The role of temperature in nucleation processes

The role of temperature in nucleation processes

Ter Horst, J.H.
Bedeaux, D.
Kjelstrup, S.

Mechanical, Maritime and Materials Engineering

Process and Energy

2011-02-01

Heat and mass transfers are coupled processes, also in nucleation. In principle, a nucleating cluster would have a different temperature compared to the surrounding supersaturated old phase because of the heat release involved with attaching molecules to the cluster. In turn a difference in temperature across the cluster surface is a driving force for the mass transfer to and from the cluster. This coupling of forces in nonisothermal nucleation is described using mesoscopic nonequilibrium thermodynamics, emphasizing measurable heat effects. An expression was obtained for the nonisothermal nucleation rate in a one-component system, in the case where a temperature difference exists between a cluster distribution and the condensed phase. The temperature is chosen as a function of the cluster size only, while the temperature of the condensed phase is held constant by a bath. The generally accepted expression for isothermal stationary nucleation is contained as a limiting case of the nonisothermal stationary nucleation rate. The equations for heat and mass transport were solved for stationary nucleation with the given cluster distribution and with the temperature controlled at the boundaries. A factor was defined for these conditions, determined by the heat conductivity of the surrounding phase and the phase transition enthalpy, to predict the deviation between isothermal and nonisothermal nucleation. For the stationary state described, the factor appears to give small deviations, even for primary nucleation of droplets in vapor, making the nonisothermal rate smaller than the isothermal one. The set of equations may lead to larger and different thermal effects under different boundary conditions, however.

enthalpy
heat conduction
heat of transformation
liquid-vapour transformations
mass transfer
nucleation

http://resolver.tudelft.nl/uuid:44d57fe5-5ea1-48c2-8b98-d6311d2124b6

https://doi.org/10.1063/1.3544689

American Institute of Physics

0021-9606

http://jcp.aip.org/resource/1/jcpsa6/v134/i5/p054703_s1

Journal of Chemical Physics, 134 (5), 2011

Institutional Repository

journal article

(c) 2011 The Author(s)
American Institute of Physics