Evaporator for Individual Quick Freezing (IQF) Freezers in the Food Industry

Evaporator for Individual Quick Freezing (IQF) Freezers in the Food Industry

The evaporator for Individual Quick-Freezing (IQF) freezers in the food industry is a core thermal component tailored to the unique demands of IQF technology—namely, rapidly freezing individual food particles (e.g., peas, shrimp, berries) without clumping, while ensuring food safety, hygiene, and energy efficiency.

IQF evaporators are designed for refrigerants that enable ultra-low temperatures and high heat transfer efficiency. The most common option is Ammonia.

Ammonia (NH₃): Dominant in large-scale industrial IQF freezers (e.g., 10+ ton/hour capacity). Ammonia has excellent thermodynamic properties (high latent heat of vaporization). Requires stainless steel tubes (ammonia is corrosive to carbon steel).

The evaporator operates as part of a closed refrigeration cycle, with four key steps tailored to IQF:

Refrigerant Evaporation: Low-pressure liquid refrigerant (e.g., ammonia) enters the evaporator’s stainless steel tubes. As it flows through the tubes, it absorbs heat from the high-velocity air passing over the fins and evaporates into a gas.

Air Cooling: The air (drawn in by powerful fans) is cooled from ambient temperature to -35°C to -45°C as it passes over the finned tubes. This cold air is then directed uniformly onto the food products (e.g., on a vibrating belt or in a fluidized bed).

Rapid Food Freezing: The cold air removes heat from the food surface at a rate of 10–50 W/m²·K (much faster than static freezers). This causes the food’s surface water to freeze in <1 minute, forming a thin ice shell that prevents clumping. The core of the food then freezes within 3–10 minutes (depending on product size), preserving texture and nutrients.

Refrigerant Recirculation: The gaseous refrigerant exits the evaporator, is compressed by a refrigeration compressor, and condenses back into a liquid to repeat the cycle.

IQF evaporators are optimized for food safety, efficiency, and product quality—critical for industries like seafood, fruits, vegetables, and prepared meals:

Hygiene Compliance: Stainless steel construction is non-reactive, easy to clean (compatible with CIP—Clean-in-Place systems), and meets global food safety standards (FDA, EU 10/2011). No risk of material leaching into food.

High Freezing Efficiency: Finned tube design and forced convection enable fast freezing rates (reduces "large ice crystal formation," which damages cell structures in fruits/meats). This preserves flavor, texture, and nutritional value.

Energy Savings: Hot gas defrost systems minimize energy loss (vs. electric defrost), and the use of ammonia (high thermal efficiency) reduces overall refrigeration cycle energy consumption by 15–30% vs. HFC-based systems.

Clogging Resistance: Wide fin spacing and smooth tube surfaces prevent food particles (e.g., small berries, diced vegetables) from sticking to the evaporator, ensuring consistent airflow and avoiding process downtime.

Scalability: Evaporators can be customized in size (from small "pilot" units to large tunnel freezers for industrial production) and configuration (horizontal/vertical coils, single/multiple fan banks) to match production capacity.

IQF evaporators are used in all types of IQF freezers, which process a wide range of food products:

Fruits & Vegetables: Peas, carrots, green beans, strawberries, blueberries, mango chunks.

Seafood: Shrimp, scallops, squid, small fish (e.g., sardines).

Meats & Poultry: Diced chicken, ground beef patties, meatballs, bacon bits.

Prepared Foods: French fries, pizza toppings (e.g., pepperoni, mushrooms), dumplings, spring rolls.