Air Blast Tunnel Freezers is a batch freezer that blows deep-frozen air through the layers of trays stacked on loading trolleys. It is the most flexible unit in the batch freezing family: tray-packed vegetables, seafood, meat, fish and pre-processed goods all run on the same machine, at a lower capital cost than a contact plate freezer.
Tan Long designs and builds air blast freezing tunnels to each plant's own capacity at its factory in Duc Hoa 1 Industrial Park, Tay Ninh (formerly Long An), meeting HACCP/FDA standards. The equipment runs on both NH3 refrigerant and Freon.
Which industries use air blast freezing tunnels?
These are the sectors where Tan Long installs air blast freezing tunnels most often:
- Seafood processing: fish fillets, shrimp, squid and frozen export products.
- Food and meat processing: carcass meat, cut meat and ready-prepared foods.
- Agricultural produce and vegetables: vegetables and fruit that need rapid cooling after harvest.
Each sector has different requirements for temperature range, contact materials and capacity. Please contact Tan Long's engineering team for advice on the right configuration for your products.
What is an air blast freezing tunnel? Operating principle and technical standards
Technical characteristics of Tan Long air blast freezing tunnels
- Freezes a wide range of products: tray-packed vegetables, seafood, meat and fish, and pre-processed goods
- Quick freezing of products at low temperatures maintains the natural quality of the product
- High heat exchange efficiency, saving energy consumption
- Simple construction with relatively low capital cost.
- Designed and built to HACCP/FDA standards. Easy to clean, meeting food safety and hygiene requirements.
- A wide range of freezing capacities, and capacity can be designed to the customer's requirement
Working principle
Product is laid on trays stacked in layers on a loading trolley with a fixed gap between them, and the trolleys are pushed into the tunnel batch by batch. Fans blow cold air to the far end of the room, where it turns downwards and passes through the layers of trays. With thousands of deep-frozen air jets in direct, continuous contact with the surface, the thermal boundary layer around the product is broken up and cold air penetrates to the core. Freezing therefore happens quickly. Once the required temperature is reached, product is removed from the trays and moved into storage
Air blast freezer insulation panel
The wall, ceiling and floor panels are insulated with 125 mm polyurethane at a density of 40-42 kg/m3, applied with a high-pressure spray machine.
- Wall panel: Inside covered with 0.6mm thick SUS 304 stainless steel, outside covered with 0.8mm thick SUS 304 stainless steel with anti-scratch tape.
- Ceiling panel: Inside covered with 0.6mm thick SUS 304 stainless steel, outside covered with 0.6mm thick SUS 304 stainless steel with anti-scratch tape.
- Base panel: The inside is covered with 1.2mm thick SUS 304 stainless steel, the outside is covered with 0.6mm thick SUS 304 stainless steel, cast and welded seamlessly, waterproof. The freezer floor is sloped enough to drain water thoroughly during cleaning.
- The sliding door is insulated with 100 mm polyurethane at a density of 40-42 kg/m3. Both faces are clad in 0.6 mm SUS 304 stainless steel with a protective film against scratching. All fittings are imported from Europe. The door has a silicone sealing gasket, a frame heater element to prevent frost build-up, and a lock with an anti-entrapment mechanism.
Condenser
The evaporator uses stainless steel or copper heat exchange tubes and aluminum fins depending on the refrigeration system. The technical parameters of the evaporator are calculated and selected in the most optimal way to ensure high heat exchange efficiency, continuous operation for a long time, saving energy costs. The evaporator is provided by famous suppliers such as Guntner, Thermofin, Kelvion (EU).
Evaporator fan
Fans are made of aluminum alloy, high performance, low energy consumption, supplied by Ziehl-Abegg or Rosenberg of Germany.
The fan motor is a type made specifically for air blast freezing tunnels, rated IP56 for complete thermal and moisture protection. The motor casing carries a special protective coating so it runs reliably in deep-frozen conditions. Motors are supplied by ABB or WEG
Specifications
- Products frozen: shrimp, fish, meat and pre-processed foods
- Product core temperature in/out: +10⁰C/-18⁰C
- Evaporating temperature of the refrigerant: typically designed to be between -40°C and -47°C, depending on the product being frozen.
