Thermal Furnace Research Articles

Elastic and Mechanical Fatigue at High Temperatures of High-Alumina Castables with Addition of Partially Stabilized Zirconia

This work evaluates the impact of added zirconia on the thermomechanical and thermoelastic fatigue properties of high-alumina refractory castables. Three testing scenarios are presented in the study: 1) Resonant Frequency Damping Analysis (RFDA) after cyclic temperature changes with and without mechanical load, 2) Refractoriness under Load (RuL) tests, and 3) results of abrupt temperature shifts between two high temperatures in a special thermal shock furnace. The tested refractory formulations were a reference castable based on tabular alumina and two castables each containing 13.75 mass-% of zirconia. The formulations of the zirconia castables had an addition of either fully-stabilized zirconia doped with 8 mol-% yttria (Y-FSZ) or partially-stabilized zirconia doped with 3 mol-% calcia (Ca-PSZ). The Y-FSZ castable displayed elastic and mechanical behaviour by means of RFDA and RuL similar to the reference sample and had good recovery after thermal shock testing. The Ca-PSZ formulation showed some beneficial toughening through energy dissipation of progressing cracks, but after cooling exhibited the matrix fracturing influence of the martensitic zirconia phase transformation which would negatively impact service life of the refractory.

Input–Output Linearizing Control Strategy for an Ethylene Dichloride Cracking Furnace Using a Coupled PDE-ODE Model

An input–output (I/O) linearizing control scheme for a gas-fired thermal cracking furnace is developed for a tubular reactor coil, which is a type of tubular reactor surrounded by gas-fired burners in the furnace. Due to the simultaneous interaction between the spatially distributed dynamics of the reactor coil and the lumped radiating wall, the typical proportional-integral-derivative control widely used in industry may have insufficient performance to handle the complexity. In this work, a feedback I/O linearizing controller is applied to control a cracking furnace system that is described by a coupled PDE-ODE model: ethylene dichloride cracking. The cracked gas temperature is manipulated through the fuel gas flow to achieve the desired trajectories. Control performances of the developed controller are illustrated through simulation results for servo and regulatory problems. The proposed method provides more robustness to handle control problems without offset.

The Law of Insulation Failure of ZR-VV Cables under the Circumstances of Different Thermal Environments

The law of insulation failure of PVC insulated PVC sheathed flame retardant cable (ZR-VV) under the circumstances of three different protection modes and six different thermal radiation fluxes is discussed in this paper. The indigenous designed SDR-1 thermal radiation test furnace for plastic cables is used to simulate different thermal environments, in which the thermal radiation fluxes are 3kW/m2、5kW/m2、7kW/m2、24kW/m2、40kW/m2、56kW/m2 respectively and the three different protection modes are directly exposed, protected by metal tube and protected by flame retardant PVC tube. From the results of the experiments, the followings can be concluded: ▪ The insulation failure time and the thermal radiation flux of ZR-VV cables have exponential relations under a particular protection mode. ▪ The insulation failure time gets longer obviously when it is protected by tube than exposed directly. On the whole, the flame retardant PVC tube protects better than the metal tube in low thermal radiation flux. However, both two have similar protection effects when the thermal radiation flux is high. ▪ The insulation failure temperature of this kind of cables is about (183.5±10.7%)°C.

Influence of Al Particle Size and Firing Profile on Void Formation in Rear Local Contacts of Silicon Solar Cells

In this paper, the influence of Al particle size and the applied firing profile on void formation in local rear contacts of wafer-based silicon solar cells is investigated. Samples with a passivated emitter and rear cell (PERC) rear, but without front metallization, were metalized with six different Al screen-printing pastes, i.e., both commercial and homemade, featuring different particle size distributions and fired in a rapid thermal processing furnace with different firing profiles. Voids were detected with scanning acoustic microscopy measurements, and the fraction of voids in rear local contacts was analyzed. It was shown that the heating phase of the firing process has the strongest influence on void formation. With slower heating, void formation could be reduced to a fraction lower than 5% of the local contact area. Furthermore, it was shown that Al pastes consisting of a mixture of small and large Al particle sizes have a positive effect on the formation of voids.

