Incandescent Tungsten Filament Research Articles

Low-Cost Radiant Heater for Rapid Response, High-Temperature Heating

High-temperature processing has an irreplaceable role in many research and industrial applications. Despite remarkable development spanning over a century, the pursuit of even higher thermal flux density and more rapid thermal transients has not slowed down. As part of the ongoing energy evolution, many industrial applications are transitioning from direct combustion of fossil fuels as primary energy sources to increasing electrification, capable of adapting to renewable power grids. Thus, there is an emerging need for electrical heaters that can replace burners and supply the heat demand, especially at the highest temperatures. In this study, we report on a radiant heater design that can achieve cyclic heating/cooling rates of up to 400 K min–1 and a temperature range in excess of 1,800 K, comparable to those of commercial infrared gold image furnaces, at high surface and volumetric power densities. The heater consists of a modular unit of incandescent tungsten filament and is enclosed in an evacuated ceramic envelope, chemically inert, tolerant of thermal shock, and impervious to gasses. The material and manufacture cost of such heaters, which is estimated at ∼$0.05/W, is less than 0.03% of that for infrared gold image furnaces, which is at >$2/W. Tests of more than 10,000 demanding cycles (high temperature and high heating/cooling rate) over 350 h of total operational time and in different temperature ranges confirm the robust performance of radiant heater prototypes. The design is widely applicable to high-temperature reactor and furnace designs. In thermochemistry research and practice, these radiant heaters could offer multiple benefits compared to solar simulators, lasers, infrared gold furnaces, ceramic heaters, or direct concentration of solar input.

Tailoring high-temperature radiation and the resurrection of the incandescent source.

In solar cells, the mismatch between the Sun's emission spectrum and the cells' absorption profile limits the efficiency of such devices, while in incandescent light bulbs, most of the energy is lost as heat. One way to avoid the waste of a large fraction of the radiation emitted from hot objects is to tailor the thermal emission spectrum according to the desired application. This strategy has been successfully applied to photonic-crystal emitters at moderate temperatures, but is exceedingly difficult for hot emitters (>1,000 K). Here, we show that a plain incandescent tungsten filament (3,000 K) surrounded by a cold-side nanophotonic interference system optimized to reflect infrared light and transmit visible light for a wide range of angles could become a light source that reaches luminous efficiencies (∼40%) surpassing existing lighting technologies, and nearing a limit for lighting applications. We experimentally demonstrate a proof-of-principle incandescent emitter with efficiency approaching that of commercial fluorescent or light-emitting diode bulbs, but with exceptional reproduction of colours and scalable power. The ability to tailor the emission spectrum of high-temperature sources may find applications in thermophotovoltaic energy conversion and lighting.

One-pot synthesis of three bismuth oxyhalides (BiOCl, BiOBr, BiOI) and their photocatalytic properties in three different exposure conditions

AbstractBiOCl, BiOBr, and BiOI have been synthesized by wet chemical route using bismuth nitrate (Bi(NO3)3.5H2O) and potassium halides, KCl, KBr, and KI, using a mixture of de-ionized water and ethanol as the solvent. Synthesized samples were characterized by X-ray diffraction and high-resolution SEM to observe the crystalline phase and crystallite size. Effective surface areas of the synthesized samples were estimated by Brunauer–Emmett–Teller studies. Photoactive properties of these samples were studied under three types of light exposure conditions viz. UV light from mercury vapour lamp, natural sunlight, and visible radiations from a 100-W incandescent tungsten filament. Degradation of methyl orange (MO) in aqueous media was estimated spectrophotometerically in visible range from the area under the curve with a peak at 464 nm. Kinetic constant for degradation reaction was calculated assuming the pseudo-first-order degradation mechanism. It was revealed that all the three samples show excellent degrada...

Heat and mass transfer processes in incandescent lamps and development of gas mixtures for their filling

A model of a working gas medium for incandescent lamps (ILs) is described. Within the framework of the molecular-kinetic theory, with the help of Langmuir's concept of a stagnant layer about the incandescent tungsten filament, the mathematical model of heat and mass transfer processes for quasistationary operating conditions of the IL was formulated. In this case, the thermodiffusion contribution to tungsten mass transfer and temperature-dependent transfer coefficients of a working mixture were taken into account. With the solution of the transfer equations, the design formulas for the integral heat flux (loss) from the incandescent body and the integral mass flow of tungsten atoms through a filling gas in the IL containing a cylindrical (spherical) incandescent body were obtained. Based on the calculated heat losses from the incandescent body and mass transfer speed of the tungsten atoms in different gas media, effective compositions of multicomponent filling mixtures (N 2 -Ar-Kr and N 2 -Ar-Kr-Xe) are developed for commonly used bispiral krypton general-purpose ILs. Their applications allow the reduction of the cost of the lamps, while the luminous efficacy and the operating life of the lamps are the same as (or better than) those of lamps with the standard filling mixtures, N 2 -Kr.

