Effect Of Preheating Temperature Research Articles

Soot and PAH formation in laminar diffusion flames of RP-3 jet kerosene and its surrogates at preheat temperature

For investigating the effects of preheat temperature on the soot/PAH formation of RP-3 kerosene surrogates, planar laser-induced incandescence (PLII), planar laser-induced fluorescence of PAH (PAH-PLIF) and chemical kinetic simulation are conducted in several laminar diffusion flames. The goal is to provide a surrogate that matches well with the soot formation characteristics of RP-3 kerosene and to investigate the mechanism behind the temperature sensitivity of different surrogates. Firstly, surrogate S1 (30.3% n-hexadecane, 39.8% iso-cetane, 29.8% o-xylene, in mole fraction) is formulated to obtain a surrogate with good reproducibility of soot formation characteristics corresponding to the RP-3 jet kerosene. Compared with another reported surrogate S2, S1 presents a higher soot yield due to its higher PAH formation and a stronger soot formation propensity. With elevated preheat temperature, soot yield of all the studied flames gets higher, and the temperature sensitivities for soot formation of S1 and S2 are shown with little difference. By further analyzing the PAH results experimentally and numerically, the temperature sensitivity for soot yield of S2 is more closely related to the temperature sensitivity of PAH precursors, while the subsequent processes after soot inception may be more important to the temperature dependence of S1.

Effect of preheat temperature, pressure, and residence time on methanation performance

The present work studies the effect of reagent preheat temperature on methanation while maintaining the initial temperature of the catalytic bed constant. An adiabatic packed bed reactor was used with 193 g of commercial 10% Ni/Al2O3 catalyst. The tested preheat temperatures were 25 °C, 100 °C, 180 °C, and 280 °C, while the initial catalytic bed temperature was 280 °C. Two tests were performed in which the effect of preheat temperature was evaluated: the first comparing gas hourly space velocities (GHSVs) of 935 h−1 and 1559 h−1, and the second comparing gauge pressures of 0 bar, 1 bar, and 4 bar. Similar behavior was observed for the temperature inside the reactor and final CO2 conversion for preheating temperatures of 100 °C, 180 °C, and 280 °C at a gauge pressure of 0 bar. However, at this pressure, conversion was considerably reduced for the preheat temperature of 25 °C, due to a large part of the catalytic bed serving to preheat the reactants to the minimum reaction temperature. This effect can be partially attenuated by decreasing the GHSV, due to the increased residence time. Finally, increased pressure significantly improved the final CO2 conversion for all preheating temperatures (Tin), and attenuates the effect of Tin. These results show that certain operating conditions do not require as high a reactant preheat temperature for methanation, which offers energy savings in certain processes such as power-to-gas (P2G), where the hydrogen is produced from electrolysis and can leave the process at a lower temperature than that required for methanation.

Thermal treatment effect on the mechanical properties of 1570, 1580 and 1590 aluminum alloys

The study addresses the effect of thermal treatment on the mechanical properties and grain size of magnesium rich alloys with small scandium additions 1570, 1580 and 1590. The effect of preheat temperature (within 260440 С range) and soaking time (within 2 100 hours range) on yield strength, tensile strength and relative elongation of the alloys under investigation was analyzed. Mechanical properties were determined using uniaxial tensile tests in accordance with ISO 6892-1. In addition, for some modes the microstructure was studied for Al3Mg2 -phase presence and distribution by optical metallography methods depending on thermal treatment conditions. The studies demonstrated that supersaturated solid solution in the 1570 alloy decomposes faster in the entire studied temperature range, and after 48 hours soaking, its strength properties start degrading. At the same time, the 1580 and 1590 alloys are much more thermally stable, with slightly lower yield strength after long soaking time, while tensile strength remains unchanged. The conditions of 260 C annealing temperature are not favorable for plastic properties, severely degrading (due to -phase formation) in the 1570 and 1580 alloys. Plastic properties degradation is not so evident at higher soaking temperature, however, the 1590 alloy maintains the highest plasticity indices.

Effect of Preheat Temperature and Welding Sequence on the Temperature Distribution and Residual Stress in the Weld Overlay Repair of Hydroturbine Runner.

The hydroturbine runner is the core of the whole hydroelectric generating unit, which is employed to transform water energy into mechanical energy. In the process of service, the runner frequently suffers from abrasion due to erosion and cavitation. Defects are usually repaired by welding. To acquire suitable weld cladding repair process parameters, a combination of experimental and numerical simulation was applied to investigate the temperature and weld residual stress distribution in the repair zone under the different welding repair approaches. The results illustrate that the temperature and welding residual stress distribution of the blade and the shroud are out of symmetry, the temperature conduction rate is faster on the blade side, and the high-stress zone is predominantly concentrated in the weld and its adjacent area. When the preheating temperature is up to 150 °C, the peak value of welding residual stress reaches a minimum of 796.29 MPa. The welding sequence can adjust the distribution trend of welding residual stresses. The welding sequence of three-stage welding can effectively reduce the welding residual stresses near the shroud at the water outlet side of the blade. The results of the study will provide theoretical guidance for the welding repair of hydraulic turbine runners.

