So what can you do with natural refrigerants and where can you do it? That formed the basis of case studies presented at the second Atmosphere America Natural Refrigerants Conference in Washington, D.C.
The summer event came amidst a tightening regulatory landscape especially in Europe with regards to the familiar f-gas synthetic refrigerants. But for this conference, the current drive for naturals comes, first, in showing that they can work in refrigeration applications most commonly cooled by f-gases such as HCFCs and HFCs; and, second, that the natural option can be less costly.
It was in those contexts that many case histories were offered.
Retrofitting R-22 Systems
The idea of retrofitting an existing R-22 refrigeration system with CO2 in a large supermarket was the topic of Marc-André Lesmerises, CEO of Carnot Refrigeration.
“For several supermarket chains around the world, the decision of using transcritical CO2 refrigeration systems in their new stores was done in the past and they are now enjoying the benefits of this decision,” he said. “But the retrofit of existing sites is a more challenging decision.”
He said such a retrofit is not easy, especially while the store is open and refrigerated equipment needs to continue to operate. But, is it energy wise? He answered, “Yes, as cost will depend on the planning with the operation team and how many phases. An engineered solution will have a huge impact on the cost and the skill of the labor is key.”
CO2 Supermarket System
A case study of a supermarket using CO2 was presented by Jeff Newel, director of research and development, systems division, Hillphonenix.
“The project illustrated one of the ways to use CO2 in a supermarket to reduce the synthetic refrigerant charge and lower the systems overall equivalent CO2 emissions.”
The store, located in Thousand Oaks, Calif., used a medium-temperature CO2 secondary system with fully flooded coils for efficient heat transfer and a low-temperature cascade system with a smartvalve system for EEV control.
Using a carbon dioxide heat pump was the topic of a field study done by Merle Rocke, founder, CEO, and chairman of EcoThermics Corp. He described the use of the technology at a U.S. bakery. The approach was to use a dedicated CO2 heat recovery heat pump granting hot water for sanitation and supplemental a/c and dehumidification serving plant production areas. The project demonstrated, according to the presentation, capability for simultaneous water heating and space conditioning with a CO2 heat pump.
A presentation from Vicente Guilabert, R&D and technology director, Huayi Compressors, focused on using propane (R-290) as an alternative to HFC-404a in light commercial refrigeration in North America.
Among points he made: “R-290 is one of the most environment-friendly alternatives. It has EPA SNAP [Environmental Protection Agency Significant New Alternatives Program] approval. It is applied in some of the most efficient appliances produced in Europe with very positive results. R-290 systems do not require significant changes versus current HFCs and versus other ecological alternatives (such as CO2). It has reasonable working pressures and allows the use of lower-displacement compressors versus HFC-134a and HFO-1234yf to get equivalent cooling capacity.”
He did note that a “weak point of R-290 is the SNAP approval limitation of 150-gram charge per circuit. This restriction is under discussion to extend the maximum charge.”
Using hydrocarbons (HCs) in a bottle-cooler application was the topic of Sidnei Oliveira, CAE global manager, Tecumseh Products Co. The project involved converting the unit from HFC-134a to R-290 (propane). He said, “A significant reduction of 22 percent of system energy consumption was achieved using R-290. This is an example of green solutions improving system performance.” He further noted that the conversion stayed within the EPA SNAP approval limit of 150 grams.
Conquering HC Barriers
Douglas Schmidt, North American sales manager, commercial products, Embraco North America, led a presentation focused on conquering the barriers of HC technology.” Schmidt put his presentation in the context of a sense of urgency. “World climate changes mean urgent actions are mandatory, yet the international community is still far from a global agreement about emission reduction. There are good intentions but not any specific actions for f-gas regulations.”
Meanwhile, some of the technology barriers for HCs involve training, which he said is improving the initial investment which may require governmental incentives, and the current EPA SNAP 150-gram limit. He cited chest freezers, vertical freezers, ice machines, and glass door merchandisers.
“We have achieved some great progress so far, but more action is required to move the market. With 150-gram propane charges, it is possible to cover most unitary, plug-in applications. The two circuit solution can provide additional gains in terms of cabinet efficiency.”
This article is the first in a two-part series reviewing case histories presented at the second Atmosphere America Natural Refrigerants conference. Additional papers will be highlighted in the Sept. 2 Refrigeration Zone of The NEWS. For additional information on the presented case histories, visit www.atmo.org.
Publication date: 8/5/2013