Preheating Process Research Articles

Structures and dielectric performances of Mn/Y alternately doped BST films prepared by a novel preheating process

Mn (2%, 5%, 8%)/Y (1%) alternately doped BST multilayer thin films have been prepared by a modified sol-gel method on Pt/Ti/SiO2/Si substrates. The effects of Mn doping contents on the structures and dielectric properties of the films are studied by XRD, XPS, FESEM, EDS, and C–V. Meanwhile, a graded preheating (GP) process is designed to modify the conventional preheating (CP) process. It is found that for the two processes, the doped Mn2+ ions first enter into Ti sites and then into Sr sites with an increase of doping content, but the GP process mainly promotes Mn2+ ions to enter into Ti sites independence of the doping content. Therefore, the GP process leads to a more obvious enhancement on nonlinear dielectric properties, in particular a more marked increase in tunability and a more evident decrease in dielectric loss of the BST films. It is implied that the GP process is an effective route to improve the dielectric properties of BST films for the applications of tunable microwave devices. The effects of the CP process with different temperatures on the BST films and the modified mechanisms are also discussed.

Effects of pre-heat conditions on diffusion hardening of pure titanium by vacuum rapid nitriding

The pre-heat treatment in vacuum rapid nitriding process was introduced to improve the surface hardening characteristics such as thick depth, high hardness and particularly to reduce the processing time. The pre-heat treatment was maintained for 30min with an interval of 10°C at the temperatures of 700–800°C under a high vacuum to allow the absorption of oxygen atoms on the titanium surface into the inner side. The following nitriding processes were equally performed at the same condition as 800°C for 1h. As a result, the depth of a hardened layer in the sample, which was treated at 800°C for 1h with the pre-heat treatment at 760°C for 30min, was similar to that of the treated sample at 800°C for 3h without pre-heat treatment and the depth was about 40μm. The processing time can be largely reduced by introducing the pre-heat treatment process. The pre-heated specimens showed a longer wear lifetime by more than three times and higher friction resistance than that of PVD or non-nitrided specimens. The surface gradient-hardened layers exhibited excellent wear resistance and could prevent separation or debonding between matrix and the coated layer effectively.

A size-dependent free volume prediction model of Zr55Cu30Al10Ni5 bulk metallic glass in the supercooled liquid region

The specimen size has a significant influence on the flow behavior of Zr55Cu30Al10Ni5 bulk metallic glass throughout thermoplastic compression processes in the supercooled liquid region. Due to enhanced structural relaxation, the recovery enthalpy increases with specimen size decreasing. Based on combined differential scanning calorimetry experiments and finite element modeling simulations, the different free volume annihilations caused by the specific surface area discrepancy are considered as the main cause of size-dependent free volume variation during the pre-heating process. Thermodynamics and structural relaxation theory are introduced to provide a reasonable explanation of the size-dependent flow behavior at elevated temperatures. A novel prediction model involving size-induced free volume variations has been established by considering the influences of compression deformation variables. The quantitative theoretical prediction agrees well with experimental data, which indicates that the developed prediction model can accurately describe the size-dependent free volume annihilation and generation during the thermoplastic forming process. Furthermore, the reasonable theoretical analysis and size-dependent free volume prediction model provide a profound understanding of the size-dependent flow behavior and its relation to internal structural evolution behaviors of metallic glasses.

Electronic Weight Propose for UV Lights Based on UV Dosage, Applied to Intake Water Purifier

This paper exhibits a planning philosophy for electronic balance connected to UV (ultraviolet radiation) lights for a drinking water purifier, giving customizable UV dosage keeping in mind the end goal to guarantee the inactivation of microorganisms' multiplication, generally found in untreated water, which can be hurtful to human wellbeing. The outline strategy depends on the MSSS (Multiple Segment Summation Source) display, utilized for characterizing the UV dosage connected to penstock purifiers, considering drenched lights on a water slide fenced in area, which in blend with its pressure driven conduct, give a decent execution to the microorganisms UV assimilation along the whole purifier structure pipes. In this manner, an electronic weight that ensures a controlled preheating process for the UV light terminals before its start and sets the ostensible control point on the unfaltering state was actualized in a request to provide the planned UV measurement.

