Freeze Dryer: What is a Freeze Dryer?-华纳真人娱乐 " name="keywords" />
Freeze Dryer vs. Lyophilizer
A Freeze Dryer’s 3 Primary Stages
A freeze dryer works in three phases, with the first and most critical being the freezing phase. Proper freeze drying can reduce drying times by 30%.
Freeze dryers use various methods to freeze the product. Freezing can be done in a freezer, a chilled bath (shell freezer), or on a shelf in the freeze dryer. The freeze dryer cools the material below its triple point to ensure that sublimation, rather than melting, will occur. This preserves the material’s physical form.
Primary Drying (Sublimation) Phase
Secondary Drying (Adsorption) Phase
Eutectic Point or Eutectic Temperature
Is the point at which the product only exists in the solid phase, representing the minimum melting temperature. Not all products have a eutectic point or there may be multiple eutectic points.
During freeze drying, the maximum temperature of the product before its quality degrades by melt-back or collapse.
The material forms crystals when frozen.
Has a eutectic point or multiple eutectic points
Fast freezing creates small crystals which are hard to dry
Annealing can help form bigger crystals
Multi-component mixtures which do not crystallize and do not have a eutectic point. They turn into a ‘glass.’
Does not have a eutectic point
For amorphous materials, freeze drying needs to be performed below
The point at which the product softens to the extent that it can no longer support its own structure. This can be a problem for many reasons:
Loss of physical structure
Decreased solubility
Lots of ablation (splat)