title: Evaporation from open microchannel grooves.
abstract: The evaporation of water from open u-shaped microchannel grooves was investigated with particular emphasis on the roles of channel width and air flow conditions. Given the small dimensions of the microchannels, all measurements were conducted in a range where convection and diffusion are of equal importance and known correlations for the calculation of mass transfer coefficients cannot be applied. The evaporation rates were measured using a new optical method and a gravimetric method. Both measurement methods yielded mass transfer coefficients that are in agreement with each other. The observed relation between mass transfer coefficient, air velocity and channel width vastly differs from the predictions obtained from macroscopic structures. With respect to diagnostic devices we conclude that analyte concentration in an open microchannel groove strongly increases even within short times due to the evaporation process and we show that wider channels are more favourable in terms of minimizing the relative evaporation rate.
authors.affiliation: Institute of Thermal Process Engineering, Thin Film Technology, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany.
authors.forename: Sibylle
authors.initials: S
authors.lastname: Kachel
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhou
authors.forename: Philip
authors.initials: P
authors.lastname: Scharfer
authors.forename: Christian
authors.initials: C
authors.lastname: Vrančić
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Petrich
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Schabel
mesh_terms: D004058:Diffusion; D057446:Hydrodynamics; D046210:Microfluidic Analytical Techniques; D014835:Volatilization; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water