Investigation of factors affecting drying characteristics of pellets made from iron-bearing converter sludge

High initial moisture in converter sludge enhanced the bursting risk during drying and made this process difficult. In this investigation, effects of parameters on their drying properties were studied through orthogonal tests in a baking cup equipped with a cross flow adjusting system to simulate the two stage thermal condition in a travelling grate. The upper layer bursting rate and the bottom layer dehydration rate are considered as main indicators of drying performance. ANOVA results show that factors of temperature in the 2nd drying and time in the 1st drying have remarkable influence on the upper bursting rate, occupying 45.80 and 34.82% of the total contribution. While time and flow rate in the 2nd drying are significant factors on the bottom dehydration rate, accounting for 56.09 and 27.03%. Additionally, the upper bursting rate decreases with the increasing 1st drying time and decreasing 2nd drying temperature. The bottom dehydration rate increases with the increase of 1st drying time, 2nd drying time and 2nd drying flow rate. Under the optimal condition of temperature 150°C, flow rate 1.5 m s−1, time 9 min in the 1st drying stage, and temperature 200°C, flow rate 1.5 m s−1, time 6 min in the 2nd stage, no burst occurs, and the bottom dehydration rate is as high as 88.81%. These results could be used as the basis for subsequent preheating and reduction process.

Penelitian Penggunaan Bahan Bakar Nabati (Bbn) pada Mesin Diesel Stasioner sebagai Upaya Mengurangi Ketergantungan terhadap Bahan Bakar Minyak

Research on used biofuel for stationary diesel engine as an effort to reduce defendency fuel oil has been done. The objective is to stationary diesel engines are widely used by farmers for tractors and other farm machinery can be use d biofuel as a substitute fuel oil . The research method was taken, consist of : (1) pressing and degumming process, (2) viscosities test, (3) effect the use jathropa curcas as fuel to the diesel engine component, namely : plunger and plunger housing, injector, cylinder head, piston and oil. The jathropa curcas which become fuel for engine diesel must be passing on pre-heating process at converter before goes to high pressure fuel pump (bosch pump). The aim of pre-heating process is to decrease the viscosity value of vegetable oil to be equal with diesel fuel. Based on endurance test for 17 hour, fit to SAE Paper No.942010 showed that engine diesel can be running well and performance can not change which is significant but there was much more deposit at piston head that is 12.55% compare to diesel fuel.

전자빔을 이용한 Stellite21 분말 예열공정에 관한 기초 연구

A powder spreading phenomenon is one of disadvantageous characteristics of the powder bed fusion process using electron beams. The powder spreading phenomenon can be controlled using a pre-heating process of metallic powders. The aim of this paper was to investigate the pre-heating process of Stellite21 powder using electron beams. Powder spreading experiments were performed to examine the influence of process parameters on the spreading behaviors of Stellite21 powder. Powder heating experiments were carried to investigate the effects of the focusing current of the electron beam on the quality of the heated region. Using the results of the powder spreading and heating experiments, an appropriate combination of process parameters was obtained. The pre-heating experiment of Stellite21 was performed using the estimated combination of process parameters. The results of preheating experiments showed that the pre-heated Stelllite21 layer with desired characteristics can be created when the estimated combination of process parameters is applied.

Finite Element Analysis of Heat Transfer Effects on Asphalt Pavement Heated by Pre-Heater Unit Used in Hot In-Place Recycling

PURPOSES: The national highways and expressways in Korea constitute a total length of 17,951 km. Of this total length of pavement, the asphalt pavement has significantly deteriorated, having been in service for over 10 years. Currently, hot in-place recycling (HIR) is used as the rehabilitation method for the distressed asphalt pavement. The deteriorated pavement becomes over-heated, however, owing to uncontrolled heating capacity during the pre-heating process of HIR in the field. METHODS: In order to determine the appropriate heating method and capacity of the pre-heater at the HIR process, the heating temperature of asphalt pavement is numerically simulated with the finite element software ABAQUS. Furthermore, the heating transfer effects are simulated in order to determine the inner temperature as a function of the heating system (IR and wire). This temperature is ascertained at , , , , , and from a slab asphalt specimen prepared in the laboratory. The inner temperature of this specimen is measured at the surface and five different depths (1 cm, 2 cm, 3 cm, 4 cm, and 5 cm) by using a data logger. RESULTS: The numerical simulation results of the asphalt pavement heating temperature indicate that this temperature is extremely sensitive to increases in the heating temperature. Moreover, after 10 min of heating, the pavement temperature is 36%~38% and 8%~10% of the target temperature at depths of 25 mm and 50 mm, respectively, from the surface. Therefore, in order to achieve the target temperature at a depth of 50 mm in the slab asphalt specimen, greater heating is required of the IR system compared to that of the gas. CONCLUSIONS : Numerical simulation, via the finite element method, can be readily used to analyze the appropriate heating method and theoretical basis of the HIR method. The IR system would provide the best heating method and capacity of HIR heating processes in the field.

