Shrimp
Vertical air jets crust freeze raw or cooked shrimp in seconds, stopping belt sticking and keeping weight loss under 0.5%.
Impingement Tunnel Freezer
Square’s impingement tunnel freezer is built for flat, thin products like burger patties, fish fillets, shrimp, scallops, and poultry fillets that need fast crust freezing and minimal weight loss.
High velocity vertical air jets (15 to 30 m/s) hit the top and bottom of the product to break the insulating air layer. This freezes products in 3 to 20 minutes at a fraction of liquid nitrogen cost.
Perpendicular air jets (15 to 30 m/s) strip the thermal boundary layer for cryogenic class freezing speeds
Minimizes cellular drip loss and keeps product dehydration below 0.5 to 0.8%
Modular linear stainless steel construction with full access sanitation doors
Product Features
Why Choose Square's Impingement Tunnel Freezer
Fast vertical air jets, patented coil design, and easy washdown tunnel construction.
Efficient Fans
- High pressure centrifugal fans deliver stable 15 to 30 m/s nozzle exit velocities across the full belt width.
- Open access fan plenum simplifies washdown and routine inspection.
- Totally enclosed motors engineered for continuous low temperature operation at −40°C.
Efficient Evaporator (Patent Number ZL200610097776.5)
- Designed with European thermal software (Patent No. ZL200610097776.5).
- Hydraulically expanded tubes lock tightly into aluminum fins for fast heat transfer.
- Variable fin spacing slows frost buildup and leaves coils easy to wash.
Hygienic Design
A fully welded SUS304 stainless steel interior and sloped drain floor remove dirt traps and standing water for fast daily sanitation.
Air Defrosting System (Patent Number ZL201620108920.X)
Our patented air defrost system (Patent No. ZL201620108920.X) blows frost off the coil fins during production so shifts can run longer.
Technical Specifications
Parameters
Standard specifications are listed below. We size belt width, tunnel length, nozzle plates, and cooling circuits for your product.
| Configuration | Modular linear tunnel with top and bottom air jet impingement |
|---|---|
| Belt width | 600 to 1,500 mm |
| Tunnel length | 4 to 24 m (modular, field extendable) |
| Air jet velocity | 15 to 30 m/s (VFD adjustable per product) |
| Operating temperature | −30°C to −40°C (air) |
| Refrigerant | NH₃ (R717) / CO₂ (R744) / HFC (pump recirculated or DX) |
| Evaporator | Aluminum or stainless steel tube/fin, variable fin pitch, twin bank option |
| Defrost | Automated hot gas, water, or electric defrost |
| Belt type | Stainless steel wire mesh, solid stainless steel strip, or modular plastic belt |
| Freezing time | 3 to 20 min (stepless VFD belt speed control) |
| Control system | PLC touchscreen HMI, recipe storage, per module zone control, VPN diagnostics |
| Typical lead time | 14 to 18 weeks |
| Design life | 15+ years (structural); 5 to 8 years (conveyor belt under normal operation) |
Design Details
How Each Subsystem Is Engineered
Open each section below to see how key parts of the freezer work.
Impingement vs. Crossflow Freezing
In conventional crossflow freezing, cold air travels horizontally across the product, leaving a stagnant boundary layer of air (0.5 to 2 mm thick) that acts as thermal insulation. Impingement jets break through this boundary layer:
- Air jet velocity of 15 to 30 m/s directed perpendicular to top and bottom product surfaces
- Strips away the insulating boundary layer, increasing the surface heat transfer coefficient by 2 to 3×
- Forms a surface crust in 2 to 5 minutes compared to 8 to 15 minutes in crossflow tunnels
- Ideal for thin, flat products with a high surface to core ratio
Nozzle Design & CFD Optimization
Impingement nozzle geometry directly governs freezing uniformity. Square uses CFD simulation to optimize nozzle configuration per product type:
- Round nozzles: highest local heat transfer for discrete products (burger patties, fillets, cookies)
- Slot nozzles: continuous velocity curtain across the belt width for sheeted or formed products
- Nozzle to product clearance calibrated to maintain jet coherence without disturbing lightweight items
Production Continuous Defrost
Twin evaporator banks enable defrosting without stopping production:
- Two evaporator banks per module, each sized for 60 to 70% of total duty
- When Bank A defrosts, Bank B handles full load at reduced throughput
- Defrost banks alternate on schedule or pressure drop trigger
- Recovers 2 to 4 hours of production time per day vs single bank systems
Belt Selection & Product Handling
Belt type is critical for impingement performance:
- Open mesh belt: Allows bottom impingement air to reach product directly. Best for IQF and structured products
- Solid belt: Required for soft, deformable products (raw dough, wet batter). Bottom cooling via belt conduction only
- Plastic modular belt: For sticky products. Lower thermal mass than steel, reducing refrigeration load
Automation & Line Integration
The linear modular tunnel architecture simplifies upstream and downstream line integration:
- Direct inline transfer from forming, battering, breading, or slicing equipment
- Seamless downstream handoff to packaging machines or a spiral freezer for deep core freezing
- Two stage line option: an impingement crust freezing module ahead of a spiral freezer eliminates belt grid marks on soft products
- Siemens PLC synchronizes belt speed and thermal setpoints with upstream and downstream equipment
Proven in These Food Applications
Shellfish
Rapid impingement freezing locks in natural moisture, glaze uptake, and firm texture across scallops, mussels, and clam meat.
Fish Fillets
Dual top and bottom impingement jets freeze thin fish fillets and portioned steaks flat without curling or ice crystal damage.
Frequently Asked Questions
No. We set nozzle height, air pressure, and fan speed for each product so the air jets freeze a surface crust on shrimp or fillets without blowing pieces around.
Impingement freezing achieves freezing speeds comparable to liquid nitrogen cryogenic freezers while operating at mechanical refrigeration costs, freezing flat and diced products in minutes instead of hours.
Square holds ISO 9001, ISO 45001, CE, PED, ASME (U and U2 stamps), EAC, CSA, CRN, and CNAS laboratory accreditation, supported by 300+ patents, 300+ R&D engineers, and 300+ installation and service engineers.
We customize the impingement tunnel freezer to your product and line layout, adjusting high-velocity airflow, conveyor speed, belt configuration, refrigerant circuit, patented ADF air defrost (ZL201620108920.X), and hygiene options to accommodate different shapes, sizes, and moisture levels.
An impingement freezer shoots fast air jets at the top and bottom of the food to strip away warm surface air, freezing flat items in minutes with minimal weight loss.
Engineering Inquiry
Discuss Your Impingement Tunnel Freezer Project
Tell us your product thickness and capacity for an impingement freezer quote.
Our engineers reply within 24 hours. All project details are kept confidential.
