High-power gas-discharge lamps as heating elements of radiant heating units

✍ Scribed by B.B. Petrikevich

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 324 KB
• Volume: 4
• Category: Article
• ISSN: 0894-1777
• DOI: 10.1016/0894-1777(91)90012-g

✦ Synopsis

IIVarious industries and technologies have been making ever broader use of materials and structures subjected in their service or operation to very severe thermal effects. Experimental units for heat testing of such high-temperature materials and structural components made of them employ three main heating techniques; convective, radiant, and combined heating.

Convective heating is afforded by shock tubes, hypersonic wind tunnels, and gas-dynamic units with gas heating. The common drawback of convective heating units is their low efficiency factor and, in some cases, their poor ecological ratings.

Radiant heating is relatively free of these drawbacks. Infrared incandescent lamps are broadly employed for radiant heating. They are easy to use and are readily combined into multiple-lamp modules of diverse configurations, the maximum size of the heated surface being limited solely by the available electric power of the experimental unit. It is exceedingly difficult, however, to obtain temperatures in excess of 1500 K at the surface of a material by using infrared lamps. Substantially higher temperatures of working surfaces (above 2000 K) are attainable when xenon-filled tubular ac gas-discharge water-cooled lamps are used as the heating elements. Experiments on developing and refining gas-discharge envelopes and cooling and power supply systems have yielded two types of such lamps: DTP-10/200 with 0.2-m electrode spacing for maximum electric power to 100 kVA and heat flow density at the cooling jacket surface to 3.5 x 10 6 W/m2; and DTP-10/500 with 0.5 m electrode spacing, maximum electric power to 180 kVA, and heat flow density at the cooling jacket surface to 3 x 106 W/m 2. These lamps are structurally simple to assemble into multiple-lamp modules. Optical concentrators make it possible to step up the heat flow density at the surface of a material specimen to 5.0 x l06 W/m 2. Nonuniformity of distribution of the heat flow density at the surface of a specimen or structure can be eliminated by using specifically shaped reflecting devices.