Fleetowner 5522 Refrigerationinnovation Web
Fleetowner 5522 Refrigerationinnovation Web
Fleetowner 5522 Refrigerationinnovation Web
Fleetowner 5522 Refrigerationinnovation Web
Fleetowner 5522 Refrigerationinnovation Web

Cooling with nitrogen

Aug. 10, 2015
“It was really cool technology. It was completely different than an engine mounted on the trailer making all these emissions, all this noise, just to cool what’s inside the box. It costs less and the maintenance on it is so much less than a reefer, so the true cost to own is absolutely less than a conventional reefer.” - Ross Froat, manager of engineering and IT for the Technology and Maintenance Council at ATA

Near-zero emissions, much less noise, low maintenance. That’s the sales pitch behind liquid nitrogen (LN2)-based cooling systems for trucks and trailers. So what’s the catch? Unfamiliarity with LN2, mainly, and some reluctance on the part of temperature-controlled carriers to move away from tried-and-true diesel-powered compressors.

But, with more and more regulatory focus on greenhouse gases, that comfort level with diesel systems may have run its course. And, backers of nitrogen systems say, proven alternatives are increasingly available for fleets to evaluate.

Nitrogen has been used in cooling systems for some time, but for transportation it’s been “difficult to work with,” explains Tom Tait, vice president for Reflect Scientific, a Utah-based, publicly traded company whose Cryometrix brand develops and markets technologies in cryogenic cooling for the medical, pharmaceutical, industrial, and transportation markets.

The Cryometrix AZE, the company’s entry into trucking, is “very similar” to a standard refrigeration system, he says. Simply, the AZE uses a heat exchanger “to suck all the cold we can” out of the gaseous nitrogen as it circulates through the system. Additionally, the system requires no trailer modifications to install.

“It’s a complete drop-in unit,” Tait says. “Same bolt pattern, a little less weight, but everything’s in there: the tanks, the exchange unit, the fan, the control mechanism—everything.”

A tractor-trailer with an AZE unit was tested last year with a fleet making a run from Salt Lake City to Denver, a 525-mi., seven-stop run over 24 hours. The test units have since been pulled out of service, and Reflect Scientific has been reviewing the results.

“After all the data gathering, we had to bring it all back and ask, ‘What did we learn? How do we make it better?’” Tait says.

Of note, many of the subsequent changes have been “small things; the practical, everyday things”—changes such as finding a better place to put the master on/off switch or the fill line.

The operation is really so simple there’s almost nothing to it,” Tait continues. “But it’s the layout that you have to test to get it right.”

The cooldown time is “really quick,” and it is controlled by the amount of LN2 flowing through the system, whether a trickle or a blast—as compared to a compressor system, which is either running or not, he adds. “We can hit minus 20 deg. F like nothing. Of course, for your best efficiency you wouldn’t need to do that.”

Liquid nitrogen, as a cooling media, “turns out to be pretty efficient,” Tait says. And diesel units, although they might be efficient “on the burn side,” lose much of the efficiency in converting that energy to cold air through the compressor.

According to Tait, other operational advantages include both the cost of LN2 and the stability of the market. “Ours is a very cost-competitive technology as far as the consumable portion of it goes,” Tait says.

Likewise, the low maintenance system—valves and fans are the only moving parts—mean greatly reduced downtime compared to compressor-based systems, he adds.

In terms of price, the AZE will be positioned to be competitive with diesel-powered reefer units. “We might be able to come in lower at some point, but right now we’re aiming for their exact price point, and it’s not a problem,” Tait says.

For the immediate future, the company’s plan is to work with the state of California as it implements a pilot program to encourage adoption of carbon-alternative technologies.

Direct cooling

While the Cryometrix system uses a heat exchanger to cool the trailer, similar to a traditional reefer, a direct system has no heat exchanger. Instead, cold nitrogen gas is injected into the trailer cavity.

“Our system eliminates all of that extra stuff,” Hazen Sills, director of business development for Boreas Nitrogen Cooling Systems, says. “The advantage is you don’t have a lot of wasted energy.”
The Boreas system, developed by privately held JFE Industries, allows independent temperature control of three different zones in the trailer, in contrast to a system in which the trailer is coldest nearest the refrigeration unit.

Additionally, the direct injection cuts the precooling time for the trailer “basically to zero,” according to Sills.

As with an indirect system, the Boreas system has “virtually no moving parts.” Electronically controlled valves manage the flow of the nitrogen, which is stored in liquid form in cylinders beneath the trailer. The nitrogen boils into a gas as it’s released through the system’s plumbing and dispersed inside the trailer. The total weight, with a full supply of nitrogen, “is about equivalent” to a diesel-powered reefer unit, he notes.

