Mass transfer coefficient for silica in liquid water at 200°C

In previous reports on the mass transfer coefficient of quartz glass in water, we were able to determine that this is significantly larger in liquid water than in saturated water vapor as the surrounding medium. From literature results by Zouine et al. (2007) a lower limit value of the time parameter h/√D in eq.(4) of >10$^{-6}$ h$^{-1/2}$, could be deduced for 200°C and liquid water. One explanation for this result could be, among other things, an increased roughness due to the dissolution of the surface layers of the glass in water than is to be expected for water vapour.