Clinical Observations on the Treatment of Solitary Rectal Ulcer Syndrome (SRUS) with Stapled Transanal Rectal Resection (STARR) Surgery

In the present study, a 3D model of the industrial thermal reactor furnace of sulfur recovery units (SRUs) was simulated using the commercial CFD code ANSYS-FLUENT. The RNG-k-ε turbulence model and the eddy-dissipation-concept for taking into account the interactions of chemical reactions and turbulent flow were used in the computational model. The radiative transport was analyzed using the discrete ordinates method. Detailed reaction mechanisms were introduced in the CFD model for providing accurate predictions of combustion and the resulting species concentrations. The furnace geometry that was identical to those used in the industry was simulated. The predicted species composition distribution, temperature distribution, and absolute pressure, were in close good agreement with the corresponding measured data. Relative errors between the CFD results and the industrial data in terms of H2S conversion and overall efficiency were, respectively, 0.081% and 0.56%. New aspects of influence of geometric parameters such as burner, choke ring, and checker wall on the hydrodynamics and thermal behavior of the reactor furnace were also discussed.

Advances in CO2 gasification reactivity of biomass char through utilization of radio frequency irradiation

A straightforward and well-known reaction for CO2 activation is the “Boudouard reaction”, wherein, CO2 is reacted with carbon (char) to produce CO. In this study, a RF (radio frequency) heating system was developed to perform the Boudouard reaction by passing CO2 through a packed bed of PNS (pistachio nut shell) char. High CO2 conversion of 84% was achieved at 850 °C. When similar experiments were performed in thermal electric furnace, the conversion was only 38%. For further expanding the knowledge on RF-induced gasification, sodium (Na) was incorporated into char skeleton and gasified with CO2 under RF irradiation. RF gasification of Na-catalyzed char pronouncedly improved in the reaction, where sustainable CO2 conversion of 99% was attained at 850 °C. The predominance of RF over thermal heating was highly reflected in kinetic studies, where the activation energies of 26.7, 46.9 and 183.9 kJ/mol were obtained for catalytic and non-catalytic RF and thermal gasification, respectively. In RF gasification studies, it was attempted to improve the quality of mix gases, simulating air and steam gasification gas compositions, through the Boudouard reaction. The heating value of the gases simulating air and steam gasification improved from 6.4 to 8.0 MJ/m3 and 7.6–10.4 MJ/m3, respectively.

Rapid thermal annealing: An efficient method to improve the electrical properties of tellurium compensated Interfacial Misfit GaSb/GaAs heterostructures

The effect of thermal annealing on Te compensated Interfacial Misfit GaSb/GaAs heterostructures is investigated by using two different thermal annealing procedures, namely rapid thermal annealing and furnace annealing. The electrical properties of the devices are studied by using Current–Voltage, Capacitance–Voltage and Deep Level Transient Spectroscopy techniques. It is observed that rapid thermal annealing treatment is superior in terms of improvement of the electrical characteristics compared to furnace annealing treatment. The lowest leakage current and defect concentration are obtained when rapid thermal annealing is employed.

Synthesis, structural, and field electron emission properties of quasi-aligned carbon nanotubes from gutter oil

Quasi-aligned carbon nanotubes (CNTs) have been successfully synthesised from the simple pyrolysis of gutter oil as starting material and ferrocene as a catalyst. The synthesis process was performed at synthesis and vaporisation temperatures of 800 and 250 °C, respectively, in a thermal chemical vapour deposition furnace. The CNTs synthesised using gutter oil have an overall diameter of about 30–50 nm, length of 30 μm, ID/IG ratio of 0.66, and purity of 81%, comparable to those obtained using conventional carbon sources. A field electron emission study of the CNTs exhibited a low turn-on and threshold field of 1.94 and 2.94 V μm−1, which corresponded to current densities of 100 μA cm−2 and 1.0 mA cm−2, respectively which indicate that the CNTs synthesised are suitable candidates for use as field electron emitters. The synthesised CNTs from gutter oil also open up potential mass production applications in energy storage devices. This study demonstrates that gutter oil, a low-cost and readily available resource, can be used as an inexpensive carbon source for the mass production of CNTs.

Impact of gas-phase chemistry on the composition of biomass pyrolysis products

In the present paper, significance of gas-phase chemical reactions occurring in thermal analysis furnace is evaluated. Free radical species form as a result of biomass thermal decomposition and may give rise to chain reactions. Gas portion emitted by the sample analyzed flows to detector (mass spectrometer in our study) in finite time interval, so chemical reactions may change its composition. Quantitative assessment of this change was made based on data about amount of active species that may initiate kinetic chains. Radical trap method was used to determine radical species amount. Toluene vapors was fed to carrier gas and flowed in thermal analysis furnace reacting with radical species produced from biomass thermal decomposition. Stable radical species—benzyl—is reaction product that can be detected by mass spectrometer. Results show that radical species concentration in gas produced from biomass gasification (639 ppm for pyrolysis stage and 3581 ppm for char gasification stage) is too small to change gas-phase composition significantly in time interval for which gas has been achieving detector. Comprehensive kinetic model for toluene oxidation in oxidizer lack conditions is developed based on widely known mechanisms. Radical species amount estimates may be useful as initial information in heterogeneous combustion modeling.

