Heater wire

The lowest cost means of controlling temperature is to regulate the power applied to a heater (wire coil) by means of a variable transformer. Since there is no feedback, there is no means to compensate for changes in line voltage fluctuations or changes in ambient temperature, both of which usually are considerable. 

Utsunomiya et al. [11,12] reported an accumulation-type CTL-based sensor based on this mechanism. The alumina powder (y-Al2()3, 300 mesh in grain size, 30 mg) filled in a glazed ceramic pot (5 mm in diameter) including an electric heater wire was used as a sensor catalyst. First, the catalyst was heated to 500 °C to remove previous adsorbates, then was quenched to room temperature and allowed to adsorb the sample gas for a certain time. 

Since the specimens were supported from the balance by a 2-mil Nichrome wire, a direct measurement of the specimen temperature was impractical. Instead, the temperature of the inner ceramic tube between the heater wires and under a surrounding ceramic coating at a point opposite the specimen in the tube was taken as the sample temperature. Previous observations for our system showed that the tube and the specimen had a temperature difference of less than 1°C. when the system was heated at a rate of 3° to 4°C. per minute at temperatures of 800° to 950"C. The temperature was measured, using a platinum and platinum-10 % rhodium thermocouple with a White potentiometer. 

The heater wire of Ex. 2-4 is submerged in a fluid maintained at 93°C. The convection heat-transfer coefficient is 5.7 kW/m2 °C. Calculate the center temperature of the wire. 

A 2-kW resistance heater wire whose thermal conductivity is k = 18 W/m - K has a radius of = 0.15 cm and a length of Z. = 40 cm, and is used for space heating. Assuming Constant thermal conductivity and one-dimensional heat transfer, express the mathematical formulation (the differential equation and the boundary conditions) of this heat conduction problem during steady operation. Do not solve. 

Heater wires of oxide-coated metal cathodes in electronic tubes (W, W-ThOa, porous W infiltrated with barium-aluminum compounds). BaO coating reduces the work function and thus increases the emission. 

Chromel-Alumel Molybdenum (K-type) Heater Wires Thermocouples... 

Tubing, rubber, to drain the overflow Tubing, rubber, to fill the desiccator Wire, to connect heaters Wire, double strand with male plug at one end and alligator clips at the other end. 

Figure 3.34. Schematic diagram of the high-pressure thermobalance enclosure. A, end plate with threaded opening for gas inlet fitting B, Buna-N O-ring C. pressure cell D. high-pressure connector for control cable E, balance movement F. furnace chamber G. furnace thermocouple H, furnace heater wire in Marinite insulation J. hexdrive bolts K, end plate with threaded opening for gas outlet fitting (68).

All modem thermionic ionization detectors (TED) employ a solid surface, composed of a ceramic or glass matrix doped with an alkali metal salt in the form of a bead or cylinder, molded onto an electrical heater wire as the thermionic source [254,270,271]. 

The source can be heated by a variety of techniques. Resistance heating can be used, employing W, Mo, or Ta heater wire or tape. These have the advantage that their low vapour pressures do not cause contamination of the deposit. The source can be contained in a crucible made of boron nitride or titanium diboride. Induction heating can also be used to heat a susceptor source contained in a nonsusceptor crucible. Electric-arc and laser-beam sources can also be used to heat the evaporant. 

It is necessary to make small corrections for finite heater wire diameter, finite wire length, and finite sample mass. These have been discussed in detail for liquids by Horrocks and McLaughlin [32], who found that the corrections were only significant for short heating times. This technique has been used with polymers [3.3- 37], and has also been developed in the form of a conductivity probe [38 40] for making single point measurements on. for example, foams. 

Figure 14 Isothermal displacement calorimeter with cooling module. A, stainless-steel support tube, B, vent tube C, current and potential leads for heater D, connector for feed tube E, Teflon plug F, vent plug G, heateriwire supports H, baffles I, Teflon support ], heater wires K, stirrer magnet L, stirrer paddle A,feed tube N, thermistor P, Teflon feed cup Q, water inlet tube R, copper heat sink S, 5Q era precision-bore Dewar flask T, 0-rings U, coin-silver cooling rod V, copper cup W, coin-silver support rods X, copper heat shield Y, coin-silver bar Z, cooling module (Reproduced by permission from J. them, and Eng. Data, 1966, 11, 189)...

V, 1500W electrical target heater (wiring and heating element —... 

A TN supply feeds a domestic immersion heater wired in 2.5 mm PVC insulated copper cable and incorporates a 1.5 mm CPC. The circuit is correctly protected with a 15 A semi-enclosed fuse to BS 3036. Establish by calculation that the CPC is of an adequate size to meet the requirements of lET Regulation 543.1.3. The characteristics of the protective device are given in lET Regulation Fig 3A2(a) of Appendix 3. 

The single-storage heater is heated by an electric element embedded in bricks and rated between 6 and 15kW depending upon its thermal capacity. A radiator of this capacity must be supplied on its own circuit, in cable capable of carrying the maximum current demand and protected by a fuse or miniature circuit-breaker (MCB) of 30, 45 or 60 A as appropriate. At the heater position, a DP switch must be installed to terminate the fixed heater wiring. The flexible cables used for the final connection to the heaters must be of the heat-resistant type. 

PP extrusion temperatures average 260°C. Dies must be heated, either with cartridge heaters fit into holes drilled into the die body or plate heaters fastened to the exterior of the die. These are electric resistance heaters, wired in zones, and controlled via a thermocouple feeding back to an instrument, or a programable logic control (PLC). Temperahne control is usually within 1°C. In applications where air knives or vacuum boxes are also used, it is advisable to heat the die lips. 

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