CO2 than slow pyrolysis above a final temperature of 500 °C. The polarity of compounds in biochar was reduced with increasing temperature and the presence of CaO was only found in biochar at a high temperature of 700 °C. The specific surface area of biochar was higher under fast heating pyrolysis (5.534–7.469 m2 g−1) than that under slow heating pyrolysis (4.076–6.414 m2 g−1).

Effect of heating rate and precursor composition on secondary phase formation during Cu2ZnSnS4 thin film growth and its properties

Cu2ZnSnS4 (CZTS) as an absorber material has proven its potential for high efficiency solar cells. However, commercial viability for low cost photovoltaic depends on improving its efficiency beyond the existing values which require an understanding of secondary phase formation. In this work, CZTS layer of up to one micron thickness is prepared by sulfurization (annealing in the sulfur environment) of a precursor prepared using magnetron co-sputtering of Cu, Zn and Sn on soda lime glass. Precursor composition during co-sputtering and heating rate of the sulfurization process were varied to study its effect on secondary phase formation during CZTS growth. Characterization techniques like X-ray diffraction, Raman spectroscopy and UV-Vis spectroscopy were used to detect the phases formed in the film. Scanning electron microscopy and energy dispersive x-ray spectroscopy were performed to estimate the elemental composition and its distribution in the film. The studies and the results obtained therein bring out the impact of heating rate on the grain size. Simultaneously the secondary phase formation is found to be affected more by precursor composition than the heating rate. Raman measurements and bandgap estimation from UV-visible absorption spectra indicated the formation of ZnS in the film. The study showed the possibility to completely avoid the formation of both copper sulfide (CuS, Cu2S, etc.) as well as ZnS secondary phases under certain combination of process parameters.

Molecular dynamics study of alloying process of Cu–Au nanoparticles with different heating rates

In this paper, molecular dynamics (MD) simulation is utilized for the investigation of impact of heating rates on Au and Cu nanoparticles alloying process. Aggregation of contacted nanoparticles experiences three stages due to the contacting, while the alloying process can be distinguished into five regimes because of the contacting and melting. Different heating rates result in different contact temperatures. The decrease of the potential energy can be observed when the temperature reaches the melting temperature. When the temperature reaches the melting point, shrinkage ratio and relative gyration radius have drastic changes during the alloying process. It is shown that heating rates have an apparent effect on the shrinkage ratio and the relative gyration radius during the fusing process, and the shrinkage ratio and the relative gyration radius of Au and Cu alloying systems with lower heating rates have relative larger increasing ratio and decreasing ratio, respectively.

Impact of heating rates on the evolution of function groups of the biochar from lignin pyrolysis

Understanding evolution of the functionalities of biochar versus temperature is a prerequisite for exploring application of biochar as functional carbon materials. In this study, pyrolysis of lignin with different heating rates was conducted. The results indicated that the higher heating rate promoted formation of more gases via the accelerated cracking of both the organic components of biochar and the volatile products. In addition, the deoxygenation reactions were suppressed at higher heating rate with short residence time, leading to the biochar with lower heating value and energy yield. The in situ Diffuse Reflection Infrared Fourier Transform Spectra (DRIFTS) characterization of the lignin pyrolysis indicated monotonous increase of the abundance of =C−H, C=C and C−O−C functionalities versus increasing pyrolysis temperature. However, the −OH, −CH3 and C−H2 in alkanes and the C=O were not thermally stable. Abundance of −OH maintained a plateau in 200−450 °C, while that for −CH3 and C−H2 in alkanes also reached maximum at ca. 450 °C and the further increasing heating temperature led to significant decomposition. The decomposition of C=O started at the lower temperatures of 200–325 °C, and the lactones, unconjugated alkyl aldehydes, alkyl esters, conjugated aldehydes/ketones experienced distinct temperature-abundance histories.

Impact of heating rate and solvent on Ni-based catalysts prepared by solution combustion method for syngas methanation

Abstract Ni-Al2O3 catalysts prepared by solution combustion method for syngas methanation were enhanced by employing various heating rate and different solvent. The catalytic properties were tested in syngas methanation. The result indicates that both of heating rate and solvent remarkably affect Ni particle size, which is a key factor to the catalytic activity of Ni-Al2O3 catalysts for syngas methanation. Moreover, the relationship between Ni particle size and the production rate of methane per unit mass was correlated. The optimal Ni-Al2O3 catalyst prepared in ethanol at 2°C/min, achieves a maximum production rate of methane at the mean size of 20.8 nm.