As for the trailer, the Boreas system requires no changes to a trailer’s insulation system, but the company works with trailer manufacturers to develop a build spec to accommodate the plumbing, sensors, and valves.

The technical challenge has been to perfect the electronic controls. The Boreas system currently delivers about half the temperature variance of a compressor-driven system, Sills says.

While the cooling system itself is comparatively simple, extra precautions are required because a person can’t breathe the nitrogen-rich air in the trailer. The safety system consists of a fan in the nose of the trailer to vent the gaseous nitrogen when the driver is ready to unload, and a sensor-based “safety bar” on the door of the trailer to prevent anyone from entering the container until the nitrogen has been dispersed. The process takes 5 to 10 minutes and can be achieved in about the time it takes the driver to back into the receiving dock and get the trailer door open, Sills explains.

“We’re one of the first in the heavy-truck industry to have an ISO-certified product that meets the functional safety specification,” he says.

Boreas boasts 40 trailers currently in service, half of which have been in service for two years. The test fleet belongs to a large grocery distributor, and the company is currently working on demonstration arrangements with other fleets.

Promising technology

If nitrogen is such a good solution, why hasn’t it caught on yet with North American fleets?
Ross Froat, manager of engineering and IT for the Technology and Maintenance Council at ATA, wrote about the advantages of using liquid nitrogen to cool trailers a year ago. That TMC Connect blog post was widely read, he notes. And, with a handful of related mentions in the trade press, he anticipated the trend might develop into something substantial.

“It was really cool technology,” says Froat. “It was completely different than an engine mounted on the trailer making all these emissions, all this noise, just to cool what’s inside the box. It costs less and the maintenance on it is so much less than a reefer, so the true cost to own is absolutely less than a conventional reefer.”

But in researching the issue, he discovered that while liquid nitrogen is used in Europe for transportation cooling, he found little interest from the fleets that are active in TMC. Simply, fleets were reluctant to look seriously into the technology because of concerns over acquiring and maintaining a supply of LN2.

“There’s a lot confusion in the air. It’s a new technology. And even with diesel prices and maintenance, [fleets] felt they still come out on top with a conventional reefer,” Froat recalls. “But based on my research, it’s very safe and environmentally friendly.”

“This is something that’s potentially a game-changer that people just don’t know about,” Froat says. “It’s got a lot of potential but not enough hype, I guess. There are a lot of pros and not many cons.”

LN2 infrastructure

So, how would a fleet provide liquid nitrogen for its trucks and trailers equipped with the technology?

Reflect Scientific is working with liquid nitrogen suppliers, and Tait says the price of LN2 “drops tremendously” when purchased in bulk. Typically, a storage tank is leased but total cost still comes in well below diesel.

“What we’re aiming for is a hub-and-spoke distribution for day trips,” Tait says, and he notes that a large grocery distributor typically would have liquid nitrogen on site for other cooling needs. “All we’re doing is utilizing what’s there and adding a fueling facility.”

And while the Cryometrix unit is capable of doing long-haul, Tait doesn’t anticipate the infrastructure will develop immediately.

Similarly, the Boreas system—with an onboard supply that could last about two-and-one-half days—can feasibly cool a cross-country trip, but nitrogen would need to be available for a return run. Because the nitrogen must be vented at each delivery, the longer, uninterrupted runs make the most sense for a direct cooling system.

Both the Cryometrix and Boreas systems are refueled directly, versus swapping out tanks, and the refueling can be handled by a driver with basic nitrogen handling training. Tait explains the only real difference in fueling is the temperature of liquid nitrogen. Gloves and goggles are required.
“It’s just like filling up with diesel—it’s a liquid that just happens to be very cold,” Tait says.

Options range from portable systems, such as trailered nitrogen tanks, that would be brought in as needed by a gas supplier to permanent on-site storage and fill stations.

Cryometrix will be marketed to medium and large fleets, Tait notes, mainly because of that additional infrastructure as well as the maintenance savings. Similarly, the company is working with the LN2 suppliers and large fleets to generate interest in demonstration units.

For Boreas, which made its industry debut at NPTC earlier this year, the primary initial interest has been around the fuel savings, the associated environmental benefits, and preservation control.  
“It really just depends on the fleet size and what makes sense,” Sills says.

“You have to have a fleet mentality,” adds TMC’s Froat. “You have to fill up at the terminal and make sure it comes back before it runs out.”

New EPA rules mandate changes in reefer cooling, insulation compounds

An advanced degree in chemistry might not be required to understand the Environmental Protection Agency’s latest push to protect the ozone layer and combat global warming, but it certainly helps. The layman’s takeaway for trucking is that key compounds used in refrigerated transport cooling systems and insulation are scheduled to be banned, and the likely replacements are either more expensive, less effective or both.

