Study on thermal related constraints and their effects on micro tubular coil heaters

Abstract

Micro tubular coil heaters have been widely investigated because newlineof their extensive applications in PET (PolyEthylene Terephthalate) newlinepreformed moulds, hot runner nozzles and bushings, thin walled container newlinemoulds and other micro systems. Micro tubular coil heaters are made as newlinerectangular, square and circular sections, with or without built-in newlinethermocouple. The main features of these heaters are 360º heated area, newlinereadily confirms to surface, fast response and quick heat transfer, helical coil newlinedesign for superior performance, good resistance to corrosion and it can newlineeasily be coupled with J or K type thermocouple. The helical wound heating newlinewire is made of a high temperature resistant Ni/Cr alloy and the insulation consists of superior grade of magnesium oxide (MgO). As the heaters are newlineswaged, they have excellent electrical insulation and high heat transfer even newlineat high sheath temperature. The experimental investigation of Nichrome newlinemicro tubular coil heater proved that this is suitable for low temperature newlineapplications only. Therefore alternate materials for micro tubular coil heater newlineare to be identified for medium and high temperature applications. Raman spectroscopy is a commonly used tool in bio-diagnostics newlineand micro sensor technology. Surface-enhanced Raman scattering provides newlinehigh signal enhancements, especially at micro and nanostructure metallic newlinesurfaces. It is a spectroscopic technique used to study vibrational, rotational, newlineand other low-frequency modes in a system. It relies on inelastic scattering of monochromatic light usually from a laser in the visible, near infrared or near newlineultraviolet range. The laser light interacts with molecular vibrations, phonons newlineor other excitations in the system, resulting in the energy of the laser phonons newlinebeing shifted up or down. The shift in energy gives information about the newlinevibrational modes in the system.