Effect of initial temperature on joint of aluminum alloy to galvanized steel welded by MIG arc brazing-fusion welding process

The variation of initial temperature of the base metal is conducted by a preheat treatment process, and its effect on metal insert gas (MIG) arc dissimilar metal brazing-fusion joint of aluminum alloy (Al) to steel plate is studied. Results show that though increasing the initial temperature of base metal, the joint appearance improves and wetting ability of liquid Al on steel becomes better. Three different zones are observed at brazed interface in all the joints. Zn-rich zone at weld toe and Zn-rich zone at weld root are characterized by the existence of Zn, while central zone is identified due to the formation of intermetallic compounds (IMCs) layer. The IMCs layer becomes thicker with the rise of initial temperature because of the increased peak temperature. At the initial temperature of 100 °C, the joint achieves the highest tensile strength of 180 MPa, which is equivalent to 80 % of that of Al alloy base metal and fractures at heat affected zone on Al side. The initial temperature of base metal influences the mechanical properties and fracture position of the joint through governing the thickness of IMCs layer and wetting ability of liquid Al alloy on the surface of steel.

Electronic Ballast Design for UV Lamps based on UV Dose, applied to Drinking Water Purifier.

This paper presents a design methodology for an electronic ballast applied to ultraviolet radiation (UV) lamps for a drinking water purifier, providing adjustable UV dose in order to ensure the inactivation of microorganisms’ reproduction, commonly found in untreated water, which can be harmful to human health. The design methodology is based on the multiple segment summation source model, used for defining the UV dose applied to penstock purifiers, considering immersed lamps on a water slide enclosure, which in combination with its hydraulic behavior, provide a good performance for the microorganisms UV absorption along the entire purifier structure ducts. Thus, the water purifier was designed using hydrostatic simulations, in order to ensure compliance with the NSF/ANSI Standard 55, for commercial and residential applications. Thereby, an electronic ballast that guarantees a controlled preheating process for the UV lamp electrodes before its ignition and sets the nominal power point on the steady state, was implemented in order to guarantee the designed UV dose. Furthermore, the ballast incorporates a power factor correction flyback input rectifier stage, in discontinuous conduction mode, with universal input voltage range (90 V $_{\text{rms}}$ –240 V $_{\text{rms}}$ ), attending the limits imposed by IEC 61000-3-2 Standard, for class-C devices.

Optimization of Solar Integration in Biomass Fuelled Steam Plants

This paper is focused on solar-biomass integration and presents a thermodynamic analysis of solar power utilization replacing the steam bleeds of a regenerative Hirn cycle plant, biomass fuelled, in feedwater pre heating process. In solar-biomass integrated configuration an energy conversion efficiency of solar energy has been evaluated in order to compare the use of solar energy in solo and hybrid configurations. Such efficiency has been adopted as optimization parameter for the best hybrid plant configuration, varying steam pressure and regeneration parameters.

Investigation of the correlation between dielectric function, thickness and morphology of nano-granular ZnO very thin films

Thin nano-granular ZnO layers were prepared using a sol–gel synthesis and spin-coating deposition process with a thickness ranging between 20 and 120nm. The complex dielectric function (ϵ) of the ZnO film was determined from spectroscopic ellipsometry measurements. Up to a critical thickness close to 60nm, the magnitude of both the real and the imaginary parts of ϵ rapidly increases and then slowly tends to values closer to the bulk ZnO material. This trend suggests a drastic change in the film porosity at both sides of this critical thickness, due to the pre-heating and post-crystallization processes, as confirmed by additional characterization of the structure and the morphology of the ZnO films.

Effects of preheat treatment on microstructure evolution and properties of brazed-fusion welded joint of aluminum alloy to steel

Microstructure and mechanical properties of brazed-fusion welded joint of aluminum alloy to galvanized steel were studied by analyzing and comparing the as-welded state and that with preheat treatment at different temperatures. The preheat treatment process not only increased the spreadability of weld seam and thickness of intermetallic compound (IMC) layer at brazed interface but also changed phase composition of IMC layer. In as-welded joint, there were two IMC layers (layer I included θ-Fe4Al13 and τ5-Al8Fe2Si adjacent to weld seam, and layer II was composed of η-Fe2Al5 near the steel side), while a newly formed nanoscale Fe-rich layer III which might consist of FeAl and Fe3Al was found in the joint with preheat treatment, causing by interdiffusion between layer II and Fe at high temperature. Incomplete brazing at weld root deteriorated the strength of as-welded joint. The joint with preheat treatment at 100°C, fractured at heat-affected zone on aluminum alloy side, exhibited the highest strength which reached nearly 80% of that of aluminum alloy. The thicker IMC layer at weld root led to the fracture at brazed interface when preheat treatment at 200°C.

