How a vacuum cooling machine works

Vacuum Cooling uses vacuum technology to rapidly reduce the temperature of products. This process is based on the evaporation of moisture at low pressure. This device is commonly used in the food industry, especially for cooling products such as dill, edible vegetables, soup vegetables, lettuce, cauliflower, flowers, and other foods that require rapid cooling after cooking or harvesting. (How Vacuum Cooling Works)

Scientific principles of vacuum cooling::

• Lowering the boiling point of water in a vacuum: At an atmospheric pressure of 1 atm, water boils at 100°C, but in a vacuum environment (low pressure), water evaporates at a lower temperature (for example, at a pressure of 6 mbar, water evaporates at 0°C).
• Surface moisture evaporation: By creating a vacuum, the moisture on the surface of the product (e.g., water in vegetable leaves or meat) evaporates rapidly. This evaporation removes the latent heat of evaporation from the product and reduces its temperature uniformly.

Steps of Car Vacuum Cooling::

1. Placing the product in the container:

• Products that require rapid cooling (such as leafy vegetables, meat, bread, or flowers) are placed in a special compartment.

2. Creating a vacuum:

• Using vacuum pumps, the pressure inside the chamber is significantly reduced. The pressure typically reaches 4 to 10 millibars (mbar).

3. Moisture evaporation:

• At low pressure, the boiling point of water decreases. For example, at a pressure of 6 mbar, water evaporates at 0°C.
• Moisture on the surface of the product (such as water on vegetable leaves or the surface of meat) begins to evaporate.

4. Heat absorption:

• Evaporation of moisture absorbs latent heat of vaporization from the product. This heat is taken from the product and its surroundings, resulting in a rapid decrease in the product temperature.

5. Stopping the process:

• Once the desired temperature is reached (usually between 1 and 4°C), the pressure is returned to normal.
• The cooled product exits the machine and is ready for use or packaging.

Practical example::

Suppose a shipment of lettuce is at a temperature of 30°C after harvest. The steps for cooling it with a vacuum cooling machine are as follows:

• The lettuce is placed in the machine's compartment.
• The pressure inside the chamber is reduced to 6 mbar.
• The moisture on the surface of the lettuce begins to evaporate, absorbing the latent heat of evaporation.
• Within 20 to 30 minutes, the temperature of the lettuce drops from 30°C to 2°C.
• The cooled lettuce is removed from the machine.

Main components of the vacuum cooling machine::

1. Vacuum chamber: A space where products are placed and the pressure inside is reduced.

2. Vacuum pump: Used to create a vacuum and reduce the pressure inside the chamber. Rotary vane or turbomolecular pumps are commonly used.

3. Temperature and pressure control system: To monitor and precisely regulate the cooling process.

4. Humidity recovery system: In some models, evaporated moisture is recovered by condensers to prevent water loss.

5. Cooling system: To assist in the cooling process and temperature control.

Advantages of using vacuum cooling::

• High speed: cooling products in 20 to 30 minutes (depending on the type of product).
• Maintaining quality: Preventing spoilage, preserving the color, texture, and nutritional value of products.
• Reduces bacterial growth: Rapid cooling limits the growth of microorganisms.
• Energy saving: It consumes less energy than traditional methods (such as cold air or cold water).
• Uniformity in cooling: The entire product is cooled uniformly.

Applications of vacuum cooling machine::

1. Food industry:

• Cooling leafy vegetables (lettuce, spinach, cabbage), dill, etc.
• Cooling baked goods (bread, cakes, biscuits).
• Cooling meat and protein products.

2. Flower and plant industry:

• Extend the life of cut flowers (roses, lilies) by cooling them quickly after harvest.

3. Pharmaceutical industries:

• Rapid cooling of some temperature-sensitive pharmaceuticals.

(How the vacuum cooling machine works)

To purchase a vacuum cooling device from Golmehr Sanat Valiasr Company, you can contact the sales department.