Effect of pre-heating temperature on ZnO thin films prepared by ultrasonic atomization and pyrolysis technique

Effect of pre-heating temperature on ZnO thin films prepared by ultrasonic atomization and pyrolysis technique

On the Surface Welding of Pearlitic Rails: The Control of Dilution and Microstructure

This work studies the surface welding parameters for a practical repair for pearlitic rail grades: R260 and R350HT. A filler metal containing low carbon (0.15 %), high silicon (0.5 %) and nickel (2.5 %), self-shielded flux-core welding electrode (FCAW-S) is the candidate in order to ensure the preferable carbide-free bainite. The film-like morphology of the retained austenite is reported to promote the wear resistance and is ensured by silicon and nickel. The effect of preheat temperature and dilution on the microstructure and resulting hardness can be concluded. Too high dilution, as a result of high current and travel speed, and the reheating during the welding of the second layer can result in martensite formation and too high hardness. Proper control of the dilution ensures satisfactorily hardness and avoids martensite formation.

The effect of pre-heat temperature on the microstructure and abrasive wear properties of laser metal deposited near-eutectic Fe-28Cr-2.9C alloy

Fe-Cr-C near-eutectic alloys are commonly used in wear resistant parts in mining applications, due to their excellent erosion and abrasion wear resistance. Laser metal deposition is an additive technology that presents opportunities for manufacturing mining components, as well as repairing worn areas of wear resistant parts. However, Fe-Cr-C hypoeutectic alloys are very hard and brittle and are often considered “unweldable” due to the lack of ductility required to accommodate thermal stresses. Therefore, controlling key processing parameters, such as preheating temperature and cooling rate, plays a crucial role in achieving crack-free layers with a refined microstructure. The aim of this study was to investigate the effect of substrate preheat temperature on the microstructure and wear properties of laser metal deposited Fe-28Cr-2.9C alloy. The microstructure and wear properties were analyzed for three different preheating conditions. The microstructure consisted of a near-eutectic structure consisting of M7C3 carbides + austenite, which has been mostly transformed to martensite. Increasing the preheating temperature increased the carbide size and retained austenite in the matrix, which was detrimental for the wear resistance.

The effect of pre-heat temperature on the formability of a glass-fibre/polypropylene and steel-based fibre–metal laminate

The effect of pre-heat temperature on the formability of a glass-fibre/polypropylene and steel-based fibre–metal laminate

The effect of protein profile and preheating on denaturation of whey proteins and development of viscosity in milk protein beverages during heat treatment

The effect of preheat temperature (63 or 77 °C for 30 s; final heat 120 °C for 30 s) and casein to whey protein ratio on the physical characteristics of 3.3%, w/w, dairy protein beverages was investigated. Dispersions preheated at 77 °C had lower viscosity than dispersions preheated at 63 °C. Casein‐containing dispersions had significantly lower levels of α‐lactalbumin denaturation than whey protein‐only dispersions. A higher proportion of casein improved the thermal stability of protein dispersions. Overall, alteration of preheat temperature and casein to whey protein ratio can influence dairy beverage quality, with increasing levels of casein reducing physical changes due to heat treatment.

Effect of preheat temperature and post-process treatment on the microstructure and mechanical properties of stainless steel 410 made via ultrasonic additive manufacturing

Ultrasonic additive manufacturing (UAM) is a solid-state manufacturing technology for producing near-net shape metallic parts combining additive ultrasonic metal welding and subtractive machining. Even though UAM has been demonstrated to produce robust metal builds in Al–Al, Al–Ti, Al-steel, Cu–Cu, Al–Cu, and other material systems, UAM welding of high strength steels has proven challenging. This study investigates process and post-processing methods to improve UAM steel weld quality and demonstrates the UAM fabrication of stainless steel 410 (SS 410) builds which possess, after post-processing, mechanical properties comparable with bulk material. Unlike UAM fabrication of softer metals, this study shows that increasing the baseplate temperature from 38∘C (100∘F) to 204∘C (400∘F) improves interfacial strength and structural homogeneity of the UAM steel samples. Further improvement in strength is achieved through post-processing. The hot isostatic pressing (HIP) post treatment improves the shear strength of UAM samples to 344 MPa from 154 MPa for as-welded samples. Microstructural analyses with SEM and EBSD show no evidence of body centered cubic (BCC) ferrite to face centered cubic (FCC) austenite transformation taking place during UAM welding of SS 410. The weld quality improvement of UAM steel at higher baseplate temperatures is believed to be caused by the reduction of the yield strength of SS 410 at elevated temperature. HIP treatment is shown to increase the overall hardness of UAM SS 410 from 204 ± 7 HV to 240 ± 16 HV due to the formation of local pockets of martensite. Nanohardness tests show that the top of layer n is harder than the bottom of layer n+1 due to grain boundary strengthening.

