Laboratory measurement of water nucleation using a laminar flow tube reactor

Abstract

Homogeneous nucleation rate measurements of 1-butanol in helium: A comparative study of a thermal diffusion cloud chamber and a laminar flow diffusion chamber A Laminar Flow Tube Reactor ͑LFTR͒ was used to study the nucleation of water vapor. Computational analysis was carried out to define the operating conditions of the LFTR suitable for water nucleation measurements. An interface between the LFTR and a mass spectrometer was developed to analyze the chemical content of the freshly nucleated water particles. Contaminants were detected in the initial configuration of the LFTR. As a result, improvements were made to the LFTR to achieve ultrahigh purity conditions in the system. The nucleation rate of water vapor as a function of supersaturation was measured over the temperature range 210-250 K. The first measurement of the nucleation rate of water at a temperature of 210 K was obtained. Reasonable agreement with the classical theory predictions is observed for temperatures in the range 230-250 K. However, below 220 K, classical theory begins to overestimate nucleation rates compared to experimental data and the disagreement grows with decreasing temperature. The experimental data obtained provide an excellent benchmark for further nucleation studies of binary, ternary, and more complex systems.

Molecular dynamics simulations of the nucleation of water: Determining the sticking probability and formation energy of a cluster

“…In the case of water, the deviations between the nucleation rates predicted by the classical nucleation theory and the experimental values are in the order of 10 2 -10 3 . 6,13,18,[20][21][22][23][24][25][26][27] The nucleation rates obtained by molecular dynamics (MD) and Monte Carlo (MC) simulations also significantly differ from the predictions of the CNT. The nucleation rate is governed by the formation free energy of a critical cluster, which is the smallest thermodynamically stable cluster.…”

Overview: Homogeneous nucleation from the vapor phase—The experimental science

“…These methods can be static or involve flows, and key devices in this class include the (upward) thermal diffusion cloud chamber (TDCC), [137][138][139][140] laminar flow diffusion devices (LFDDs) 141 such as the laminar flow diffusion chamber (LFDC), 67,73,[142][143][144] the laminar flow tube reactor 145,146 (LFTR), and the gas evaporation condensation chamber (GECC). 147,148 …”

Real-Time Measurement of Electronic Cigarette Aerosol Size Distribution and Metals Content Analysis

“…32 In a flow type system (like e-cigarette), nucleation occurs in a very narrow zone. 32,33 Because the aerosol formation rate is an exponential function of vapor concentration and temperature 32 , it is very difficult to perform valid calculations, accurately predict conditions of aerosol formation in the e-cigarette, and define the location of the nucleation zone. It is possible that part of the nanoparticles do not pass through the nucleation zone, or there may be not enough vapor to condense on all of the nanoparticles in which case some of the nanoparticles would not grow to submicron size.…”