When a cooling tunnel’s length is reduced by half, the product’s residence time under active cooling drops by 50% if conveyor speed is kept constant. To maintain the same throughput (pieces per minute) and still achieve sufficient cooling, several process parameters must be adjusted-but these changes bring inherent risks that any manufacturer, including KorNutra, must carefully evaluate during process development.
Process Parameters That Would Need to Change
Cooling rate depends on the temperature difference between the product and the cooling medium, the velocity and turbulence of that medium, and the thermal properties of the product. Halving the tunnel length means you have to extract the same amount of heat in half the time. The following adjustments would be the primary levers:
- Air temperature setpoint: Lower the supply air temperature significantly (e.g., from 10°C down to 0-4°C or even lower). This increases the ΔT driving force and can shorten cooling time, but it must stay above the product’s freeze point to avoid surface damage.
- Air velocity and flow pattern: Increase fan speeds to raise air velocity, and consider adding baffles or air knives to create high-turbulence impingement jets. Higher velocity improves the convective heat transfer coefficient, removing heat faster.
- Conveyor speed (throughput): If throughput was previously limited by cooling capacity, you might actually need to reduce conveyor speed to give product more time in the now‑shorter tunnel, which would lower throughput. To truly maintain throughput, you would keep speed constant and rely on the other parameters to compensate. However, if you raise speed to offset production demand, the cooling challenge becomes even more severe.
- Product load pattern: Spreading the product into a thinner bed or single layer increases exposed surface area and reduces the thermal mass that each air stream must cool, effectively speeding cooling without changing line speed.
- Supplement formulation (if adjustable): In some cases, reformulating with a lower gelatin or moisture content, or adding a quicker‑setting binder, can reduce the cooling load. This is a formulation change, not a line parameter, but it directly impacts cooling demands.
Risks of Operating a Halved Cooling Tunnel
Forcing more intense cooling in a shorter space introduces several quality and operational risks that could lead to rejected product or equipment damage:
- Non‑uniform cooling and thermal shock: Aggressive cold air can chill the product surface rapidly while the core remains soft or warm. This creates internal stress, leading to cracking, surface defects, or split supplements-especially in gummy and coated tablet operations.
- Condensation and moisture issues: Very cold air can cause ambient moisture to condense on the product or tunnel surfaces when the product exits into a warmer room. This results in sticky, cloudy, or misshapen pieces that are difficult to package.
- Over‑drying of surfaces: High‑velocity, low‑temperature air accelerates moisture loss from the product surface, possibly causing a dry, leathery skin that traps moisture inside and affects texture and shelf stability.
- Cold shock to ingredients: Some sensitive active ingredients or encapsulation systems may degrade or rupture under extreme temperature swings, reducing the supplement’s effectiveness.
- Increased energy consumption and equipment strain: Lowering air setpoints and running fans at maximum capacity dramatically raises energy costs. Condensing units may frost over, and repeated thermal cycling can shorten equipment life.
- Process control difficulty: A shortened tunnel leaves very little margin for error. A small fluctuation in ambient conditions, product loading, or initial product temperature can result in under‑cooled product reaching packaging, causing clumping, deformation, or microbial stability concerns.
In practice, cutting a cooling tunnel length in half and maintaining throughput is not a trivial adjustment. It requires careful engineering justification, thorough validation runs, and often a compromise in one or more quality attributes. KorNutra’s process specialists would typically evaluate such a change only when expanding an existing line is impossible and all thermal and product behavior has been mapped through precise trials.