Freeze dryer temperature range and specific temperature settings
The temperature range of the freeze dryer varies depending on the product type and specific application. For example, the condenser refrigeration temperature of the traditional cold storage freeze dryer is about -40℃, which is suitable for low-end solid fruits and vegetables. The plate layer refrigeration temperature of the pharmaceutical freeze dryer is about -55℃ to -60℃, which is suitable for pharmaceutical products, cosmetics, biological products, etc. The condenser refrigeration temperature of the new food freeze dryer is about -65℃, which is suitable for solid fruits and vegetables, liquid products, heat-sensitive products, etc.
Specific temperature requirements at different stages
The freeze drying process is divided into three stages: freezing, sublimation and analytical drying. The freezing stage requires freezing the material, the sublimation stage is the process of directly changing the water from solid to gas, and the analytical stage is to remove the adsorbed water that is strongly bound to the solid. The specific temperature setting can be adjusted according to the eutectic point of the material, usually the low temperature can reach -30℃, and the high temperature can reach 100℃.
The effect of temperature on freeze drying effect
Temperature has a direct impact on the freeze drying effect. The pre-freezing temperature should be 5-10℃ lower than the eutectic point of the product to ensure that the water is completely frozen. If the pre-freezing temperature is too high, the water cannot be completely frozen, which may cause local boiling and bubbling during the drying process, affecting the product quality. In addition, the cold trap temperature has a significant impact on the water capture capacity. Usually, a cold trap temperature of around -60℃ is an ideal choice.