- Freezing room temperature: -33oC to -35⁰C
- Refrigerant feed method: pumped circulation.
- Refrigerant: NH3 or R22 gas.
- Defrost method: water.
Tan Long - A reputable and quality address for supplying and installing air blast freezers
You are looking for an address that provides air blast freezer Genuine, can change capacity to suit your production scale Tan Long air blast freezer system will be the right choice for you.
Tan Long is a unit providing technical solutions, design and installation. air blast freezer systemUsing services at Tan Long, you will get:
- A team of technicians consults, designs, and installs systems suitable for the scale and production goals of the business.
- Full service
- One-time quote, no additional charges during installation
- Detailed operating instructions after installation
- Regular equipment maintenance helps ensure stable and durable operation
If you need to install an air blast freezer, contact Tan Long immediately via hotline. (+84) 933357058 for quick support.
The three batch freezing machines compared
Batch freezing differs from continuous individual freezing in that product is loaded in one go, runs the full cycle and is only then removed. The three machines below differ in how cold is transferred into the product, which in turn changes output and cycle time:
| Criteria | Air Blast Tunnel Freezers | Air blast freezer (TABF) | Contact plate freezer (TCF) |
|---|---|---|---|
| Cold transfer method | Cold air blown through the layers of trays on the loading trolley | Forced cold air inside a compartmented chamber | Direct contact between the plate and the product block |
| Output | Designed to each plant's requirement | 300 / 450 / 600 kg per batch | 1,000 / 1,200 / 1,500 kg per batch |
| Suitable product | Tray-packed vegetables, seafood, meat and fish, pre-processed goods | Fish fillets and whole fish, meat, battered products, agricultural produce | Shrimp, fish and seafood in block form |
| Cycle time | Depends on the product type and the thickness of the stacked layer | Depends on the product type; freezing chamber at -33 to -37°C | 60 – 90 minutes |
| Cooling capacity | To design | 40 / 60 / 80 kW | To the pumped or gravity-fed liquid configuration |
| Strength | The most flexible on product type, with low capital cost | Compartmented, so product is loaded and unloaded in stages with little cold loss | The highest output for the same floor area, and the shortest freezing time |
| Limit | Requires tray loading and trolley handling | Takes up a long footprint: 7.7 to 15.1 m depending on capacity | Only runs block-form product, not loose product |
When the requirement is to freeze product individually rather than in batches, the right machine is the IQF conveyor rather than any of the three above.
Compared with other freezing equipment
The air blast freezing tunnel is the high-output batch option. When the scale or the product form is different, consider these three groups:
- Air Blast Freezer — the same forced-air principle but on a smaller scale, taking up less floor space, suitable when output is not yet large enough to justify a tunnel.
- Contact freezer — cold transferred through direct plate contact, giving a much shorter freezing time but only running flat block-form product.
- Mesh belt IQF freezer — continuous rather than batch freezing, used when the line runs continuously and product must be frozen individually.
See the full range of industrial refrigeration equipment built by Tan Long.
What is a suitable evaporating temperature?
Air blast freezers are typically designed with Evaporation temperature ranges from -40°C to -47°C.. This is not a default setting for all freezers: the final figure depends on the product type, the required freezing time, and the operating limits of the compressor.
When exchanging parameters, it is necessary to distinguish between three temperature quantities that are often used interchangeably:
| Quantity | Meaning | What is it used for? |
|---|---|---|
| Product core temperature | Temperature at the slowest cooling zone in the product. | Confirm the quality of the frozen product. |
| Air temperature | Air temperature at a specific measurement location | Distinguish between air entering the racking system, air leaving the racking system, and air passing through the rows. |
| Evaporating Temperature t₀ | The saturation temperature corresponds to the refrigerant pressure at the evaporator. | Selecting indoor units and designing the refrigeration system. |
The core temperature is the point of highest temperature at the end of the freezing process, and it does not necessarily coincide with the geometric center of the product.
Should the evaporator temperature be set at -45°C?
That's possible, if -45°C is the calculated operating point and the entire device meets it. But -45°C is not a mandatory condition. To achieve a product temperature of -18°C or -20°C, lowering the evaporation temperature increases the temperature difference at the coil and also increases the compression ratio if the condensing temperature remains constant. Therefore, the cooling capacity and compressor efficiency must be re-checked.
