Heating wire

Finally, the beam — composed mainly of single substrate and solvent molecules and very small clusters — is passed through a heated wire grid, where the last declustering and desolvation occurs, leaving a beam of substrate molecules. 

The major methods used for vaporization (ablation) include lasers, electrically heated wires, or sample holders and electrical discharges (arcs, sparks). 

The equihbrium is reversed at high temperature. The iodide is decomposed by passing the vapor over an electrically heated wire (1300—1400°C), yielding purified sohd titanium and iodine gas which is recycled. The iodide process also appHes to the purification of zirconium, hafnium, and siUcon. 

Materials and Reactions. Candle systems vary in mechanical design and shape but contain the same genetic components (Fig. 1). The candle mass contains a cone of material high in iron which initiates reaction of the soHd chlorate composite. Reaction of the cone material is started by a flash powder train fired by a spring-actuated hammer against a primer. An electrically heated wire has also been used. The candle is wrapped in insulation and held in an outer housing that is equipped with a gas exit port and rehef valve. Other elements of the assembly include gas-conditioning filters and chemicals and supports for vibration and shock resistance (4). 

Fig. 10. Free2e drying profiles for A, whole milk, and B, nonfat milk. Heat was transmitted by radiation from heated wires above the fro2en milk which rested in a transparent plastic tray. (-----------------------) is the induction period. Total pressure was 33 Pa (0.25 mm Hg).

MI Cables (mineral insulated cables. Fig. 10-181) are the electric heat tracers of choice for high-temperature applications. High-temperature applications are generally considered to maintain temperatures above 250°F or exposure temperatures above 420°F where self-regulating heaters cannot be used. MI cable consists of one or two heating wires, magnesium oxide insulation (from whence it gets its... 

Heiz-dampf, m. steam for heating, -draht, m. heating wire hot filament. 

Cyclic Oxidation In many industrial applications it is particularly important for the component to be resistant to thermal shock for example, resistance-heating wires or blading for gas turbines. Chromia, and especially alumina, scales that form on nickel-base alloys are prone to spalling when thermally cycled as a result of the stress build-up arising from the mismatch in the thermal expansion coefficients of the oxide and the alloy as well as that derived from the growth process. A very useful compilation of data on the cyclic oxidation of about 40 superalloys in the temperature range 1 000-1 I50°C has been made by Barrett et... 

A further range of instruments detects the cooling effect of the moving air over a heated wire or thermistor, and converts the signal to velocity. Air velocities down to 1 m/s can be measured with claimed accuracies of 5%, and lower velocities can be indicated. 

Altman and Nichols (A4) were the first to test the constant ignition-temperature approach experimentally. These investigators ignited samples of double-base propellants with electrically heated wires located on the propellant surface. The ignition delay was measured from the time of application... 

FI. Farber, E. A., Free convection heat transfer from electrically heated wires, J. Appl. Phys. 22, 1437 (1951). 

If a heated wire is immersed in a fluid, the rate of loss of heat will be a function of the flowrate. In the hot-wire anemometer a fine wire whose electrical resistance has a high temperature coefficient is heated electrically. Under equilibrium conditions the rate of loss of heat is then proportional to /2f2, where Q. is the resistance of the wire and / is the current flowing. 

In boiling liquids on a submerged surface it is found that the heat transfer coefficient depends very much on the temperature difference between the hot surface and the boiling liquid. The general relation between the temperature difference and heat transfer coefficient was first presented by Nukiyama(77) who boiled water on an electrically heated wire. The results obtained have been confirmed and extended by others, and Figure 9.52 shows the data of Farber and Scorah<78). The relationship here is complex and is best considered in stages. 

The micro reactor contained a heating function (imlike [R 4] and the other versions of this reactor concept [R 5] and [R 6], decribed below) via a heating wire connected to a potentiostat [19], This wire was integrated into the micro reactor by placing it in the mold before pouring the liquid PDMS. 

P 60] The dehydration of 1-hexanol to hexane and of ethanol to ethane were conducted at 155 °C. Heating was accomplished by a heating wire inserted in the micro reactor s top plate. This wire was connected to a potentiostat (0-270 V) temperature was monitored by a digital thermometer with the probe close to the reaction channel. A syringe pump was applied for liquid transport [19]. A flow rate of 3 pi min was applied. The alcohols were purged with nitrogen directly prior to reaction to minimize coke formation. 

Pulse-mode pyrolyzers include resistively-heated electrical filaments or ribbons and radio frequency induction-heated wires [841,842,846,848,849]. The filament or ribbon-type pyrolyzers are simple to construct. Figure 8.45, and typically consist of an inert wire or ribbon (Pt or Pt-Rh alloy) connected to a high-current power supply. Samples soluble in a volatile solvent are applied to the fileutent as a thin film. Insoluble materials are placed in a crucible or quartz tube, heated by a basket-lilce shaped or helical wound filiunent. The coated filament is contained within a low dead volume chamber through which the carrier gas flows, sweeping the pyrolysis products onto the column. The surface temperatui of the filament is raised rapidly from ambient temperature to He equilibrium pyrolysis temperature. This... 

Most of the work initially was with the more volatile transition metals, i.e. the first row metals plus palladium, silver and gold, because these were easy to evaporate in reasonable quantities in simple apparatus. However, efforts to use the less volatile metals of the second and third rows gained momentum. Skell used sublimation of resistively heated wires of molybdenum and tungsten to make the remarkably stable [Mo(rj4-C4H6)3] and [W(1j4-C4H6)3] (42). Green... 

The Ru single crystal was oriented by Laue x<-ray back-scattering to within 1° of the Ru(001) plane, cut by a diamond saw and mechanically polished. After being etched in hot aqua regia for about 15 min, the crystal was spot welded to two tantalum heating wires which were connected to two stainless steel electrodes on a sample manipulator. The temperature was monitored by a Pt/Pt-10% Rh thermocouple which was spot welded to the back of the crystal. 

Pyrolysis experiments were performed using a heated wire grid technique. Reactor details have been reported previously [7, 8]. The technique has been successfully applied in both pyrolysis and gasification studies [8, 10, 11]. In brief, the mesh or grid is housed in a stainless steel chamber known as the grid reactor (Fig. 8.1). The reactor is 227 mm long and has an inner diameter of 15 mm. The grid (9x4 mm) is constructed of interwoven wires (platinum/rhodium 10%)... 

Dittmann at al. later developed a very simple method for preparing such stationary phases [41 ]. They packed a capillary with 3-pm ODS beads and then drew a heated wire along the capillary to achieve sintering of the beads. Since changes in the drawing speed directly affected both EOF and retention, they inferred that the heat treatment led to detachment of a part of the C18 ligands from the silica beads. 

The importance of the heated wire test was the ability to monitor the additional variable of the temperature within the chamber. The temperature of the heated wire element was recorded for each reaction. The graph (Figure 4). displaying temperature in relation to percent hydrogen in air at atmospheric pressure, demonstrates that as the hydrogen percentage increased, the reaction occurred at a higher temperature. 

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