Fabrication of bismuth copper vanadate electrodes through feasible chemical solution method for visible light-induced water oxidation

Film electrodes of a ternary metal oxide, bismuth copper vanadate (BiCu2VO6), were fabricated directly on FTO (fluorine-doped tin oxide glass) substrates by a chemical solution method using precursor solution of the component metal ions. To improve the purity of BiCu2VO6 films, temperature and time in pre-heating process were carefully selected by thermogravimetric and differential thermal analysis and X-ray photoelectron spectroscopy of the precursor film. The fabrication of pure BiCu2VO6 films keeping tight contact to the FTO substrate was confirmed by X-ray diffraction, cross-sectional scanning electron microscope images, and scratching the film using a soft paper. The band gap energy E g = 2.10 V and the flat band potential U FB = 0.43 V (vs. SHE at pH 0) for BiCu2VO6 were obtained. For the photoelectrode, wavelength dependence of the incident photon to current efficiency (IPCE) corresponded to the absorption spectrum, and the IPCE exhibited several-folds larger values than those of the electrode fabricated by depositing BiCu2VO6 particles on an FTO substrate.

Process integration analysis and some economic-environmental implications for an innovative environmentally friendly recovery and pre-treatment of steel scrap

The use of Zinc-coated steel (e.g. galvanized steel) in melting cycles based on Electric Arc Furnaces can increase the production of harmful dust and hazardous air emissions. This article describes a novel process to simultaneously preheat and remove the coating from the scrap surface before the melting phase. The zinc in coating is removed in the gas phase by chloride containing syngas combustion and collected in a dedicated recovery system. Two possible innovative process routes are described, which involve plastic waste pre-treatment, shredded plastic gasification/pyrolysis, steel scrap preheating and zinc recovery processes. The routes have been modeled in an integrated flowsheet, in order to allow a comprehensive simulation and optimization of the pretreatment processes. The process optimization results in possible energy savings of over 300MJ/t of preheated scrap charged in the Electric Arc Furnace for steel production. Moreover, a comparison among different scenarios according to economic and environmental criteria has been carried out.

Thick tungsten coating on ferritic–martensitic steel applied with a vacuum plasma spray coating method

The characteristics of thick tungsten layers coated onto ferritic–martensitic (FM) steel blocks using a vacuum plasma spray system were investigated. Because of the large differences in thermal properties between tungsten and FM steel, it is difficult to coat a thick tungsten layer onto FM steel without delamination or detachment of the coated layer from the substrate. To avoid detachment of the tungsten layer from the FM steel surface, the optimization of the coating process was studied in this work. The tungsten layer having a 3.7mm thickness was coated using 43kW DC torch power at 16kPa of chamber pressure with a mixture of argon, hydrogen, and helium. The adhesion between the coating layer and the FM steel was enhanced by inserting pre-heating process before coating process, which increased the penetration of molten tungsten droplets into the FM substrate. The hardness of the coating layer was about 380–400HV, which was 80 to 95% of the hardness levels for commercial bulk tungsten monoblocks, and the porosity, purity, and morphology properties of the tungsten coating layer were also discussed. To evaluate the homogeneity of the layer bonding between the FM steel and the tungsten coating layer, an ultrasonic test was also performed.

The Effect of Aluminum Concentration on The Phase Evolution of The Ternary Ceramics Of (Ti-Al-C) System

