Impingement Tunnel Freezer

Square‘s tunnel freezer is suitable for quickly freezing granular, diced, flat food and other foods that require a good appearance after freezing such as shrimp, fish fillets, meat burgers, etc.

Our tunnel freezer utilizes high-velocity air jets that direct their force at the top and bottom of a food product to remove the air, or thermal barrier, surrounding the product surface.

This allows for faster freezing of the product and reduces processing times considerably, giving freezing times similar to those provided by cryogenic equipment. In addition, operating costs are similar to those of traditional mechanical equipment.

  • Faster freezing, juicier foods, less drip loss

  • Energy saving and small footprint

  • Efficient, Energy-Saving, Easy Cleaning

Product Features

Why Choose Square's Impingement Tunnel Freezer

Explore the original product feature overview, including Efficient Fans, Efficient Evaporator (Patent Number ZL200610097776.5), Hygiene Design, and the key technical advantages behind this system.

  • Fans

    Efficient Fans

    • High-efficiency centrifugal fan, which meets the needs of large air volume and high air speed.
    • The fan structure is easy to clean and maintain.
    • The fully-sealed motor runs smoothly and lasts long.
  • Efficient Evaporator

    Efficient Evaporator (Patent Number ZL200610097776.5)

    • The design was simulated with European professional heat exchanger software.
    • All tubes are expanded hydraulically rather than mechanically. More uniform expansion and tighter fit between tube and fins. Improved heat exchanging performance.
    • Variable fin pitch used to delay the frost formation on the fin’s surface. Longer frosting interval.
    • Easy access and cleaning.
    • Fin material: Aluminum, aluminum-magnesium alloy.
  • Hygiene Design

    Hygiene Design

    Hygiene design, all stainless steel structural parts, are fully welded and fully compliant with food processing hygiene practices.

  • Air Defrosting System

    Air Defrosting System (Patent Number ZL201620108920.X)

    Remove frost from the evaporator fin surface in time during the operation of the freezer. Ensure long and continuous operation of the freezer, reduce evaporator frosting, and improve productivity.

Technical Specifications

Parameters

Custom dimensions, capacity, and configuration matched to your production requirements.

Configuration Straight-line tunnel — modular sections, top + bottom impingement
Belt width 600 – 1,500 mm
Tunnel length 4 – 24 m (modular, extendable)
Air jet velocity 15 – 30 m/s (adjustable per product)
Operating temperature −30°C to −40°C (air)
Refrigerant NH₃ (Ammonia) / CO₂ / Freon — pump-recirculated or DX
Evaporator Aluminium tube / fin, variable fin pitch, twin-bank for continuous defrost
Defrost Hot gas / Water / Electric — automated cycle initiation
Belt type Stainless steel mesh / Solid belt / Plastic modular belt
Freezing time 3–20 min (product-dependent, belt speed variable)
Control system PLC touchscreen, recipe storage, per-module zone control, VPN
Typical lead time 14–18 weeks
Design life 15+ years (structural); 5–8 years (belt, normal operation)

Design Details

How each subsystem is engineered

Expand any section below for the engineering approach behind each critical subsystem — with links to detailed Technology pages.

In cross-flow freezing, cold air travels horizontally across the product — but a boundary layer of still air (0.5–2 mm thick) naturally forms on product surfaces, acting as insulation. Impingement jets break through this boundary layer:

  • Air jet velocity 15–30 m/s perpendicular to product surface
  • Breaks insulating boundary layer — heat transfer coefficient 2–3× higher
  • Surface freeze in 2–5 minutes vs 8–15 minutes in cross-flow
  • Most beneficial for thin, flat products where surface-to-core ratio is high

Impingement nozzle geometry directly affects freezing performance. Square uses CFD simulation to optimize per product type:

  • Round nozzles: highest local heat transfer, best for products with gaps (burger patties, cookies)
  • Slot nozzles: uniform coverage across belt width, best for continuous product sheets
  • Nozzle-to-product distance: optimized for jet coherence — too close = uneven, too far = velocity decay
  • CFD model validated against in-situ velocity measurements during commissioning

Twin evaporator banks enable defrosting without stopping production:

  • Two evaporator banks per module, each sized for 60–70% 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 2–4 hours of production time per day vs single-bank systems

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

The straight-line tunnel design simplifies upstream/downstream integration:

  • Direct in-line with forming, battering, breading equipment upstream
  • Direct transfer to packing or spiral freezer for core freezing downstream
  • Common configuration: Impingement tunnel (surface set) → Spiral freezer (core freeze) for high-throughput lines
  • Siemens PLC integrates with line-wide control system

Proven in These Food Applications

  • Burger Patties

  • Fish Fillets

  • Chicken Portions

  • Pizza

    • Frequently Asked Questions

    No. Our system is carefully calibrated to ensure uniform airflow that freezes rapidly without physically damaging or drying out delicate items like shrimp or fillets.

    Impingement freezing achieves similar speeds to cryogenic freezers, but with much lower operating costs, freezing most products in minutes instead of hours.

    We own CE, EAC, INF, CNAS, ISO, ASME, PED, U2, CSA, CRN certifications and 300+ patents, as well as 350+ engineers. Square vertically integrated production ensures quality control from raw materials.

    Square offers customized one-stop cold chain solution that meets your requirements. The high-speed airflow and adjustable conveyor system are designed to accommodate a variety of shapes, sizes, and moisture levels, while still ensuring fast and even freezing.

    An impingement tunnel freezer uses high-velocity air jets directed at the top and bottom of the product to break the surface thermal barrier, enabling rapid freezing with minimal product deformation.

    Case Studies

    Impingement Tunnel Freezer installations in operation worldwide

    Real production lines with performance data — not renderings, not claims. Each installation documented with commissioning data.

    Engineering Inquiry

    Self-Stacking Spiral Freezer installations in operation worldwide

    The more detail you provide, the more precise our engineering response. An engineer — not a sales representative — will review your requirements.

    We typically respond within 1–2 business days. Your information is kept confidential.