The correct decision-making process involves running comparative trials of the two approved modes on equivalent batches, recording the time to center, kWh/batch, yield, and product quality. Only select the lower mode when the benefits in yield or quality outweigh the electricity costs.
What is the Freezing Retention Time in a blast freezer?
Freezing Retention Time depends on the product type, size, packaging, inlet temperature, batch volume, air conditions, and required core temperature. Two example test conditions illustrate how significant the difference can be:
| Product | Input | Air | Time for the core to reach -20°C |
|---|---|---|---|
| The whole fish is approximately 125 mm thick. | +5°C | -35°C, 5 m/s | around 5 o'clock |
| The scampi meat is 18 mm thick. | +5°C | -35°C, 3 m/s | approximately 26 minutes |
The actual cycle time includes loading, unloading, cleaning, and defrosting. Daily productivity is calculated from the cycle time and production schedule. Freezing quality must be confirmed by a core temperature curve at locations representative of the slowest freezing zone (low air zone).
Why has the air reached the desired temperature, but the core of the product hasn't?
Air temperature and product core temperature are two different control parameters. The air sensor may have reached the set value while the product is thick or located in an area with weak airflow and has not yet frozen sufficiently. Common causes include:
- The incoming goods are warmer or heavier than designed.Check the weighing slip and the batch temperature.
- Thicker products, stackable items, or packaging with many empty spaces.Compare the actual specifications with the tested sample.
- Air distribution is uneven.Check the vehicle position, tray orientation, air vents, and return air ducts when the tunnel is fully loaded.
- The evaporator coil is covered in thick frost, or the fan is malfunctioning.Check both the heat exchange through the coil and the airflow.
- Insufficient cooling capacity at the work point.Compare the refrigerant level, compressor status, cooling, and batch load.
- Incorrect measurementCheck the probe, insertion depth, and calibration; avoid letting the probe touch the tray or rest in a hollow slot.
The inspection sequence should proceed from measuring and calibrated goods, to air distribution, and finally to adjusting the refrigeration system.
How to calculate the capacity of a blast freezer.
It is necessary to distinguish between three quantities that are not interchangeable: production capacity (kg/batch or kg/hour), cooling capacity (kW cooling) and electrical power (kW of electricity).
Average cooling load due to the product is calculated based on energy balance:
Qsp = m × Δh / (3.600 × t) (kW)
- m: product weight (kg)
- Δh: enthalpy difference from the input state to the output state (kJ/kg), including the phase transition.
- t: useful freezing time (hours)
| A hypothetical example for preliminary calculation. | Value |
|---|---|
| Product weight m | 2,000 kg |
| The enthalpy difference Δh (assumed) | 300 kJ/kg |
| Freezing Retention Time is useful. | 4 hours |
| Average product load | 2,000 × 300 / (3,600 × 4) = 41.7 kW |
| Additional loads (trays, vehicles, hatch covers, air ingress, fans, lights) — assumed | 18.3 kW |
| Average cooling load illustration | 60.0 kW |
60 kW is the average load, for example., There is not enough information to choose a compressor.. Engineers must also check the load variation in the batch, frost conditions, cooling capacity over the required time, and the actual capacity of the compressor, evaporator, and condenser at the design evaporator and condenser temperatures. This formula is an energy balance calculation and is not used to predict freezing time.
How much electricity does a blast freezer consume?
Electricity consumption must be calculated according to kWh/batch or kWh/ton of finished product meets requirements, This cannot be inferred from the tunnel volume or the installed engine power.
Ebatch = Total electrical energy of compressor, fan, pump, cooler, defrost and related loads within the measurement range. Power consumption rate e = Ebatch The finished product volume meets the requirements.
Example (not a standard): 2 tons of finished product per batch, average load of 60 kW for 5 hours, plus 20 kWh auxiliary power → Ebatch = 60 × 5 + 20 = 320 kWh; e = 320 / 2 = 160 kWh/ton.
To reduce electricity consumption: standardize incoming temperature, run batches according to design specifications, maintain good cooling, complete batches according to confirmed criteria, and schedule batches to avoid peak hours. Do not arbitrarily reduce fan speed without checking for the impact on the area receiving weak airflow. Maintain condenser Keeping it clean is one of the most effective ways to reduce compressor power consumption.
