The kinetics of desorption with an interfacial resistance and concentration-dependent diffusivity

✍ Scribed by M. Cable; G.E. Cardew

• Publisher: Elsevier Science
• Year: 1977
• Tongue: English
• Weight: 666 KB
• Volume: 32
• Category: Article
• ISSN: 0009-2509
• DOI: 10.1016/0009-2509(77)87011-5

✦ Synopsis

The ktnetuzs of desorption have been calculated numerIcally for a senu-mfimte body with a strongly concentration-dependent dflusivity and a surface resistance whch lmuts the flux into the gas phase The chosen values of the parameters were smular to those Involved m expenments wtth glass melts It 1s shown that the relation between total flux and time can be described by the equation for a system with constant ddfuslvlty, even though no slmrlanty solution exists The fit 1s not perfect but dlscrepancles are small and he wlthm the range of probable expenmentat errors The parameters (surface resistance and ddfuslvlty) gvmg the best fit of the constant property model are best considered as empmcal curve fittmg parameters because they can have different sigmticances over the range of conditions covered, the apparent dlffusivity IS sometImes lower than apphes anywhere within the system A rehable test of whether ddfuslvity IS concentratlondependent requves measurement of concentration chstnbution or, at least, mterface concentration even when data are avadable for a range of initial concentrations