NITROBOOST™: A Turbocharger for Freezers

Using liquid nitrogen, Linde’s NITROBOOST™ technology helps frozen food customers reach maximum freezer performance with minimal disruption.

An artistic photograph of a cupcake with colorful sprinkles being partly frozen with liquid nitrogen on a dark background

The global frozen food market is expected to grow from what was 251.2 billion USD in 2021 to 373.8 billion USD by 2028. For companies in this sector, a growing market means growing pressure when it comes to production rate: which means asking more and more of their existing refrigeration systems. The problem is not growth however, it is outgrowth. “Food processors might encounter performance problems because they sized their system a decade ago and have outgrown that production rate,” explains John Girard, Senior Technology Expert in Food & Beverage Applications at Linde, “Now, their freezers are simply not meeting the capacity they require.”

But Linde has a solution: the NITROBOOST Supplemental Refrigeration System is an easily retrofitted technology that delivers a rapid, flexible increase to refrigeration capacity when needed most.

A Question of Retrofitting; Not Refitting

Linde is known for offering a wide range of innovative cryogenic solutions for the food and beverage industry but given that around 90% of the sector still uses mechanical systems like blast or spiral freezers, replacement is not necessarily the aim of the game. “It’s about supplementing what the customers already have to help boost their productivity,” explains Soujanya Jampala, Commercialization Director for Food & Beverage Applications. Cryogenic systems have their advantages: small footprint, quick freezing times, and fast installation but as Jampala explains, it might be a case of using a sledgehammer to crack a nut. “Food processors might only need a 20% increase in capacity, but they don’t want to invest in expensive new equipment or undergo a facility renovation that requires weeks of downtime.” That’s where Linde’s retrofitted cryo-mechanical solution comes in.

A close-up of Linde's NITROBOOST fin tube heat exchanger coils inside an insulated unit.

Adding more capacity essentially comes down to space. At the core of any freezing technology is heat transfer. And heat transfer is all about surface area. “These blast and spiral mechanical freezers are the size of a large room with as much heat exchanger surface as possible squeezed into it,” says Richard Novak, Senior Technology Expert at Linde, and co-lead on the project. “Often, there’s simply no room in the box to add more surface area.” The advantage of NITROBOOST is that by increasing the surface area by only a small percentage, you will see a significant boost in capacity. That’s because liquid nitrogen - operating at -320F - is just so much colder than the typically used refrigerants like ammonia or freon. “We can get five to ten times as much refrigeration out of the same amount of coil,” Novak adds.

Image showing a modular, self-contained NITROBOOST unit mounted on the wall of a large industrial freezer.
Always Safe; Not Always On

Retrofitting NITROBOOST is made easier by the fact that it was developed as a modular, self-contained system, complete with coils, defrost mechanism and PLC. Where space is an issue in existing setups, enough can usually be found for the small, insulated boxes containing the fin tube heat exchanger coils - which pack a refrigeration punch according to Girard: “One unit measures around 36in x 15in x 15in and we can get 3.5 tons of refrigeration out of it.”

The system can be installed quickly and easily, box by box, with just a couple of people without the need for heavy lifting equipment. A typical installation will see up to 4 boxes mounted inside or on the wall or ceiling of the existing freezer along with fan units and ducting work and of course, an on-site nitrogen supply. “Safety is paramount when nitrogen is being vaporized,” explains Girard, “With NITROBOOST, Liquid nitrogen travels safely through a pipeline to the coils and is then vented to the atmosphere.”

Not only is it a safe solution but it is economical too. Unlike pre-chillers for example - where you install a cryogenic tunnel in front of the mechanical freezer - NITROBOOST isn’t “always on”. Girard describes it as a “turbocharger for your freezer” in the sense that “it just kicks in when you need that extra performance.” That might be getting the freezer to the target operating temperature quicker or keeping the temperature at the set-point throughout the day.

Catering for the Cooked Frozen Industry

NITROBOOST suits the cooked frozen product market particularly well - baked goods, cooked vegetables, but especially meat and poultry. When hot products like these come into the freezer, moisture loss occurs via steam. That moisture inevitably ends up in the mechanical system, forming frost on the coils and reducing the freezer’s performance. Meat and poultry products for example can be subjected to stringent regulations when it comes to how fast they are cooled down to temperature. In such cases, NITROBOOST can boost the freezer performance and help processors hit those target times.

“It has always been our quest to find a solution for mechanical freezers that is primarily safe as well as economical and with a low footprint,” says Jampala, “With NITROBOOST I think we’ve found it.”

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