The influence of a thin gold film on vibrational excitation of hydrogen molecules

The vibrational populations have been measured for hydrogen molecules issuing from a cell containing a mixture of atomic and molecular hydrogen in the presence of an incandescent tungsten filament. The cell walls were covered with a gold film by in situ evaporation. The gold film was observed to exist in two forms, the first being transformed irreversibly into the second by annealing. The observed behavior of the vibrational populations differed from those observed previously with other metals in that the relative distributions depended on the filament temperature. This behavior was interpreted as being the result of either special characteristics of the hydrogen–tungsten interaction at the filament or the presence of a potential barrier in the reaction path for the formation of hydrogen molecules by the process of recombinative desorption.

Chemical vapor deposition of novel electronic materials from carbon disulfide

An organic amorphous semiconductor with unusual electrical switching capability has been synthesized by the direct decomposition of carbon disulfide. Metallic black highly conducting (above 10 2 Ω −1 cm −1) thin films of approximate composition C 3S have been prepared by the simple passage of dilute carbon disulfide vapors over an incandescent tungsten filament. Film growth rates greater than 10 μm h −1 are observed. The coatings are hard, adherent on a wide variety of substrates, thermally stable, and remarkably inert to all but the most severe mineral acid digestion. The carbon sulfide solids behave like varistors, following Ohm's law over many decades of current up to a threshold voltage, typically 1–10 V, beyond which the current surges, independent of applied voltage. The threshold voltage is uniquely temperature dependent, reaching a maximum as the temperature is reduced from room temperature, then decreasing once again at cyrogenic temperatures.

A New Detector-based Spectral Emission Scale

The realization of a new detector-based scale of spectral radiant power with an uncertainty of ± 0,1% is described. The paper reports the use of novel dye laser techniques to characterize the spectral responsivity of a number of interference filter radiometers. These were used to relate the spectral power distribution of a number of incandescent tungsten filament lamps to the spectral responsivity scale realized by the NPL cryogenic radiometer. The results of the new realization have been compared with the previous NPL spectroradiometric and photometric scales, and showed agreement within their estimated uncertainties.

Reaction of hydrogen atoms with oxygen adsorbed on Cu(110)

The kinetics of the reaction of hydrogen with oxygen adsorbed on a Cu(110) surface was studied at room temperature with AES and ISS. The reaction proceeded only when H 2 was predissociated by an incandescent tungsten filament. The reaction rate was first order in oxygen coverage and approximately half-order in H 2 pressure, indicating that the rate determining step is the reaction between hydrogen atoms and oxygen. Variations of the initial coverage of adsorbed oxygen did not measurably affect the calculated rate coefficient.

Modern radiation thermometers: calibration and traceability to national standards

Abstract

ChemInform Abstract: ADSORPTION AND RECOMBINATION OF HYDROGEN ATOMS ON GLASS SURFACES. PART 1. METHOD OF STUDY AND THE MECHANISM OF RECOMBINATION AT 77 AND 273 K

AbstractDie Mechanismen der H‐Atomrekombination an der Oberfläche eines Pyrex‐Kölbchens (1 dm3) werden durch Verfolgung der Druckänderungen während und nach der Dissoziation von H2 an einem weißglühenden W‐Draht in einer UHV‐Apparatur (10‐5‐10‐3N m‐2 H2) untersucht.

Adsorption and recombination of hydrogen atoms on glass surfaces. Part 1.—Method of study and the mechanism of recombination at 77 and 273 K

The mechanisms by which hydrogen atoms recombine on the surface of a 1 dm3 Pyrex glass bulb have been studied by following the changes in pressure during and after dissociation of molecular hydrogen at an incandescent tungsten filament. Experiments were conducted in a system capable of ultra high vacuum using hydrogen pressures in the range 10–5–10–3 N m–2.