Determination of the thermo-mechanical properties in starch and starch/gluten systems at low moisture content – A comparison of DSC and TMA

The impact of heating rate on the glass transition (Tg) and melting transitions observed by differential scanning calorimetry (DSC) on starch and a starch/gluten blend (80:20 ratio) at low moisture content was examined. The results were compared to those determined by thermo-mechanical analysis (TMA). Comparison with dynamic mechanical thermal analysis (DMTA) and phase transition analysis (PTA) is also discussed. Higher heating rates increased the determined Tg as well as the melting peak temperatures in both starch and the starch/gluten blend. A heating rate of 5°C/min gave the most precise value of Tg while still being clearly observed above the baseline. Tg values determined from the first and second DSC scans were found to differ significantly and retrogradation of starch biopolymers may be responsible. Tg values of starch determined by TMA showed good agreement with DSC results where the Tg was below 80°C. However, moisture loss led to inaccurate Tg determination for TMA analyses at temperatures above 80°C.

Physical properties and heterojunction device demonstration of aluminum-doped ZnO thin films synthesized at room ambient via sol–gel method

ZnO and some of its ternary wide-bandgap alloys offer interesting opportunities for designing materials with tunable band gaps, strong piezoresistivity and controlled electrical conductance with high optical transparency. Synthesizing these materials on arbitrary substrates using low-cost and unconventional techniques can help in integrating semiconductors with different physical, electrical, and optical characteristics on a single substrate for heterogeneous integration of multifunctional devices. Here we report the successful synthesis of aluminum (Al) doped ZnO (AZO) thin films on soda-lime glass, silicon and fluorine doped tin oxide (FTO) pre-coated glass substrates by using sol–gel deposition method at ambient condition. X-ray diffraction (XRD) analysis revealed that varying degree of Al doping significantly impacts the crystal orientation, semiconductor bandgap and optical transparency of the film. Crystal structure of the film is also found to be strongly correlated to the characteristics of the substrate material. The impact of heating rate during post annealing process is studied and optimized in order to improve the surface morphology of the deposited films. Optical characterizations have revealed that bandgap energy of AZO films can be tuned between 3.30eV and 4.1eV as the Al concentration is varied from 1% to 20%. Similarly, electrical characteristics of these films indicate that 1% AZO film has the lowest resistivity of 2.2×10−2Ωcm. Finally, 1% Al doped AZO thin film was used in fabricating a p-Si/n-AZO heterojunction, which exhibited good diode characteristics with more than five orders of magnitude rectification ratio and an ideality factor of 3.28.

Impact of the Baking Duration on Bread Staling Kinetics

This paper presents a study on the impact of the duration of the baking plateau on staling kinetics in the case of bread crumb made of sourdough; it follows Le-Bail et al. Journal of Cereal Science 50:235–240, (2009)a previous study proposed by Le-Bail et al. Journal of Cereal Science 50:235–240, (2009) on the impact of heating rate during baking on staling parameters. Degassed bread dough was baked in a miniaturized baking system with baking plateau of 0, 4, and 8 min at 98 °C corresponding to a total baking time of 10, 14 and 18 min respectively (simulating from underbaked to fully baked bread). Results showed that longer baking time resulted in the higher Young’s modulus of the baked dough at the end of staling was. It was observed as in Le-Bail et al. Journal of Cereal Science 50:235–240, (2009) that the crystallization of amylopectin occurred a few days before the hardening of the baked crumb during staling. The amount of freezable water decreased during staling (over 10 days period), which was in agreement with the increase in amylopectin crystallites during staling which trap water. The amount of soluble amylose increased with increasing duration of the baking plateau at 98 °C, indicating that for prolonged baking, an increasing amount of amylose is leached outside of the starch granules. This was proposed as an explanation for the higher Young’s modulus of the crumb at the end of staling.

An Assessment of Using Glow Curve Fitting Procedures for Obtaining Information on Exposure History

A detailed analysis has been performed of the usefulness of glow peak area ratios to determine when, during a dosemeter assignment period, an exposure has taken place. Several heating rates, including the fast rates usually used in routine dosimetry, have been used to quantify the impact of heating rate on such analysis. Large differences in glow peak positions and smaller changes in peak widths resulted from different heating rates. The results indicate that curve fitting techniques and determination of peak area ratios to determine exposure history have very limited usefulness at heating rates generally used in routine dosimetry.

Heating Rate Affects Thermal Properties and Network Formation for Vicilin and Ovalbumin at Various pH Values

ABSTRACTThe impact of heating rate on the strength and type of networks formed with ovalbumin and vicilin were investigated at three pH levels. Changes in protein conformation and structure development were monitored with differential scanning calorimetry (DSC) and dynamic rheology. Networks were characterized by rheological properties and microstructure. Under conditions which promoted the formation of well crosslinked networks, slower heating rates resulted in stronger networks but had little impact on the type of network. As conditions were shifted to promote aggregation rather than network formation, the impact of heating rate was reduced so that for both ovalbumin and vicilin at pH 5, network characteristics were essentially independent of heating rate.