How to arrange items for faster and more even freezing.
The air velocity is approximately 5 m/s This is a reference value for many blast freezers. This is the average velocity in the gap between the product, not the velocity at the fan opening.
- Maintain the correct number of carts, trays, weight, and thickness of goods per tray according to the confirmed batch.
- Position the tray slots facing the direction of the air; do not stack them beyond the permitted limit.
- Do not place the unit too close to the air supply and return lines, as this will block them.
- Keep the air deflector and baffle in place; excessively large gaps create a path for the air to bypass the deflector.
- When transporting multiple types of goods together, controlling them by grouping them together is the slowest process.
- Keep a diagram and photos of the standard batch layout; recheck it each time you change packaging or specifications.
There is no single centimeter-sized gap that applies to all tunnels; the gaps between the tray, the vehicle, and the wall must conform to the airflow distribution design of each tunnel.
Common operating errors and troubleshooting methods
| Phenomena | Initial inspection approach |
|---|---|
| The air has reached the desired temperature, but the core hasn't. | Measure center, thickness, packaging, batch weight, and airless zone. |
| The traffic is uneven. | Tray orientation, vehicle position, air bypass, individual fan status |
| Batch time increases gradually | Frost buildup, defrosting, coil cleanliness, cooling conditions |
| The surface loses water, its quality deteriorates. | Storage time, air conditions, packaging, post-freezing processing steps |
| Low suction pressure | Actual load, air, snow, fluid level, sensor inaccuracies |
| The compressor is giving a warning or making unusual noises. | Stop according to procedure; find the cause before restarting. |
| Freezing on the floor or door | Leaky gasket, moisture ingress, water leakage, heating function |
Freezing does not improve the quality of the original feedstock, so the evaluation of the hatch must be linked to the pre-freezing treatment. The defrosting schedule is based on the design, the condition of the system, and operating data. Operators must not disable safety devices or interfere with the refrigerant system without prior assignment and training.
Key parameters to finalize when designing and inspecting an air blast freezer.
- Product type, maximum size, packaging, batch volume, input temperature.
- Output core temperature, sampling location, measurement method, committed cycle time.
- The equipment selection table is based on the correct refrigerant, evaporation temperature, condensation temperature, and load conditions.
- The layout includes the number of carts and trays, airflow patterns, and plans for cleaning and defrosting.
- Perform a load test with a representative batch; simultaneously record the core temperature, air temperature, time, and power consumption.
- Emergency exits open from the inside, warning system, security, and operating instructions are provided.
Sample acceptance criteria: “Freeze … kg of product …, maximum thickness … mm, input temperature …°C, packaging …, according to the approved stacking scheme; the core temperature at the inspection points reaches …°C for … hours.” The values are finalized in the project documentation and the measurement method is agreed upon before testing.
Frequently asked questions about air blast freezing tunnels
How does an air blast freezing tunnel work?
Product is laid on trays stacked in layers on a loading trolley with a fixed gap between them, and the trolleys are pushed into the tunnel batch by batch. Fans blow cold air to the far end of the room, where it turns downwards and passes through the layers of trays. Thousands of deep-frozen air jets touch the product directly, so it cools quickly and evenly.
What products can an air blast freezing tunnel handle?
Tray-packed vegetables, seafood, meat and fish, and pre-processed goods. That is this machine's advantage over the contact freezer which only runs block-form product.
What capacity does an air blast freezing tunnel have?
There is no fixed configuration — the tunnel is designed to each plant's real output. Tan Long calculates capacity from the output per batch, the product type, the thickness of the stacked layer and the required freezing time, and only then fixes the tunnel dimensions and the cooling capacity.
Air blast freezing tunnel or air blast freezer — which fits better?
Choose the tunnel when the product range is varied and capital cost matters. Choose the air blast freezer when you need a standard 300 to 600 kg per batch configuration and want compartments so product can be loaded and unloaded in stages without losing cold from the whole chamber.
Does an air blast freezing tunnel meet food hygiene standards?
Yes. It is designed and built to HACCP/FDA standards with easily cleaned surfaces. This is a mandatory requirement for export processing plants.
Is glazing needed after the air blast freezing tunnel?
