I. How Vacuum Precooling Actually Works
Place freshly harvested fruits and vegetables into a sealed vacuum chamber and evacuate the air. When the pressure drops to below 600Pa, moisture on the surface of the fruits and vegetables begins to evaporate at low temperature. For every 1% of moisture evaporated, the temperature drops by approximately 6℃. In 30–50 minutes, the temperature can drop from 25–35℃ to 0–2℃.
Key: Vacuum precooling does not "freeze" the product; it is "evaporative cooling". The moisture loss rate is controlled at 2–3%.
II. Core System Composition
2.1 Vacuum System
The vacuum pump draws the pressure down to below 600Pa. Leybold rotary vane pumps are used, with dual pumps in parallel for large models.
2.2 Refrigeration System — Water Catcher
The water catcher is essentially an evaporator; its surface temperature is maintained at 5–10℃, and water vapor condenses into water and is discharged. A vacuum precooler must have a refrigeration system.
2.3 Control System
PLC-controlled, automatically running the entire cycle. The core is pressure control — evacuate to the set pressure → maintain the pressure range → the product reaches the target temperature → break the vacuum and discharge.
III. CVF Series Model Selection Parameters
| Model | Processing Capacity | Power | Compressor | Vacuum Pump |
|---|---|---|---|---|
| CVF-1000A-2P | 1000kg | 39.9kW | Bitzer 30.7kW | Leybold 5.5kW |
| CVF-2000E-4P | 2000kg | 77.8kW | Hanbell 61.6kW | 11kW |
| CVF-3000-6P | 3000kg | 89.3kW | Hanbell 61.6kW | 22.5kW |
| CVF-4000W-10P | 4000kg | 99.7kW | Hanbell 73.2kW | 7.5kW×2+Roots |
IV. Cooling Processes for Different Product Categories
| Category | Loading Capacity | Cooling Time | Moisture Loss Rate | Target Temperature |
|---|---|---|---|---|
| Leafy Vegetables | 6–8kg/m² | 25–40min | 1.5–3% | 0–2°C |
| Edible Fungi | 5–7kg/m² | 20–35min | 1–2% | 0–2°C |
| Flower and Fruit Vegetables | 8–10kg/m² | 30–50min | 2–3.5% | 2–5°C |
V. Comparison with Other Precooling Methods
| Method | Cooling Time | Moisture Loss Rate | Investment Cost |
|---|---|---|---|
| Vacuum Precooling | 20–40min | 1.5–3% | Medium-High |
| Forced-Air Cooling | 4–12h | 3–5% | Low |
| Cold Water Precooling | 30–60min | 0–1% | Medium |
| Cold Storage | 12–24h | 5–10% | Medium |
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