A spectroscopic study of the pulsed gas discharge in crossed electric and magnetic fields

The pulsed gas discharge in crossed electric and magnetic fields was studied spectroscopically in the wavelength range between 3100 and 4660 Å. A 5 μF, 800 V condenser bank was discharged through a cylindrical magnetron with an incandescent tungsten filament operated at argon pressures between 5 × 10−5 and 5 × 10−4 Torr. The axial magnetic field was 600 G. The spectrum contains lines of ionized argon; no atomic argon lines were observed. Ionized oxygen and atomic lines of tungsten were the main impurities. All wavelengths emitted by the pulsed discharge lie between 3900 and 4660 Å. The majority of ion lines have upper 4p states (in the case of ArII) and 3p states (in the case of OII).

Sticking probability of light hydrocarbons on tungsten

Hydrocarbons were decomposed on the surface of an incandescent tungsten filament in a low pressure flow reactor. The rate of conversion of tungsten to ditungsten carbide W2C was measured by a resistance method. Carbon accumulation on the outer W2C surface was prevented by rapid inward diffusion. The sticking probability γ was defined as the probability that a room temperature hydrocarbon molecule striking the hot W2C surface would undergo complete decomposition to carbon and hydrogen. The value of γ for different hydrocarbons, measured over a 300-fold range of conversion rates, increased in the order: methane<propane≃cyclopropane<neopentane. Mixing of hydrogen gas with the hydrocarbon reactant markedly increased γ. For example, at a filament temperature of 2610°K, γ increased from 6.4 × 10–3(methane only) to 2.6 × 10–2(methane plus hydrogen). This novel effect is explained by carbon patches on the W2C surface. These patches are associated with low values of γ but can be removed by adsorbed hydrogen.

Spectral Reflectance Measurement of Fluorescent Matersals

Spectrophotometric methods with monochromatic light sources are being widely used in dyestuff and paint industries for the measurement of fluorescent characteristics of materials. These methods are not practical when we wonder how the characteristics would be in sunlight or under incandescent tungsten-filament and fluorescent lamps.A new type fluorescence reflectance measuring attachment for recording spectrophotometers is devised. As the light source, a 500 W Xe lamp regarded as the nearest approach to the sunlight is used.The light falls perpendicularly on the sample and a standard white surface simultaneously and the reflected lights in 45° direction fall alternately on the slit of the recording spectrophotometer by means of a set of plane and concave mirrors.Curves of spectral reflectance in a range of 370-700 mμ are recorded on charts.Several colored samples of fluorescent and non-fluorescent finished sheets of cloth have been measured and the results are compared with the data obtained on a Hardy-type spectrophotometer.

Interaction of Hydrogen with Tungsten

Measurements have been made under ultra-high vacuum conditions of the rates and isotherms for the adsorption of hydrogen on tungsten, the rate of desorption of hydrogen from tungsten, and the rate of formation of atomic hydrogen by an incandescent tungsten filament. When hydrogen chemisorbs on tungsten at 77°, the sticking probability is 0.1 and two distinct states of binding, α and β, may be isolated at adsorption pressures as low as 2.5×10—9 mm. Analysis of desorption kinetics of the most tightly bound state, β, shows that hydrogen chemisorbs as atoms since evaporation is second order in adsorbed hydrogen. For nβ&amp;lt; 30×1012 molecules/cm2, vM=(5×10−3)n2exp(−31 000/RT) molecules/cm2-sec. At higher coverages, a decrease in heat of desorption is observed which is due to surface heterogeneity. At equilibrium, the amount adsorbed in the β state obeys a Temkin isotherm between 273° and 373°K; evaporation of hydrogen in the β state occurs down to temperatures as low as 77°K. Isosteric heats agree with heats derived from desorption measurements. The α state, populated before the β state is saturated at 77°K, is proportional to hydrogen pressure and probably consists of molecular hydrogen on top of the primary atomically chemisorbed layer. The rate of evaporation of atomic hydrogen when the filament temperature is raised above 1100°K is vA=(2.2×1013)n exp(−67 000/RT) molecules/cm2-sec. For pressures below 10—7 mm and filament temperatures above 1475°K, the fraction of molecules striking the filament surface that is dissociated is constant and at least 0.05. Values of surface coverage and the rate of formation of atomic hydrogen as a function of filament temperature and hydrogen pressure are derived from experimental data.