Growth of ZnO Nanorods by Template-Free Sol-Gel Dip-Coating Technique: Effect of Pre-Annealing Temperature

In this work, we studied the effect of pre-heating temperature on the structural and optical properties of ZnO nanorods grown by free template sol-gel dip-coating technique. The prepared films were pre-heated at different temperatures: 240, 260, 280 and 300 °C, then annealed at 500 °C for one hour. The structural properties of the prepared samples were investigated by X-ray diffraction (XRD) and the surface morphologies were studied by scanning electron microscope (SEM). The optical properties were studied by means of UV-Visible spectrophotometer. The XRD diffraction spectra show that all the prepared samples have a ZnO wurtzite structure with a preferential orientation along (002) axis. SEM micrographs revealed the formation of well-aligned ZnO nanorods for the sample preheated at 280 °C. The prepared ZnO nanorod structured thin films are highly transparent in the visible region with an average transmittance above 85 % in the 400–800 nm wavelength range.

The Effect of Pre-heating Temperature on Structural and Optical Properties ZnO Thin Film Synthesized using Sol-Gel spin Coating Method

The synthesis of ZnO thin film has been successfully carried out using the sol-gel spin coating method. The production of ZnO thin film was grown on a glass substrate with a rotation speed of 5000 rpm and calcined with pre-heating temperature variations of 250, 300 and 350°C and post-heating at a temperature of 550°C. The results of the characterization of ZnO thin films with XRD showed that all crystal structures in the form of hexagonal wurtzite with the largest crystal size for 350°C pre-heating temperature were 35.3 nm. Morphology of ZnO thin films resulting from SEM characterization in the form of crystallite granules and most of them are round and almost uniform and compact. The results of the characterization of ZnO thin film with UV-Vis showed the highest transmittance value for 350°C pre-heating temperature was 53.9%. The highest absorbance value for 250°C pre-heating temperature is 1,192. The biggest energy band gap value for 350°C pre-heating temperature is 3.15 eV.

Effects of Preheating and Storage Temperatures on Aroma Profile and Physical Properties of Citrus-Oil Emulsions.

Citrus oils are used as good carrier oil for emulsion fabrication due to their special flavor and various health-promoting functions. In this study, the effects of preheating temperature (30, 40, 50, 60, and 70 °C) and storage temperature (4, 25, and 37 °C) on aroma profiles and physical properties of three citrus-oil (i.e., mandarin, sweet orange, and bergamot oils) emulsions were systematically investigated for the first time. The results demonstrated the significant impact of temperature on aroma profile and physical properties. The abundance of d-limonene was found to be the main factor determining the aroma of the three citrus-oil emulsions at different preheating and storage temperatures, while β-linalool and linalyl acetate were important for the aroma of bergamot oil emulsion. Preheating temperature showed a profound impact on the aroma of citrus-oil emulsions, and the aroma of different citrus oil emulsions showed different sensitivity to preheating temperature. Storage temperature was also able to alter the properties of citrus oil emulsions. The higher was the storage temperature, the more alteration of aroma and more instability of the emulsions there was, which could be attributed to the alteration of the oil components and the properties of emulsions. Among all three emulsions, bergamot-oil emulsion was the most stable and exhibited the most potent ability to preserve the aroma against high temperature. Our results would facilitate the application of citrus-oil emulsions in functional foods and beverages.

Analysis on the effects of pre-heating temperature on mechanical properties of pellets made from corn stalk powder

Analysis on the effects of pre-heating temperature on mechanical properties of pellets made from corn stalk powder

The 2D Finite Element Microstructure Evaluation of V-Shaped Arc Welding of AISI 1045 Steel

In the present study, V-shaped arc welding of the AISI 1045 steel is modeled by using 2D Finite Element Model (FEM). The temperature distribution, microstructure, grain growth, and the hardness of the heat-affected zone (HAZ) of the welding are simulated. The experimental work is carried out to validate the FE model. The very close agreement between the simulation and experimental results show that the FE model is very effective for predicting the microstructure, the phase transformation, the grain growth and the hardness. The effect of preheat temperature on the martensite formation is analysed, and it is shown that 225 °C preheating completely eliminates the martensite formations for the 12 mm thick plate.

