How to improve the freeze-drying efficiency of Sihuan freeze-drying vacuum freeze-drying machine

The drying of Sihuan freeze-drying vacuum freeze dryer is to freeze the material containing a large amount of water into a solid, and then directly sublime the water vapor in the solid under a certain vacuum condition
.

The material itself remains in the freezer ice shelf and retains the same volume after drying
.

When porous ice sublimates, it needs to absorb heat, causing the temperature of the product itself to drop and slowing the rate of sublimation
.

In order to increase the sublimation speed and shorten the drying time, it is necessary to properly heat the product
.

The whole drying process is carried out at lower temperature
.

So how can this freeze-drying efficiency be improved? 1.
The form and composition of the material According to the form of the lyophilisate, it is usually divided into solid and liquid
.

The shape of the solid and the concentration of the liquid have a greater impact on the lyophilization rate
.

2.
Pre-quick freezing rate The size of the crystals formed during the freezing process of the four-ring freeze-drying vacuum freeze dryer has a great influence on the drying speed and the dissolution speed of the dried product
.

The process of quick freezing and slow freezing has the following differences: quick freezing produces smaller ice crystals, while slow freezing produces larger ice crystals
.

Large ice crystals are good for sublimation, and small ice crystals are not good for sublimation
.

Rapid freezing results in low sublimation rates and fast desorption rates
.

Slow freezing results in fast sublimation and slow decomposition
.

3.
When the material is freeze-dried, its surface area has a corresponding proportional relationship with the thickness of the material after being packaged in the container, that is, freeze-drying is related to the loading capacity
.

Small surface area and thickness facilitate water sublimation, easy freeze drying, and ideal quality
.

Generally, the thinner the material thickness, the faster the heat and mass transfer, and the shorter the drying time
.

However, if the thickness of the material is thin, less material is dried in each batch in the freeze-drying area, which is not conducive to improving the yield per unit of freeze-drying area and unit time
.

4.
Drying chamber pressure The pressure in the drying chamber of the four-ring freeze-drying vacuum freeze dryer will affect the speed of heat and mass transfer
.

In terms of mass transfer, the lower the pressure, the better
.

In terms of heat transfer, the higher the pressure, the better
.

The mass transfer rate mainly depends on the temperature and pressure of the sublimation interface and the surface of the drying layer
.

In order to increase the escape rate of water vapor in the drying layer, one is to increase the temperature of the sublimation interface and increase the pressure of water vapor at the interface
.

This is to increase the vacuum degree of the drying chamber and reduce the vapor pressure on the surface of the drying layer
.