EPA last month published a final rule specifying the details of its updated Significant New Alternatives Policy (SNAP), a program that is designed to evaluate and regulate substitutes for chemicals that are being phased out under the Clean Air Act .

While the first two rounds of SNAP focused on ozone depletion, the third iteration takes aim at climate change and targets emissions of hydrofluorocarbons (HFCs), explains Robert York, strategic marketing manager for Dow Polyurethanes.

Among other changes, the SNAP plan calls for the elimination of the use of specific HFC “blowing agents,” which refrigerated trailer manufacturers use in polyurethane insulation.

The current blowing agents—the chemical compounds that put the “bubbles” in the foam, specifically HFC 134a and 245fa—that are scheduled to be eliminated do indeed have substantially higher potential negative impact rates on release to the atmosphere than carbon dioxide, York adds.

However, he also points out that the percentage of total greenhouse gas emissions is miniscule.
The good news for trucking is that there are “quite a few options,” though each has “strengths and weaknesses,” York notes. Hydrofluoroolefin (HFO) compounds can deliver even better insulation at the same thickness as current formulations but will be much more expensive. Hydrocarbon (HC) compounds are less expensive but also have less insulating value, meaning additional thickness and weight.

York adds that a refrigerated trailer currently comes with about 1,000 lbs. of foam insulation. He also emphasizes that any simple explanation of the chemistry involved “has lots of caveats.”
“It’s not nearly as black and white as I might make it sound. There’s a lot of chemistry that will make HCs perform a little bit better, or you can try to cheapen an HFO formulation,” he says. “It’s really complex science at the heart of formulating these foams for trailers.”

For these HFCs and the application, EPA’s proposed rule set Jan. 1, 2017, as the date the prohibition would take effect. Dow and others in the more than 7,500 comments submitted argued that a Jan. 1, 2020, timeframe would be more realistic. A delay would give the industry enough time to come up with the best formulations, to build trial trailers and put some miles on them, and to make any adjustments needed before going into full production, York explains.

Utility Trailer Manufacturing, the country’s largest producer of reefer freight trailers at more than 20,000 a year, also argued that the 2017 date was not feasible. In its comment, filed last summer, Utility said its foam supplier had only recently provided a new compound for evaluation. The foam was unacceptable in a number of areas and “did not meet the required minimums to demonstrate long-term stability.” Tests were underway on a more expensive formulation, the company noted, but early results again showed problems.

And EPA listened, opting for the 2020 implementation.

Thermo King aims to further cut GHG emissions

As new guidelines on global warming and greenhouse gas emissions emerge, Thermo King is trying to help fleets cut their emissions footprint. The company has tapped into a technology it has been using in Europe for several months in a new generation of trailer and self-powered refrigeration units.

The units with lower global warming potential (GWP) are pending approval by the U.S. Environmental Protection Agency under the Significant New Alternatives Policy program, the company said.
“Our intent has always been to offer operators the choice of how and when to lower their GHG footprint without compromising the product performance they expect from Thermo King,” Ray Pittard, president, said. “We made this new line of trailer and self-powered truck units available to customers in Europe, the Middle East and Africa earlier this year and have sold more than 500 units in the first three months of the product’s release. We are delighted to offer North American customers the same choices.”

According to Thermo King, the new products are safe, energy-efficient and reliable.
The company is using a next-generation refrigerant that cuts GWP in half compared to refrigerants that are currently being used today for these applications.

Thermo King is using refrigerant manufacturer Chemours’ Opteon XP44 (R-452A) product.
The company said it will continue to offer its current products and ensure that optimum levels of service are offered throughout the products’ lifecycle until customers are ready to transition.

About the Author

Kevin Jones 1 | Editor

Kevin Jones has an odd fascination with the supply chain. As editor of American Trucker, he focuses on the critical role owner-ops and small fleets play in the economy, locally and globally. And he likes big trucks.

Sponsored Recommendations

Stop Sweating Temperature Excursions

Advanced chemical indicators give you the peace of mind that comes from reliable insights into your supply chains. Compromised shipments can be identified the moment they arrive...

How Electric Vehicles Help You Prolong the Life of Your Fleet

Before adopting electric vehicles for commercial/government fleets, prioritize cost inquiries. Maintenance is essential; understand the upkeep of EV fleets. Here’s what you need...

How to Choose the Right Route Planning Solution

This free buyer's guide will help equip you with the knowledge and insights needed to analyze route planning software and vendors in the market and, ultimately, make an informed...

How to Put Your Trucking Data to Work

How fleets can overcome data overload to optimize operations and get ahead.

Voice your opinion!

To join the conversation, and become an exclusive member of FleetOwner, create an account today!