In this work it has been tried to introduce this type of new materials as reproducible industrial materials and overtake some production obstacles by exploring on the direction of chemistry structure relation. In this study composition was prepared from elemental powders (Titanium, Aluminum and carbon black) by using the powder metallurgy techniques, under different concentration due to the change in the Ti to Al concentration. The concentrations are (10% Al-80%Ti-10%C), (20%Al-70%Ti-10%C) and (30%Al-60%Ti-10%C).A compacted sample were formed in cold press using a 30ton followed by heat treatment started from (600˚C, 800˚C, 1200˚C and end in 1400˚C). The effect of Al concentration on phase evolution in the Ti-Al-C system has been investigated and the effects of cold pressing as well as heat treatment have been investigated. X-ray diffraction (XRD) and SEM technique we used for phase evolution. The density and porosity percentage were calculated using Archimedes method, also the micro hardness was measured under that different process. The XRD, SEM data shows that, by increasing the Al concentration intermediate phases like TiAl3 and/or TiAl appear to be stable instead of the H phase. By raising the temperature, transformations accurse to produce both MAX phase structures in this system Ti2AlC and Ti3AlC2. This production pathway from the intermediate phase to ternary phase is suggested to be the more accepted, and it depends on atomic mobility. No evidence for the direct formation of MAX phases from elemental powders is found which may explain the need of high temperatures to produce such phases since the breaking of bonds is required for the intermediate phase. Finally, the use of pre-heating process decreases the temperature of formation of the MAX phases with the effect of the highest Al concentration.

Numerical study of cullet glass subjected to microwave heating and SiC susceptor effects. Part II: Exergy transfer analysis

The mathematical model of exergy transfer in cullet glass heated by microwave inside of a cubical cavity with the aid of a susceptor is presented. Part I of this paper presented a numerical combined electromagnetic and heat transfer model by applying both transient Maxwell’s equations and heat transfer equations. Then, the electromagnetic and temperature fields were used to obtain the exergy transfer analysis in the oven. Exergy transfer analysis informs us about the efficiency of energy transformations taking place during the heating process, since it explains how the quality of the energy behaves along the heating process. The rate of internal exergy, exergy flowing and destroyed exergy were obtained and presented for this transient process. Part I showed that the susceptor location could change the temperature fields of cullet glass. So, an exergy analysis is important to understand the irreversibilities produced by a susceptor during preheating (microwaves activation) and heating process of the cullet glass, and how they could be minimized. Exergy transfer analysis shows how both, electromagnetic and heat transfer, are responsible of the irreversibilities generated in the heating process.

Experiment verified simulation study of the operating sequences on the performance of adsorption cooling system

In this study, simulation was conducted to investigate the effect of heat recovery, mass recovery, pre-heating and pre-cooling processes and their combinations on the system performance of a double-bed adsorption cooling system. The model developed consists of pressure variations and detailed compressible flow with flow resistance, which other similar studies had not taken into consideration, thus a detailed simulation of mass recovery, and pre-heating and pre-cooling processes is included in this study. A double-bed adsorption cooling system with silica gel and water as adsorbent-adsorbate pair was built for verifying the simulation models. Based on the simulation results, it was found that the basic cycle provided a COP and SCP of 0.20 and 57.6 W/kg, respectively. By conducting heat recovery for 30 seconds, the COP was increased by 20% to 0.24 compared to the basic cycle. The SCP was also increased to 66.4 W/kg, a 15% increase. The major advantage through conducting the mass recovery is in the SCP, whereby it was increased by 40% to 80.8W/kg. Additionally, performing only the pre-heating and pre-cooling process can also bring some benefits to the system. Therefore, for adsorption cooling systems that cannot carry out the mass recovery and/or heat recovery cycles, performing pre-heating and pre-cooling process only is recommended. This not only can reduce the cost, but also simplify the control program of the systems. Moreover, mass recovery followed by pre-heating and pre-cooling cycle is highly preferred when the SCP is the optimization target, since the SCP was hugely increased by 41% to 81.4 W/kg.

Dynamic study of steam generation from low-grade waste heat in a zeolite–water adsorption heat pump

A novel zeolite–water adsorption heat pump system based on a direct-contact heat exchange method to generate steam from low-grade waste gas and water has been proposed and examined experimentally. Superheated steam (200 °C, 0.1 MPa) is generated from hot water (70–80 °C) and dry air (100–130 °C). A dynamic model for steam generation process is developed to describe local mass and heat transfer. This model features a three-phase calculation and a moving water–gas interface. The calculations are carried out in the zeolite–water and zeolite–gas regions. Model outputs are compared with experimental results for validation. The thermal response inside the reactor and mass of steam generated is well predicted. Numerical results show that preheat process with low-temperature steam is an effective method to achieve local equilibrium quickly, thus generation process is enhanced by prolonging the time and increasing mass of the generated steam. Besides, high-pressure steam generation up to 0.5 MPa is possible from the validated dynamic model. Future work could be emphasized on enhancing high-pressure steam generation with preheat process or mass recovery operation.