There are two commonly used methods for freeze-drying machines:

1..Direct control: Directly measure the temperature of the product. When its value is lower than the set value, it is heated by electricity, and when its value exceeds the set value, it is frozen and cooled. The disadvantage of this method is that due to the natural transmission process of object temperature, overshoot and hysteresis phenomena in temperature measurement and control can cause periodic changes in the control state.

2. Indirect control: Monitoring and controlling the shelf temperature during the freeze-drying process and using a time temperature program to obtain the required product temperature - this is a good control process. However, the time temperature program method requires a lot of experience with the product, which is a statistical method of taking the average value to achieve a high degree of consistency in repeated operation of freeze-drying machines, which is very important for production.

Can the four ring freeze-drying experimental freeze-drying machine freeze dry liquid raw materials?

The amount of water vapor in the compressed air of a freeze-drying machine is determined by the temperature of the compressed air: while maintaining the working pressure of the compressed air without changing, reducing the temperature of the compressed air can reduce the water vapor composition in the compressed air, while unnecessary water vapor will solidify into a liquid. The freeze-drying machine uses this basic principle to select refrigeration dry compressed air. Therefore, the freeze-drying machine has a refrigeration unit. The refrigeration unit of a freeze-drying machine consists of four basic components: a refrigeration unit, a cooler, an air conditioning evaporator, and an air conditioning expansion valve.

The purpose of a freeze-drying machine is to freeze a substance with water content into a solid, and then sublime the water in it from the solid to a vapor state, in order to remove water and store the substance. Simply put, it is a dry and impetuous entire process achieved based on refrigerated raw materials. The freeze-drying machine is equipped with a LCD display screen and a Chinese page, with a test sample drying curve chart; It has a refrigeration compressor and a heat exchanger, which further expands the refrigeration capacity of the air conditioning and improves the water harvesting capacity; Its cold trap has a large opening, no internal fan coil, and has a pre freezing effect on the test sample. In addition, the pre cooling frame can be used as a drainage bucket to accelerate the drying rate. The cold trap and actual operating surface are all stainless steel plates, corrosion-resistant and easy to smooth, and the fully transparent bell cover.