In Situ Arsenic Doping of CdTe/Si by Molecular Beam Epitaxy

p-Type doping of the absorbed layer has been a significant challenge for CdTe solar cells. In this work, we report on in situ arsenic doping of molecular beam epitaxy (MBE) CdTe grown on Si(211) and the use of a cadmium overpressure to enhance incorporation. When growing CdTe:As without a Cd overpressure, extremely high As fluxes are required to achieve noticeable amounts of arsenic incorporation. By supplying a Cd flux during growth, the As incorporation increases by an order of magnitude. By including a Cd overpressure during growth, we have obtained single-crystal CdTe:As films with As incorporation concentration of \(1\times 10^{17} \, \mathrm {\rm cm}^{-3}\). An activation anneal was performed on these films in a rapid thermal annealing furnace, resulting in p-type layers with net carrier concentration of ∼5 × 1016 cm−3.

Fabrication of Cu2SnS3 thin-film solar cells with power conversion efficiency of over 4%

Cu2SnS3 (CTS) thin films were produced by the co-evaporation of Cu, Sn, and cracked sulfur, followed by annealing. The as-deposited films were then annealed at 570 °C for 5 min in the presence of 100 mg of sulfur lumps in a rapid thermal processing furnace filled with N2 gas at atmospheric pressure. Solar cells were then fabricated using the CTS films as absorber layers, and their efficiency was evaluated for different Cu/Sn compositional ratios. The largest grain size was found for films with a slightly Sn-rich composition. The highest performance was obtained for solar cells containing a CTS thin film with a Cu/Sn ratio of about 1.9. A cell with a Cu/Sn ratio of 1.87 exhibited an open-circuit voltage of 258 mV, a short-circuit current density of 35.6 mA/cm2, a fill factor of 0.467, and a power conversion efficiency of 4.29%.

A Simplified Thermal Diffusion Process for Making the Silicon p-n Junction Using Sol-Gel Thin Films as the Educational Application

Learning by the actual experience of fabrication and evaluation of a p-n junction is a very effective way for students to obtain a deep meaningful understanding of the fundamentals of semiconductor physics. To achieve this requirement at a real-world classroom situation, a simplified fabrication process for making the silicon p-n junction as the educational application was studied. The process without using the lithography process, and in use of simple thermal diffusion furnace under the air environment for the impurity thermal diffusion process by using phosphorous silicate glass (PSG) thin film prepared by the Sol-Gel material as the phosphorus (P) diffusion source was proposed and tested. As the results, it was obtained that the impurity concentration and diffusion depth were controlled well by this method, and good rectification phenomenon of the p-n junction was successfully observed. The typical diode factor n of the p-n junction was approximately 2.3. The p-n junction also performed well as a solar cell. The FF is approximately 0.7. These results show that it is possible to use the p-n junction prepared by this simplified process as the educational device to help students’ understanding of the theory of the p-n junction.

Inkjet Printing of Microporous Silica Gas Separation Membranes

Inkjet printing was applied to manufacture silica‐based gas separation membranes, which were coated on a pore‐graduated alumina substrate with a mesoporous γ‐alumina interlayer. A silica sol diluted by 1‐propanol was used to print the membrane layer followed by thermal treatment in a rapid thermal processing furnace. The membrane thickness was varied between 30 and 110 nm by conducting one, two, and three coating steps. In the latter case, H2 permeance in the range of 2.0 × 10−8–3.3 × 10−8 mol/s·m2·Pa combined with H2/CO2 selectivities in the range of 15–25 were achieved, proving the concept that inorganic gas separation membranes can be successfully processed by inkjet printing.

