Three-dimensional time-dependent computer modeling of the electrothermal atomizers for analytical spectrometry

• Complete 3D transient model of various electrothermal atomizers was developed.
• Model can predict atomic absorbance signal for given optical detector.
• Atomization of three chemical elements were modeled: Ag, Cu, In.
• Periodical reverse gas flow (10 Hz) occurs in the THGA in variety of time steps.
• The tungsten helix atomizer looks like a solid cylinder for upstream shielding gas.

A full three-dimensional nonstationary numerical model of graphite electrothermal atomizers of various types is developed. The model is based on solution of a heat equation within solid walls of the atomizer with a radiative heat transfer and numerical solution of a full set of Navier–Stokes equations with an energy equation for a gas. Governing equations for the behavior of a discrete phase, i.e., atomic particles suspended in a gas (including gas-phase processes of evaporation and condensation), are derived from the formal equations molecular kinetics by numerical solution of the Hertz–Langmuir equation. The following atomizers test the model: a Varian standard heated electrothermal vaporizer (ETV), a Perkin Elmer standard THGA transversely heated graphite tube with integrated platform (THGA), and the original double-stage tube-helix atomizer (DSTHA). The experimental verification of computer calculations is carried out by a method of shadow spectral visualization of the spatial distributions of atomic and molecular vapors in an analytical space of an atomizer.