Sublimation front temperature

Sublimation front temperature recorded and on display, exceeded tolerances activate the safety system (etas)... 

Figure 6 Average Tsh, Tpr, c,md, sd, T-i, T a during three test runs with product A 1, shelf temperature Tsh 2, product temperature Tpr with PT 100 in the product 3a, Pc during MD 3b psn during SD 4, sublimation front temperature Tice 5, condenser temperature Tix,.

Fig. 3.7 Ice sublimation front temperature Comparison between PRA model (diamonds), Milton s model (triangles), Obert s model (circles) and mean product temperatures (squares) measured by thermocouples (Chouvenc et o/., 2004a).

Since the water vapor pressure increases exponentially with the temperature, the drying rates during freeze-drying processes, which vary in a similar way, are strongly dependent on the sublimation front temperatures that is, on the shelf temperature. 

A quasi-stationary period during which the sublimation rate is quite constant. This corresponds to a quasi-steady state with an approximately constant sublimation front temperature. The duration of this plateau period seems to decrease as the sublimation temperature increases. The experimental data presented in Fig. 3.21 show that the sublimation rate increases by about a factor of two for an increase of 20 °C in the shelf temperature (from 25 to —5 °C). 

---