The calculation of the shadow factor of single coil filament
A computer method for calculating the power-reduction factor of a single-coil filament is presented. The filament of incandescent lamps is coiled, which is why a fraction of radiation is trapped in the filament. The relationships between the geometric parameters of a cylindrical helix (pitch ratio and mandrel ratio) and the shadow factor are developed. A FORTRAN program based on the numerical solution of algebraic equations and on three-dimensional numerical integration has been developed.<<ETX>>
Illuminating physics with gas-filled lamps: Exponent-rules
For gas-filled incandescent lamps we exploit the fact that their operation is significantly affected by coiling of the filament, convective-conductive loss in the Langmuir sheath and backscattering of tungsten atoms by the gas. These features are incorporated as correction factors in the temperature indices which parameterize the intrinsic properties of tungsten such as emissivity, resistivity, evaporation rate, etc together with the bulb observables e.g., life, lumen, power, etc. A chi squares procedure is adopted to the said index corrections leading to excellent reproduction of 14 exponent-rules. The resulting temperature parameterizations can be profitably employed in any application related to gas-filled lamps.
Radiation-Conserving Incandescent Lamps
In this paper, the technology of an energy-conserving incandescent lamp is described. The lamp has a spherical envelope coated with a multilayer heat mirror of TiO2-Ag-TiO2. The coated envelope focuses the infrared radiation back to a centered compact filament of high emissivity while transmitting the visible wavelengths. The energy savings depend on the emissivity of the filament and the effective reflectance and visible transmittance of the coated envelope. Performance has been evaluated both in a model lamp system and in actual lamps.