NATURALS EXPAND TO MEET COMMERCIAL DEMAND

As hedrofluorocarbons and hydrochlorofluorocarbons are being increasingly phased out to meet government and regulatory requirements, natural refrigerants are candidates to fill the void, getting a closer look from many types of businesses installing smaller refrigeration systems, such as supermarkets and convenience stores.

However, natural refrigerants do face challenges. Not only are there pros and cons for each natural refrigerant, but there are also regulatory gaps that stand in the way of some systems and not many technicians are trained to work with natural refrigerants.

Natural refrigerants — ammonia, propane, butane and CO2 — were all among the original refrigerants used at the genesis of the mechanical refrigeration industry, but they fell out of favor in the 1930s as synthetic refrigerants were introduced, said William Greulich, principal at Kensington Consulting.

Vincent Grass, global refrigeration leader, corporate operations, engineering services, Nestlé Ltd., said, “Natural refrigerants, including CO2 , ammonia, water and air and hydrocarbons, such as propane and iso-butane, do not harm the ozone layer and have negligible or no global warming effects. They occur in nature’s biochemical processes and have been used since the 19th century and are not subject to phase-out controls.”

Now that HFCs and HCFCs are being phased out, Grass said moving straight to safe and efficient natural refrigerant solutions wherever legally feasible has been seen as being the most sustainable and responsible alternative for Nestlé in the long term.

Meanwhile, codes, in some areas, are lagging behind.

“Code has been written more or less around the unnatural refrigerants … use of natural refrigerants in large industrial systems has always been possible with the existing code, but there have been certain issues no one wanted to tackle with smaller systems because the other refrigerants were easier. You had boundaries and had to make the facility robust from a safety standpoint.”

William Greulich, principal at Kensington Consulting

“Code has been written more or less around the [synthetic] refrigerants,” Greulich said. He added that use of natural refrigerants in large industrial systems has always been possible with the existing code, but there have been certain issues no one wanted to tackle with smaller systems because the other refrigerants were easier and considered safer. “You had boundaries and had to make the facility robust from a safety standpoint.”

Bob Port, director of technical services, supply chain engineering, with ConAgra Foods, said the gaps in codes and standards make it more difficult than necessary to install and design hydrocarbon and ammonia systems. “There are a lot of legal roadblocks which have to be worked through,” Port said.

Greulich said in many cases, regulation has been replaced by “the idea there would be so-called listed pieces of equipment.” Regulators look for equipment that is UL listed and some states, such as Ohio, write directly into code which UL listings are compliant. “The wrinkle is UL doesn’t have a lot of listing standards for small packaged natural refrigerant systems,” Greulich said.

Another challenge in the United States is that a lot of CO2 equipment was developed in Europe, and in order to be used in North America, the products have to be UL approved. “That is very different than European standards. A lot of parts cannot be approved because they don’t meet the UL standards,” said Andre Patenaude, director of CO2 business development for Emerson Climate Technologies.

Greulich said getting equipment UL listed, is a costly and complicated process. “This has created an awkward situation,” he said. “We go to the code official and say, ‘We want to put in this propane chiller.’ The code official says, ‘Great, is there a listing?’”

Patenaude said that could shift as the International Electrotechnical Commission, which the UL follows, alters its testing procedures to be closer to Europe’s. “That is going to make it easier for American companies to adopt European designed products,” he said.

Greulich said everyone is interested in smaller systems and the first one to get through the UL process will have a large market.

CURRENT USES

Natural refrigerants are being used in a number of places, Patenaude said. “Coca-Cola uses CO2 as their refrigerant of choice in their dispensing machines. Unilever uses propane in a lot of their small, spot-contained merchandisers. Propane is also being used in self-contained cases to a gram limit of 150 grams,” he explained.

Meanwhile, there are approximately 52 supermarkets in the U.S. that use CO2 transcritical booster systems, Patenaude said.

Beginning in January 2015, every new horizontal chest freezer Nestlé buys to store ice cream uses natural refrigerants rather than synthetic refrigerants. “These freezers represent 70 percent of Nestlé’s total spend on freezers. They also consume 50 percent less energy than earlier models and are more efficient for customers to run,” Grass said. “New ambitious targets for 2016 and onwards will be communicated in our 2015 Nestlé in Society annual report.”

Port said he is seeing a blurring of the line between what commercial food distributors and industrial food producers are doing. “You’re starting to see commercial guys employ things that are more industrial. In the commercial world, they’re looking to use more CO2 and secondary refrigerant applications and limit their charge,” Port said.