A 5.1% efficient kesterite Cu2ZnSnS4 (CZTS) thin film solar cell prepared using modified sulfurization process

AbstractCu2ZnSnS4 (CZTS) absorber thin films are prepared by sulfurization of sputtered Cu/Sn/Zn (CZT) stacked metallic precursor. The modified sulfurization process is adapted to prepare photovoltaic quality CZTS films. Specifically, sputtered CZT precursor films are sulfurized in sulfur powder contained graphite box using rapid thermal processing furnace at 580 °C for 10 min, in N2(95%) + H2S (5%) atmosphere. The Cu‐poor CZTS films with various Cu/(Zn+Sn) ratio are prepared by varying Cu layer deposition time. The effect of Cu/(Zn+Sn) ratio on the properties of CZTS films is investigated. The CZTS thin film solar cells with Cu/(Zn+Sn)=0.76 shows best conversion efficiency of 5.1% (Voc: 573 mV, Jsc: 18.38 mA/cm2, FF: 0.48%, and active area: 0.31 cm2). (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

PECULIARITY OF FORMING TRANSPARENT CONDUCTING FILMS ON BASIS OF OXIDES INDIUM-TIN FOR CONTACTS ON GAN-BASED LIGHT EMITTING DIODES

ITO thin films were prepared by electron beam deposition method over a range of processing conditions. The target material used in this study was an ITO pellet with a composition: In2O3 90 wt% and SnO2 10 wt%. The evaporation conditions were: a vacuum of 5 × 10-4 or 4 × 10-2 Pa and the rate of evaporation were controlled within the range 0.075–0.4 nm/s. The thickness of thin film was controlled by using a quartz crystal thickness monitor, resulting in films having 200 nm. After the deposition, the samples were annealed in a thermal annealing furnace in air or nitrogen at 300-700 оC for 30 s. Experiments aimed at choosing the optimal atmosphere for annealing the films yielded the different results. Indium tin oxide coatings properties were researching as a function of the deposition atmosphere and conditions of a thermal annealing. The ITO films deposited and annealed under the optimized conditions work well as the transparent conducting electrode in the light emitting diodes based on GaN.

Effect of a Second Annealing Process on the Properties of BaTiO3 Thin Films on Polycrystalline Nickel Substrates Grown by Polymer-Assisted Deposition

Ferroelectric BaTiO3 thin films were successfully deposited on nickel foils by a chemical solution technique named polymer-assisted deposition. It is found that a second annealing in oxygen using a rapid thermal annealing furnace would strongly affect the electric properties of the as-prepared thin films. Dielectric and ferroelectric properties have been systematically studied. The correlation between the second annealing conditions and dielectric properties was established and discussed. Optimized second annealing condition was found.

Solution to Problem of Heating of Metal in the Furnace Taking into Account Pulse Nature of Heating

The method of calculation of heating of metal in the thermal furnace taking into account pulse system of heating is presented in article. The experimental dataobtained on the pusher furnace, heated by high-speed recuperative torches with pulse system of burning of fuel are submitted.

Comparison of Oxidation and Thermal Shock Performance of Thermal Barrier Coatings

Operating temperatures in gas turbine engines have reached to 1200°C with the latest developments in coating technology. Thermal shock and furnace oxidation tests are widely used to determine thermal barrier coating (TBC) performance and its durability in aircraft applications. This paper presents the results of thermal shock and furnace oxidation tests, carried out with regard to the microstructure and TGO (thermally grown oxide) growth behavior of TBC systems. Isothermal oxidation behavior of TBCs was evaluated through examination of microstructure, formation, and growth behavior of TGO layers at 1200°C for different time periods in furnace oxidation tests. On the other hand, thermal shock behavior of TBC was evaluated through examination of its durability at 1200°C with thermal shock test, which was carried out until the coating failure became visible. The relationship between the TGO growth and oxidation behavior was discussed using furnace oxidation test results.

Fabrication and Crystal Structure Analysis of a CIGS Solar Cell Absorber by Thermal Annealing of Sputtered CIG Precursors Deposited with a Se Layer

Various Cu(In,Ga)Se2 (CIGS) films were prepared by using in-line sputter for CIG precursor and evaporator for selenization. Deposition parameters are substrate temperature at sputtering process, post annealing temperature (400∼500°C) and annealing method (thermal furnace and high-temperature in-situ XRD). Temperature dependent XRD patterns of the samples were measured with high temperature option and this pattern shows that post annealing at 400∼500°C is necessary for CIGS absorber deposition with no second phase by in-line sputtering. The CIGS film which is annealed at 500°C shows good crystallographic property and there is no second phase like Cu2−xSe.

Imaging of the Asymmetric DC Discharge: Visualization to Adjust Plasma in the Novel PECVD Reactor

Normal asymmetric glow dc discharge in the thermal furnace converted into the efficient PECVD system was imaged to adjust the structure of the plasma column to the two possible localizations of the process zone. The visualization revealed the possibility to use short and long discharge configurations for the plasma-enabled growth and processing of various nanostructures in the modified setup. Images of the discharge in the two localizations are presented.