The adsorption of methane by barium films in the presence of a thermionic current

The adsorption of methane at pressures of 7×10 -7to 7×10 -6torr has been studied both in the presence and absence of a thermionic current drawn from a tungsten filament, using the capillary flow method of Wagener, and maintaining the pressure over the barium film constant. The pumping speeds of barium films covering up to 160 cm 2 and up to 20 mg in weight under normal conditions were very small and were less than 5 cc/sec at 1.5×10 -6 torr. The presence of an incandescent tungsten filament caused a slight increase in pumping speed of the barium films of about 10–20 cc/sec. Drawing an emission current from the filament appreciably increased the pumping speed of the getter, the increase amounting to 70–100 cc/sec at 1.5×10 -6 torr with a current of 5 mA. The pumping speed was independent of the area and weight of barium film but was approximately proportional to the thermionic current; it was almost independent of the pressure, up to 7×10 -6 torr, and hence the adsorption rate (pumping speed × pressure) was roughly proportional to pressure. The results show that the adsorption rate on barium films of methane activated by electron impact is determined entirely by the frequency of electron-gas molecule collisions. It is not known whether the active species consists entirely of ions or whether non-ionized radicals and molecules resulting from the decomposition of methane are involved.

Interaction of Atomic Hydrogen with Glass

An omegatron ion resonance mass spectrometer has been used to study residual gases in an ultra-high vacuum system. Atomic hydrogen, produced from molecular hydrogen by an incandescent tungsten filament, reacts with glass to produce contaminant molecules, CO, H2O, and CH4, whose presence seriously interferes with studies of surface phenomena. Such spurious effects are substantially reduced by substituting a lanthanum boride-coated tantalum filament for the tungsten electron source of an ionization gauge used to measure pressures of hydrogen. Quantitative measurements of the binding of atomic hydrogen by glass show the existence of two distinct binding sites of nearly equal population that are occupied simultaneously at low surface coverages and low temperatures. The rate of recombination of atomic hydrogen bound to glass is proportional to the number adsorbed and is much smaller than the rate of recombination of atomic hydrogen impinging on a glass surface from the vapor phase.

Noise and Electron Temperatures of Some Cold Cathode Argon Discharges

Noise temperatures at 3000 Mc were compared with the corresponding electron temperatures for the positive columns of some cold cathode discharges in argon. The noise temperatures were measured using a superheterodyne receiver of low noise figure, by comparing the noise outputs of the various tubes with that from a commercial fluorescent lamp of measured noise output, a rapid comparison between known and unknown noise powers being effected by means of a hand-operated wave-guide switch. The noise temperature of the fluorescent lamp in its mounting was measured by comparison with an absolute standard consisting of an incandescent tungsten filament lamp fitted in a suitable wave-guide holder. Electron temperatures were measured by the Langmuir single-probe method. It is concluded that for most of the tubes measured, noise temperature, and electron temperature are in close agreement as required by the theories.

Cleanup of Atomic Hydrogen

When hydrogen is dissociated by an incandescent tungsten filament in a glass tube, some of it is cleaned up if the tube is cooled in liquid air. The amount cleaned up can be greatly increased by coating the inner wall with mercury or copper. In one experiment the amount cleaned up in cold mercury was equivalent to 14 monolayers of atomic hydrogen. The cleanup proceeded at a diminishing rate until the pressure fell to the value at which hydrogen left the mercury as fast as it entered. When hydrogen was cleaned up in a very thin coating of mercury there were 1.5 to 1.8 atoms of mercury per atom of hydrogen. All the cleaned-up gas was recovered when the tube was brought to room temperature. After cleanup in copper there was little recovery until the temperature rose above —150°K.

Motion Picture Studio Lighting and Process Photography Report

THE BASIC COLOR sensitivity of the Technicolor process has been changed to a color temperature of 3350 K. When white light sources, such as sunlight, are used, the camera optical systems are filtered for proper balance. Incandescent tungsten filament lamps of the proper color temperatures are used unfiltered. When carbon arcs are used mixed with unfiltered tungsten lamps it becomes necessary to filter the carbon arcs to the lower color temperature. This is accomplished by using one MT-2 and one Y-1 filter on all high-intensity arc spotlamps and one MT-2 filter only on Duarc flood lamps. It is possible, however, to filter the camera optical train for sunlight balance and use the carbon-arc floodlamps unfiltered, the high-intensity carbon-arc spotlamps with only a Y-1 light yellow straw filter, and to filter the incandescent lamps with whiterlite filters as in the past. This gives the system a greater latitude so it may be used with incandescent tungsten lamps alone, where desired, at a key-light level as low as 150 ft-c; or with carbon arcs, or sunlight, with a key-light level of 300 ft-c; or with mixed lighting in either case provided the light sources are all adjusted to the balance of the particular camera filter system.