Size the refrigeration for a cold room or freezer from panel transmission, product cooling and freezing, air infiltration, people, lights and fans — then apply the safety factor and compressor run time to get capacity in kW, TR and BTU/h.
Preliminary load estimate. Product properties are typical values; respiration heat of fresh produce, defrost heat, packaging and pallets, and door strip curtains or air curtains all affect the final selection. Select equipment from manufacturer data at the actual evaporating and condensing conditions.
| Component | kWh/day | Share |
|---|
| Product | c above freezing | c below freezing | Latent heat | Freezing point |
|---|---|---|---|---|
| Vegetables (general) | 3.9 kJ/kg·K | 2.0 | 300 kJ/kg | −0.8 °C |
| Fruit (apples, citrus) | 3.6 | 1.9 | 280 | −1.1 °C |
| Dairy (milk, cheese) | 3.8 | 2.0 | 290 | −0.6 °C |
| Meat — beef / lamb | 3.2 | 1.7 | 230 | −1.7 °C |
| Poultry | 3.3 | 1.8 | 246 | −2.8 °C |
| Fish / seafood | 3.6 | 1.9 | 270 | −2.2 °C |
| Ice cream | 3.3 | 1.9 | 220 | −5.6 °C |
| Beverages (bottled) | 3.9 | — | — | not frozen |
Typical values in the range given by ASHRAE food property data; use measured data for a specific product.
A cold room does not run its compressor 24 hours a day. Coolers above about +2 °C defrost by stopping the compressor; freezers need electric or hot-gas defrost several times a day. Dividing the daily load by 16–18 running hours rather than 24 is what turns a load into an equipment capacity — skip it and the unit is undersized by 25–35%.
6 × 4 × 3 m vegetable cooler at +2 °C, 100 mm PUR panels, 35 °C / 50% outside, 1,000 kg/day entering at 25 °C, 18 h run time.
Add transmission through the panels, the heat removed from the product (including freezing when applicable), infiltration through the door, and internal heat from people, lights and fans. Add a safety factor and divide the daily total by the compressor running hours.
It depends mainly on the product intake and temperature, not just room size. A small vegetable cooler may need under 1 TR, while the same room used as a blast freezer can need several times more. Use the calculator with your actual intake.
Coolers above 0 °C commonly use 75–100 mm PUR panels; freezers at −18 to −25 °C commonly use 125–150 mm, and blast freezers 150–200 mm, often with floor insulation and heating to prevent frost heave.
The system needs time to defrost the evaporator and a margin for peak days. Sizing on 16–18 running hours gives the unit capacity to recover; sizing on 24 hours undersizes it.
No. Fresh fruit and vegetables keep respiring and release heat in storage. Add it from ASHRAE food data where the stored mass is large relative to daily intake.
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