Freeze Dryer: Equipment Tab

Variable Definitions, Ranges and Default Values

The following table shows the meaning of the variables appearing in this tab, as well as their default values and their generally acceptable range. Note that due to the manner by which the variables are used by the sizing and costing equations, the range of acceptable values may be further reduced.

Symbol Key: ○ User-specified value (always input); ● Calculated value (always output); ◙ Sometimes input, sometimes output

Sizing: Design Mode

In Design Mode, the user specifies the depth of wet cake (see Freeze Drying: Oper. Conds Tab) and the system calculates the tray area by dividing the calculated wet cake volume by the wet cake depth. The system also calculates the sublimation capacity (in kg H2O or other solvent per cycle) based on the percentage of components that sublimate. If the calculated sublimation capacity exceeds the maximum, the system assumes multiple units operating in parallel with a total sublimation capacity equal to the calculated.

Sizing: Rating Mode

In Rating Mode, the user specifies the number of parallel units, their tray area and their sublimation capacity and the system calculates the wet cake depth. If the calculated wet cake depth exceeds the maximum allowable value, the user is warned.

Costing

The equipment purchase cost is estimated using built-in correlations derived from vendor data. The equipment cost is a function of the sublimation capacity with minimum sublimation capacity of 10 kg/cycle.

Other Variables

●      Equipment Heat Capacity; the product of equipment mass times its specific heat capacity. It is used by operations that are executed in the vessel and involve heating and/or cooling. If part of the heat exchange is directed to the vessel, then this variable is used to estimate heating/cooling losses.

For more information on this equipment, see Freeze Dryer or Discrete Freeze Dryer.

For information on the left-hand side variables and options, see Equipment Data Dialog: Equipment tab.