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>>
The Coiling Factor in the Tungsten Filament Lamps
Papers on tungsten lamps appearing in the pedagogic journals have been essentially assuming straight wire filaments however, in actual practice it is either single coiled or double coiled. This paper reports for the first time the D.D. Van Hover expression for the value of resistance of a coil and Milan R. Vukcevich theory based on coiled-ribbon filament for the radiation energy value from a coil. These expressions are applied to the coiled-wire filaments lamps of 6, 10, 25, 40, 60, 100, 200, 300, and 500 watts to estimate the values of pitch ratio, mandrel ratio and the temperature of the corresponding coil. For simplicity only the single coiled filament lamp cases are considered.
The convection and conduction of heat in gases
In a previous∗ paper the author has shown that the “convection” of heat from hot wires in a gas consists essentially of conduction through a film of relatively stationary gas around the wire. From this theory the following method was derived for calculating the power necessary to maintain a wire at any given temperature.