It depends on the product. Seafood for export usually goes through glazing with a automatic spray coating machine to form a protective ice coating, then through a refreezing conveyor to refreeze that coating before packing.
How does a blast freezer differ from an IQF conveyor belt freezer?
Air blast freezers provide batch freezing on trays, carts, or racks, offering flexibility for various specifications, including packaged goods; capacity is calculated in kg/batch with cycle time. IQF conveyor belts provide continuous freezing on a conveyor belt, suitable for products requiring individual pieces; capacity is calculated in kg/hour under specific product and conditions.
What is the air velocity inside the air blast freezer?
Approximately 5 m/s is a reference value for many tunnels, calculated as the average velocity in the gap between the product and not at the fan inlet. The final value depends on the product and the air distribution configuration.
How much electricity does a blast freezer consume per ton of goods?
There are no standard consumption rates. Power consumption must be measured in kWh/batch or kWh/ton of finished product meeting requirements, including compressor, fan, pump, cooling, and defrosting. It cannot be derived from the volume of the cellar or the power of the motor.
Request advice and a quotation
Tan Long designs and builds industrial refrigeration equipment at its plant in Duc Hoa 1 Industrial Park, Tay Ninh (formerly Long An), so capacity and dimensions can be adjusted to the actual site. Call 0933 357 058 (Mr. Thinh) or send a quotation request with your output per shift and your main product type.
Technical standards applied to air blast freezing tunnels
Equipment supplied by Tan Long is manufactured to the following standards and material requirements:
- HACCP
- FDA
- SUS 304 stainless steel
- polyurethane insulation
- NH3 refrigerant
- Freon refrigerant
- IP protection rating
Depending on each project's requirements, the engineering team will advise on the material configuration and connection standards that best suit the plant's existing system.
How Tan Long advises on and supplies air blast freezing tunnels
Tan Long controls both design and manufacture at its plant in Duc Hoa 1 Industrial Park, Tay Ninh (formerly Long An), so the investor deals with a single point of contact from survey to handover:
- Survey and requirement definition: engineers work directly at the plant to establish capacity, layout, refrigerant and real operating conditions.
- Technical proposal: calculating a suitable configuration and discussing it with the investor's technical team before it is fixed.
- Detailed design: drawings are prepared and materials and equipment selected to match the refrigerant and the operating temperature range.
- Manufacture and works testing: machining, assembly and a test run before the unit leaves the factory.
- Installation and acceptance: connection into the plant's system, load testing and handover with the technical documentation.
- Warranty and operating support: operating instructions for the plant's technical team and fault support during the warranty period.
Why choose Tan Long for air blast freezing tunnels?
Tan Long is a refrigeration engineering joint stock company with more than 20 years in industrial refrigeration, serving seafood and food processing plants and large-scale cold stores across Vietnam.
- In-house manufacturing: its own factory in Duc Hoa 1 Industrial Park, Tay Ninh (formerly Long An), with no dependence on outside subcontractors.
- Turnkey D&B capability: design and construction under one roof, reducing the risk of a gap between the drawings and what is actually installed.
- Complete documentation: equipment is handed over with technical files and CO/CQ certificates of origin.
- Engineers with field experience: advice based on each plant's actual system configuration rather than selling from a catalogue.
- Support after handover: the technical team is on hand for operation and maintenance throughout the equipment's life.
For advice on a specific configuration, please contact Tan Long's engineering team or see the projects already delivered.
Related technical reading
- What is quick freezing? The secret to keeping food fresh.
- Properly freezing jackfruit - The secret to successful export.
- How to freeze mangoes without browning, keeping them fresh and preserving their flavor.
- Ca Mau Seafood Processing and Service Joint Stock Corporation – NH3 refrigeration and IQF
- Vietnam Clean Seafood Joint Stock Company – NH3 refrigeration and IQF
Related pages
- TABF air blast freezer
- TCF contact plate freezer
- Automatic spray coating machine
- REF refreezing conveyor
- Industrial cold storage – turnkey design and installation
- NH3 refrigeration systems for processing plants
- 29 projects delivered by Tan Long
- The range of industrial refrigeration equipment Tan Long designs and builds
- Design consultancy, installation and maintenance services for refrigeration systems
