Condensation of supersaturated vapors of hydrogen bonding molecules: Ethylene glycol, propylene glycol, trimethylene glycol, and glycerol

Nucleation rate data, obtained from expansion wave tube experiments, are reported for several vapor-gas mixtures at high pressure. Results are given for water-vapor in the presence of helium and nitrogen gas, and for n-nonane in helium and methane. For all these mixtures, carrier gas pressures of 10, 25, and 40 bar have been applied, with temperatures ranging from 230 to 250 K. An extended form of the nucleation theorem ͑in terms of the derivative of the nucleation rate with respect to carrier gas pressure͒ is derived, which appears to be very helpful in the interpretation of high pressure data. It can be used to obtain the carrier gas content of the critical nucleus directly from the pressure dependence of experimental nucleation rates. Combining this method with the theoretical considerations of part I of this paper ͓J. Chem. Phys. 111, 8524 ͑1999͒, preceding paper͔: the nucleation behavior of water at high pressures of both helium and nitrogen can quantitatively be understood. For n-nonane in helium our ''pressure perturbation approach'' is also valid. For n-nonane in methane, however, this approach fails because of the high methane solubility in the liquid phase.

Section: Introductionmentioning

confidence: 53%

Nucleation at high pressure. II. Wave tube data and analysis

Luijten

Peeters

Dongen

1999

“…In diffusion cloudchamber experiments, [1][2][3][4][5] for example, marked effects of carrier-gas pressure on the rate of nucleation and the critical supersaturation were seen. For a water/nitrogen system, however, a recent experiment 6 using a high pressure pulseexpansion wave tube demonstrated that when the nucleation rate is plotted as a function of conventional supersaturation ͑i.e., the ratio of the partial vapor pressure of the supersaturated vapor to the equilibrium vapor pressure of the pure component͒, the carrier-gas pressure effect is hardly discernible.…”

Section: Introductionmentioning

confidence: 99%

Effect of carrier-gas pressure on barrier to nucleation: Monte Carlo simulation of water/nitrogen system

Zeng

2001

Carrier gases are used in most nucleation experiments for releasing the latent heat generated during vapor condensation. In the analysis of experimental data it is often assumed that the carrier gas is inert and would not participate in the nucleation process of the target gas. Several recent nucleation experiments show that the influence of carrier gases to nucleation rate is not negligible under certain conditions. To gain more insight into the carrier-gas effect, we carry out Monte Carlo simulation to compute the free energy of formation of water clusters in the presence of a nitrogen carrier gas. At fixed temperature ͑240 K͒ and chemical potential, it is found that the barrier height to nucleation increases with the carrier-gas pressure. This barrier enhancement is attributed to the increase of equilibrium vapor pressure of water in the presence of carrier gas, which results in a decrease of supersaturation. It is also found that the simulation results are consistent with the binary-nucleation theorem.

“…The inclusion of carrier gas particles in the simulation is to mimic real experiments of nucleation [15][16][17][18] where the carrier gas plays a major role in releasing the latent heat generated from nuclei formation. The interaction potential of target-target is a Lennard-Jones ͑LJ͒ type, i.e., a͒ Author to whom correspondence should be addressed.…”

Section: A Molecular Dynamics Simulationmentioning

confidence: 99%

Molecular dynamics simulation of supersaturated vapor nucleation in slit pore

Yasuoka

Gao

Zeng

2000

Molecular dynamics simulations of nucleation of Lennard-Jones vapor confined in a slit pore have been performed. The walls of the slit pore are structureless walls; each wall interacts with vapor molecules via Lennard-Jones 9-3 potential. The rate of nucleation in the steady state is determined by analyzing time evolution of the cluster size distribution. At the same vapor density and temperature, the nucleation rate in the slit pore is higher than in the homogeneous vapor ͓K. Yasuoka and M. Matsumoto, J. Chem. Phys. 109, 8451 ͑1998͔͒, irrespective of the strength of attraction between the wall and vapor molecules. However, this attraction strongly affects the process of nucleus formation: if the attraction is weak ͑a drying wall͒, nuclei tend to form in the middle of the pore, whereas if the attraction is strong ͑a wetting wall͒, the nucleus formation originates from two sources, the surface diffusion of adsorbed molecules and deposition of clusters formed in the middle of the pore.