Cryogenic impingement: Boosting freezing efficiency

New wave: Combining good vibrations with nitrogen power, Linde’s CRYOLINE® CWI makes freezing seafood more efficient.

To the unassuming observer, the action inside Linde’s freezing tunnel may resemble a shrimp disco, with the crustaceans gently moving to the vibes of the device’s agitation technique. It’s a wave-like kind of rhythm – hence the freezer’s name: CRYOWAVE® .

First developed in 2002, the agitation technology was a quantum leap in food freezing. Why? It smoothly separates the shrimp, as well as other individually quick-frozen (IQF) items, such as mushrooms, meatballs, diced chicken, and fruit from surrounding objects and dislodges them from the freezing belt. The result: Items are exposed to the coolant from all sides and kept in one piece, thus ensuring convenience.

The CRYOWAVE® controllable vibration technology was a quantum leap in freezing foodstuff.

CRYOLINE CWI Freezer, side front angle II, closed
The CWI fully harnesses the cooling power of liquid nitrogen.

Today’s game-changer in cryogenic freezing

Now the wave is picking up momentum. In the new generation of high-capacity CRYOLINE® CWI  freezer, Linde is combining the IQF vibration movement with the patented impingement technology – making the CWI a true game-changer in cryogenic food freezing.

The CRYOLINE® CWI fully harnesses the power of nitrogen (N2) as a cooling agent, delivering heat transfer rates two to three times those of standard tunnel freezers. This makes the application up to 20% more efficient. This means you can freeze more products – seafood, diced chicken, pizza toppings, you name it – with the same machine size. Or, you can maintain capacity with a smaller machine requiring less space. Nevertheless, the choice of freezer depends on the product that is to be frozen.

Extracting heat in next to no time

So what is this impingement all about? Pressurised liquid nitrogen, with a temperature of -196°C, is sprayed onto the product at high velocity to freeze it immediately. This way, the CWI can extract heat faster. Increasing the nitrogen’s speed is effective: It permeates the food items’ thermal resistance and creates an ice crust around them – locking in natural flavours, nutrients, and moisture. With cryogen impingement, you have five to ten times less dehydration than with conventional freezers. By limiting weight loss, the CWI significantly improves product yield. These flash-freeze effects provide prime IQF quality, something that cannot be achieved with mechanical freezers that operate at -40°C.

A high-velocity air stream

Due to the rapid heat exchange inside the freezer, most of the nitrogen instantly turns into gas. A set of jet-like blower wheels powerfully moves the nitrogen through the tunnel, creating a high-speed gas flow. Impingement plates help increase the static pressure and the overall airstream velocity. You can have the gas move at 20-30 metres per second – but you still stay in full control, depending on your product. While poultry and potatoes may be cooled with such power, lower speeds should be used for peas and berries to prevent them being blown away. A key side effect: The blower-wheels help avoid blind spots where nitrogen deposits can form piles of snow and ice.

Whether it’s seafood, meat or vegetables that you’re freezing: The CRYOLINE® CWI makes sure it’s done in an efficient and effective way. And while your products inside the CWI move to its wavy beat, you’ll certainly have your finger on the pulse of quality freezing.

Shrimp freezing process, ATZ Hamburg
Spraying liquid N₂ onto shrimp at high speed freezes them in an instant.