The temperature of the cold trap in the freeze dryer (Lyophilizer) has an important impact on the drying process, especially in terms of water removal, sample quality and energy consumption. Freeze dryers usually dry by freezing the sample and then sublimating the water under vacuum at low temperature. In this process, the cold trap plays a vital role, which is used to collect water vapor during the sublimation process. If the cold trap temperature is set differently, it will have different effects on the drying effect, mainly reflected in the following aspects:
1. Sublimation efficiency
The cold trap temperature is low: When the cold trap temperature is low, water vapor will quickly condense to the cold trap surface during the sublimation process, which helps to improve the sublimation efficiency because water can be quickly removed from the sample. Low-temperature cold traps can reduce vapor reflux, thereby keeping the drying process smooth.
High cold trap temperature: If the cold trap temperature is too high, the sublimated water vapor may not condense in time, resulting in an incomplete condensation process or vapor reflux into the sample, which in turn affects the drying speed and sample quality.
2. Vacuum effect
Low-temperature cold trap: Low-temperature cold trap helps to more effectively assist the rate of decrease of vacuum degree, and the vacuum can achieve a lower vacuum effect.
High-temperature cold trap: Too high cold trap temperature may cause the vacuum pump to start, and the vacuum cannot be reduced, so the negative pressure in the drying chamber cannot reach a certain effect, which may cause damage to the sample.
3. Drying time
Low-temperature cold trap: Under the action of low-temperature cold trap, water vapor can condense quickly, thereby accelerating the sublimation process and reducing the drying time.
High-temperature cold trap: If the temperature of the cold trap is too high, the water vapor in the sublimation process may not be effectively condensed, thereby extending the drying time and affecting production efficiency.
