A cryogenic supersonic nozzle apparatus to study homogeneous nucleation of Ar and other simple molecules.
We present a supersonic nozzle apparatus to study homogeneous nucleation of argon and other simple molecules. Experiments can be conducted with pure condensable vapor or with condensable vapor-carrier gas mixtures. The flow through the nozzle is continuous, and expansions typically start at temperatures T(0) in the range of 100<T(0)/K<120, and pressures p(0) in the range of 30<p(0)/kPa<36. The gas mixture is cooled using a tube and fin heat exchanger by evaporating liquid nitrogen on the tube side. The nozzle sidewalls are also cooled with liquid nitrogen to maintain them at a temperature approximately 20 K higher than the stagnation temperature. Static pressure measurements detect the onset of condensation, and the other properties of the flow are derived by integrating the diabatic flow equations. We present sample experimental results for pure argon where at the onset of condensation, temperatures T(on) range from 47.5<T(on)/K<49.5 and pressures p(on) range from 4.2<p(on)/kPa<4.9.
Sinha
Somnath
S
Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio 43210, USA.
Laksmono
Hartawan
H
Wyslouzil
Barbara E
BE