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:
- محصولاتی که نیاز به خنک‌کردن سریع دارند (مانند سبزیجات برگ‌دار، گوشت، نان یا گل‌ها) در یک محفظه مخصوص قرار می‌گیرند.
2. Creating a vacuum:
- با استفاده از پمپ‌های خلأ، فشار داخل محفظه به‌طور قابل‌توجهی کاهش می‌یابد. فشار معمولاً به ۴ تا ۱۰ میلی‌بار (mbar) می‌رسد.
3. Moisture evaporation:
- در فشار پایین، نقطه جوش آب کاهش می‌یابد. به‌عنوان مثال، در فشار ۶ mbar، آب در دمای ۰°C تبخیر می‌شود.
- Moisture on the surface of the product (such as water on vegetable leaves or the surface of meat) begins to evaporate.
4. Heat absorption:
- تبخیر رطوبت، گرمای نهان تبخیر را از محصول جذب می‌کند. این گرما از محصول و محیط اطراف آن گرفته می‌شود و در نتیجه، دمای محصول به سرعت کاهش می‌یابد.
5. Stopping the process:
- پس از رسیدن به دمای مطلوب (معمولاً بین ۱ تا ۴°C)، فشار به حالت عادی بازگردانده می‌شود.
- 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.
- فشار داخل محفظه به ۶ mbar کاهش می‌یابد.
- The moisture on the surface of the lettuce begins to evaporate, absorbing the latent heat of evaporation.
- در مدت 2۰ تا 30 دقیقه، دمای کاهو از ۳۰°C به ۲°C کاهش می‌یابد.
- 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::
- سرعت بالا: خنک‌کردن محصولات در 20 تا ۳۰ دقیقه (بسته به نوع محصول).
- 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:
- خنک‌کردن سبزیجات برگ‌دار (کاهو، اسفناج، کلم) ، شوید و …
- 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.