Effect of pre-heating temperature on structural and optical properties of sol-gel derived Zn0.8Cd0.2O thin films

Zn0.8Cd0.2O thin films prepared using the spin-coating method were investigated. X-ray diffraction, scanning electron microscopy, and UV-Vis spectrophotometry were employed to illustrate the effects of the pre-heating temperature on the crystalline structure, surface morphology and transmission spectra of Zn0.8Cd0.2O thin films. When the thin films were pre-heated at 150 °C, polycrystalline ZnO thin films were obtained. When the thin films were pre-heated at temperatures of 200 °C or higher, preferential growth of ZnO nanocrystals along the c-axis was observed. Transmission spectra showed that thin films with high transmission in the visible light range were prepared and effective bandgap energies of these thin films decreased from 3.19 eV to 3.08 eV when the pre-heating temperature increased from 150 °C to 300 °C.

Effects of pre-heating temperature and formulation on porosity, moisture content, and fat content of fried batters

The effect of pre-heating temperatures on moisture and fat contents, and porosity of fried batters was studied. Batter pre-heated at 60 °C showed higher moisture content, lower fat content and lower porosity than non-pre-heated batter and batters pre-heated at 70 and 80 °C. Moisture content, fat content, and porosity at 4 min frying for batters with different pre-heating treatments ranged from 35.08 to 39.37, 3.92 to 5.16, and 13.14 to 45.31 %, respectively. Because of significant reduction in fat content, 60 °C pre-heating temperature was chosen to study the effect of batter formulations on moisture and fat contents, and porosity. Different wheat to rice flour ratios were prepared, and then each batter was pre-heated at 60 °C. Batters with higher wheat flour content showed higher moisture content, and lower fat content and porosity than batters with higher rice flour.

600 MPa급 플럭스 코어드 아크 용접금속의 저온균열에 미치는 예열 온도 및 미세조직의 영향

600 MPa급 플럭스 코어드 아크 용접금속의 저온균열에 미치는 예열 온도 및 미세조직의 영향

Effects of time-temperature profiles on glow curves of germanium-doped optical fibre

The Germanium (Ge) doped silica optical fibres have demonstrated the great potential to be developed as a thermoluminescent (TL) dosimeter that can be used in various applications in radiotherapy, diagnostic radiology, UV dosimetry system and food irradiation industry. Different time-temperature profile (TTP) parameters of the TL reader have been employed by many researchers in various of TL studies. Nevertheless, none of those studies adequately addressed the effects of the reader's preheat temperature and heating rate on the kinetic parameters of the TL glow curve specifically, the Ge-doped silica optical fibres. This research addresses the issue of TTP parameters with special attention to the determination of the kinetic parameters of the glow curve. The glow curve responses were explored and the kinetic parameters were analyzed by the WinGCF software, to show the effect of the preheat temperature and heating rate of the reader on Ge-doped fibre irradiated with 18Gy of 6MV photons radiation. The effect of TTP parameters was discussed and compared against the commercial fibre and tailored made fibre of 6mol% Ge-doped of flat and cylindrical shape. The deconvolution of glow peaks and the kinetic parameters were obtained by the WinGCF software. This enables to fit accurately (1.5%<FOM<5.0%) for all measured glow curves. A positive, moderate linear relationship exists between the TL response and the heating rate when the specific preheat temperature was used to read commercial fibre (50°C) and cylindrical fibre (80°C and 160°C). It is found that the glow peaks of cylindrical fibre exhibit the highest peak integral as compared to flat and commercial fibres. This study revealed the possible relationship between the reader's TTP parameters and the kinetic parameters of TL glow curves for the commercial and tailored made Ge-doped silica optical fibres.

Effect of the FCAW Welding Process and Post Weld Heat Treatment on the Properties and Microstructure of the Weld Joints of Heat Treated 4330V Steel

4330V is a high strength, high toughness, heat treatable low alloy steel for application in the oil, gas and aerospace industries. It is typically used for large diameter drilling parts where high toughness and strength are required. The research describes the effect of preheat temperature, interpass temperature, heat input, and post weld heat treatment on strength, hardness, toughness, and changes to microstructure in the weld joint. Welding with the lower heat input and no post weld heat treatment resulted in optimal mechanical properties in the weld metal. Austempering at 400 °C resulted in optimal mechanical properties in the HAZ. Increasing preheat and interpass temperature from 340 °C to 420 °C did not improve Charpy V-notch values or ultimate tensile strength in the weld metal or heat affected zones. The higher temperature increased the width of the heat affected zone. Austempering at 400 °C reduced HAZ hardness to a level comparable to the base metal. Both tempering and austempering at 400 °C for 10 hours reduced toughness in the weld metal.