Ammonia has been used for decades as a refrigerant, but has been relegated to large systems in food processing plants and warehouses. “It has been a specialty refrigerant on the jumbo end of the scale,” Port said, adding that years ago, if he were looking at installing a big freezer, he would have gone down the ammonia path. “The ability to do anything else didn’t exist ten years ago. Now I have the technology available in CO2 , and the CO2 is much more efficient for the low temperature applications.”

For more than five years, Nestlé has installed refrigeration systems using hydrocarbons and CO2 for various cooling applications in factories, small distribution centers, research and development centers, office, Nestlé shops and data centers, Grass said.

Port said the industry is still working to figure out low-charge ammonia systems. “We’re finding out they’re more limited and less flexible in a lot of places than we want,” he said. He added that he plans to employ some of these types of systems as he replaces medium sized halocarbon (R-22), refrigeration systems in ConAgra’s plants.

“I have a lot and it presents a challenge to replace some of those smaller systems. Trying to do it with an industrial ammonia system is not cost effective,” Port said. “In small systems the cost to operate doesn’t necessarily add up to significant amounts of dollars. In the bigger systems I deal with, it’s a no brainer because of the complex system demands and operating cost, it’s a much bigger animal.”

“The biggest drawback for CO2 is in warm ambiance — it is that the basic system is less efficient than a traditional HFC system …There is a tremendous amount of research and development going on right now to make those systems more efficient in warm ambient temperatures.”

Andre Patenaude, director of CO2 business development for Emerson Climate Technologies

NAVIGATING THE PROS AND CONS OF NATURAL REFRIGERANTS

All natural refrigerants face certain limitations and have their pros and cons. For example, CO2 has zero ozone depletion and a global warming potential of one, which is extremely low when compared to the HFC R-404A that has a global warming potential of 3,922. However, CO2 operates at higher pressures. “Instead of operating at a high pressure of 250 pounds, you could be operating at 1,500 pounds. That is very different,” Patenaude said.

The critical point of CO2 — the highest pressure and temperature where the refrigerant can still condense — is very low relative to other refrigerants and the triple point — the pressure at which CO2 turns to dry ice. And that can be a challenge. “If someone makes a mistake and allows the pressure to drop to 61 pounds, the CO2 turns to dry ice and locks up. The only thing they can do is wait for the ice to sublime, or go to vapor. That is critical from a service and design point of view,” he said.

“The biggest drawback for CO2 is in warm ambiance – it is that the basic system is less efficient than a traditional HFC system,” Patenaude said. “There is a tremendous amount of research and development going on right now to make those systems more efficient in warm ambient temperatures.”

“The biggest challenge facing the CO2 refrigeration industry is improving efficiency in warm ambient operation, Patenaude said. “There is a tremendous amount of research and development going on right now to make those systems more efficient in warm ambients.

Patenaude said CO2 systems are loaded with electronics to optimize performance relative the HFC systems.

Port said a benefit of CO2 is that it is a much denser refrigerant than ammonia. “The vessel sizes, pipe sizes and coil sizes get smaller and the horsepower per ton to run CO2 in these lower ranges is much better than with ammonia,” Port said. “If I had the opportunity to go build a new frozen food plant today, I would go CO2 -ammonia cascade.”

In large cascade systems, ammonia is generally used as the primary refrigerant chiller, cooling the CO2 , Patenaude explained. “Generally supermarkets won’t use ammonia because of safety concerns, however they are trying to find inventive ways of taking advantage of both ammonia and CO2 . There are a few stores in the US that have small ammonia chiller / CO2 cascade system on the roof. They chill the CO2 and send it into the store,” he explained.

Mark Stencel, IIAR chair-elect and director of strategic accounts at Bassett Mechanical, said there is a growing breadth of applications that are using two-refrigerant systems, combining ammonia with another refrigerant.

When it comes to propane, the challenge is flammability, but the benefit is that it is very close to R-22, and can work with the similar components. “Going to propane is very close to HCFC/ HFC, from and applied costs point of view, Patenaude said, adding that modifications / product certifications have to be made due to its flammability.

When it comes to natural refrigerants, Port said companies want to ensure that they’ll have qualified technicians to work on equipment that uses them. “If I deploy a refrigerant, do we have the people, the knowledge base and the skill sets out there to work on it and take care of it? I think that is a bigger challenge,” Port said.

Another challenge is that while newer systems are becoming more complex, fewer technicians are entering the field, Patenaude explained. “From an electronics point of view, our industry is trying to figure out how to dumb-down something that is becoming a lot more complex,” Patenaude said.