Why Cooling Tunnel Length Matters
AMC
AMC
2026-08-27 14:48:54
Tunnel length determines residence time—how long the product spends inside the tunnel. Residence time is belt speed multiplied by length. If the tunnel is too short for the belt speed, the product exits soft, marks the conveyor, and demoulds badly.
The cheapest way to protect everything upstream is a cooling tunnel long enough and controlled enough to finish the job. Length is the parameter people most often under-buy.
For high-capacity industrial lines, tunnels can extend up to 30 meters or more. Manufacturers offer modular tunnel sections (typically 2–3 meters per module) that can be combined to achieve the required total length.
Different products require different residence times, which directly affect length:
| Product Type |
|
Reasoning | |
| Freeze-dried fruit / thin-coated products | 3.2–6 meters | Minimal coating thickness; rapid heat transfer | |
| Soft desserts / puffed products | 6–8 meters minimum | Sensitive to thermal shock; requires gentle cooling | |
| Nut biscuits / thick-coated products | 8+ meters | Thick coating means more heat to remove | |
| Molded chocolate bars | 8–12 meters | Requires full crystallization through the bar | |
| High-capacity enrobing lines | 18–30 meters | Extended residence time at high belt speeds |